Severe Storms

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1136 AM CDT Wed Aug 28 2024 Valid 281630Z - 291200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTH DAKOTA/SOUTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDWEST/OHIO VALLEY TO MID-ATLANTIC... ...SUMMARY... Severe thunderstorms are expected across parts of the Dakotas and from the Ohio Valley to the Mid-Atlantic Coast. ...Dakotas... Have upgraded portions of south-central North Dakota/north-central South Dakota to a categorical Enhanced Risk for what should be a relatively greater likelihood and concentration of severe storms late this afternoon through early/mid-evening. A prominent upper-level trough centered over western Montana and southern Alberta will continue generally eastward over the Canadian Prairies and toward the northern High Plains, with a trough-preceding/basal upper-level jet resulting in considerably strengthening southwesterly winds aloft by peak heating into tonight. This will be atop an increasingly moist boundary layer (dewpoints increasing through the 60s F) ahead of a surface low across South Dakota and a front extending northward into North Dakota. Thunderstorms should develop near the front by late afternoon/early evening, perhaps initially across North Dakota where overall forcing will be greater, and subsequently southward into South Dakota where richer low-level moisture and greater buoyancy will reside. Given steep lapse rates and the reservoir of instability, these initial storms should be supercells capable of very large hail amidst strengthening flow aloft. Large to very large hail and severe wind gusts will be the most common hazards, although a tornado risk may also exist particularly across north-central South Dakota/far south-central North Dakota near the surface low/warm front-related triple point where moisture/low-level SRH will be maximized. Over time, relatively weak mid-level flow may encourage a transition to messier, quasi-linear modes with embedded LEWP/bow formations for a few hours. Activity should weaken overnight as it moves into stabilizing boundary-layer air, though a 45-55-kt low-level jet may encourage persistence of a cluster or two tonight into the eastern Dakotas. ...Midwest/Ohio Valley to Mid-Atlantic States... Widely scattered to scattered thunderstorms will pose a risk for damaging winds particularly mid/late afternoon through early/mid-evening regionally. Some hail may also occur on a more marginal and isolated basis. This severe risk will primarily span parts of Indiana/Ohio eastward to the coastal Mid-Atlantic/Delmarva vicinity, although the overall extent and magnitude of today's risk is still a bit uncertain. The boundary layer will not be overly moist by late-summer standards, particularly across the middle Ohio River Valley, but a relatively richer moist axis (through the lowest 2-3 km AGL) extends this morning from the upper Ohio Valley eastward toward the coastal Mid-Atlantic/Northeast. The boundary layer will also not be overly unstable later today, with severe-adequate MLCAPE generally limited to 2000 J/kg MLCAPE. Aside from differential heating related to last night's convection across the Midwest, several impetuses for thunderstorm development to the south of the primary Great Lakes front may include the eastward transitions of MCVs across southeast Lower Michigan and north-central Illinois, which should be influential into the Lake Ontario/New York/northern Pennsylvania and lower/middle Ohio Valley vicinities, respectively, later this afternoon and evening. Effective shear will tend to be limited to 20-25 kt, but slowly-increasing-with-height deep-layer westerlies will support multicell-related damaging wind/some hail potential as low-level lapse rates steepen and the boundary layer moderately destabilizes this afternoon. ..Guyer/Wendt.. 08/28/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1136 AM CDT Wed Aug 28 2024 Valid 281630Z - 291200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTH DAKOTA/SOUTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDWEST/OHIO VALLEY TO MID-ATLANTIC... ...SUMMARY... Severe thunderstorms are expected across parts of the Dakotas and from the Ohio Valley to the Mid-Atlantic Coast. ...Dakotas... Have upgraded portions of south-central North Dakota/north-central South Dakota to a categorical Enhanced Risk for what should be a relatively greater likelihood and concentration of severe storms late this afternoon through early/mid-evening. A prominent upper-level trough centered over western Montana and southern Alberta will continue generally eastward over the Canadian Prairies and toward the northern High Plains, with a trough-preceding/basal upper-level jet resulting in considerably strengthening southwesterly winds aloft by peak heating into tonight. This will be atop an increasingly moist boundary layer (dewpoints increasing through the 60s F) ahead of a surface low across South Dakota and a front extending northward into North Dakota. Thunderstorms should develop near the front by late afternoon/early evening, perhaps initially across North Dakota where overall forcing will be greater, and subsequently southward into South Dakota where richer low-level moisture and greater buoyancy will reside. Given steep lapse rates and the reservoir of instability, these initial storms should be supercells capable of very large hail amidst strengthening flow aloft. Large to very large hail and severe wind gusts will be the most common hazards, although a tornado risk may also exist particularly across north-central South Dakota/far south-central North Dakota near the surface low/warm front-related triple point where moisture/low-level SRH will be maximized. Over time, relatively weak mid-level flow may encourage a transition to messier, quasi-linear modes with embedded LEWP/bow formations for a few hours. Activity should weaken overnight as it moves into stabilizing boundary-layer air, though a 45-55-kt low-level jet may encourage persistence of a cluster or two tonight into the eastern Dakotas. ...Midwest/Ohio Valley to Mid-Atlantic States... Widely scattered to scattered thunderstorms will pose a risk for damaging winds particularly mid/late afternoon through early/mid-evening regionally. Some hail may also occur on a more marginal and isolated basis. This severe risk will primarily span parts of Indiana/Ohio eastward to the coastal Mid-Atlantic/Delmarva vicinity, although the overall extent and magnitude of today's risk is still a bit uncertain. The boundary layer will not be overly moist by late-summer standards, particularly across the middle Ohio River Valley, but a relatively richer moist axis (through the lowest 2-3 km AGL) extends this morning from the upper Ohio Valley eastward toward the coastal Mid-Atlantic/Northeast. The boundary layer will also not be overly unstable later today, with severe-adequate MLCAPE generally limited to 2000 J/kg MLCAPE. Aside from differential heating related to last night's convection across the Midwest, several impetuses for thunderstorm development to the south of the primary Great Lakes front may include the eastward transitions of MCVs across southeast Lower Michigan and north-central Illinois, which should be influential into the Lake Ontario/New York/northern Pennsylvania and lower/middle Ohio Valley vicinities, respectively, later this afternoon and evening. Effective shear will tend to be limited to 20-25 kt, but slowly-increasing-with-height deep-layer westerlies will support multicell-related damaging wind/some hail potential as low-level lapse rates steepen and the boundary layer moderately destabilizes this afternoon. ..Guyer/Wendt.. 08/28/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1136 AM CDT Wed Aug 28 2024 Valid 281630Z - 291200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTH DAKOTA/SOUTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDWEST/OHIO VALLEY TO MID-ATLANTIC... ...SUMMARY... Severe thunderstorms are expected across parts of the Dakotas and from the Ohio Valley to the Mid-Atlantic Coast. ...Dakotas... Have upgraded portions of south-central North Dakota/north-central South Dakota to a categorical Enhanced Risk for what should be a relatively greater likelihood and concentration of severe storms late this afternoon through early/mid-evening. A prominent upper-level trough centered over western Montana and southern Alberta will continue generally eastward over the Canadian Prairies and toward the northern High Plains, with a trough-preceding/basal upper-level jet resulting in considerably strengthening southwesterly winds aloft by peak heating into tonight. This will be atop an increasingly moist boundary layer (dewpoints increasing through the 60s F) ahead of a surface low across South Dakota and a front extending northward into North Dakota. Thunderstorms should develop near the front by late afternoon/early evening, perhaps initially across North Dakota where overall forcing will be greater, and subsequently southward into South Dakota where richer low-level moisture and greater buoyancy will reside. Given steep lapse rates and the reservoir of instability, these initial storms should be supercells capable of very large hail amidst strengthening flow aloft. Large to very large hail and severe wind gusts will be the most common hazards, although a tornado risk may also exist particularly across north-central South