Severe Storms

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon Jul 29 2024 Valid 291630Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS...AND PORTIONS OF THE MIDWEST/LOWER OHIO VALLEY... ...SUMMARY... Scattered strong to severe thunderstorms may occur across parts of the northern/central Plains this afternoon and evening, and also over portions of the Midwest and Lower Ohio Valley mainly this evening through the early overnight hours. ...Northern/Central Plains into the Upper Midwest... Various 12Z observed soundings across the northern/central High Plains show shallow/limited low-level moisture in the wake of prior convection and a weak front, with PWAT values generally less than 1 inch. Still, sufficient moisture to support weak to moderate instability should be in place through this afternoon along/east of a weak surface trough near the border of ND/SD and MT/WY. Large-scale ascent should remain fairly modest in a mostly zonal mid/upper-level westerly flow regime, with a low-amplitude mid-level shortwave trough over southern Saskatchewan/Manitoba and ND expected to move eastward through the period. Another weak mid-level perturbation evident on water vapor satellite imagery late this morning should also move eastward from the northern Rockies across the adjacent High Plains through this evening. Both of these features should aid isolated to scattered thunderstorms developing across parts of ND/SD and western NE by late afternoon, generally along/east of the weak surface trough. Modest low-level flow is expected to veer to westerly and gradually strengthen with height to around 30-40 kt through mid levels. Similar values of deep-layer shear will support organized updrafts, including the potential for a few supercells. Large hail generally 1-2 inches in diameter will be possible with any sustained, discrete convection through the early evening. With a long, generally straight hodograph forecast at mid/upper levels, splitting supercells may occur. Still, overall coverage of intense thunderstorms remains somewhat uncertain given the modest large-scale ascent. The potential for convection to grow upscale this evening into one or more bowing clusters also appears rather uncertain given the weak low-level mass response forecast. If a cluster can develop, then severe/damaging winds, with some potentially up to 75 mph given rather steep low/mid-level lapse rates, would become a greater threat with time through the evening hours across central/eastern ND/SD and northern NE. An isolated severe wind threat may persist with eastward extent into southern MN and IA tonight with any cluster that can persist along an axis of greater instability. ...Midwest/Lower Ohio Valley into the Tennessee Valley/Southeast... A large area of convection from an earlier MCS across the Midwest has devolved into an area of disorganized showers and thunderstorms late this morning across the lower OH Valley vicinity. Extensive outflow from this activity has surged southward to the Ozarks to parts of western KY based on recent visible satellite and radar imagery. But, airmass recovery is already well underway across parts of central MO, with southwesterly surface/low-level winds advecting a very moist airmass northward towards the mid MS Valley and western portions of the Midwest/OH Valley. Convective evolution across these areas later today into tonight remains rather uncertain given the early-day convection. Even so, most guidance continues to remain insistent that a moderately to strongly unstable environment will become re-established across parts of eastern MO into southern/central IL/IN by early evening. If this destabilization can occur, then potential for intense thunderstorms, including supercells, and a bowing cluster could be realized. Forcing for ascent for this robust convection will likely be tied to southwesterly low-level warm/moist advection, and a mid-level vorticity maximum forecast to move eastward from WI/IL to the Great Lakes region. Sufficiently strong northwesterly mid/upper-level flow and veering winds through the column will support generally 25-35 kt of deep-layer shear and updraft organization. It appears possible that initial supercells with an isolated large hail threat may quickly transition to a linear cluster with greater severe/damaging wind potential with time this evening/tonight across the lower OH Valley and vicinity. Sufficient low-level shear should also be present to support some threat for a couple of tornadoes with any semi-discrete thunderstorms, although the mode may quickly become messy this evening with multiple mergers/interactions. Given the continued uncertainty in convective evolution later today into tonight, only small expansions have been made to the Slight Risk across this region. A broader area of isolated strong to damaging wind potential remains apparent across parts of the TN Valley into the Southeast, where moderate to strong instability and marginal deep-layer shear may support loosely organized clusters spreading generally southeastward this afternoon/evening. ...Mid-Atlantic... Modestly enhanced northwesterly mid/upper-level flow will overspread parts of the eastern Mid-Atlantic and Delmarva Peninsula on the western periphery of a mid-level cyclone that will continue to advance northward across New England today. As the boundary layer across this region warms and becomes weakly to moderately unstable, a few strong thunderstorms could develop within this regime during the afternoon. Locally moderate instability and effective shear around 30-35 kt should support some potential for isolated damaging gusts and marginally severe hail with the more robust cores. ..Gleason/Moore.. 07/29/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon Jul 29 2024 Valid 291630Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS...AND PORTIONS OF THE MIDWEST/LOWER OHIO VALLEY... ...SUMMARY... Scattered strong to severe thunderstorms may occur across parts of the northern/central Plains this afternoon and evening, and also over portions of the Midwest and Lower Ohio Valley mainly this evening through the early overnight hours. ...Northern/Central Plains into the Upper Midwest... Various 12Z observed soundings across the northern/central High Plains show shallow/limited low-level moisture in the wake of prior convection and a weak front, with PWAT values generally less than 1 inch. Still, sufficient moisture to support weak to moderate instability should be in place through this afternoon along/east of a weak surface trough near the border of ND/SD and MT/WY. Large-scale ascent should remain fairly modest in a mostly zonal mid/upper-level westerly flow regime, with a low-amplitude mid-level shortwave trough over southern Saskatchewan/Manitoba and ND expected to move eastward through the period. Another weak mid-level perturbation evident