Severe Storms

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Thu Jul 04 2024 Valid 041630Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...AND THE SOUTHERN PLAINS TO OHIO VALLEY... ...SUMMARY... Scattered severe thunderstorms will be possible this afternoon and evening across parts of the upper Mississippi Valley, and from the southern Plains to the lower Ohio Valley. ...Synopsis... An upper trough over the northern/central Plains will move generally eastward today across the Upper Midwest and mid MS Valley. A separate, convectively augmented mid-level vorticity maximum is present over southern IA/northern MO late this morning. This MCV and associated convection across the OH Valley will move east-northeastward across the OH Valley/Midwest through this evening. At the surface, a weak low should develop eastward across parts of the Upper Midwest in tandem with the large-scale upper trough. Another weak surface low should also track northeastward over the OH Valley with the remnant MCV. A convectively reinforced front draped from the southern Plains northeastward into the mid MS and OH Valleys will likely serve as a focus for strong to severe thunderstorms this afternoon and evening. ...Mid Mississippi Valley into the Ohio Valley and Mid-Atlantic... Mostly elevated thunderstorms are ongoing late this morning across the lower OH Valley. The rather moist low-level airmass along/south of a front will continue to gradually destabilize through the afternoon. Although mid-level lapse rates will remain poor, moderate instability has already developed downstream of activity moving across southern IN and western KY. Additional intensification of this convection will probably occur through early afternoon across parts of central/eastern KY and perhaps southern OH ahead of the MCV. Even though stronger mid-level flow may tend to remain displaced to the north of the front, modest but sufficient deep-layer shear should be present to support multicell clustering. Scattered damaging winds occasionally reaching severe thresholds should be the main threat with this activity as it spreads eastward across the lower OH Valley this afternoon and evening. Low-level flow is forecast to remain generally modest and veered to southwesterly. Still, sufficient speed shear will be present to support some threat for updraft rotation and perhaps a tornado or two, especially if any supercells can develop and persist. Isolated hail may also occur with more robust cores. Confidence in strong convection moving off the Blue Ridge Mountains in the Mid-Atlantic is relatively low. But, any thunderstorms that do form across this region could produce locally damaging winds. ...Southern Plains to the Ozarks... The portion of the cold front extending across the southern Plains into the Ozarks is forecast to make only slow southward progress through this evening. Even with some mid/high-level clouds persisting across these areas, robust daytime heating along/south of the front will likely encourage surface temperatures to warm into the 90s and low 100s. Even though low/mid-level flow will remain fairly weak, rather large surface temperature/dewpoint spreads (up to 30-40 degrees F) and steepened low-level lapse rates should foster a threat for mainly severe/damaging winds with any thunderstorms that can develop this afternoon and evening. Robust convection appears probable along/near the front by 22-00Z, and there appears to be some potential for an organized cluster to develop over the Ozarks/southern MO vicinity and sweep east-southeastward through the late evening. ...Upper Mississippi Valley... A focused area of ascent associated with the upper trough will overspread southern MN and northern IA today. While cloud cover remains prevalent over much of this region late this morning, there has been some recent clearing on the western edge of the cloud deck. A relatively small area of modest destabilization is still anticipated, with MLCAPE around 1000-1500 J/kg possible. A 45-60 kt mid-level jet attendant to the upper trough will overspread the developing warm sector through the afternoon. This jet will aid sufficiently strong deep-layer shear to support supercells with an associated threat for severe hail. Some clustering/upscale growth may eventually occur, which would support a greater threat for severe/damaging winds. This activity should weaken by late evening into WI and northern IL as it encounters a less unstable airmass. ..Gleason/Thornton.. 07/04/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Thu Jul 04 2024 Valid 041630Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...AND THE SOUTHERN PLAINS TO OHIO VALLEY... ...SUMMARY... Scattered severe thunderstorms will be possible this afternoon and evening across parts of the upper Mississippi Valley, and from the southern Plains to the lower Ohio Valley. ...Synopsis... An upper trough over the northern/central Plains will move generally eastward today across the Upper Midwest and mid MS Valley. A separate, convectively augmented mid-level vorticity maximum is present over southern IA/northern MO late this morning. This MCV and associated convection across the OH Valley will move east-northeastward across the OH Valley/Midwest through this evening. At the surface, a weak low should develop eastward across parts of the Upper Midwest in tandem with the large-scale upper trough. Another weak surface low should also track northeastward over the OH Valley with the remnant MCV. A convectively reinforced front draped from the southern Plains northeastward into the mid MS and OH Valleys will likely serve as a focus for strong to severe thunderstorms this afternoon and evening. ...Mid Mississippi Valley into the Ohio Valley and Mid-Atlantic... Mostly elevated thunderstorms are ongoing late this morning across the lower OH Valley. The rather moist low-level airmass along/south of a front will continue to gradually destabilize through the afternoon. Although mid-level lapse rates will remain poor, moderate instability has already developed downstream of activity moving across southern IN and western KY. Additional intensification of this convection will probably occur through early afternoon across parts of central/eastern KY and perhaps southern OH ahead of the MCV. Even though stronger mid-level flow may tend to remain displaced to the north of the front, modest but sufficient deep-layer shear should be present to support multicell clustering. Scattered damaging winds occasionally reaching severe thresholds should be the main threat with this activity as it spreads eastward across the lower OH Valley this afternoon and evening. Low-level flow is forecast to remain generally modest and veered to southwesterly. Still, sufficient speed shear will be present to support some threat for updraft rotation and perhaps a tornado or two, especially if any supercells can develop and persist. Isolated hail may also occur with more robust cores. Confidence in strong convection moving off the Blue Ridge Mountains in the Mid-Atlantic is relatively low. But, any thunderstorms that do form across this region could produce locally damaging winds. ...Southern Plains to the Ozarks... The portion of the cold front extending across the southern Plains into the Ozarks is forecast to make only slow southward progress through this evening. Even with some mid/high-level clouds persisting across these areas, robust daytime heating along/south of the front will likely encourage surface temperatures to warm into the 90s and low 100s. Even though low/mid-level flow will remain fairly weak, rather large surface temperature/dewpoint spreads (up to 30-40 degrees F) and steepened low-level lapse rates should foster a threat for mainly severe/damaging winds with any thunderstorms that can develop this afternoon and evening. Robust convection appears probable along/near the front by 22-00Z, and there appears to be some potential for an organized cluster to develop over the Ozarks/southern MO vicinity and sweep east-southeastward through the late evening. ...Upper Mississippi Valley... A focused area of ascent associated with the upper trough will overspread southern MN and northern IA today. While cloud cover remains prevalent over much of this region late this morning, there has been some recent clearing on the western edge of the cloud deck. A relatively small area of modest destabilization is still anticipated, with MLCAPE around 1000-1500 J/kg possible. A 45-60 kt mid-level jet attendant to the upper trough will overspread the developing warm sector through the afternoon. This jet will aid sufficiently strong deep-layer shear to support supercells with an associated threat for severe hail. Some clustering/upscale growth may eventually occur, which would support a greater threat for severe/damaging winds. This activity should weaken by late evening into WI and northern IL as it encounters a less unstable airmass. ..Gleason/Thornton.. 