Dakota/far south-central North Dakota near the surface low/warm front-related triple point where moisture/low-level SRH will be maximized. Over time, relatively weak mid-level flow may encourage a transition to messier, quasi-linear modes with embedded LEWP/bow formations for a few hours. Activity should weaken overnight as it moves into stabilizing boundary-layer air, though a 45-55-kt low-level jet may encourage persistence of a cluster or two tonight into the eastern Dakotas. ...Midwest/Ohio Valley to Mid-Atlantic States... Widely scattered to scattered thunderstorms will pose a risk for damaging winds particularly mid/late afternoon through early/mid-evening regionally. Some hail may also occur on a more marginal and isolated basis. This severe risk will primarily span parts of Indiana/Ohio eastward to the coastal Mid-Atlantic/Delmarva vicinity, although the overall extent and magnitude of today's risk is still a bit uncertain. The boundary layer will not be overly moist by late-summer standards, particularly across the middle Ohio River Valley, but a relatively richer moist axis (through the lowest 2-3 km AGL) extends this morning from the upper Ohio Valley eastward toward the coastal Mid-Atlantic/Northeast. The boundary layer will also not be overly unstable later today, with severe-adequate MLCAPE generally limited to 2000 J/kg MLCAPE. Aside from differential heating related to last night's convection across the Midwest, several impetuses for thunderstorm development to the south of the primary Great Lakes front may include the eastward transitions of MCVs across southeast Lower Michigan and north-central Illinois, which should be influential into the Lake Ontario/New York/northern Pennsylvania and lower/middle Ohio Valley vicinities, respectively, later this afternoon and evening. Effective shear will tend to be limited to 20-25 kt, but slowly-increasing-with-height deep-layer westerlies will support multicell-related damaging wind/some hail potential as low-level lapse rates steepen and the boundary layer moderately destabilizes this afternoon. ..Guyer/Wendt.. 08/28/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1136 AM CDT Wed Aug 28 2024 Valid 281630Z - 291200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTH DAKOTA/SOUTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDWEST/OHIO VALLEY TO MID-ATLANTIC... ...SUMMARY... Severe thunderstorms are expected across parts of the Dakotas and from the Ohio Valley to the Mid-Atlantic Coast. ...Dakotas... Have upgraded portions of south-central North Dakota/north-central South Dakota to a categorical Enhanced Risk for what should be a relatively greater likelihood and concentration of severe storms late this afternoon through early/mid-evening. A prominent upper-level trough centered over western Montana and southern Alberta will continue generally eastward over the Canadian Prairies and toward the northern High Plains, with a trough-preceding/basal upper-level jet resulting in considerably strengthening southwesterly winds aloft by peak heating into tonight. This will be atop an increasingly moist boundary layer (dewpoints increasing through the 60s F) ahead of a surface low across South Dakota and a front extending northward into North Dakota. Thunderstorms should develop near the front by late afternoon/early evening, perhaps initially across North Dakota where overall forcing will be greater, and subsequently southward into South Dakota where richer low-level moisture and greater buoyancy will reside. Given steep lapse rates and the reservoir of instability, these initial storms should be supercells capable of very large hail amidst strengthening flow aloft. Large to very large hail and severe wind gusts will be the most common hazards, although a tornado risk may also exist particularly across north-central South Dakota/far south-central North Dakota near the surface low/warm front-related triple point where moisture/low-level SRH will be maximized. Over time, relatively weak mid-level flow may encourage a transition to messier, quasi-linear modes with embedded LEWP/bow formations for a few hours. Activity should weaken overnight as it moves into stabilizing boundary-layer air, though a 45-55-kt low-level jet may encourage persistence of a cluster or two tonight into the eastern Dakotas. ...Midwest/Ohio Valley to Mid-Atlantic States... Widely scattered to scattered thunderstorms will pose a risk for damaging winds particularly mid/late afternoon through early/mid-evening regionally. Some hail may also occur on a more marginal and isolated basis. This severe risk will primarily span parts of Indiana/Ohio eastward to the coastal Mid-Atlantic/Delmarva vicinity, although the overall extent and magnitude of today's risk is still a bit uncertain. The boundary layer will not be overly moist by late-summer standards, particularly across the middle Ohio River Valley, but a relatively richer moist axis (through the lowest 2-3 km AGL) extends this morning from the upper Ohio Valley eastward toward the coastal Mid-Atlantic/Northeast. The boundary layer will also not be overly unstable later today, with severe-adequate MLCAPE generally limited to 2000 J/kg MLCAPE. Aside from differential heating related to last night's convection across the Midwest, several impetuses for thunderstorm development to the south of the primary Great Lakes front may include the eastward transitions of MCVs across southeast Lower Michigan and north-central Illinois, which should be influential into the Lake Ontario/New York/northern Pennsylvania and lower/middle Ohio Valley vicinities, respectively, later this afternoon and evening. Effective shear will tend to be limited to 20-25 kt, but slowly-increasing-with-height deep-layer westerlies will support multicell-related damaging wind/some hail potential as low-level lapse rates steepen and the boundary layer moderately destabilizes this afternoon. ..Guyer/Wendt.. 08/28/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1136 AM CDT Wed Aug 28 2024 Valid 281630Z - 291200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTH DAKOTA/SOUTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDWEST/OHIO VALLEY TO MID-ATLANTIC... ...SUMMARY... Severe thunderstorms are expected across parts of the Dakotas and from the Ohio Valley to the Mid-Atlantic Coast. ...Dakotas... Have upgraded portions of south-central North Dakota/north-central South Dakota to a categorical Enhanced Risk for what should be a relatively greater likelihood and concentration of severe storms late this afternoon through early/mid-evening. A prominent upper-level trough centered over western Montana and southern Alberta will continue generally eastward over the Canadian Prairies and toward the northern High Plains, with a trough-preceding/basal upper-level jet resulting in considerably strengthening southwesterly winds aloft by peak heating into tonight. This will be atop an increasingly moist boundary layer (dewpoints increasing through the 60s F) ahead of a surface low across South Dakota and a front extending northward into North Dakota. Thunderstorms should develop near the front by late afternoon/early evening, perhaps initially across North Dakota where overall forcing will be greater, and subsequently southward into South Dakota where richer low-level moisture and greater buoyancy will reside. Given steep lapse rates and the reservoir of instability, these initial storms should be supercells capable of very large hail amidst strengthening flow aloft. Large to very large hail and severe wind gusts will be the most common hazards, although a tornado risk may also exist particularly across north-central South Dakota/far south-central North Dakota near the surface low/warm front-related triple point where moisture/low-level SRH will be maximized. Over time, relatively weak mid-level flow may encourage a transition to messier, quasi-linear modes with embedded LEWP/bow formations for a few hours. Activity should weaken overnight as it moves into stabilizing boundary-layer air, though a 45-55-kt low-level jet may encourage persistence of a cluster or two tonight into the eastern Dakotas. ...Midwest/Ohio Valley to Mid-Atlantic States... Widely scattered to scattered thunderstorms will pose a risk for damaging winds particularly mid/late afternoon through early/mid-evening regionally. Some hail may also occur on a more marginal and isolated basis. This severe risk will primarily span parts of Indiana/Ohio eastward to the coastal Mid-Atlantic/Delmarva vicinity, although the overall extent and magnitude of today's risk is still a bit uncertain. The boundary layer will not be overly moist by late-summer standards, particularly across the middle Ohio River Valley, but a relatively richer moist axis (through the lowest 2-3 km AGL) extends this morning from the upper Ohio Valley eastward toward the coastal Mid-Atlantic/Northeast. The boundary layer will also not be overly unstable later today, with severe-adequate MLCAPE generally limited to 2000 J/kg MLCAPE. Aside from differential heating related to last night's convection across the Midwest, several impetuses for thunderstorm development to the south of the primary Great Lakes front may include the eastward transitions of MCVs across southeast Lower Michigan and north-central Illinois, which should be influential into the Lake Ontario/New York/northern Pennsylvania and lower/middle Ohio Valley vicinities, respectively, later this afternoon and evening. Effective shear will tend to be limited to 20-25 kt, but slowly-increasing-with-height deep-layer westerlies will support multicell-related damaging wind/some hail potential as low-level lapse rates steepen and the boundary layer moderately destabilizes this afternoon. ..Guyer/Wendt.. 