on water vapor satellite imagery late this morning should also move eastward from the northern Rockies across the adjacent High Plains through this evening. Both of these features should aid isolated to scattered thunderstorms developing across parts of ND/SD and western NE by late afternoon, generally along/east of the weak surface trough. Modest low-level flow is expected to veer to westerly and gradually strengthen with height to around 30-40 kt through mid levels. Similar values of deep-layer shear will support organized updrafts, including the potential for a few supercells. Large hail generally 1-2 inches in diameter will be possible with any sustained, discrete convection through the early evening. With a long, generally straight hodograph forecast at mid/upper levels, splitting supercells may occur. Still, overall coverage of intense thunderstorms remains somewhat uncertain given the modest large-scale ascent. The potential for convection to grow upscale this evening into one or more bowing clusters also appears rather uncertain given the weak low-level mass response forecast. If a cluster can develop, then severe/damaging winds, with some potentially up to 75 mph given rather steep low/mid-level lapse rates, would become a greater threat with time through the evening hours across central/eastern ND/SD and northern NE. An isolated severe wind threat may persist with eastward extent into southern MN and IA tonight with any cluster that can persist along an axis of greater instability. ...Midwest/Lower Ohio Valley into the Tennessee Valley/Southeast... A large area of convection from an earlier MCS across the Midwest has devolved into an area of disorganized showers and thunderstorms late this morning across the lower OH Valley vicinity. Extensive outflow from this activity has surged southward to the Ozarks to parts of western KY based on recent visible satellite and radar imagery. But, airmass recovery is already well underway across parts of central MO, with southwesterly surface/low-level winds advecting a very moist airmass northward towards the mid MS Valley and western portions of the Midwest/OH Valley. Convective evolution across these areas later today into tonight remains rather uncertain given the early-day convection. Even so, most guidance continues to remain insistent that a moderately to strongly unstable environment will become re-established across parts of eastern MO into southern/central IL/IN by early evening. If this destabilization can occur, then potential for intense thunderstorms, including supercells, and a bowing cluster could be realized. Forcing for ascent for this robust convection will likely be tied to southwesterly low-level warm/moist advection, and a mid-level vorticity maximum forecast to move eastward from WI/IL to the Great Lakes region. Sufficiently strong northwesterly mid/upper-level flow and veering winds through the column will support generally 25-35 kt of deep-layer shear and updraft organization. It appears possible that initial supercells with an isolated large hail threat may quickly transition to a linear cluster with greater severe/damaging wind potential with time this evening/tonight across the lower OH Valley and vicinity. Sufficient low-level shear should also be present to support some threat for a couple of tornadoes with any semi-discrete thunderstorms, although the mode may quickly become messy this evening with multiple mergers/interactions. Given the continued uncertainty in convective evolution later today into tonight, only small expansions have been made to the Slight Risk across this region. A broader area of isolated strong to damaging wind potential remains apparent across parts of the TN Valley into the Southeast, where moderate to strong instability and marginal deep-layer shear may support loosely organized clusters spreading generally southeastward this afternoon/evening. ...Mid-Atlantic... Modestly enhanced northwesterly mid/upper-level flow will overspread parts of the eastern Mid-Atlantic and Delmarva Peninsula on the western periphery of a mid-level cyclone that will continue to advance northward across New England today. As the boundary layer across this region warms and becomes weakly to moderately unstable, a few strong thunderstorms could develop within this regime during the afternoon. Locally moderate instability and effective shear around 30-35 kt should support some potential for isolated damaging gusts and marginally severe hail with the more robust cores. ..Gleason/Moore.. 07/29/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0757 AM CDT Mon Jul 29 2024 Valid 291300Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN PLAINS AND THE MIDWEST/LOWER OHIO VALLEY... ...SUMMARY... Scattered strong to severe storms are expected across parts of the central and northern Plains this afternoon and evening, and also across parts of the Midwest and lower Ohio Valley. ...Northern/central Plains and Upper Midwest... A broad upper trough with multiple embedded shortwaves will again be in place across parts of the northern Rockies into the central/northern Plains today. Steep mid-level lapse rates and strong heating will support moderate to locally strong buoyancy by afternoon across parts of the Dakotas into Nebraska. As MLCINH decreases through the afternoon, most guidance suggests at least widely scattered storm development near a surface trough from the western Dakotas into northwest Nebraska. Effective shear of 35-45 kt will support some threat for supercells, with an attendant threat of large hail (possibly in excess of 2 inches in diameter) and localized severe wind gusts. With time, evolution into one or more outflow driven clusters will be possible, with an increasing threat of damaging/severe gusts (potentially in excess of 75 mph). Longevity for any of these potential clusters into late tonight is uncertain, but some threat for damaging/locally severe gusts could spread into parts of Iowa and southern Minnesota before a more definitive weakening trend occurs. ...Midwest/Lower Ohio Valley to Tennessee Valley/Southeast... An MCS has broadened but generally weakened in the pre-dawn hours across Illinois, roughly spanning the Chicagoland area to St Louis vicinity as of 7am CDT. A relatively complex mesoscale scenario exists across the region today largely attributable to the disposition/impacts of this MCS. While severe-weather potential is apparent across the region, some spatial/temporal uncertainties exist regarding the peak/most-focused severe threat later today. This potential is highlighted by a seasonally strong belt of west-northwesterly winds aloft. While the MCS has generally weakened, and may outpace the primary reservoir of instability from the west, there is some potential that storms intensify this afternoon within a warming/increasingly unstable boundary