07/04/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Thu Jul 04 2024 Valid 041630Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...AND THE SOUTHERN PLAINS TO OHIO VALLEY... ...SUMMARY... Scattered severe thunderstorms will be possible this afternoon and evening across parts of the upper Mississippi Valley, and from the southern Plains to the lower Ohio Valley. ...Synopsis... An upper trough over the northern/central Plains will move generally eastward today across the Upper Midwest and mid MS Valley. A separate, convectively augmented mid-level vorticity maximum is present over southern IA/northern MO late this morning. This MCV and associated convection across the OH Valley will move east-northeastward across the OH Valley/Midwest through this evening. At the surface, a weak low should develop eastward across parts of the Upper Midwest in tandem with the large-scale upper trough. Another weak surface low should also track northeastward over the OH Valley with the remnant MCV. A convectively reinforced front draped from the southern Plains northeastward into the mid MS and OH Valleys will likely serve as a focus for strong to severe thunderstorms this afternoon and evening. ...Mid Mississippi Valley into the Ohio Valley and Mid-Atlantic... Mostly elevated thunderstorms are ongoing late this morning across the lower OH Valley. The rather moist low-level airmass along/south of a front will continue to gradually destabilize through the afternoon. Although mid-level lapse rates will remain poor, moderate instability has already developed downstream of activity moving across southern IN and western KY. Additional intensification of this convection will probably occur through early afternoon across parts of central/eastern KY and perhaps southern OH ahead of the MCV. Even though stronger mid-level flow may tend to remain displaced to the north of the front, modest but sufficient deep-layer shear should be present to support multicell clustering. Scattered damaging winds occasionally reaching severe thresholds should be the main threat with this activity as it spreads eastward across the lower OH Valley this afternoon and evening. Low-level flow is forecast to remain generally modest and veered to southwesterly. Still, sufficient speed shear will be present to support some threat for updraft rotation and perhaps a tornado or two, especially if any supercells can develop and persist. Isolated hail may also occur with more robust cores. Confidence in strong convection moving off the Blue Ridge Mountains in the Mid-Atlantic is relatively low. But, any thunderstorms that do form across this region could produce locally damaging winds. ...Southern Plains to the Ozarks... The portion of the cold front extending across the southern Plains into the Ozarks is forecast to make only slow southward progress through this evening. Even with some mid/high-level clouds persisting across these areas, robust daytime heating along/south of the front will likely encourage surface temperatures to warm into the 90s and low 100s. Even though low/mid-level flow will remain fairly weak, rather large surface temperature/dewpoint spreads (up to 30-40 degrees F) and steepened low-level lapse rates should foster a threat for mainly severe/damaging winds with any thunderstorms that can develop this afternoon and evening. Robust convection appears probable along/near the front by 22-00Z, and there appears to be some potential for an organized cluster to develop over the Ozarks/southern MO vicinity and sweep east-southeastward through the late evening. ...Upper Mississippi Valley... A focused area of ascent associated with the upper trough will overspread southern MN and northern IA today. While cloud cover remains prevalent over much of this region late this morning, there has been some recent clearing on the western edge of the cloud deck. A relatively small area of modest destabilization is still anticipated, with MLCAPE around 1000-1500 J/kg possible. A 45-60 kt mid-level jet attendant to the upper trough will overspread the developing warm sector through the afternoon. This jet will aid sufficiently strong deep-layer shear to support supercells with an associated threat for severe hail. Some clustering/upscale growth may eventually occur, which would support a greater threat for severe/damaging winds. This activity should weaken by late evening into WI and northern IL as it encounters a less unstable airmass. ..Gleason/Thornton.. 07/04/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Thu Jul 04 2024 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...AND LOWER OHIO VALLEY TO SOUTHERN PLAINS... ...SUMMARY... Severe thunderstorms will be possible across parts of the upper Mississippi Valley, and lower Ohio Valley to southern Plains. ...Synopsis... In mid/upper levels, strengthening ridging over the Pacific Coast will result in height rises over much of the Northwest, while the subtropical ridge weakens slightly across the Gulf Coast States and GA. Broadly cyclonic flow still will prevail from the northern Rockies across the central/northern Plains and Great Lakes. Within that flow, a well-developed shortwave trough is evident in moisture- channel imagery from the Dakotas to northeastern CO, preceded closely by a smaller but convectively augmented perturbation over parts of IA, northwestern MO and eastern KS. As these features pivot through the broader cyclonic flow today, the leading perturbation's MCV should move across northern parts of IL/IN/OH and perhaps extreme southern Lower MI. The trailing, stronger trough should extend from central MN to central NE by 00Z, then cross the remainder of MN/NE and much of IA overnight with an at least intermittently closed 500-mb low. At the surface, the 11Z analysis showed a frontal-wave low over southwestern IA, with some possible augmentation from wake effects related to an area od precip/convection to the east and southeast. A wavy cold front, with several weak lows attached, was drawn from there across eastern/southern KS, the TX Panhandle, and north- central NM, preceded by outflow boundaries from northern OK across southern MO. By 00Z, the cold front should reach northwestern IL, central MO, southwestern OK, and central NM, with diffuse warm front over central parts of IL/IN/OH near or north of a convective boundary. By 12Z, the cold front should reach northwestern IN, southern IL, southern MO, southeastern OK, north-central/northwest TX, and southern NM. ...Southern Plains to lower Ohio Valley... Multiple rounds of convection are expected across this corridor today, contributing to the overall severe potential, without sharp demarcation between the three main regimes numbered below. The outlook has been expanded northeastward up the Ohio Valley in deference to an increased severe threat related both directly and indirectly to MCV-aided convection. 1. Ahead of the MCV and accompanying perturbation, a broad area of clouds and precip is apparent from central/northern MO across southern/central IL and extending into southern IN. The southern rim of this precip area contains scattered, initially non-severe thunderstorms, utilizing a broad warm-advection/moisture-transport plume with parcels isentropically lifted to an LFC. All this activity will continue to shift eastward through the remainder of the morning, helping to reinforce the ambient baroclinic zone across the area, which in turn should help to focus later/afternoon development. Meanwhile, some of the morning activity may encounter a diurnally destabilizing boundary layer with weakening MLCINH, more purely surface-based effective-inflow parcels, and rich boundary- layer moisture. The associated outflow/differential-heating boundary may shift somewhat northward today over southern/central parts of IL/IN before the leading perturbation passes, and also, can act to back low-level flow and enlarge hodographs, in a moisture- rich, low-LCL environment. As such, some supercell/tornado potential has become evident, with damaging gusts and isolated large hail also possible. 2. Closely following that regime, and perhaps blending with the western part of it, a round of widely scattered to scattered thunderstorms is expected along/ahead of the front from central/ southern MO to the lower Ohio Valley this afternoon into evening, as large-scale ascent from the stronger/trailing shortwave trough overspreads a still very moist air mass. Strong insolation and surface dewpoints in the low/mid 70s F will offset modest mid/upper- level lapse rates to yield MLCAPE in the 1500-2500 J/kg range south of the front and outflow boundary. While warm-sector surface flow will be weak, and more veered than on the boundary, sufficient deep/speed shear still should be present for a blend of multicells and at least transient supercells, with some clustering/bowing of convection possible as well. Damaging to severe gusts will be the main threats with this activity, though a tornado and isolated large hail may occur. 