08/28/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1136 AM CDT Wed Aug 28 2024 Valid 281630Z - 291200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTH DAKOTA/SOUTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDWEST/OHIO VALLEY TO MID-ATLANTIC... ...SUMMARY... Severe thunderstorms are expected across parts of the Dakotas and from the Ohio Valley to the Mid-Atlantic Coast. ...Dakotas... Have upgraded portions of south-central North Dakota/north-central South Dakota to a categorical Enhanced Risk for what should be a relatively greater likelihood and concentration of severe storms late this afternoon through early/mid-evening. A prominent upper-level trough centered over western Montana and southern Alberta will continue generally eastward over the Canadian Prairies and toward the northern High Plains, with a trough-preceding/basal upper-level jet resulting in considerably strengthening southwesterly winds aloft by peak heating into tonight. This will be atop an increasingly moist boundary layer (dewpoints increasing through the 60s F) ahead of a surface low across South Dakota and a front extending northward into North Dakota. Thunderstorms should develop near the front by late afternoon/early evening, perhaps initially across North Dakota where overall forcing will be greater, and subsequently southward into South Dakota where richer low-level moisture and greater buoyancy will reside. Given steep lapse rates and the reservoir of instability, these initial storms should be supercells capable of very large hail amidst strengthening flow aloft. Large to very large hail and severe wind gusts will be the most common hazards, although a tornado risk may also exist particularly across north-central South Dakota/far south-central North Dakota near the surface low/warm front-related triple point where moisture/low-level SRH will be maximized. Over time, relatively weak mid-level flow may encourage a transition to messier, quasi-linear modes with embedded LEWP/bow formations for a few hours. Activity should weaken overnight as it moves into stabilizing boundary-layer air, though a 45-55-kt low-level jet may encourage persistence of a cluster or two tonight into the eastern Dakotas. ...Midwest/Ohio Valley to Mid-Atlantic States... Widely scattered to scattered thunderstorms will pose a risk for damaging winds particularly mid/late afternoon through early/mid-evening regionally. Some hail may also occur on a more marginal and isolated basis. This severe risk will primarily span parts of Indiana/Ohio eastward to the coastal Mid-Atlantic/Delmarva vicinity, although the overall extent and magnitude of today's risk is still a bit uncertain. The boundary layer will not be overly moist by late-summer standards, particularly across the middle Ohio River Valley, but a relatively richer moist axis (through the lowest 2-3 km AGL) extends this morning from the upper Ohio Valley eastward toward the coastal Mid-Atlantic/Northeast. The boundary layer will also not be overly unstable later today, with severe-adequate MLCAPE generally limited to 2000 J/kg MLCAPE. Aside from differential heating related to last night's convection across the Midwest, several impetuses for thunderstorm development to the south of the primary Great Lakes front may include the eastward transitions of MCVs across southeast Lower Michigan and north-central Illinois, which should be influential into the Lake Ontario/New York/northern Pennsylvania and lower/middle Ohio Valley vicinities, respectively, later this afternoon and evening. Effective shear will tend to be limited to 20-25 kt, but slowly-increasing-with-height deep-layer westerlies will support multicell-related damaging wind/some hail potential as low-level lapse rates steepen and the boundary layer moderately destabilizes this afternoon. ..Guyer/Wendt.. 08/28/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1136 AM CDT Wed Aug 28 2024 Valid 281630Z - 291200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTH DAKOTA/SOUTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDWEST/OHIO VALLEY TO MID-ATLANTIC... ...SUMMARY... Severe thunderstorms are expected across parts of the Dakotas and from the Ohio Valley to the Mid-Atlantic Coast. ...Dakotas... Have upgraded portions of south-central North Dakota/north-central South Dakota to a categorical Enhanced Risk for what should be a relatively greater likelihood and concentration of severe storms late this afternoon through early/mid-evening. A prominent upper-level trough centered over western Montana and southern Alberta will continue generally eastward over the Canadian Prairies and toward the northern High Plains, with a trough-preceding/basal upper-level jet resulting in considerably strengthening southwesterly winds aloft by peak heating into tonight. This will be atop an increasingly moist boundary layer (dewpoints increasing through the 60s F) ahead of a surface low across South Dakota and a front extending northward into North Dakota. Thunderstorms should develop near the front by late afternoon/early evening, perhaps initially across North Dakota where overall forcing will be greater, and subsequently southward into South Dakota where richer low-level moisture and greater buoyancy will reside. Given steep lapse rates and the reservoir of instability, these initial storms should be supercells capable of very large hail amidst strengthening flow aloft. Large to very large hail and severe wind gusts will be the most common hazards, although a tornado risk may also exist particularly across north-central South Dakota/far south-central North Dakota near the surface low/warm front-related triple point where moisture/low-level SRH will be maximized. Over time, relatively weak mid-level flow may encourage a transition to messier, quasi-linear modes with embedded LEWP/bow formations for a few hours. Activity should weaken overnight as it moves into stabilizing boundary-layer air, though a 45-55-kt low-level jet may encourage persistence of a cluster or two tonight into the eastern Dakotas. ...Midwest/Ohio Valley to Mid-Atlantic States... Widely scattered to scattered thunderstorms will pose a risk for damaging winds particularly mid/late afternoon through early/mid-evening regionally. Some hail may also occur on a more marginal and isolated basis. This severe risk will primarily span parts of Indiana/Ohio eastward to the coastal Mid-Atlantic/Delmarva vicinity, although the overall extent and magnitude of today's risk is still a bit uncertain. The boundary layer will not be overly moist by late-summer standards, particularly across the middle Ohio River Valley, but a relatively richer moist axis (through the lowest 2-3 km AGL) extends this morning from the upper Ohio Valley eastward toward the coastal Mid-Atlantic/Northeast. The boundary layer will also not be overly unstable later today, with severe-adequate MLCAPE generally limited to 2000 J/kg MLCAPE. Aside from differential heating related to last night's convection across the Midwest, several impetuses for thunderstorm development to the south of the primary Great Lakes front may include the eastward transitions of MCVs across southeast Lower Michigan and north-central Illinois, which should be influential into the Lake Ontario/New York/northern Pennsylvania and lower/middle Ohio Valley vicinities, respectively, later this afternoon and evening. Effective shear will tend to be limited to 20-25 kt, but slowly-increasing-with-height deep-layer westerlies will support multicell-related damaging wind/some hail potential as low-level lapse rates steepen and the boundary layer moderately destabilizes this afternoon. ..Guyer/Wendt.. 