layer across the lower Ohio Valley vicinity including Kentucky/southern Indiana. Damaging winds gusts could occur. Moderately strong westerly low-level flow will otherwise aggressively modify the remnant post-MCS outflow/airmass, with storm redevelopment possible by late afternoon into the evening within a warm-advection regime. Strong destabilization should generally focus across downstate south-central portions of Illinois/Indiana. Current thinking is that severe storm development may occur by late afternoon potentially initially including the I-70 vicinity/Wabash Valley. Aided by the seasonally strong winds aloft (40 kt effective shear), intense supercells are plausible, with attendant risks for isolated hail and a tornado or two. It is probable that storms will further increase during the evening and continue to pose a severe risk as they persist southeastward toward/across the Ohio River. ...Delmarva and Mid-Atlantic/Northeast States... Strengthening northwesterly mid/upper-level flow will overspread the region on the western periphery of a mid-level cyclone moving northward across New England today. As the boundary layer warms and moderately destabilizes, a few strong storms could develop within this regime during the afternoon, with moderate buoyancy and effective shear of 30-35 kt supporting the potential for isolated damaging gusts and hail. ..Guyer/Grams.. 07/29/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0757 AM CDT Mon Jul 29 2024 Valid 291300Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN PLAINS AND THE MIDWEST/LOWER OHIO VALLEY... ...SUMMARY... Scattered strong to severe storms are expected across parts of the central and northern Plains this afternoon and evening, and also across parts of the Midwest and lower Ohio Valley. ...Northern/central Plains and Upper Midwest... A broad upper trough with multiple embedded shortwaves will again be in place across parts of the northern Rockies into the central/northern Plains today. Steep mid-level lapse rates and strong heating will support moderate to locally strong buoyancy by afternoon across parts of the Dakotas into Nebraska. As MLCINH decreases through the afternoon, most guidance suggests at least widely scattered storm development near a surface trough from the western Dakotas into northwest Nebraska. Effective shear of 35-45 kt will support some threat for supercells, with an attendant threat of large hail (possibly in excess of 2 inches in diameter) and localized severe wind gusts. With time, evolution into one or more outflow driven clusters will be possible, with an increasing threat of damaging/severe gusts (potentially in excess of 75 mph). Longevity for any of these potential clusters into late tonight is uncertain, but some threat for damaging/locally severe gusts could spread into parts of Iowa and southern Minnesota before a more definitive weakening trend occurs. ...Midwest/Lower Ohio Valley to Tennessee Valley/Southeast... An MCS has broadened but generally weakened in the pre-dawn hours across Illinois, roughly spanning the Chicagoland area to St Louis vicinity as of 7am CDT. A relatively complex mesoscale scenario exists across the region today largely attributable to the disposition/impacts of this MCS. While severe-weather potential is apparent across the region, some spatial/temporal uncertainties exist regarding the peak/most-focused severe threat later today. This potential is highlighted by a seasonally strong belt of west-northwesterly winds aloft. While the MCS has generally weakened, and may outpace the primary reservoir of instability from the west, there is some potential that storms intensify this afternoon within a warming/increasingly unstable boundary layer across the lower Ohio Valley vicinity including Kentucky/southern Indiana. Damaging winds gusts could occur. Moderately strong westerly low-level flow will otherwise aggressively modify the remnant post-MCS outflow/airmass, with storm redevelopment possible by late afternoon into the evening within a warm-advection regime. Strong destabilization should generally focus across downstate south-central portions of Illinois/Indiana. Current thinking is that severe storm development may occur by late afternoon potentially initially including the I-70 vicinity/Wabash Valley. Aided by the seasonally strong winds aloft (40 kt effective shear), intense supercells are plausible, with attendant risks for isolated hail and a tornado or two. It is probable that storms will further increase during the evening and continue to pose a severe risk as they persist southeastward toward/across the Ohio River. ...Delmarva and Mid-Atlantic/Northeast States... Strengthening northwesterly mid/upper-level flow will overspread the region on the western periphery of a mid-level cyclone moving northward across New England today. As the boundary layer warms and moderately destabilizes, a few strong storms could develop within this regime during the afternoon, with moderate buoyancy and effective shear of 30-35 kt supporting the potential for isolated damaging gusts and hail. ..Guyer/Grams.. 07/29/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0757 AM CDT Mon Jul 29 2024 Valid 291300Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN PLAINS AND THE MIDWEST/LOWER OHIO VALLEY... ...SUMMARY... Scattered strong to severe storms are expected across parts of the central and northern Plains this afternoon and evening, and also across parts of the Midwest and lower Ohio Valley. ...Northern/central Plains and Upper Midwest... A broad upper trough with multiple embedded shortwaves will again be in place across parts of the northern Rockies into the central/northern Plains today. Steep mid-level lapse rates and strong heating will support moderate to locally strong buoyancy by afternoon across parts of the Dakotas into Nebraska. As MLCINH decreases through the afternoon, most guidance suggests at least widely scattered storm development near a surface trough from the western Dakotas into northwest Nebraska. Effective shear of 35-45 kt will support some threat for supercells, with an attendant threat of large hail (possibly in excess of 2 inches in diameter) and localized severe wind gusts. With time, evolution into one or more outflow driven clusters will be possible, with an increasing threat of damaging/severe gusts (potentially in excess of 75 mph). Longevity for any of these potential clusters into late tonight is uncertain, but some threat for damaging/locally severe gusts could spread into parts of Iowa and southern Minnesota before a more definitive weakening trend occurs. ...Midwest/Lower Ohio Valley to Tennessee Valley/Southeast... An MCS has broadened but generally weakened in the pre-dawn hours across Illinois, roughly spanning the Chicagoland area to St Louis vicinity as of 7am CDT. A relatively complex mesoscale scenario