3. Vertical shear generally will weaken with westward extent near and ahead of the front, but substantially hotter surface conditions will contribute to very steep boundary-layer lapse rates and "inverted-v" thermodynamic profiles in the subcloud layer. A plume of 2000-2500 J/kg MLCAPE is expected over northern OK, decreasing southwestward across northwest TX into drier and still more deeply well-mixed conditions. As such, severe downdrafts and isolated large hail will be possible, with greatest potential concentration of the gust threat in the OK to southeast KS corridor. Activity forming in this regime also may persist and move/merge into the MO environment from late afternoon into evening. ...Upper Mississippi Valley region... Scattered thunderstorms are expected to develop as early as midday, and continue through the afternoon, east through southeast of the developing mid/upper low and primary vorticity maximum. Some of this convection will become supercells, capable of large hail and damaging gusts, with clustering or line segments also possible. The most favorable low-level parameter space for that convection to become severe still appears to be across southern MN, northern IA and western WI, where residual moisture north of the optimal warm sector still will support surface dewpoints in the mid 60s F, amid pockets of favorable diurnal heating and low-level warm advection behind the morning cloud/precip plume. Large-scale ascent will occur in relation to midlevel DCVA preceding the trough aloft, and the left-exit region of a cyclonically curved, 250-300-mb speed max. Though low-level flow should be modest, favorable deep shear (effective-shear magnitudes in the 45-55-kt range) will support organized convection for several hours. Overall, this activity should diminish through the evening as nocturnal cooling and expansive outflow air collectively stabilize the boundary layer. ..Edwards/Kerr.. 07/04/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Thu Jul 04 2024 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...AND LOWER OHIO VALLEY TO SOUTHERN PLAINS... ...SUMMARY... Severe thunderstorms will be possible across parts of the upper Mississippi Valley, and lower Ohio Valley to southern Plains. ...Synopsis... In mid/upper levels, strengthening ridging over the Pacific Coast will result in height rises over much of the Northwest, while the subtropical ridge weakens slightly across the Gulf Coast States and GA. Broadly cyclonic flow still will prevail from the northern Rockies across the central/northern Plains and Great Lakes. Within that flow, a well-developed shortwave trough is evident in moisture- channel imagery from the Dakotas to northeastern CO, preceded closely by a smaller but convectively augmented perturbation over parts of IA, northwestern MO and eastern KS. As these features pivot through the broader cyclonic flow today, the leading perturbation's MCV should move across northern parts of IL/IN/OH and perhaps extreme southern Lower MI. The trailing, stronger trough should extend from central MN to central NE by 00Z, then cross the remainder of MN/NE and much of IA overnight with an at least intermittently closed 500-mb low. At the surface, the 11Z analysis showed a frontal-wave low over southwestern IA, with some possible augmentation from wake effects related to an area od precip/convection to the east and southeast. A wavy cold front, with several weak lows attached, was drawn from there across eastern/southern KS, the TX Panhandle, and north- central NM, preceded by outflow boundaries from northern OK across southern MO. By 00Z, the cold front should reach northwestern IL, central MO, southwestern OK, and central NM, with diffuse warm front over central parts of IL/IN/OH near or north of a convective boundary. By 12Z, the cold front should reach northwestern IN, southern IL, southern MO, southeastern OK, north-central/northwest TX, and southern NM. ...Southern Plains to lower Ohio Valley... Multiple rounds of convection are expected across this corridor today, contributing to the overall severe potential, without sharp demarcation between the three main regimes numbered below. The outlook has been expanded northeastward up the Ohio Valley in deference to an increased severe threat related both directly and indirectly to MCV-aided convection. 1. Ahead of the MCV and accompanying perturbation, a broad area of clouds and precip is apparent from central/northern MO across southern/central IL and extending into southern IN. The southern rim of this precip area contains scattered, initially non-severe thunderstorms, utilizing a broad warm-advection/moisture-transport plume with parcels isentropically lifted to an LFC. All this activity will continue to shift eastward through the remainder of the morning, helping to reinforce the ambient baroclinic zone across the area, which in turn should help to focus later/afternoon development. Meanwhile, some of the morning activity may encounter a diurnally destabilizing boundary layer with weakening MLCINH, more purely surface-based effective-inflow parcels, and rich boundary- layer moisture. The associated outflow/differential-heating boundary may shift somewhat northward today over southern/central parts of IL/IN before the leading perturbation passes, and also, can act to back low-level flow and enlarge hodographs, in a moisture- rich, low-LCL environment. As such, some supercell/tornado potential has become evident, with damaging gusts and isolated large hail also possible. 2. Closely following that regime, and perhaps blending with the western part of it, a round of widely scattered to scattered thunderstorms is expected along/ahead of the front from central/ southern MO to the lower Ohio Valley this afternoon into evening, as large-scale ascent from the stronger/trailing shortwave trough overspreads a still very moist air mass. Strong insolation and surface dewpoints in the low/mid 70s F will offset modest mid/upper- level lapse rates to yield MLCAPE in the 1500-2500 J/kg range south of the front and outflow boundary. While warm-sector surface flow will be weak, and more veered than on the boundary, sufficient deep/speed shear still should be present for a blend of multicells and at least transient supercells, with some clustering/bowing of convection possible as well. Damaging to severe gusts will be the main threats with this activity, though a tornado and isolated large hail may occur. 3. Vertical shear generally will weaken with westward extent near and ahead of the front, but substantially hotter surface conditions will contribute to very steep boundary-layer lapse rates and "inverted-v" thermodynamic profiles in the subcloud layer. A plume of 2000-2500 J/kg MLCAPE is expected over northern OK, decreasing southwestward across northwest TX into drier and still more deeply well-mixed conditions. As such, severe downdrafts and isolated large hail will be possible, with greatest potential concentration of the gust threat in the OK to southeast KS corridor. Activity forming in this regime also may persist and move/merge into the MO environment from late afternoon into evening. ...Upper Mississippi Valley region... Scattered thunderstorms are expected to develop as early as midday, and continue through the afternoon, east through southeast of the developing mid/upper low and primary vorticity maximum. Some of this convection will become supercells, capable of large hail and damaging gusts, with clustering or line segments also possible. The most favorable low-level parameter space for that convection to become severe still appears to be across southern MN, northern IA and western WI, where residual moisture north of the optimal warm sector still will support surface dewpoints in the mid 60s F, amid pockets of favorable diurnal heating and low-level warm advection behind the morning cloud/precip plume. Large-scale ascent will occur in relation to midlevel DCVA preceding the trough aloft, and the left-exit region of a cyclonically curved, 250-300-mb speed max. Though low-level flow should be modest, favorable deep shear (effective-shear magnitudes in the 45-55-kt range) will support organized convection for several hours. Overall, this activity should diminish through the evening as nocturnal cooling and expansive outflow air collectively stabilize the boundary layer. ..Edwards/Kerr.. 07/04/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Thu Jul 04 2024 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...AND LOWER OHIO VALLEY TO SOUTHERN PLAINS... ...SUMMARY... Severe thunderstorms will be possible across parts of the upper Mississippi Valley, and lower Ohio Valley to southern Plains. ...Synopsis... In mid/upper levels, strengthening ridging over the Pacific Coast will result in height rises over much of the Northwest, while the subtropical ridge weakens slightly across the Gulf Coast States and GA. Broadly cyclonic flow still will prevail from the northern Rockies across the central/northern Plains and Great Lakes. Within that flow, a well-developed shortwave trough is evident in moisture- channel imagery from the Dakotas to northeastern CO, preceded closely by a smaller but convectively augmented perturbation over parts of IA, northwestern MO and eastern KS. As these features pivot through the broader cyclonic flow today, the leading perturbation's MCV should move across northern parts of IL/IN/OH and perhaps extreme southern Lower MI. The trailing, stronger trough should extend from central MN to central NE by 00Z, then cross the remainder of MN/NE and much of IA overnight with an at least intermittently closed 500-mb low. At the surface, the 11Z analysis showed a frontal-wave low over southwestern IA, with some possible augmentation from wake effects related to an area od precip/convection to the east and southeast. A wavy cold front, with several weak lows attached, was drawn from there across eastern/southern KS, the TX Panhandle, and north- central NM, preceded by outflow boundaries from northern OK across southern MO. By 00Z, the cold front should reach northwestern IL, central MO, southwestern OK, and central NM, with diffuse warm front over central parts of IL/IN/OH near or north of a convective boundary. By 12Z, the cold front should reach northwestern IN, southern IL, southern MO, southeastern OK, north-central/northwest TX, and southern NM. ...Southern Plains to lower Ohio Valley... Multiple rounds of convection are expected across this corridor today, contributing to the overall severe potential, without sharp demarcation between the three main regimes numbered below. The outlook has been expanded northeastward up the Ohio Valley in deference to an increased severe threat related both directly and indirectly to MCV-aided convection. 