08/28/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Wed Aug 28 2024 Valid 281300Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO VALLEY TO THE NORTHERN MID-ATLANTIC COAST...AND ACROSS PARTS OF NORTH AND SOUTH DAKOTA... ...SUMMARY... Severe thunderstorms are expected from the Ohio Valley to the northern Mid-Atlantic Coast, and across parts of North and South Dakota. ...Synopsis... In mid/upper levels, a progressive northern-stream pattern will prevail through the period, with the main feature being a cyclone now apparent in moisture-channel imagery near the southeastern corner of BC. The associated 500-mb low should move eastward roughly along, or just north of, the international border through the period, with the accompanying trough extending south- southwestward. By 00Z, the low should be near the southwestern corner of SK, with trough to northern UT. By 12Z, the low should reach extreme south-central SK, with trough across central MT to southwestern WY. Downstream, a complex but much lower-amplitude shortwave trough was evident over Lake Superior and adjoining portions of ON and western U.P. of MI. One part of this perturbation should break eastward to the St. Lawrence Valley by the end of the period, while the trailing part drifts eastward over Lake Superior and the U.P. Of perhaps greater direct influence on convective potential, an MCV was apparent in composited radar imagery over southeastern IA. The associated perturbation should move across much of central IL today, reaching western OH by 12Z tomorrow. The 11Z surface analysis showed a cold front from northern ME west- southwestward across Lake Ontario and southern Lower MI, becoming quasistationary for the time being across southern parts of Lake Michigan and WI, to northeastern NE, then a warm front over southwestern SD, to a low over southeastern MT. This front is expected to move southeastward by 00Z to coastal NS, Cape Cod, Long Island, northern parts of MD/WV, and southern parts of OH/IN/IL, becoming a diffuse warm front northwestward over central IA, southwestern MN and central ND. There it will be overtaken by another cold front -- initially analyzed through the low over eastern MT and across northwestern WY. By 00Z, this second, stronger cold front should extend from central ND across central/ southwestern SD to east-central WY. By 12Z, the western cold front should extend from a low over southeastern ND or northeastern SD across south-central SD, western NE and northeastern CO. ...Ohio Valley to Mid-Atlantic... Widely scattered to scattered thunderstorms are expected along and south of the front today from IN to the Mid-Atlantic Coast, and perhaps the southern New England Coast/Long Island vicinity. Damaging gusts and isolated large hail will be possible. Coverage of convection is uncertain, but relative concentrations may develop downshear from what is now disorganized/nonsevere convection over OH (in the same UVV field), and ahead of the MCV over parts of IL/IN, becoming organized across parts of IN/OH. Diurnal heating of a favorably moist airmass is expected to weaken already modest ambient MLCINH along the outlook corridor by late morning. With lift along the front and prefrontal outflow/differential-heating boundaries, growth of morning to early afternoon development into one or more complexes appears to be a plausible scenario, rendering a greater wind than hail threat. Surface dewpoints commonly in the mid 60s to low 70s F will offset modest mid/upper-level lapse rates enough to contribute to peak/preconvective MLCAPE in the 800-1500 J/kg range from OH eastward, and 1000-2000 J/kg back into portions of IN. Weak, generally veered low/middle-level flow will limit vertical shear. Still, nearly unidirectional westerly flow through a deep layer will foster movement of convection parallel to the low-level moisture-instability axis. ...Dakotas... A line or arc of scattered thunderstorms should develop along/near the cold front during late afternoon into evening, perhaps initially over ND where deep-layer forcing will be stronger, then southward into greater capping in SD, as the front impinges on greater moisture and lingering boundary-layer instability. Ahead of the cold front, enough easterly component to near-surface flow will develop to support moist advection into the convective genesis zone, with surface dewpoints into the 60s F becoming common. Capping at the base of a modest EML will suppress development for much of the afternoon, especially over SD, but once frontal lift overcomes it, a corridor of 2000-3000 J/kg MLCAPE should be available southwest of (and parallel to) the warm front. Though the strongest flow aloft and large-scale ascent will remain behind the cold front, the eastern rim of stronger height falls will spread over the frontal zone, with enough mass response to both foster favorable vertical shear for supercells and enhanced storm-relative flow in low levels. Effective-shear magnitudes of 30-40 kt (locally higher) and broad low-level hodographs along and south of the warm front should foster supercell development, until mergers and upscale growth occur. Large to very large hail and severe gusts will be the main concerns, though a tornado is possible. However, relatively weak midlevel flow may encourage a transition to messier, quasi- linear mode with embedded LEWP/bow formations for a few hours. Activity should weaken overnight as it moves into stabilizing boundary-layer air, though a 45-55-kt LLJ may encourage persistence of a cluster or two tonight into the eastern Dakotas. ..Edwards/Bentley.. 08/28/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Wed Aug 28 2024 Valid 281300Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO VALLEY TO THE NORTHERN MID-ATLANTIC COAST...AND ACROSS PARTS OF NORTH AND SOUTH DAKOTA... ...SUMMARY... Severe thunderstorms are expected from the Ohio Valley to the northern Mid-Atlantic Coast, and across parts of North and South Dakota. ...Synopsis... In mid/upper levels, a progressive northern-stream pattern will prevail through the period, with the main feature being a cyclone now apparent in moisture-channel imagery near the southeastern corner of BC. The associated 500-mb low should move eastward roughly along, or just north of, the international border through the period, with the accompanying trough extending south- southwestward. By 00Z, the low should be near the southwestern corner of SK, with trough to northern UT. By 12Z, the low should reach extreme south-central SK, with trough across central MT to southwestern WY. Downstream, a complex but much lower-amplitude shortwave trough was evident over Lake Superior and adjoining portions of ON and western U.P. of MI. One part of this perturbation should break eastward to the St. Lawrence Valley by the end of the period, while the trailing part drifts eastward over Lake Superior and the U.P. Of perhaps greater direct influence on convective potential, an MCV was apparent in composited radar imagery over southeastern IA. The associated perturbation should move across much of central IL today, reaching western OH by 12Z tomorrow. The 11Z surface analysis showed a cold front from northern ME west- southwestward across Lake Ontario and southern Lower MI, becoming quasistationary for the time being across southern parts of Lake Michigan and WI, to northeastern NE, then a warm front over southwestern SD, to a low over southeastern MT. This front is expected to move southeastward by 00Z to coastal NS, Cape Cod, Long Island, northern parts of MD/WV, and southern parts of OH/IN/IL, becoming a diffuse warm front northwestward over central IA, southwestern MN and central ND. There it will be overtaken by another cold front -- initially analyzed through the low over eastern MT and across northwestern WY. By 00Z, this second, stronger cold front should extend from central ND across central/ southwestern SD to east-central WY. By 12Z, the western cold front should extend from a low over southeastern ND or northeastern SD across south-central SD, western NE and northeastern CO. ...Ohio Valley to Mid-Atlantic... Widely scattered to scattered thunderstorms are expected along and south of the front today from IN to the Mid-Atlantic Coast, and perhaps the southern New England Coast/Long Island vicinity. Damaging gusts and isolated large hail will be possible. Coverage of convection is uncertain, but relative concentrations may develop downshear from what is now disorganized/nonsevere convection over OH (in the same UVV field), and ahead of the MCV over parts of IL/IN, becoming organized across parts of IN/OH. Diurnal heating of a favorably moist airmass is expected to weaken already modest ambient MLCINH along the outlook corridor by late morning. With lift along the front and prefrontal outflow/differential-heating boundaries, growth of morning to early afternoon development into one or more complexes appears to be a plausible scenario, rendering a greater wind than hail threat. Surface dewpoints commonly in the mid 60s to low 70s F will offset modest mid/upper-level lapse rates enough to contribute to peak/preconvective MLCAPE in the 800-1500 J/kg range from OH eastward, and 1000-2000 J/kg back into portions of IN. Weak, generally veered low/middle-level flow will limit vertical shear. Still, nearly unidirectional westerly flow through a deep layer will foster movement of convection parallel to the low-level moisture-instability axis. ...Dakotas... A line or arc of scattered thunderstorms should develop along/near the cold front during late afternoon into evening, perhaps initially over ND where deep-layer forcing will be stronger, then southward into greater capping in SD, as the front impinges on greater moisture and lingering boundary-layer instability. Ahead of the cold front, enough easterly component to near-surface flow will develop to support moist advection into the convective genesis zone, with surface dewpoints into the 60s F becoming common. Capping at the base of a modest EML will suppress development for much of the afternoon, especially over SD, but once frontal lift overcomes it, a corridor of 2000-3000 J/kg MLCAPE should be available southwest of (and parallel to) the warm front. Though the strongest flow aloft and large-scale ascent will remain behind the cold front, the eastern rim of stronger height falls will spread over the frontal zone, with enough mass response to both foster favorable vertical shear for supercells and enhanced storm-relative flow in low levels. Effective-shear magnitudes of 30-40 kt (locally higher) and broad low-level hodographs along and south of the warm front should foster supercell development, until mergers and upscale growth occur. Large to very large hail and severe gusts will be the main concerns, though a tornado is possible. However, relatively weak midlevel flow may encourage a transition to messier, quasi- linear mode with embedded LEWP/bow formations for a few hours. Activity should weaken overnight as it moves into stabilizing boundary-layer air, though a 45-55-kt LLJ may encourage persistence of a cluster or two tonight into the eastern Dakotas. ..Edwards/Bentley.. 