exists across the region today largely attributable to the disposition/impacts of this MCS. While severe-weather potential is apparent across the region, some spatial/temporal uncertainties exist regarding the peak/most-focused severe threat later today. This potential is highlighted by a seasonally strong belt of west-northwesterly winds aloft. While the MCS has generally weakened, and may outpace the primary reservoir of instability from the west, there is some potential that storms intensify this afternoon within a warming/increasingly unstable boundary layer across the lower Ohio Valley vicinity including Kentucky/southern Indiana. Damaging winds gusts could occur. Moderately strong westerly low-level flow will otherwise aggressively modify the remnant post-MCS outflow/airmass, with storm redevelopment possible by late afternoon into the evening within a warm-advection regime. Strong destabilization should generally focus across downstate south-central portions of Illinois/Indiana. Current thinking is that severe storm development may occur by late afternoon potentially initially including the I-70 vicinity/Wabash Valley. Aided by the seasonally strong winds aloft (40 kt effective shear), intense supercells are plausible, with attendant risks for isolated hail and a tornado or two. It is probable that storms will further increase during the evening and continue to pose a severe risk as they persist southeastward toward/across the Ohio River. ...Delmarva and Mid-Atlantic/Northeast States... Strengthening northwesterly mid/upper-level flow will overspread the region on the western periphery of a mid-level cyclone moving northward across New England today. As the boundary layer warms and moderately destabilizes, a few strong storms could develop within this regime during the afternoon, with moderate buoyancy and effective shear of 30-35 kt supporting the potential for isolated damaging gusts and hail. ..Guyer/Grams.. 07/29/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0757 AM CDT Mon Jul 29 2024 Valid 291300Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN PLAINS AND THE MIDWEST/LOWER OHIO VALLEY... ...SUMMARY... Scattered strong to severe storms are expected across parts of the central and northern Plains this afternoon and evening, and also across parts of the Midwest and lower Ohio Valley. ...Northern/central Plains and Upper Midwest... A broad upper trough with multiple embedded shortwaves will again be in place across parts of the northern Rockies into the central/northern Plains today. Steep mid-level lapse rates and strong heating will support moderate to locally strong buoyancy by afternoon across parts of the Dakotas into Nebraska. As MLCINH decreases through the afternoon, most guidance suggests at least widely scattered storm development near a surface trough from the western Dakotas into northwest Nebraska. Effective shear of 35-45 kt will support some threat for supercells, with an attendant threat of large hail (possibly in excess of 2 inches in diameter) and localized severe wind gusts. With time, evolution into one or more outflow driven clusters will be possible, with an increasing threat of damaging/severe gusts (potentially in excess of 75 mph). Longevity for any of these potential clusters into late tonight is uncertain, but some threat for damaging/locally severe gusts could spread into parts of Iowa and southern Minnesota before a more definitive weakening trend occurs. ...Midwest/Lower Ohio Valley to Tennessee Valley/Southeast... An MCS has broadened but generally weakened in the pre-dawn hours across Illinois, roughly spanning the Chicagoland area to St Louis vicinity as of 7am CDT. A relatively complex mesoscale scenario exists across the region today largely attributable to the disposition/impacts of this MCS. While severe-weather potential is apparent across the region, some spatial/temporal uncertainties exist regarding the peak/most-focused severe threat later today. This potential is highlighted by a seasonally strong belt of west-northwesterly winds aloft. While the MCS has generally weakened, and may outpace the primary reservoir of instability from the west, there is some potential that storms intensify this afternoon within a warming/increasingly unstable boundary layer across the lower Ohio Valley vicinity including Kentucky/southern Indiana. Damaging winds gusts could occur. Moderately strong westerly low-level flow will otherwise aggressively modify the remnant post-MCS outflow/airmass, with storm redevelopment possible by late afternoon into the evening within a warm-advection regime. Strong destabilization should generally focus across downstate south-central portions of Illinois/Indiana. Current thinking is that severe storm development may occur by late afternoon potentially initially including the I-70 vicinity/Wabash Valley. Aided by the seasonally strong winds aloft (40 kt effective shear), intense supercells are plausible, with attendant risks for isolated hail and a tornado or two. It is probable that storms will further increase during the evening and continue to pose a severe risk as they persist southeastward toward/across the Ohio River. ...Delmarva and Mid-Atlantic/Northeast States... Strengthening northwesterly mid/upper-level flow will overspread the region on the western periphery of a mid-level cyclone moving northward across New England today. As the boundary layer warms and moderately destabilizes, a few strong storms could develop within this regime during the afternoon, with moderate buoyancy and effective shear of 30-35 kt supporting the potential for isolated damaging gusts and hail. ..Guyer/Grams.. 07/29/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0757 AM CDT Mon Jul 29 2024 Valid 291300Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN PLAINS AND THE MIDWEST/LOWER OHIO VALLEY... ...SUMMARY... Scattered strong to severe storms are expected across parts of the central and northern Plains this afternoon and evening, and also across parts of the Midwest and lower Ohio Valley. ...Northern/central Plains and Upper Midwest... A broad upper trough with multiple embedded shortwaves will again be in place across parts of the northern Rockies into the central/northern Plains today. Steep mid-level lapse rates and strong heating will support moderate to locally strong buoyancy by afternoon across parts of the Dakotas into Nebraska. As MLCINH decreases through the afternoon, most guidance suggests at least widely scattered storm development near a surface trough from the western Dakotas into northwest Nebraska. Effective shear of 35-45 kt will support some threat for supercells, with an attendant threat of large hail (possibly in excess of 2 inches in diameter) and localized severe wind gusts. With time, evolution into one or more outflow driven clusters will be possible, with an