1. Ahead of the MCV and accompanying perturbation, a broad area of clouds and precip is apparent from central/northern MO across southern/central IL and extending into southern IN. The southern rim of this precip area contains scattered, initially non-severe thunderstorms, utilizing a broad warm-advection/moisture-transport plume with parcels isentropically lifted to an LFC. All this activity will continue to shift eastward through the remainder of the morning, helping to reinforce the ambient baroclinic zone across the area, which in turn should help to focus later/afternoon development. Meanwhile, some of the morning activity may encounter a diurnally destabilizing boundary layer with weakening MLCINH, more purely surface-based effective-inflow parcels, and rich boundary- layer moisture. The associated outflow/differential-heating boundary may shift somewhat northward today over southern/central parts of IL/IN before the leading perturbation passes, and also, can act to back low-level flow and enlarge hodographs, in a moisture- rich, low-LCL environment. As such, some supercell/tornado potential has become evident, with damaging gusts and isolated large hail also possible. 2. Closely following that regime, and perhaps blending with the western part of it, a round of widely scattered to scattered thunderstorms is expected along/ahead of the front from central/ southern MO to the lower Ohio Valley this afternoon into evening, as large-scale ascent from the stronger/trailing shortwave trough overspreads a still very moist air mass. Strong insolation and surface dewpoints in the low/mid 70s F will offset modest mid/upper- level lapse rates to yield MLCAPE in the 1500-2500 J/kg range south of the front and outflow boundary. While warm-sector surface flow will be weak, and more veered than on the boundary, sufficient deep/speed shear still should be present for a blend of multicells and at least transient supercells, with some clustering/bowing of convection possible as well. Damaging to severe gusts will be the main threats with this activity, though a tornado and isolated large hail may occur. 3. Vertical shear generally will weaken with westward extent near and ahead of the front, but substantially hotter surface conditions will contribute to very steep boundary-layer lapse rates and "inverted-v" thermodynamic profiles in the subcloud layer. A plume of 2000-2500 J/kg MLCAPE is expected over northern OK, decreasing southwestward across northwest TX into drier and still more deeply well-mixed conditions. As such, severe downdrafts and isolated large hail will be possible, with greatest potential concentration of the gust threat in the OK to southeast KS corridor. Activity forming in this regime also may persist and move/merge into the MO environment from late afternoon into evening. ...Upper Mississippi Valley region... Scattered thunderstorms are expected to develop as early as midday, and continue through the afternoon, east through southeast of the developing mid/upper low and primary vorticity maximum. Some of this convection will become supercells, capable of large hail and damaging gusts, with clustering or line segments also possible. The most favorable low-level parameter space for that convection to become severe still appears to be across southern MN, northern IA and western WI, where residual moisture north of the optimal warm sector still will support surface dewpoints in the mid 60s F, amid pockets of favorable diurnal heating and low-level warm advection behind the morning cloud/precip plume. Large-scale ascent will occur in relation to midlevel DCVA preceding the trough aloft, and the left-exit region of a cyclonically curved, 250-300-mb speed max. Though low-level flow should be modest, favorable deep shear (effective-shear magnitudes in the 45-55-kt range) will support organized convection for several hours. Overall, this activity should diminish through the evening as nocturnal cooling and expansive outflow air collectively stabilize the boundary layer. ..Edwards/Kerr.. 07/04/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Thu Jul 04 2024 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...AND LOWER OHIO VALLEY TO SOUTHERN PLAINS... ...SUMMARY... Severe thunderstorms will be possible across parts of the upper Mississippi Valley, and lower Ohio Valley to southern Plains. ...Synopsis... In mid/upper levels, strengthening ridging over the Pacific Coast will result in height rises over much of the Northwest, while the subtropical ridge weakens slightly across the Gulf Coast States and GA. Broadly cyclonic flow still will prevail from the northern Rockies across the central/northern Plains and Great Lakes. Within that flow, a well-developed shortwave trough is evident in moisture- channel imagery from the Dakotas to northeastern CO, preceded closely by a smaller but convectively augmented perturbation over parts of IA, northwestern MO and eastern KS. As these features pivot through the broader cyclonic flow today, the leading perturbation's MCV should move across northern parts of IL/IN/OH and perhaps extreme southern Lower MI. The trailing, stronger trough should extend from central MN to central NE by 00Z, then cross the remainder of MN/NE and much of IA overnight with an at least intermittently closed 500-mb low. At the surface, the 11Z analysis showed a frontal-wave low over southwestern IA, with some possible augmentation from wake effects related to an area od precip/convection to the east and southeast. A wavy cold front, with several weak lows attached, was drawn from there across eastern/southern KS, the TX Panhandle, and north- central NM, preceded by outflow boundaries from northern OK across southern MO. By 00Z, the cold front should reach northwestern IL, central MO, southwestern OK, and central NM, with diffuse warm front over central parts of IL/IN/OH near or north of a convective boundary. By 12Z, the cold front should reach northwestern IN, southern IL, southern MO, southeastern OK, north-central/northwest TX, and southern NM. ...Southern Plains to lower Ohio Valley... Multiple rounds of convection are expected across this corridor today, contributing to the overall severe potential, without sharp demarcation between the three main regimes numbered below. The outlook has been expanded northeastward up the Ohio Valley in deference to an increased severe threat related both directly and indirectly to MCV-aided convection. 1. Ahead of the MCV and accompanying perturbation, a broad area of clouds and precip is apparent from central/northern MO across southern/central IL and extending into southern IN. The southern rim of this precip area contains scattered, initially non-severe thunderstorms, utilizing a broad warm-advection/moisture-transport plume with parcels isentropically lifted to an LFC. All this activity will continue to shift eastward through the remainder of the morning, helping to reinforce the ambient baroclinic zone across the area, which in turn should help to focus later/afternoon development. Meanwhile, some of the morning activity may encounter a diurnally destabilizing boundary layer with weakening MLCINH, more purely surface-based effective-inflow parcels, and rich boundary- layer moisture. The associated outflow/differential-heating boundary may shift somewhat northward today over southern/central parts of IL/IN before the leading perturbation passes, and also, can act to back low-level flow and enlarge hodographs, in a moisture- rich, low-LCL environment. As such, some supercell/tornado potential has become evident, with damaging gusts and isolated large hail also possible. 2. Closely following that regime, and perhaps blending with the western part of it, a round of widely scattered to scattered thunderstorms is expected along/ahead of the front from central/ southern MO to the lower Ohio Valley this afternoon into evening, as large-scale ascent from the stronger/trailing shortwave trough overspreads a still very moist air mass. Strong insolation and surface dewpoints in the low/mid 70s F will offset modest mid/upper- level lapse rates to yield MLCAPE in the 1500-2500 J/kg range south of the front and outflow boundary. While warm-sector surface flow will be weak, and more veered than on the boundary, sufficient deep/speed shear still should be present for a blend of multicells and at least transient supercells, with some clustering/bowing of convection possible as well. Damaging to severe gusts will be the main threats with this activity, though a tornado and isolated large hail may occur. 