08/28/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Wed Aug 28 2024 Valid 281300Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO VALLEY TO THE NORTHERN MID-ATLANTIC COAST...AND ACROSS PARTS OF NORTH AND SOUTH DAKOTA... ...SUMMARY... Severe thunderstorms are expected from the Ohio Valley to the northern Mid-Atlantic Coast, and across parts of North and South Dakota. ...Synopsis... In mid/upper levels, a progressive northern-stream pattern will prevail through the period, with the main feature being a cyclone now apparent in moisture-channel imagery near the southeastern corner of BC. The associated 500-mb low should move eastward roughly along, or just north of, the international border through the period, with the accompanying trough extending south- southwestward. By 00Z, the low should be near the southwestern corner of SK, with trough to northern UT. By 12Z, the low should reach extreme south-central SK, with trough across central MT to southwestern WY. Downstream, a complex but much lower-amplitude shortwave trough was evident over Lake Superior and adjoining portions of ON and western U.P. of MI. One part of this perturbation should break eastward to the St. Lawrence Valley by the end of the period, while the trailing part drifts eastward over Lake Superior and the U.P. Of perhaps greater direct influence on convective potential, an MCV was apparent in composited radar imagery over southeastern IA. The associated perturbation should move across much of central IL today, reaching western OH by 12Z tomorrow. The 11Z surface analysis showed a cold front from northern ME west- southwestward across Lake Ontario and southern Lower MI, becoming quasistationary for the time being across southern parts of Lake Michigan and WI, to northeastern NE, then a warm front over southwestern SD, to a low over southeastern MT. This front is expected to move southeastward by 00Z to coastal NS, Cape Cod, Long Island, northern parts of MD/WV, and southern parts of OH/IN/IL, becoming a diffuse warm front northwestward over central IA, southwestern MN and central ND. There it will be overtaken by another cold front -- initially analyzed through the low over eastern MT and across northwestern WY. By 00Z, this second, stronger cold front should extend from central ND across central/ southwestern SD to east-central WY. By 12Z, the western cold front should extend from a low over southeastern ND or northeastern SD across south-central SD, western NE and northeastern CO. ...Ohio Valley to Mid-Atlantic... Widely scattered to scattered thunderstorms are expected along and south of the front today from IN to the Mid-Atlantic Coast, and perhaps the southern New England Coast/Long Island vicinity. Damaging gusts and isolated large hail will be possible. Coverage of convection is uncertain, but relative concentrations may develop downshear from what is now disorganized/nonsevere convection over OH (in the same UVV field), and ahead of the MCV over parts of IL/IN, becoming organized across parts of IN/OH. Diurnal heating of a favorably moist airmass is expected to weaken already modest ambient MLCINH along the outlook corridor by late morning. With lift along the front and prefrontal outflow/differential-heating boundaries, growth of morning to early afternoon development into one or more complexes appears to be a plausible scenario, rendering a greater wind than hail threat. Surface dewpoints commonly in the mid 60s to low 70s F will offset modest mid/upper-level lapse rates enough to contribute to peak/preconvective MLCAPE in the 800-1500 J/kg range from OH eastward, and 1000-2000 J/kg back into portions of IN. Weak, generally veered low/middle-level flow will limit vertical shear. Still, nearly unidirectional westerly flow through a deep layer will foster movement of convection parallel to the low-level moisture-instability axis. ...Dakotas... A line or arc of scattered thunderstorms should develop along/near the cold front during late afternoon into evening, perhaps initially over ND where deep-layer forcing will be stronger, then southward into greater capping in SD, as the front impinges on greater moisture and lingering boundary-layer instability. Ahead of the cold front, enough easterly component to near-surface flow will develop to support moist advection into the convective genesis zone, with surface dewpoints into the 60s F becoming common. Capping at the base of a modest EML will suppress development for much of the afternoon, especially over SD, but once frontal lift overcomes it, a corridor of 2000-3000 J/kg MLCAPE should be available southwest of (and parallel to) the warm front. Though the strongest flow aloft and large-scale ascent will remain behind the cold front, the eastern rim of stronger height falls will spread over the frontal zone, with enough mass response to both foster favorable vertical shear for supercells and enhanced storm-relative flow in low levels. Effective-shear magnitudes of 30-40 kt (locally higher) and broad low-level hodographs along and south of the warm front should foster supercell development, until mergers and upscale growth occur. Large to very large hail and severe gusts will be the main concerns, though a tornado is possible. However, relatively weak midlevel flow may encourage a transition to messier, quasi- linear mode with embedded LEWP/bow formations for a few hours. Activity should weaken overnight as it moves into stabilizing boundary-layer air, though a 45-55-kt LLJ may encourage persistence of a cluster or two tonight into the eastern Dakotas. ..Edwards/Bentley.. 08/28/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Wed Aug 28 2024 Valid 281300Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO VALLEY TO THE NORTHERN MID-ATLANTIC COAST...AND ACROSS PARTS OF NORTH AND SOUTH DAKOTA... ...SUMMARY... Severe thunderstorms are expected from the Ohio Valley to the northern Mid-Atlantic Coast, and across parts of North and South Dakota. ...Synopsis... In mid/upper levels, a progressive northern-stream pattern will prevail through the period, with the main feature being a cyclone now apparent in moisture-channel imagery near the southeastern corner of BC. The associated 500-mb low should move eastward roughly along, or just north of, the international border through the period, with the accompanying trough extending south- southwestward. By 00Z, the low should be near the southwestern corner of SK, with trough to northern UT. By 12Z, the low should reach extreme south-central SK, with trough across central MT to southwestern WY. Downstream, a complex but much lower-amplitude shortwave trough was evident over Lake Superior and adjoining portions of ON and western U.P. of MI. One part of this perturbation should break eastward to the St. Lawrence Valley by the end of the period, while the trailing part drifts eastward over Lake Superior and the U.P. Of perhaps greater direct influence on convective potential, an MCV was apparent in composited radar imagery over southeastern IA. The associated perturbation should move across much of central IL today, reaching western OH by 12Z tomorrow. The 11Z surface analysis showed a cold front from northern ME west- southwestward across Lake Ontario and southern Lower MI, becoming quasistationary for the time being across southern parts of Lake Michigan and WI, to northeastern NE, then a warm front over southwestern SD, to a low over southeastern MT. This front is expected to move southeastward by 00Z to coastal NS, Cape Cod, Long Island, northern parts of MD/WV, and southern parts of OH/IN/IL, becoming a diffuse warm front northwestward over central IA, southwestern MN and central ND. There it will be overtaken by another cold front -- initially analyzed through the low over eastern MT and across northwestern WY. By 00Z, this second, stronger cold front should extend from central ND across central/ southwestern SD to east-central WY. By 12Z, the western cold front should extend from a low over southeastern ND or northeastern SD across south-central SD, western NE and northeastern CO. ...Ohio Valley to Mid-Atlantic... Widely scattered to scattered thunderstorms are expected along and south of the front today from IN to the Mid-Atlantic Coast, and perhaps the southern New England Coast/Long Island vicinity. Damaging gusts and isolated large hail will be possible. Coverage of convection is uncertain, but relative concentrations may develop downshear from what is now disorganized/nonsevere convection over OH (in the same UVV field), and ahead of the MCV over parts of IL/IN, becoming organized across parts of IN/OH. Diurnal heating of a favorably moist airmass is expected to weaken already modest ambient MLCINH along the outlook corridor by late morning. With lift along the front and prefrontal outflow/differential-heating boundaries, growth of morning to early afternoon development into one or more complexes appears to be a plausible scenario, rendering a greater wind than hail threat. Surface dewpoints commonly in the mid 60s to low 70s F will offset modest mid/upper-level lapse