increasing threat of damaging/severe gusts (potentially in excess of 75 mph). Longevity for any of these potential clusters into late tonight is uncertain, but some threat for damaging/locally severe gusts could spread into parts of Iowa and southern Minnesota before a more definitive weakening trend occurs. ...Midwest/Lower Ohio Valley to Tennessee Valley/Southeast... An MCS has broadened but generally weakened in the pre-dawn hours across Illinois, roughly spanning the Chicagoland area to St Louis vicinity as of 7am CDT. A relatively complex mesoscale scenario exists across the region today largely attributable to the disposition/impacts of this MCS. While severe-weather potential is apparent across the region, some spatial/temporal uncertainties exist regarding the peak/most-focused severe threat later today. This potential is highlighted by a seasonally strong belt of west-northwesterly winds aloft. While the MCS has generally weakened, and may outpace the primary reservoir of instability from the west, there is some potential that storms intensify this afternoon within a warming/increasingly unstable boundary layer across the lower Ohio Valley vicinity including Kentucky/southern Indiana. Damaging winds gusts could occur. Moderately strong westerly low-level flow will otherwise aggressively modify the remnant post-MCS outflow/airmass, with storm redevelopment possible by late afternoon into the evening within a warm-advection regime. Strong destabilization should generally focus across downstate south-central portions of Illinois/Indiana. Current thinking is that severe storm development may occur by late afternoon potentially initially including the I-70 vicinity/Wabash Valley. Aided by the seasonally strong winds aloft (40 kt effective shear), intense supercells are plausible, with attendant risks for isolated hail and a tornado or two. It is probable that storms will further increase during the evening and continue to pose a severe risk as they persist southeastward toward/across the Ohio River. ...Delmarva and Mid-Atlantic/Northeast States... Strengthening northwesterly mid/upper-level flow will overspread the region on the western periphery of a mid-level cyclone moving northward across New England today. As the boundary layer warms and moderately destabilizes, a few strong storms could develop within this regime during the afternoon, with moderate buoyancy and effective shear of 30-35 kt supporting the potential for isolated damaging gusts and hail. ..Guyer/Grams.. 07/29/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0326 AM CDT Mon Jul 29 2024 Valid 011200Z - 061200Z ...DISCUSSION... A mid-level trough, likely near the Upper Midwest Thursday morning, will slowly move east through the end of this week and the weekend as a large amplitude ridge builds over the western CONUS. This slow moving trough will be the primary feature associated with potential severe weather during the extended forecast period. On D4/Thu, a large cluster of storms will likely be ongoing in the western Great Lakes in response to the forcing from the mid-level trough and moderately strong isentropic ascent. A very moist airmass (mid 70s dewpoints) will likely remain on the southern/southwest extent of any ongoing convection. This will likely be the focus for potential severe weather threat across Illinois/Indiana/Ohio on Thursday. Strong instability will be present, however shear will be somewhat weak, except for portions of Illinois where mid-level flow will strengthen during the late afternoon/evening. There is still uncertainty regarding the timing and amplitude of this mid-level trough. Therefore, no severe weather probabilities will be added at this time. As the mid-level trough continues east on D5/Fri and into the weekend, moisture quality, and thus instability, is forecast to weaken. In addition, the slowing/deamplifying nature of the mid-level trough will result in weakening mid-level flow. Therefore, while some isolated/widely scattered severe weather threat may occur across portions of the eastern CONUS, a more organized severe weather threat appears unlikely. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0326 AM CDT Mon Jul 29 2024 Valid 011200Z - 061200Z ...DISCUSSION... A mid-level trough, likely near the Upper Midwest Thursday morning, will slowly move east through the end of this week and the weekend as a large amplitude ridge builds over the western CONUS. This slow moving trough will be the primary feature associated with potential severe weather during the extended forecast period. On D4/Thu, a large cluster of storms will likely be ongoing in the western Great Lakes in response to the forcing from the mid-level trough and moderately strong isentropic ascent. A very moist airmass (mid 70s dewpoints) will likely remain on the southern/southwest extent of any ongoing convection. This will likely be the focus for potential severe weather threat across Illinois/Indiana/Ohio on Thursday. Strong instability will be present, however shear will be somewhat weak, except for portions of Illinois where mid-level flow will strengthen during the late afternoon/evening. There is still uncertainty regarding the timing and amplitude of this mid-level trough. Therefore, no severe weather probabilities will be added at this time. As the mid-level trough continues east on D5/Fri and into the weekend, moisture quality, and thus instability, is forecast to weaken. In addition, the slowing/deamplifying nature of the mid-level trough will result in weakening mid-level flow. Therefore, while some isolated/widely scattered severe weather threat may occur across portions of the eastern CONUS, a more organized severe weather threat appears unlikely. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0326 AM CDT Mon Jul 29 2024 Valid 011200Z - 061200Z ...DISCUSSION... A mid-level trough, likely near the Upper Midwest Thursday morning, will slowly move east through the end of this week and the weekend as a large amplitude ridge builds over the western CONUS. This slow moving trough will be the primary feature associated with potential severe weather during the extended forecast period. On D4/Thu, a large cluster of storms will likely be ongoing in the western Great Lakes in response to the forcing from the mid-level trough and moderately strong isentropic ascent. A very moist airmass (mid 70s dewpoints) will likely remain on the southern/southwest extent of any ongoing convection. This will likely be the focus for potential severe weather threat across Illinois/Indiana/Ohio on Thursday. Strong instability will be present, however shear will be somewhat weak, except for portions of Illinois where mid-level flow will strengthen during the late afternoon/evening. There is still uncertainty regarding the timing and amplitude of this mid-level trough. Therefore, no severe weather probabilities will be added at this time. As the mid-level trough continues east on D5/Fri and into the weekend, moisture quality, and thus instability, is forecast to weaken. In addition, the slowing/deamplifying nature of the mid-level trough will result in weakening mid-level flow. Therefore, while some isolated/widely scattered severe weather threat may occur across portions of the eastern CONUS, a more organized severe weather threat appears unlikely. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0326 AM CDT Mon Jul 29 2024 Valid 011200Z - 061200Z ...DISCUSSION... A mid-level trough, likely near the Upper Midwest Thursday morning, will slowly move east through the end of this week and the weekend as a large amplitude ridge builds over the western CONUS. This slow moving trough will be the primary feature associated with potential severe weather during the extended forecast period. On D4/Thu, a large cluster of storms will likely be ongoing in the western Great Lakes in response to the forcing from the mid-level trough and moderately strong isentropic ascent. A very moist airmass (mid 70s dewpoints) will likely remain on the southern/southwest extent of any ongoing convection. This will likely be the focus for potential severe weather threat across Illinois/Indiana/Ohio on Thursday. Strong instability will be present, however shear will be somewhat weak, except for portions of Illinois where mid-level flow will strengthen during the late afternoon/evening. There is still uncertainty regarding the timing and amplitude of this mid-level trough. Therefore, no severe weather probabilities will be added at this time. As the mid-level trough continues east on D5/Fri and into the weekend, moisture quality, and thus instability, is forecast to weaken. In addition, the slowing/deamplifying nature of the mid-level trough will result in weakening mid-level flow. Therefore, while some isolated/widely scattered severe weather threat may occur across portions of the eastern CONUS, a more organized severe weather threat appears unlikely. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0326 AM CDT Mon Jul 29 2024 Valid 011200Z - 061200Z ...DISCUSSION... A mid-level trough, likely near the Upper Midwest Thursday morning, will slowly move east through the end of this week and the weekend as a large amplitude ridge builds over the western CONUS. This slow moving trough will be the primary feature associated with potential severe weather during the extended forecast period. On D4/Thu, a large cluster of storms will likely be ongoing in the western Great Lakes in response to the forcing from the mid-level trough and moderately strong isentropic ascent. A very moist airmass (mid 70s dewpoints) will likely remain on the southern/southwest extent of any ongoing convection. This will likely be the focus for potential severe weather threat across Illinois/Indiana/Ohio on Thursday. Strong instability will be present, however shear will be somewhat weak, except for portions of Illinois where mid-level flow will strengthen during the late afternoon/evening. There is still uncertainty regarding the timing and amplitude of this mid-level trough. Therefore, no severe weather probabilities will be added at this time. As the mid-level trough continues east on D5/Fri and into the weekend, moisture quality, and thus instability, is forecast to weaken. In addition, the slowing/deamplifying nature of the mid-level trough will result in weakening mid-level flow. Therefore, while some isolated/widely scattered severe weather threat may occur across portions of the eastern CONUS, a more organized severe weather threat appears unlikely. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0233 AM CDT Mon Jul 29 2024 Valid 311200Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EASTERN SOUTH DAKOTA...SOUTHERN MINNESOTA...NORTHWEST IOWA...AND FAR NORTHEAST NEBRASKA... ...SUMMARY... Scattered strong to severe storms are possible from the Plains to the southern Great Lakes and the Appalachians to portions of New England. ...Synopsis... On Wednesday, a relatively zonal mid-level pattern will exist across the CONUS with several embedded shortwave troughs. The easternmost of these mid-level troughs will advance east across the Appalachians and off the Atlantic Coast on Wednesday. A weak, potentially convectively enhanced shortwave trough, may move through the northwesterly flow across the Midwest/southern Great Lakes. The strongest/most pronounced mid-level shortwave trough will cross the central Plains during the day on Wednesday. At the surface, a weak surface low will be located in the Nebraska vicinity with a very moist (mid to upper 70s dewpoints) airmass to its east. ...Eastern SD, southern MN, northwest IA, and far northeast NE... Strong instability will be present across the central Plains into the Upper Midwest in the presence of mid 70s dewpoints and very steep (9+ C/km) mid-level lapse rates. Ascent ahead of the mid-level shortwave trough traversing the Plains in combination with a strengthening low-level jet should result in thunderstorm development sometime during the afternoon/evening across eastern South Dakota and potentially Nebraska. As this mid-level trough advances east, mid-level flow will strengthen to 35 to 40 knots which will provide ample shear for storm organization. Any storms which develop could be supercellular initially, but will likely grow upscale into an MCS relatively quickly. ...Midwest into the Ohio Valley... Additional storms or storm clusters may be possible amid strong instability along a stationary front from the western Great Lakes to the Ohio Valley. Storm coverage remains questionable given height rises across the region and a lack of an obvious forcing mechanism and relatively warm low-mid level temperatures. However, a very unstable and moderately sheared environment along this zone would support severe thunderstorms. Details of embedded mid-level shortwave troughs or convectively enhanced features which may aid in storm development may become evident in later forecasts. Therefore, a broad marginal risk seems most appropriate at this time to address this conditional threat. ..Bentley.. 