3. Vertical shear generally will weaken with westward extent near and ahead of the front, but substantially hotter surface conditions will contribute to very steep boundary-layer lapse rates and "inverted-v" thermodynamic profiles in the subcloud layer. A plume of 2000-2500 J/kg MLCAPE is expected over northern OK, decreasing southwestward across northwest TX into drier and still more deeply well-mixed conditions. As such, severe downdrafts and isolated large hail will be possible, with greatest potential concentration of the gust threat in the OK to southeast KS corridor. Activity forming in this regime also may persist and move/merge into the MO environment from late afternoon into evening. ...Upper Mississippi Valley region... Scattered thunderstorms are expected to develop as early as midday, and continue through the afternoon, east through southeast of the developing mid/upper low and primary vorticity maximum. Some of this convection will become supercells, capable of large hail and damaging gusts, with clustering or line segments also possible. The most favorable low-level parameter space for that convection to become severe still appears to be across southern MN, northern IA and western WI, where residual moisture north of the optimal warm sector still will support surface dewpoints in the mid 60s F, amid pockets of favorable diurnal heating and low-level warm advection behind the morning cloud/precip plume. Large-scale ascent will occur in relation to midlevel DCVA preceding the trough aloft, and the left-exit region of a cyclonically curved, 250-300-mb speed max. Though low-level flow should be modest, favorable deep shear (effective-shear magnitudes in the 45-55-kt range) will support organized convection for several hours. Overall, this activity should diminish through the evening as nocturnal cooling and expansive outflow air collectively stabilize the boundary layer. ..Edwards/Kerr.. 07/04/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Thu Jul 04 2024 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...AND LOWER OHIO VALLEY TO SOUTHERN PLAINS... ...SUMMARY... Severe thunderstorms will be possible across parts of the upper Mississippi Valley, and lower Ohio Valley to southern Plains. ...Synopsis... In mid/upper levels, strengthening ridging over the Pacific Coast will result in height rises over much of the Northwest, while the subtropical ridge weakens slightly across the Gulf Coast States and GA. Broadly cyclonic flow still will prevail from the northern Rockies across the central/northern Plains and Great Lakes. Within that flow, a well-developed shortwave trough is evident in moisture- channel imagery from the Dakotas to northeastern CO, preceded closely by a smaller but convectively augmented perturbation over parts of IA, northwestern MO and eastern KS. As these features pivot through the broader cyclonic flow today, the leading perturbation's MCV should move across northern parts of IL/IN/OH and perhaps extreme southern Lower MI. The trailing, stronger trough should extend from central MN to central NE by 00Z, then cross the remainder of MN/NE and much of IA overnight with an at least intermittently closed 500-mb low. At the surface, the 11Z analysis showed a frontal-wave low over southwestern IA, with some possible augmentation from wake effects related to an area od precip/convection to the east and southeast. A wavy cold front, with several weak lows attached, was drawn from there across eastern/southern KS, the TX Panhandle, and north- central NM, preceded by outflow boundaries from northern OK across southern MO. By 00Z, the cold front should reach northwestern IL, central MO, southwestern OK, and central NM, with diffuse warm front over central parts of IL/IN/OH near or north of a convective boundary. By 12Z, the cold front should reach northwestern IN, southern IL, southern MO, southeastern OK, north-central/northwest TX, and southern NM. ...Southern Plains to lower Ohio Valley... Multiple rounds of convection are expected across this corridor today, contributing to the overall severe potential, without sharp demarcation between the three main regimes numbered below. The outlook has been expanded northeastward up the Ohio Valley in deference to an increased severe threat related both directly and indirectly to MCV-aided convection. 1. Ahead of the MCV and accompanying perturbation, a broad area of clouds and precip is apparent from central/northern MO across southern/central IL and extending into southern IN. The southern rim of this precip area contains scattered, initially non-severe thunderstorms, utilizing a broad warm-advection/moisture-transport plume with parcels isentropically lifted to an LFC. All this activity will continue to shift eastward through the remainder of the morning, helping to reinforce the ambient baroclinic zone across the area, which in turn should help to focus later/afternoon development. Meanwhile, some of the morning activity may encounter a diurnally destabilizing boundary layer with weakening MLCINH, more purely surface-based effective-inflow parcels, and rich boundary- layer moisture. The associated outflow/differential-heating boundary may shift somewhat northward today over southern/central parts of IL/IN before the leading perturbation passes, and also, can act to back low-level flow and enlarge hodographs, in a moisture- rich, low-LCL environment. As such, some supercell/tornado potential has become evident, with damaging gusts and isolated large hail also possible. 2. Closely following that regime, and perhaps blending with the western part of it, a round of widely scattered to scattered thunderstorms is expected along/ahead of the front from central/ southern MO to the lower Ohio Valley this afternoon into evening, as large-scale ascent from the stronger/trailing shortwave trough overspreads a still very moist air mass. Strong insolation and surface dewpoints in the low/mid 70s F will offset modest mid/upper- level lapse rates to yield MLCAPE in the 1500-2500 J/kg range south of the front and outflow boundary. While warm-sector surface flow will be weak, and more veered than on the boundary, sufficient deep/speed shear still should be present for a blend of multicells and at least transient supercells, with some clustering/bowing of convection possible as well. Damaging to severe gusts will be the main threats with this activity, though a tornado and isolated large hail may occur. 3. Vertical shear generally will weaken with westward extent near and ahead of the front, but substantially hotter surface conditions will contribute to very steep boundary-layer lapse rates and "inverted-v" thermodynamic profiles in the subcloud layer. A plume of 2000-2500 J/kg MLCAPE is expected over northern OK, decreasing southwestward across northwest TX into drier and still more deeply well-mixed conditions. As such, severe downdrafts and isolated large hail will be possible, with greatest potential concentration of the gust threat in the OK to southeast KS corridor. Activity forming in this regime also may persist and move/merge into the MO environment from late afternoon into evening. ...Upper Mississippi Valley region... Scattered thunderstorms are expected to develop as early as midday, and continue through the afternoon, east through southeast of the developing mid/upper low and primary vorticity maximum. Some of this convection will become supercells, capable of large hail and damaging gusts, with clustering or line segments also possible. The most favorable low-level parameter space for that convection to become severe still appears to be across southern MN, northern IA and western WI, where residual moisture north of the optimal warm sector still will support surface dewpoints in the mid 60s F, amid pockets of favorable diurnal heating and low-level warm advection behind the morning cloud/precip plume. Large-scale ascent will occur in relation to midlevel DCVA preceding the trough aloft, and the left-exit region of a cyclonically curved, 250-300-mb speed max. Though low-level flow should be modest, favorable deep shear (effective-shear magnitudes in the 45-55-kt range) will support organized convection for several hours. Overall, this activity should diminish through the evening as nocturnal cooling and expansive outflow air collectively stabilize the boundary layer. ..Edwards/Kerr.. 07/04/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Thu Jul 04 2024 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...AND LOWER OHIO VALLEY TO SOUTHERN PLAINS... ...SUMMARY... Severe thunderstorms will be possible across parts of the upper Mississippi Valley, and lower Ohio Valley to southern Plains. ...Synopsis... In mid/upper levels, strengthening ridging over the Pacific Coast will