rates enough to contribute to peak/preconvective MLCAPE in the 800-1500 J/kg range from OH eastward, and 1000-2000 J/kg back into portions of IN. Weak, generally veered low/middle-level flow will limit vertical shear. Still, nearly unidirectional westerly flow through a deep layer will foster movement of convection parallel to the low-level moisture-instability axis. ...Dakotas... A line or arc of scattered thunderstorms should develop along/near the cold front during late afternoon into evening, perhaps initially over ND where deep-layer forcing will be stronger, then southward into greater capping in SD, as the front impinges on greater moisture and lingering boundary-layer instability. Ahead of the cold front, enough easterly component to near-surface flow will develop to support moist advection into the convective genesis zone, with surface dewpoints into the 60s F becoming common. Capping at the base of a modest EML will suppress development for much of the afternoon, especially over SD, but once frontal lift overcomes it, a corridor of 2000-3000 J/kg MLCAPE should be available southwest of (and parallel to) the warm front. Though the strongest flow aloft and large-scale ascent will remain behind the cold front, the eastern rim of stronger height falls will spread over the frontal zone, with enough mass response to both foster favorable vertical shear for supercells and enhanced storm-relative flow in low levels. Effective-shear magnitudes of 30-40 kt (locally higher) and broad low-level hodographs along and south of the warm front should foster supercell development, until mergers and upscale growth occur. Large to very large hail and severe gusts will be the main concerns, though a tornado is possible. However, relatively weak midlevel flow may encourage a transition to messier, quasi- linear mode with embedded LEWP/bow formations for a few hours. Activity should weaken overnight as it moves into stabilizing boundary-layer air, though a 45-55-kt LLJ may encourage persistence of a cluster or two tonight into the eastern Dakotas. ..Edwards/Bentley.. 08/28/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Wed Aug 28 2024 Valid 281300Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO VALLEY TO THE NORTHERN MID-ATLANTIC COAST...AND ACROSS PARTS OF NORTH AND SOUTH DAKOTA... ...SUMMARY... Severe thunderstorms are expected from the Ohio Valley to the northern Mid-Atlantic Coast, and across parts of North and South Dakota. ...Synopsis... In mid/upper levels, a progressive northern-stream pattern will prevail through the period, with the main feature being a cyclone now apparent in moisture-channel imagery near the southeastern corner of BC. The associated 500-mb low should move eastward roughly along, or just north of, the international border through the period, with the accompanying trough extending south- southwestward. By 00Z, the low should be near the southwestern corner of SK, with trough to northern UT. By 12Z, the low should reach extreme south-central SK, with trough across central MT to southwestern WY. Downstream, a complex but much lower-amplitude shortwave trough was evident over Lake Superior and adjoining portions of ON and western U.P. of MI. One part of this perturbation should break eastward to the St. Lawrence Valley by the end of the period, while the trailing part drifts eastward over Lake Superior and the U.P. Of perhaps greater direct influence on convective potential, an MCV was apparent in composited radar imagery over southeastern IA. The associated perturbation should move across much of central IL today, reaching western OH by 12Z tomorrow. The 11Z surface analysis showed a cold front from northern ME west- southwestward across Lake Ontario and southern Lower MI, becoming quasistationary for the time being across southern parts of Lake Michigan and WI, to northeastern NE, then a warm front over southwestern SD, to a low over southeastern MT. This front is expected to move southeastward by 00Z to coastal NS, Cape Cod, Long Island, northern parts of MD/WV, and southern parts of OH/IN/IL, becoming a diffuse warm front northwestward over central IA, southwestern MN and central ND. There it will be overtaken by another cold front -- initially analyzed through the low over eastern MT and across northwestern WY. By 00Z, this second, stronger cold front should extend from central ND across central/ southwestern SD to east-central WY. By 12Z, the western cold front should extend from a low over southeastern ND or northeastern SD across south-central SD, western NE and northeastern CO. ...Ohio Valley to Mid-Atlantic... Widely scattered to scattered thunderstorms are expected along and south of the front today from IN to the Mid-Atlantic Coast, and perhaps the southern New England Coast/Long Island vicinity. Damaging gusts and isolated large hail will be possible. Coverage of convection is uncertain, but relative concentrations may develop downshear from what is now disorganized/nonsevere convection over OH (in the same UVV field), and ahead of the MCV over parts of IL/IN, becoming organized across parts of IN/OH. Diurnal heating of a favorably moist airmass is expected to weaken already modest ambient MLCINH along the outlook corridor by late morning. With lift along the front and prefrontal outflow/differential-heating boundaries, growth of morning to early afternoon development into one or more complexes appears to be a plausible scenario, rendering a greater wind than hail threat. Surface dewpoints commonly in the mid 60s to low 70s F will offset modest mid/upper-level lapse rates enough to contribute to peak/preconvective MLCAPE in the 800-1500 J/kg range from OH eastward, and 1000-2000 J/kg back into portions of IN. Weak, generally veered low/middle-level flow will limit vertical shear. Still, nearly unidirectional westerly flow through a deep layer will foster movement of convection parallel to the low-level moisture-instability axis. ...Dakotas... A line or arc of scattered thunderstorms should develop along/near the cold front during late afternoon into evening, perhaps initially over ND where deep-layer forcing will be stronger, then southward into greater capping in SD, as the front impinges on greater moisture and lingering boundary-layer instability. Ahead of the cold front, enough easterly component to near-surface flow will develop to support moist advection into the convective genesis zone, with surface dewpoints into the 60s F becoming common. Capping at the base of a modest EML will suppress development for much of the afternoon, especially over SD, but once frontal lift overcomes it, a corridor of 2000-3000 J/kg MLCAPE should be available southwest of (and parallel to) the warm front. Though the strongest flow aloft and large-scale ascent will remain behind the cold front, the eastern rim of stronger height falls will spread over the frontal zone, with enough mass response to both foster favorable vertical shear for supercells and enhanced storm-relative flow in low levels. Effective-shear magnitudes of 30-40 kt (locally higher) and broad low-level hodographs along and south of the warm front should foster supercell development, until mergers and upscale growth occur. Large to very large hail and severe gusts will be the main concerns, though a tornado is possible. However, relatively weak midlevel flow may encourage a transition to messier, quasi- linear mode with embedded LEWP/bow formations for a few hours. Activity should weaken overnight as it moves into stabilizing boundary-layer air, though a 45-55-kt LLJ may encourage persistence of a cluster or two tonight into the eastern Dakotas. ..Edwards/Bentley.. 08/28/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Aug 28 2024 Valid 311200Z - 051200Z ...DISCUSSION... Medium-range global models continue to suggest limited severe potential Days 4-5 (Saturday and Sunday) largely within the northeastern quarter of the country, followed by several days of what appears likely to be minimal severe risk through the remainder of the period. Day 4/Saturday, upper-level height falls are progged to shift across the Great Lakes/Midwest/Northeast, as a strengthening upper trough advances east-southeastward across Ontario and the Upper Great Lakes region. A weak cold front will cross the Lower Great Lakes/Appalachians, with likelihood for showers and thunderstorms accompanying this front. However, with stronger flow aloft limited to areas from Pennsylvania northward, where instability should remain limited, overall severe risk appears at this time to remain too low to warrant inclusion of a risk area associated with this frontal passage. Limited severe potential may also exist for a few hours in the afternoon and early evening over the Upper Mississippi Valley area, as a stronger/reinforcing cold front surges southeastward out of Canada across the Upper Mississippi Valley and Great Lakes region and into central Plains and Upper Midwest overnight. Though only modest moisture -- and thus weak afternoon pre-frontal destabilization -- is expected, low-topped convection is expected during the afternoon across parts of Upper Michigan/Wisconsin and perhaps Minnesota. Strong northwesterly flow aloft would support fast-moving storms, and possibly a risk for damaging winds locally. Again though, this potential appears too limited/uncertain to include a risk area at this time. Day 5, the surging cold front is