07/29/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0233 AM CDT Mon Jul 29 2024 Valid 311200Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EASTERN SOUTH DAKOTA...SOUTHERN MINNESOTA...NORTHWEST IOWA...AND FAR NORTHEAST NEBRASKA... ...SUMMARY... Scattered strong to severe storms are possible from the Plains to the southern Great Lakes and the Appalachians to portions of New England. ...Synopsis... On Wednesday, a relatively zonal mid-level pattern will exist across the CONUS with several embedded shortwave troughs. The easternmost of these mid-level troughs will advance east across the Appalachians and off the Atlantic Coast on Wednesday. A weak, potentially convectively enhanced shortwave trough, may move through the northwesterly flow across the Midwest/southern Great Lakes. The strongest/most pronounced mid-level shortwave trough will cross the central Plains during the day on Wednesday. At the surface, a weak surface low will be located in the Nebraska vicinity with a very moist (mid to upper 70s dewpoints) airmass to its east. ...Eastern SD, southern MN, northwest IA, and far northeast NE... Strong instability will be present across the central Plains into the Upper Midwest in the presence of mid 70s dewpoints and very steep (9+ C/km) mid-level lapse rates. Ascent ahead of the mid-level shortwave trough traversing the Plains in combination with a strengthening low-level jet should result in thunderstorm development sometime during the afternoon/evening across eastern South Dakota and potentially Nebraska. As this mid-level trough advances east, mid-level flow will strengthen to 35 to 40 knots which will provide ample shear for storm organization. Any storms which develop could be supercellular initially, but will likely grow upscale into an MCS relatively quickly. ...Midwest into the Ohio Valley... Additional storms or storm clusters may be possible amid strong instability along a stationary front from the western Great Lakes to the Ohio Valley. Storm coverage remains questionable given height rises across the region and a lack of an obvious forcing mechanism and relatively warm low-mid level temperatures. However, a very unstable and moderately sheared environment along this zone would support severe thunderstorms. Details of embedded mid-level shortwave troughs or convectively enhanced features which may aid in storm development may become evident in later forecasts. Therefore, a broad marginal risk seems most appropriate at this time to address this conditional threat. ..Bentley.. 07/29/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0233 AM CDT Mon Jul 29 2024 Valid 311200Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EASTERN SOUTH DAKOTA...SOUTHERN MINNESOTA...NORTHWEST IOWA...AND FAR NORTHEAST NEBRASKA... ...SUMMARY... Scattered strong to severe storms are possible from the Plains to the southern Great Lakes and the Appalachians to portions of New England. ...Synopsis... On Wednesday, a relatively zonal mid-level pattern will exist across the CONUS with several embedded shortwave troughs. The easternmost of these mid-level troughs will advance east across the Appalachians and off the Atlantic Coast on Wednesday. A weak, potentially convectively enhanced shortwave trough, may move through the northwesterly flow across the Midwest/southern Great Lakes. The strongest/most pronounced mid-level shortwave trough will cross the central Plains during the day on Wednesday. At the surface, a weak surface low will be located in the Nebraska vicinity with a very moist (mid to upper 70s dewpoints) airmass to its east. ...Eastern SD, southern MN, northwest IA, and far northeast NE... Strong instability will be present across the central Plains into the Upper Midwest in the presence of mid 70s dewpoints and very steep (9+ C/km) mid-level lapse rates. Ascent ahead of the mid-level shortwave trough traversing the Plains in combination with a strengthening low-level jet should result in thunderstorm development sometime during the afternoon/evening across eastern South Dakota and potentially Nebraska. As this mid-level trough advances east, mid-level flow will strengthen to 35 to 40 knots which will provide ample shear for storm organization. Any storms which develop could be supercellular initially, but will likely grow upscale into an MCS relatively quickly. ...Midwest into the Ohio Valley... Additional storms or storm clusters may be possible amid strong instability along a stationary front from the western Great Lakes to the Ohio Valley. Storm coverage remains questionable given height rises across the region and a lack of an obvious forcing mechanism and relatively warm low-mid level temperatures. However, a very unstable and moderately sheared environment along this zone would support severe thunderstorms. Details of embedded mid-level shortwave troughs or convectively enhanced features which may aid in storm development may become evident in later forecasts. Therefore, a broad marginal risk seems most appropriate at this time to address this conditional threat. ..Bentley.. 07/29/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0233 AM CDT Mon Jul 29 2024 Valid 311200Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EASTERN SOUTH DAKOTA...SOUTHERN MINNESOTA...NORTHWEST IOWA...AND FAR NORTHEAST NEBRASKA... ...SUMMARY... Scattered strong to severe storms are possible from the Plains to the southern Great Lakes and the Appalachians to portions of New England. ...Synopsis... On Wednesday, a relatively zonal mid-level pattern will exist across the CONUS with several embedded shortwave troughs. The easternmost of these mid-level troughs will advance east across the Appalachians and off the Atlantic Coast on Wednesday. A weak, potentially convectively enhanced shortwave trough, may move through the northwesterly flow across the Midwest/southern Great Lakes. The strongest/most pronounced mid-level shortwave trough will cross the central Plains during the day on Wednesday. At the surface, a weak surface low will be located in the Nebraska vicinity with a very moist (mid to upper 70s dewpoints) airmass to its east. ...Eastern SD, southern MN, northwest IA, and far northeast NE... Strong instability will be present across the central Plains into the Upper Midwest in the presence of mid 70s dewpoints and very steep (9+ C/km) mid-level lapse rates. Ascent ahead of the mid-level shortwave trough traversing the Plains in combination with a strengthening low-level jet should result in thunderstorm development sometime during the afternoon/evening across eastern South Dakota and potentially Nebraska. As this mid-level trough advances east, mid-level flow will strengthen to 35 to 40 knots which will provide ample shear for storm organization. Any storms which develop could be supercellular initially, but will likely grow upscale into an MCS relatively quickly. ...Midwest into the Ohio Valley... Additional storms or storm clusters may be possible amid strong instability along a stationary front from the western Great Lakes to the Ohio Valley. Storm coverage remains questionable given height rises across the region and a lack of an obvious forcing mechanism and relatively warm low-mid level temperatures. However, a very unstable and moderately sheared environment along this zone would support severe thunderstorms. Details of embedded mid-level shortwave troughs or convectively enhanced features which may aid in storm development may become evident in later forecasts. Therefore, a broad marginal risk seems most appropriate at this time to address this conditional threat. ..Bentley.. 