result in height rises over much of the Northwest, while the subtropical ridge weakens slightly across the Gulf Coast States and GA. Broadly cyclonic flow still will prevail from the northern Rockies across the central/northern Plains and Great Lakes. Within that flow, a well-developed shortwave trough is evident in moisture- channel imagery from the Dakotas to northeastern CO, preceded closely by a smaller but convectively augmented perturbation over parts of IA, northwestern MO and eastern KS. As these features pivot through the broader cyclonic flow today, the leading perturbation's MCV should move across northern parts of IL/IN/OH and perhaps extreme southern Lower MI. The trailing, stronger trough should extend from central MN to central NE by 00Z, then cross the remainder of MN/NE and much of IA overnight with an at least intermittently closed 500-mb low. At the surface, the 11Z analysis showed a frontal-wave low over southwestern IA, with some possible augmentation from wake effects related to an area od precip/convection to the east and southeast. A wavy cold front, with several weak lows attached, was drawn from there across eastern/southern KS, the TX Panhandle, and north- central NM, preceded by outflow boundaries from northern OK across southern MO. By 00Z, the cold front should reach northwestern IL, central MO, southwestern OK, and central NM, with diffuse warm front over central parts of IL/IN/OH near or north of a convective boundary. By 12Z, the cold front should reach northwestern IN, southern IL, southern MO, southeastern OK, north-central/northwest TX, and southern NM. ...Southern Plains to lower Ohio Valley... Multiple rounds of convection are expected across this corridor today, contributing to the overall severe potential, without sharp demarcation between the three main regimes numbered below. The outlook has been expanded northeastward up the Ohio Valley in deference to an increased severe threat related both directly and indirectly to MCV-aided convection. 1. Ahead of the MCV and accompanying perturbation, a broad area of clouds and precip is apparent from central/northern MO across southern/central IL and extending into southern IN. The southern rim of this precip area contains scattered, initially non-severe thunderstorms, utilizing a broad warm-advection/moisture-transport plume with parcels isentropically lifted to an LFC. All this activity will continue to shift eastward through the remainder of the morning, helping to reinforce the ambient baroclinic zone across the area, which in turn should help to focus later/afternoon development. Meanwhile, some of the morning activity may encounter a diurnally destabilizing boundary layer with weakening MLCINH, more purely surface-based effective-inflow parcels, and rich boundary- layer moisture. The associated outflow/differential-heating boundary may shift somewhat northward today over southern/central parts of IL/IN before the leading perturbation passes, and also, can act to back low-level flow and enlarge hodographs, in a moisture- rich, low-LCL environment. As such, some supercell/tornado potential has become evident, with damaging gusts and isolated large hail also possible. 2. Closely following that regime, and perhaps blending with the western part of it, a round of widely scattered to scattered thunderstorms is expected along/ahead of the front from central/ southern MO to the lower Ohio Valley this afternoon into evening, as large-scale ascent from the stronger/trailing shortwave trough overspreads a still very moist air mass. Strong insolation and surface dewpoints in the low/mid 70s F will offset modest mid/upper- level lapse rates to yield MLCAPE in the 1500-2500 J/kg range south of the front and outflow boundary. While warm-sector surface flow will be weak, and more veered than on the boundary, sufficient deep/speed shear still should be present for a blend of multicells and at least transient supercells, with some clustering/bowing of convection possible as well. Damaging to severe gusts will be the main threats with this activity, though a tornado and isolated large hail may occur. 3. Vertical shear generally will weaken with westward extent near and ahead of the front, but substantially hotter surface conditions will contribute to very steep boundary-layer lapse rates and "inverted-v" thermodynamic profiles in the subcloud layer. A plume of 2000-2500 J/kg MLCAPE is expected over northern OK, decreasing southwestward across northwest TX into drier and still more deeply well-mixed conditions. As such, severe downdrafts and isolated large hail will be possible, with greatest potential concentration of the gust threat in the OK to southeast KS corridor. Activity forming in this regime also may persist and move/merge into the MO environment from late afternoon into evening. ...Upper Mississippi Valley region... Scattered thunderstorms are expected to develop as early as midday, and continue through the afternoon, east through southeast of the developing mid/upper low and primary vorticity maximum. Some of this convection will become supercells, capable of large hail and damaging gusts, with clustering or line segments also possible. The most favorable low-level parameter space for that convection to become severe still appears to be across southern MN, northern IA and western WI, where residual moisture north of the optimal warm sector still will support surface dewpoints in the mid 60s F, amid pockets of favorable diurnal heating and low-level warm advection behind the morning cloud/precip plume. Large-scale ascent will occur in relation to midlevel DCVA preceding the trough aloft, and the left-exit region of a cyclonically curved, 250-300-mb speed max. Though low-level flow should be modest, favorable deep shear (effective-shear magnitudes in the 45-55-kt range) will support organized convection for several hours. Overall, this activity should diminish through the evening as nocturnal cooling and expansive outflow air collectively stabilize the boundary layer. ..Edwards/Kerr.. 07/04/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Thu Jul 04 2024 Valid 071200Z - 121200Z ...DISCUSSION... ...D4/Sunday... The upper-level trough will dig slightly farther south into Oklahoma before lifting northeastward on Monday. For portions of the central/southern Plains, both the ECMWF and GFS suggest that convection will develop along the intersection of the cold and warm front within a weak surface low. Similar to Saturday, moisture will not be overly rich, but northward moisture return will be in progress. Convection is forecast to grow upscale into an MCS and move southward into the greater buoyancy. With differences in the position and intensity of the surface low, as well as possible impacts from convection on Saturday, predictability remains too low for the introduction of 15% total severe probabilities. TC Beryl continues to move towards the Yucatan Peninsula and is expected to reach the Mexican coast south of Brownsville, TX on Sunday per latest NHC forecasts. Some tornado risk is possible for parts of South Texas, but magnitude and spatial extent of this risk will depend on how much the TC restrengthens after interacting with the Peninsula and where the system will actually track late this weekend into early next week. ...D5/Monday and beyond... The upper-level trough will slowly make progress into the Midwest and eventually into the Ohio Valley and Northeast. While some severe risk is possible ahead of this trough, questions regarding destabilization and general lack of robust surface features during the upcoming week keep confidence too low for highlights at this time. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Thu Jul 04 2024 Valid 071200Z - 121200Z ...DISCUSSION... ...D4/Sunday... The upper-level trough will dig slightly farther south into Oklahoma before lifting northeastward on Monday. For portions of the central/southern Plains, both the ECMWF and GFS suggest that convection will develop along the intersection of the cold and warm front within a weak surface low. Similar to Saturday, moisture will not be overly rich, but northward moisture return will be in progress. Convection is forecast to grow upscale into an MCS and move southward into the greater buoyancy. With differences in the position and intensity of the surface low, as well as possible impacts from convection on Saturday, predictability remains too low for the introduction of 15% total severe probabilities. TC Beryl continues to move towards the Yucatan Peninsula and is expected to reach the Mexican coast south of Brownsville, TX on Sunday per latest NHC forecasts. Some tornado risk is possible for parts of South Texas, but magnitude and spatial extent of this risk will depend on how much the TC restrengthens after interacting with the Peninsula and where the system will actually track late this weekend into early next week. ...D5/Monday and beyond... The upper-level trough will slowly make progress into the Midwest and eventually into the Ohio Valley and Northeast. While some severe risk is possible ahead of this trough, questions regarding destabilization and general lack of robust surface features during the upcoming week keep confidence too low for highlights at this time. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Thu Jul 04 2024 Valid 071200Z - 121200Z ...DISCUSSION... ...D4/Sunday... The upper-level trough will dig slightly farther south into Oklahoma before lifting northeastward on Monday. For portions of the central/southern Plains, both the ECMWF and GFS suggest that convection will develop along the intersection of the cold and warm front within a weak surface low. Similar to Saturday, moisture will not be overly rich, but northward moisture return will be in progress. Convection is forecast to grow upscale into an MCS and move southward into the greater buoyancy. With differences in the position and intensity of the surface low, as well as possible impacts from convection on Saturday, predictability remains too low for the introduction of 15% total severe probabilities. TC Beryl continues to move towards the Yucatan Peninsula and is expected to reach the Mexican coast south of Brownsville, TX on Sunday per latest NHC forecasts. Some tornado risk is possible for parts of South Texas, but magnitude and spatial extent of this risk will depend on how much the TC restrengthens after interacting with the Peninsula and where the system will actually track late this weekend into early next week. ...D5/Monday and beyond... The upper-level trough will slowly make progress into the Midwest and eventually into the Ohio Valley and Northeast. While some severe risk is possible ahead of this trough, questions regarding destabilization and general lack of robust surface features during the upcoming week keep confidence too low for highlights at this time. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Thu Jul 04 2024 Valid 071200Z - 121200Z ...DISCUSSION... ...D4/Sunday... The upper-level trough will dig slightly farther south into Oklahoma before lifting northeastward on Monday. For portions of the central/southern Plains, both the ECMWF and GFS suggest that convection will develop along the intersection of the cold and warm front within a weak surface low. Similar to Saturday, moisture will not be overly rich, but northward moisture return will be in progress. Convection is forecast to grow upscale into an MCS and move southward into the greater buoyancy. With differences in the position and intensity of the surface low, as well as possible impacts from convection on Saturday, predictability remains too low for the introduction of 15% total severe probabilities. TC Beryl continues to move towards the Yucatan Peninsula and is expected to reach the Mexican coast south of Brownsville, TX on Sunday per latest NHC forecasts. Some tornado risk is possible for parts of South Texas, but magnitude and spatial extent of this risk will depend on how much the TC restrengthens after interacting with the Peninsula and where the system will actually track late this weekend into early next week. ...D5/Monday and beyond... The upper-level trough will slowly make progress into the Midwest and eventually into the Ohio Valley and Northeast. While some severe risk is possible ahead of this trough, questions regarding destabilization and general lack of robust surface features during the upcoming week keep confidence too low for highlights at this time. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Thu Jul 04 2024 Valid 071200Z - 121200Z ...DISCUSSION... ...D4/Sunday... The upper-level trough will dig slightly farther south into Oklahoma before lifting northeastward on Monday. For portions of the central/southern Plains, both the ECMWF and GFS suggest that convection will develop along the intersection of the cold and warm front within a weak surface low. Similar to Saturday, moisture will not be overly rich, but northward moisture return will be in progress. Convection is forecast to grow upscale into an MCS and move southward into the greater buoyancy. With differences in the position and intensity of the surface low, as well as possible impacts from convection on Saturday, predictability remains too low for the introduction of 15% total severe probabilities. TC Beryl continues to move towards the Yucatan Peninsula and is expected to reach the Mexican coast south of Brownsville, TX on Sunday per latest NHC forecasts. Some tornado risk is possible for parts of South Texas, but magnitude and spatial extent of this risk will depend on how much the TC restrengthens after interacting with the Peninsula and where the system will actually track late this weekend into early next week. ...D5/Monday and beyond... The upper-level trough will slowly make progress into the Midwest and eventually into the Ohio Valley and Northeast. While some severe risk is possible ahead of this trough, questions regarding destabilization and general lack of robust surface features during the upcoming week keep confidence too low for highlights at this time. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0232 AM CDT Thu Jul 04 2024 Valid 061200Z - 071200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE SOUTHERN INTO THE NORTHERN PLAINS... ...SUMMARY... Potential for severe thunderstorms will exist across primarily parts of the Plains on Saturday. ...Synopsis... Broad, low-amplitude troughing aloft will be present within much of the CONUS apart from the West Coast. Shortwave perturbations moving through the broader trough are expected from the central Plains into the Midwest. At the surface, a low pressure system will be in southeastern Canada. The reservoir of richer surface moisture will have been pushed south of a cold front that will extend from the southern High Plains into the Mid-South and Northeast. As northwesterly flow aloft increases across the central Rockies, models suggest a lee surface low will develop within the CO/KS/NE vicinity. Models do differ on the intensity of this surface low as well as its exact position. ...Plains... Though moisture will have been reduced behind the cold front, models suggest that low 60s F dewpoints are possible perhaps as far north as Nebraska. In general, thunderstorm development is possible within the lee trough in the southern High Plains, near the surface low in the central High Plains, and also near a weak warm front/theta-e boundary in eastern Nebraska. The exact scenario which will produce the greatest severe risk remains uncertain, however. Given the remnant moisture, northwest flow advecting steep lapse rates into the region, and shortwave trough to provide forcing for ascent, some severe risk appears probable. At this point in time, large hail with initial supercells and a transition to more of a severe wind threat (given relatively large temperature-dewpoint spreads) are the primary concerns. The outlook area will likely have to be refined as additional guidance becomes available and confidence in corridors of greatest risk increases. ...Mid-Atlantic... Thunderstorms are possible along a weak cold front. Model trends have been for less storm coverage. Additionally, the trough may remain slightly displaced from the greatest buoyancy. Isolated strong to severe storms are possible, but coverage is too uncertain for highlights. ..Wendt.. 07/04/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0232 AM CDT Thu Jul 04 2024 Valid 061200Z - 071200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE SOUTHERN INTO THE NORTHERN PLAINS... ...SUMMARY... Potential for severe thunderstorms will exist across primarily parts of the Plains on Saturday. ...Synopsis... Broad, low-amplitude troughing aloft will be present within much of the CONUS apart from the West Coast. Shortwave perturbations moving through the broader trough are expected from the central Plains into the Midwest. At the surface, a low pressure system will be in southeastern Canada. The reservoir of richer surface moisture will have been pushed south of a cold front that will extend from the southern High Plains into the Mid-South and Northeast. As northwesterly flow aloft increases across the central Rockies, models suggest a lee surface low will develop within the CO/KS/NE vicinity. Models do differ on the intensity of this surface low as well as its exact position. ...Plains... Though moisture will have been reduced behind the cold front, models suggest that low 60s F dewpoints are possible perhaps as far north as Nebraska. In general, thunderstorm development is possible within the lee trough in the southern High Plains, near the surface low in the central High Plains, and also near a weak warm front/theta-e boundary in eastern Nebraska. The exact scenario which will produce the greatest severe risk remains uncertain, however. Given the remnant moisture, northwest flow advecting steep lapse rates into the region, and shortwave trough to provide forcing for ascent, some severe risk appears probable. At this point in time, large hail with initial supercells and a transition to more of a severe wind threat (given relatively large temperature-dewpoint spreads) are the primary concerns. The outlook area will likely have to be refined as additional guidance becomes available and confidence in corridors of greatest risk increases. ...Mid-Atlantic... Thunderstorms are possible along a weak cold front. Model trends have been for less storm coverage. Additionally, the trough may remain slightly displaced from the greatest buoyancy. Isolated strong to severe storms are possible, but coverage is too uncertain for highlights. ..Wendt.. 