forecast to shift southeastward into the Northeast/New England, and southward across the Ohio Valley area. Similar to Day 4 potential for low-topped storms farther northwest, convection will likely develop along the front through the afternoon -- particularly across the New England vicinity. However, given the frontal passage the prior day, questions with respect to available moisture -- and thus destabilization potential -- exist at this time. As such, despite the strong front and strong flow aloft, severe risk again appears limited and uncertain, precluding introduction of a risk area for now. The cold front is expected to have moved offshore of New England and the Mid-Atlantic region by the start of Day 6, becoming quasistationary in a west-to-east manner across the Southeast and Mid South, on the southern fringe of a Canadian High settling into the northeastern quarter of the country. While convection will likely occur near and south of this front where moist Gulf air will remain in place, this region will remain well south of the enhanced flow aloft. Therefore, severe risk appears minimal -- and should remain so through the end of the period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Aug 28 2024 Valid 311200Z - 051200Z ...DISCUSSION... Medium-range global models continue to suggest limited severe potential Days 4-5 (Saturday and Sunday) largely within the northeastern quarter of the country, followed by several days of what appears likely to be minimal severe risk through the remainder of the period. Day 4/Saturday, upper-level height falls are progged to shift across the Great Lakes/Midwest/Northeast, as a strengthening upper trough advances east-southeastward across Ontario and the Upper Great Lakes region. A weak cold front will cross the Lower Great Lakes/Appalachians, with likelihood for showers and thunderstorms accompanying this front. However, with stronger flow aloft limited to areas from Pennsylvania northward, where instability should remain limited, overall severe risk appears at this time to remain too low to warrant inclusion of a risk area associated with this frontal passage. Limited severe potential may also exist for a few hours in the afternoon and early evening over the Upper Mississippi Valley area, as a stronger/reinforcing cold front surges southeastward out of Canada across the Upper Mississippi Valley and Great Lakes region and into central Plains and Upper Midwest overnight. Though only modest moisture -- and thus weak afternoon pre-frontal destabilization -- is expected, low-topped convection is expected during the afternoon across parts of Upper Michigan/Wisconsin and perhaps Minnesota. Strong northwesterly flow aloft would support fast-moving storms, and possibly a risk for damaging winds locally. Again though, this potential appears too limited/uncertain to include a risk area at this time. Day 5, the surging cold front is forecast to shift southeastward into the Northeast/New England, and southward across the Ohio Valley area. Similar to Day 4 potential for low-topped storms farther northwest, convection will likely develop along the front through the afternoon -- particularly across the New England vicinity. However, given the frontal passage the prior day, questions with respect to available moisture -- and thus destabilization potential -- exist at this time. As such, despite the strong front and strong flow aloft, severe risk again appears limited and uncertain, precluding introduction of a risk area for now. The cold front is expected to have moved offshore of New England and the Mid-Atlantic region by the start of Day 6, becoming quasistationary in a west-to-east manner across the Southeast and Mid South, on the southern fringe of a Canadian High settling into the northeastern quarter of the country. While convection will likely occur near and south of this front where moist Gulf air will remain in place, this region will remain well south of the enhanced flow aloft. Therefore, severe risk appears minimal -- and should remain so through the end of the period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Aug 28 2024 Valid 311200Z - 051200Z ...DISCUSSION... Medium-range global models continue to suggest limited severe potential Days 4-5 (Saturday and Sunday) largely within the northeastern quarter of the country, followed by several days of what appears likely to be minimal severe risk through the remainder of the period. Day 4/Saturday, upper-level height falls are progged to shift across the Great Lakes/Midwest/Northeast, as a strengthening upper trough advances east-southeastward across Ontario and the Upper Great Lakes region. A weak cold front will cross the Lower Great Lakes/Appalachians, with likelihood for showers and thunderstorms accompanying this front. However, with stronger flow aloft limited to areas from Pennsylvania northward, where instability should remain limited, overall severe risk appears at this time to remain too low to warrant inclusion of a risk area associated with this frontal passage. Limited severe potential may also exist for a few hours in the afternoon and early evening over the Upper Mississippi Valley area, as a stronger/reinforcing cold front surges southeastward out of Canada across the Upper Mississippi Valley and Great Lakes region and into central Plains and Upper Midwest overnight. Though only modest moisture -- and thus weak afternoon pre-frontal destabilization -- is expected, low-topped convection is expected during the afternoon across parts of Upper Michigan/Wisconsin and perhaps Minnesota. Strong northwesterly flow aloft would support fast-moving storms, and possibly a risk for damaging winds locally. Again though, this potential appears too limited/uncertain to include a risk area at this time. Day 5, the surging cold front is forecast to shift southeastward into the Northeast/New England, and southward across the Ohio Valley area. Similar to Day 4 potential for low-topped storms farther northwest, convection will likely develop along the front through the afternoon -- particularly across the New England vicinity. However, given the frontal passage the prior day, questions with respect to available moisture -- and thus destabilization potential -- exist at this time. As such, despite the strong front and strong flow aloft, severe risk again appears limited and uncertain, precluding introduction of a risk area for now. The cold front is expected to have moved offshore of New England and the Mid-Atlantic region by the start of Day 6, becoming quasistationary in a west-to-east manner across the Southeast and Mid South, on the southern fringe of a Canadian High settling into the northeastern quarter of the country. While convection will likely occur near and south of this front where moist Gulf air will remain in place, this region will remain well south of the enhanced flow aloft. Therefore, severe risk appears minimal -- and should remain so through the end of the period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Aug 28 2024 Valid 311200Z - 051200Z ...DISCUSSION... Medium-range global models continue to suggest limited severe potential Days 4-5 (Saturday and Sunday) largely within the northeastern quarter of the country, followed by several days of what appears likely to be minimal severe risk through the remainder of the period. Day 4/Saturday, upper-level height falls are progged to shift across the Great Lakes/Midwest/Northeast, as a strengthening upper trough advances east-southeastward across Ontario and the Upper Great Lakes region. A weak cold front will cross the Lower Great Lakes/Appalachians, with likelihood for showers and thunderstorms accompanying this front. However, with stronger flow aloft limited to areas from Pennsylvania northward, where instability should remain limited, overall severe risk appears at this time to remain too low to warrant inclusion of a risk area associated with this frontal passage. Limited severe potential may also exist for a few hours in the afternoon and early evening over the Upper Mississippi Valley area, as a stronger/reinforcing cold front surges southeastward out of Canada across the Upper Mississippi Valley and Great Lakes region and into central Plains and Upper Midwest overnight. Though only modest moisture -- and thus weak afternoon pre-frontal destabilization -- is expected, low-topped convection is expected during the afternoon across parts of Upper Michigan/Wisconsin and perhaps Minnesota. Strong northwesterly flow aloft would support fast-moving storms, and possibly a risk for damaging winds locally. Again though, this potential appears too limited/uncertain to include a risk area at this time. Day 5, the surging cold front is forecast to shift southeastward into the Northeast/New England, and southward across the Ohio Valley area. Similar to Day 4 potential for low-topped storms farther northwest, convection will likely develop along the front through the afternoon -- particularly across the New England vicinity. However, given the frontal passage the prior day, questions with respect to available moisture -- and thus destabilization potential -- exist at this time. As such, despite the strong front and strong flow aloft, severe risk again appears limited and uncertain, precluding introduction of a risk area for now. The cold front is expected to have moved offshore of New England and the Mid-Atlantic region by the start