07/29/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0233 AM CDT Mon Jul 29 2024 Valid 311200Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EASTERN SOUTH DAKOTA...SOUTHERN MINNESOTA...NORTHWEST IOWA...AND FAR NORTHEAST NEBRASKA... ...SUMMARY... Scattered strong to severe storms are possible from the Plains to the southern Great Lakes and the Appalachians to portions of New England. ...Synopsis... On Wednesday, a relatively zonal mid-level pattern will exist across the CONUS with several embedded shortwave troughs. The easternmost of these mid-level troughs will advance east across the Appalachians and off the Atlantic Coast on Wednesday. A weak, potentially convectively enhanced shortwave trough, may move through the northwesterly flow across the Midwest/southern Great Lakes. The strongest/most pronounced mid-level shortwave trough will cross the central Plains during the day on Wednesday. At the surface, a weak surface low will be located in the Nebraska vicinity with a very moist (mid to upper 70s dewpoints) airmass to its east. ...Eastern SD, southern MN, northwest IA, and far northeast NE... Strong instability will be present across the central Plains into the Upper Midwest in the presence of mid 70s dewpoints and very steep (9+ C/km) mid-level lapse rates. Ascent ahead of the mid-level shortwave trough traversing the Plains in combination with a strengthening low-level jet should result in thunderstorm development sometime during the afternoon/evening across eastern South Dakota and potentially Nebraska. As this mid-level trough advances east, mid-level flow will strengthen to 35 to 40 knots which will provide ample shear for storm organization. Any storms which develop could be supercellular initially, but will likely grow upscale into an MCS relatively quickly. ...Midwest into the Ohio Valley... Additional storms or storm clusters may be possible amid strong instability along a stationary front from the western Great Lakes to the Ohio Valley. Storm coverage remains questionable given height rises across the region and a lack of an obvious forcing mechanism and relatively warm low-mid level temperatures. However, a very unstable and moderately sheared environment along this zone would support severe thunderstorms. Details of embedded mid-level shortwave troughs or convectively enhanced features which may aid in storm development may become evident in later forecasts. Therefore, a broad marginal risk seems most appropriate at this time to address this conditional threat. ..Bentley.. 07/29/2024 Read more

MD 1724 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR SOUTHEAST SD...NORTHEAST NE AND WESTERN IA
Mesoscale Discussion 1724 NWS Storm Prediction Center Norman OK 1239 AM CDT Mon Jul 29 2024 Areas affected...southeast SD...northeast NE and western IA Concerning...Severe potential...Watch possible Valid 290539Z - 290745Z Probability of Watch Issuance...40 percent SUMMARY...Isolated large hail and severe gusts may remain possible through the pre-dawn hours early this morning with a pair of slow-moving supercells over the Mid-Missouri Valley. DISCUSSION...In between a broader MCV over northeast IA and a smaller MCV in central SD, a pair of slow-moving supercells have developed along the southeast SD/northeast NE border area. This activity is within a zone of lower-level warm theta-e advection, with increasingly pronounced MLCIN in the warm-moist sector to its south-southwest. Most guidance suggests that the advection regime should gradually subside within this corridor over the next several hours. But given the upstream MCV over central SD moving about twice as fast as these storms, it is plausible that a merging may occur during the next few hours. One of the 00Z NSSL-MPAS runs, which appears to have a decent handle on both convective areas, supports this scenario. This could result in the initial primary threat of large hail, transitioning to more of a severe wind threat later this morning. ..Grams/Guyer.. 07/29/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DMX...FSD...OAX...LBF... LAT...LON 42189836 42849952 43409933 43749866 43109704 42629568 42039537 41509573 41669697 42189836 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0158 AM CDT Mon Jul 29 2024 Valid 301200Z - 311200Z ...Synopsis... A midlevel trough will advance eastward across the northern Rockies and adjacent High Plains during the day, while broad/enhanced west-southwesterly flow aloft persists across the Great Basin. ...Northern Rockies/Intermountain West... Large-scale ascent accompanying the eastward-moving midlevel trough will promote widely scattered thunderstorms across portions of the northern Rockies/Intermountain West into the northern Plains during the afternoon and evening. While many of these storms will be capable of producing measurable rainfall, quick eastward-moving storms (around 25-35 mph) will still favor a mix of wet/dry thunderstorms over dry fuels. As a result, some lightning-induced ignitions will be possible -- especially along the peripheries of any rain cores. ...Great Basin... Boundary-layer mixing into the modestly enhanced west-southwesterly flow aloft will lead to locally dry/breezy conditions across parts of the Great Basin during the afternoon. While locally elevated conditions are possible, winds should be slightly weaker than the day prior, and the overall threat appears too localized for an Elevated area at this time. ..Weinman.. 07/29/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0158 AM CDT Mon Jul 29 2024 Valid 301200Z - 311200Z ...Synopsis... A midlevel trough will advance eastward across the northern Rockies and adjacent High Plains during the day, while broad/enhanced west-southwesterly flow aloft persists across the Great Basin. ...Northern Rockies/Intermountain West... Large-scale ascent accompanying the eastward-moving midlevel trough will promote widely scattered thunderstorms across portions of the northern Rockies/Intermountain West into the northern Plains during the afternoon and evening. While many of these storms will be capable of producing measurable rainfall, quick eastward-moving storms (around 25-35 mph) will still favor a mix of wet/dry thunderstorms over dry fuels. As a result, some lightning-induced ignitions will be possible -- especially along the peripheries of any rain cores. ...Great Basin... Boundary-layer mixing into the modestly enhanced west-southwesterly flow aloft will lead to locally dry/breezy conditions across parts of the Great Basin during the afternoon. While locally elevated conditions are possible, winds should be slightly weaker than the day prior, and the overall threat appears too localized for an Elevated area at this time. ..Weinman.. 07/29/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more