07/04/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0232 AM CDT Thu Jul 04 2024 Valid 061200Z - 071200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE SOUTHERN INTO THE NORTHERN PLAINS... ...SUMMARY... Potential for severe thunderstorms will exist across primarily parts of the Plains on Saturday. ...Synopsis... Broad, low-amplitude troughing aloft will be present within much of the CONUS apart from the West Coast. Shortwave perturbations moving through the broader trough are expected from the central Plains into the Midwest. At the surface, a low pressure system will be in southeastern Canada. The reservoir of richer surface moisture will have been pushed south of a cold front that will extend from the southern High Plains into the Mid-South and Northeast. As northwesterly flow aloft increases across the central Rockies, models suggest a lee surface low will develop within the CO/KS/NE vicinity. Models do differ on the intensity of this surface low as well as its exact position. ...Plains... Though moisture will have been reduced behind the cold front, models suggest that low 60s F dewpoints are possible perhaps as far north as Nebraska. In general, thunderstorm development is possible within the lee trough in the southern High Plains, near the surface low in the central High Plains, and also near a weak warm front/theta-e boundary in eastern Nebraska. The exact scenario which will produce the greatest severe risk remains uncertain, however. Given the remnant moisture, northwest flow advecting steep lapse rates into the region, and shortwave trough to provide forcing for ascent, some severe risk appears probable. At this point in time, large hail with initial supercells and a transition to more of a severe wind threat (given relatively large temperature-dewpoint spreads) are the primary concerns. The outlook area will likely have to be refined as additional guidance becomes available and confidence in corridors of greatest risk increases. ...Mid-Atlantic... Thunderstorms are possible along a weak cold front. Model trends have been for less storm coverage. Additionally, the trough may remain slightly displaced from the greatest buoyancy. Isolated strong to severe storms are possible, but coverage is too uncertain for highlights. ..Wendt.. 07/04/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0232 AM CDT Thu Jul 04 2024 Valid 061200Z - 071200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE SOUTHERN INTO THE NORTHERN PLAINS... ...SUMMARY... Potential for severe thunderstorms will exist across primarily parts of the Plains on Saturday. ...Synopsis... Broad, low-amplitude troughing aloft will be present within much of the CONUS apart from the West Coast. Shortwave perturbations moving through the broader trough are expected from the central Plains into the Midwest. At the surface, a low pressure system will be in southeastern Canada. The reservoir of richer surface moisture will have been pushed south of a cold front that will extend from the southern High Plains into the Mid-South and Northeast. As northwesterly flow aloft increases across the central Rockies, models suggest a lee surface low will develop within the CO/KS/NE vicinity. Models do differ on the intensity of this surface low as well as its exact position. ...Plains... Though moisture will have been reduced behind the cold front, models suggest that low 60s F dewpoints are possible perhaps as far north as Nebraska. In general, thunderstorm development is possible within the lee trough in the southern High Plains, near the surface low in the central High Plains, and also near a weak warm front/theta-e boundary in eastern Nebraska. The exact scenario which will produce the greatest severe risk remains uncertain, however. Given the remnant moisture, northwest flow advecting steep lapse rates into the region, and shortwave trough to provide forcing for ascent, some severe risk appears probable. At this point in time, large hail with initial supercells and a transition to more of a severe wind threat (given relatively large temperature-dewpoint spreads) are the primary concerns. The outlook area will likely have to be refined as additional guidance becomes available and confidence in corridors of greatest risk increases. ...Mid-Atlantic... Thunderstorms are possible along a weak cold front. Model trends have been for less storm coverage. Additionally, the trough may remain slightly displaced from the greatest buoyancy. Isolated strong to severe storms are possible, but coverage is too uncertain for highlights. ..Wendt.. 07/04/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0232 AM CDT Thu Jul 04 2024 Valid 061200Z - 071200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE SOUTHERN INTO THE NORTHERN PLAINS... ...SUMMARY... Potential for severe thunderstorms will exist across primarily parts of the Plains on Saturday. ...Synopsis... Broad, low-amplitude troughing aloft will be present within much of the CONUS apart from the West Coast. Shortwave perturbations moving through the broader trough are expected from the central Plains into the Midwest. At the surface, a low pressure system will be in southeastern Canada. The reservoir of richer surface moisture will have been pushed south of a cold front that will extend from the southern High Plains into the Mid-South and Northeast. As northwesterly flow aloft increases across the central Rockies, models suggest a lee surface low will develop within the CO/KS/NE vicinity. Models do differ on the intensity of this surface low as well as its exact position. ...Plains... Though moisture will have been reduced behind the cold front, models suggest that low 60s F dewpoints are possible perhaps as far north as Nebraska. In general, thunderstorm development is possible within the lee trough in the southern High Plains, near the surface low in the central High Plains, and also near a weak warm front/theta-e boundary in eastern Nebraska. The exact scenario which will produce the greatest severe risk remains uncertain, however. Given the remnant moisture, northwest flow advecting steep lapse rates into the region, and shortwave trough to provide forcing for ascent, some severe risk appears probable. At this point in time, large hail with initial supercells and a transition to more of a severe wind threat (given relatively large temperature-dewpoint spreads) are the primary concerns. The outlook area will likely have to be refined as additional guidance becomes available and confidence in corridors of greatest risk increases. ...Mid-Atlantic... Thunderstorms are possible along a weak cold front. Model trends have been for less storm coverage. Additionally, the trough may remain slightly displaced from the greatest buoyancy. Isolated strong to severe storms are possible, but coverage is too uncertain for highlights. ..Wendt.. 07/04/2024 Read more

MD 1532 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR EASTERN KANSAS INTO WESTERN MISSOURI
Mesoscale Discussion 1532 NWS Storm Prediction Center Norman OK 0135 AM CDT Thu Jul 04 2024 Areas affected...eastern Kansas into western Missouri Concerning...Severe potential...Watch unlikely Valid 040635Z - 040830Z Probability of Watch Issuance...20 percent SUMMARY...Potential for strong to severe surface gusts with thunderstorm activity spreading toward the Missouri/Kansas state border (near and south of Kansas City) through 3-4 AM CDT, appears to be waning. It seems unlikely a severe weather watch will be needed, but trends are being monitored. DISCUSSION...An ongoing cluster of storms developing eastward along the Interstate 70 corridor, and east of the Interstate 135 corridor, of central Kansas appears rooted within ascent associated with lower/mid-tropospheric warm advection. This is generally forecast to continue spreading eastward ahead of a mid-level short wave trough progressing toward the lower Missouri Valley through daybreak. Earlier stronger convection appeared to develop strong mid-level rear inflow near/east of Hill City, which eventually contributed to a number of severe surface gusts across the Hayes/Russell through Salina vicinities, including up to at least 71 kt at Salina at 0538Z. This has recently been surging southeastward toward areas near and northeast of Wichita, and is now out ahead of the stronger convection now approaching the Missouri/Kansas state border (near and south of the Greater Kansas City area) through 08-08Z. Gusts associated with southeastward surging outflow seem likely to continue to wane during the next hour or two. At the same time, potential for renewed strengthening of rear inflow and downward momentum transfer seem limited, in the presence of more modest lower/mid-tropospheric lapse rates across eastern Kansas into western Missouri. ..Kerr/Kerr.. 07/04/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LSX...SGF...EAX...TSA...TOP...ICT...OUN... LAT...LON 39179685 39449556 39389427 38739268 37009419 36959609 36999771 37839742 38589667 39179685 Read more