of Day 6, becoming quasistationary in a west-to-east manner across the Southeast and Mid South, on the southern fringe of a Canadian High settling into the northeastern quarter of the country. While convection will likely occur near and south of this front where moist Gulf air will remain in place, this region will remain well south of the enhanced flow aloft. Therefore, severe risk appears minimal -- and should remain so through the end of the period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Aug 28 2024 Valid 311200Z - 051200Z ...DISCUSSION... Medium-range global models continue to suggest limited severe potential Days 4-5 (Saturday and Sunday) largely within the northeastern quarter of the country, followed by several days of what appears likely to be minimal severe risk through the remainder of the period. Day 4/Saturday, upper-level height falls are progged to shift across the Great Lakes/Midwest/Northeast, as a strengthening upper trough advances east-southeastward across Ontario and the Upper Great Lakes region. A weak cold front will cross the Lower Great Lakes/Appalachians, with likelihood for showers and thunderstorms accompanying this front. However, with stronger flow aloft limited to areas from Pennsylvania northward, where instability should remain limited, overall severe risk appears at this time to remain too low to warrant inclusion of a risk area associated with this frontal passage. Limited severe potential may also exist for a few hours in the afternoon and early evening over the Upper Mississippi Valley area, as a stronger/reinforcing cold front surges southeastward out of Canada across the Upper Mississippi Valley and Great Lakes region and into central Plains and Upper Midwest overnight. Though only modest moisture -- and thus weak afternoon pre-frontal destabilization -- is expected, low-topped convection is expected during the afternoon across parts of Upper Michigan/Wisconsin and perhaps Minnesota. Strong northwesterly flow aloft would support fast-moving storms, and possibly a risk for damaging winds locally. Again though, this potential appears too limited/uncertain to include a risk area at this time. Day 5, the surging cold front is forecast to shift southeastward into the Northeast/New England, and southward across the Ohio Valley area. Similar to Day 4 potential for low-topped storms farther northwest, convection will likely develop along the front through the afternoon -- particularly across the New England vicinity. However, given the frontal passage the prior day, questions with respect to available moisture -- and thus destabilization potential -- exist at this time. As such, despite the strong front and strong flow aloft, severe risk again appears limited and uncertain, precluding introduction of a risk area for now. The cold front is expected to have moved offshore of New England and the Mid-Atlantic region by the start of Day 6, becoming quasistationary in a west-to-east manner across the Southeast and Mid South, on the southern fringe of a Canadian High settling into the northeastern quarter of the country. While convection will likely occur near and south of this front where moist Gulf air will remain in place, this region will remain well south of the enhanced flow aloft. Therefore, severe risk appears minimal -- and should remain so through the end of the period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Aug 28 2024 Valid 311200Z - 051200Z ...DISCUSSION... Medium-range global models continue to suggest limited severe potential Days 4-5 (Saturday and Sunday) largely within the northeastern quarter of the country, followed by several days of what appears likely to be minimal severe risk through the remainder of the period. Day 4/Saturday, upper-level height falls are progged to shift across the Great Lakes/Midwest/Northeast, as a strengthening upper trough advances east-southeastward across Ontario and the Upper Great Lakes region. A weak cold front will cross the Lower Great Lakes/Appalachians, with likelihood for showers and thunderstorms accompanying this front. However, with stronger flow aloft limited to areas from Pennsylvania northward, where instability should remain limited, overall severe risk appears at this time to remain too low to warrant inclusion of a risk area associated with this frontal passage. Limited severe potential may also exist for a few hours in the afternoon and early evening over the Upper Mississippi Valley area, as a stronger/reinforcing cold front surges southeastward out of Canada across the Upper Mississippi Valley and Great Lakes region and into central Plains and Upper Midwest overnight. Though only modest moisture -- and thus weak afternoon pre-frontal destabilization -- is expected, low-topped convection is expected during the afternoon across parts of Upper Michigan/Wisconsin and perhaps Minnesota. Strong northwesterly flow aloft would support fast-moving storms, and possibly a risk for damaging winds locally. Again though, this potential appears too limited/uncertain to include a risk area at this time. Day 5, the surging cold front is forecast to shift southeastward into the Northeast/New England, and southward across the Ohio Valley area. Similar to Day 4 potential for low-topped storms farther northwest, convection will likely develop along the front through the afternoon -- particularly across the New England vicinity. However, given the frontal passage the prior day, questions with respect to available moisture -- and thus destabilization potential -- exist at this time. As such, despite the strong front and strong flow aloft, severe risk again appears limited and uncertain, precluding introduction of a risk area for now. The cold front is expected to have moved offshore of New England and the Mid-Atlantic region by the start of Day 6, becoming quasistationary in a west-to-east manner across the Southeast and Mid South, on the southern fringe of a Canadian High settling into the northeastern quarter of the country. While convection will likely occur near and south of this front where moist Gulf air will remain in place, this region will remain well south of the enhanced flow aloft. Therefore, severe risk appears minimal -- and should remain so through the end of the period. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0229 AM CDT Wed Aug 28 2024 Valid 301200Z - 311200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM LAKES HUDSON AND ERIE WEST-SOUTHWESTWARD ACROSS THE MIDWEST... ...SUMMARY... Strong/locally severe storms will be posible from Lakes Huron and Erie southwesteward into the Midwest Friday. ...Synopsis... An upper trough will continue moving slowly eastward out of the north-central U.S. across the Great Lakes and Midwest on Friday, though the more vigorous portion of the trough is forecast to eject northeastward across Ontario into the Hudson Bay region. At the surface, a cold front is forecast to continue eastward across the Great Lakes region, southeastward across the Midwest, and southward across the Plains. By the end of the period, the front should extend from the Lower Great Lakes west-southwestward across the Ohio Valley, and into Oklahoma and northern Texas. ...Lower Michigan/northern Ohio/northwestern Pennsylvania across the Midwest... Afternoon destabilization across the Midwest ahead of the advancing cold front will support development of scattered thunderstorms. While stronger flow aloft will remain to the cool side of the front, moderate low- to mid-level westerlies extending south into the Midwest states should allow a few stronger storms to evolve, including a few small clusters/line segments. The strongest storms will pose some risk for marginal hail and wind gusts capable of mainly tree damage, into the evening hours before a nocturnal convective decrease commences. ..Goss.. 08/28/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0229 AM CDT Wed Aug 28 2024 Valid 301200Z - 311200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM LAKES HUDSON AND ERIE WEST-SOUTHWESTWARD ACROSS THE MIDWEST... ...SUMMARY... Strong/locally severe storms will be posible from Lakes Huron and Erie southwesteward into the Midwest Friday. ...Synopsis... An upper trough will continue moving slowly eastward out of the north-central U.S. across the Great Lakes and Midwest on Friday, though the more vigorous portion of the trough is forecast to eject northeastward across Ontario into the Hudson Bay region. At the surface, a cold front is forecast to continue eastward across the Great Lakes region, southeastward across the Midwest, and southward across the Plains. By the end of the period, the front should extend from the Lower Great Lakes west-southwestward across the Ohio Valley, and into Oklahoma and northern Texas. ...Lower Michigan/northern Ohio/northwestern Pennsylvania across the Midwest... Afternoon destabilization across the Midwest ahead of the advancing cold front will support development of scattered thunderstorms. While stronger flow aloft will remain to the cool side of the front, moderate low- to mid-level westerlies extending south into the Midwest states should allow a few stronger storms to evolve, including a few small clusters/line segments. The strongest storms will pose some risk for marginal hail and wind gusts capable of mainly tree damage, into the evening hours before a nocturnal convective decrease commences. ..Goss.. 08/28/2024 Read more