Severe Storms

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0754 AM CDT Thu Aug 22 2024 Valid 221300Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... The greatest threat for severe gusts and hail appears to be over parts of the central High Plains this afternoon and evening. ...Synopsis... A highly amplified pattern in mid/upper levels will persist through the period, but with some weakening noted for both mean troughing near the East Coast, and a central CONUS ridge extending northward from a high over west TX. Southwest flow over the Intermountain West will strengthen and back somewhat in response to slow southeastward movement of an intense cyclone -- now centered west of the northern OR Coast --- while a strong shortwave trough pivots through its southern semicircle and onshore the northern CA coast by the end of the period. Farther east, on the periphery of that southwest flow, a shortwave trough (with some incorporation of a Sonoran MCV from 24 hours earlier) was apparent in moisture-channel imagery over northern AZ and southern UT. This perturbation should eject northeastward over western CO by 00Z, then into the central Plains overnight, perhaps with some further convective-vorticity reinforcement then. To the north, closely spaced shortwave troughs now over south-central SK and parts of ND/southeastern SK should pivot eastward across the rest of ND, northern MN and southern/central MB through the period. At the surface, a quasistationary frontal zone from northern FL across the northern Gulf Coast, east/north TX and the TX Panhandle should remain near that position through the period, with the richest low-level moisture remaining to its south. However, gradual moisture return of more incompletely modified (yet still convectively sufficient) character is apparent up the High Plains from the Panhandles across western NE to the central Dakotas. This is east of a lee trough over eastern parts of WY/CO, and a weak cold front analyzed from north-central ND to western SD. The latter front should proceed eastward across the Dakotas and into northwestern MN through this evening. ...Central High Plains... Highly variable thunderstorm coverage is expected over this region, with the greatest density in the 15%/"slight" area, where upscale evolution of increasingly outflow-driven thunderstorm clusters should support severe-gust potential this afternoon into evening. The primary foci for formation of eventually severe activity should be the northern Raton Mesa region, Front Range/Sangre de Cristo, and/or Palmer Divide, with some contribution from the lee trough as well. Though far south and east of the stronger flow aloft, sufficient veering of wind with height is expected to result in effective-shear magnitude in the 30-40-kt range, indicating potential for some organized convection. The boundary layer will remain well-heated/ mixed and deep, with very steep lapse rates, even as moisture/ buoyancy increase eastward. With surface dewpoints in the mid 50s to mid 60s F, peak/preconvective MLCAPE should reach 1500-2000 J/kg (locally higher) in a corridor near and just east of the longitude of the CO/KS line. This will foster pulses of strong to isolated severe gusts in initially discrete to semi-discrete activity atop a drier boundary layer, becoming better-organized with potential cold-pool aggregation eastward toward east-central/northeastern CO and adjoining portions of KS/NE into the higher CAPE. While specific shape, size, and track(s) of this clustering still depend on mesoscale details, enough consensus/confidence is now apparent in the general area of greatest severe-wind potential to ratchet up unconditional probabilities a level. With MLCINH increasing eastward from about the KS/CO border longitude and nocturnal near-surface cooling, the severe threat should weaken eastward from northwestern KS and southwestern NE tonight. ...Eastern Great Basin and vicinity... Widely scattered to scattered thunderstorms are possible this afternoon into early evening, offering strong to isolated severe gusts and marginally severe hail. After the shortwave trough and related precip now over parts of this region shifts northeastward, most of the day should remain for diabatic heating/destabilization of the higher terrain across the region, with airmass recovery furthered by warm/theta-e advection from the south. In concert with available monsoonal moisture, a roughly meridional plume of essentially uninhibited MLCAPE in the 500-1500 J/kg range should develop. This will be superimposed under the southeastern rim of stronger upper flow related to the West Coast troughing/cyclone. The result should be strengthening cloud-layer shear and some potential for storm organization, as activity moves generally northeastward over well-mixed boundary layers. ...Upper Midwest... A large area of clouds and precip -- with widely scattered embedded thunderstorms -- should proceed eastward today across the remainder of eastern ND and parts of northern MN near the international border. Though the associated lead perturbation now over ND should be past the area before this afternoon, cyclonic flow aloft should continue in response to the stronger perturbation farther north, moving into MB. As such, little if any hindrance to convective potential is expected from large-scale subsidence, while the low-level airmass destabilizes diabatically from surface heating behind the morning activity. Isolated to widely scattered thunderstorms may develop along/ahead of the cold front, within a narrow plume of 1000-2000 J/kg MLCAPE supported by 60s F surface dewpoints. Modest low/middle-level flow is expected, through enough veering with height should develop to support effective-shear magnitudes locally near 35 kt. The strongest cells may produce marginally severe hail or gusts, before convection weakens this evening. ..Edwards/Mosier.. 08/22/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0754 AM CDT Thu Aug 22 2024 Valid 221300Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... The greatest threat for severe gusts and hail appears to be over parts of the central High Plains this afternoon and evening. ...Synopsis... A highly amplified pattern in mid/upper levels will persist through the period, but with some weakening noted for both mean troughing near the East Coast, and a central CONUS ridge extending northward from a high over west TX. Southwest flow over the Intermountain West will strengthen and back somewhat in response to slow southeastward movement of an intense cyclone -- now centered west of the northern OR Coast --- while a strong shortwave trough pivots through its southern semicircle and onshore the northern CA coast by the end of the period. Farther east, on the periphery of that southwest flow, a shortwave trough (with some incorporation of a Sonoran MCV from 24 hours earlier) was apparent in moisture-channel imagery over northern AZ and southern UT. This perturbation should eject northeastward over western CO by 00Z, then into the central Plains overnight, perhaps with some further convective-vorticity reinforcement then. To the north, closely spaced shortwave troughs now over south-central SK and parts of ND/southeastern SK should pivot eastward across the rest of ND, northern MN and southern/central MB through the period. At the surface, a quasistationary frontal zone from northern FL across the northern Gulf Coast, east/north TX and the TX Panhandle should remain near that position through the period, with the richest low-level moisture remaining to its south. However, gradual moisture return of more incompletely modified (yet still convectively sufficient) character is apparent up the High Plains from the Panhandles across western NE to the central Dakotas. This is east of a lee trough over eastern parts of WY/CO, and a weak cold front analyzed from north-central ND to western SD. The latter front should proceed eastward across the Dakotas and into northwestern MN through this evening. ...Central High Plains... Highly variable thunderstorm coverage is expected over this region, with the greatest density in the 15%/"slight" area, where upscale evolution of increasingly outflow-driven thunderstorm clusters should support severe-gust potential this afternoon into evening. The primary foci for formation of eventually severe activity should be the northern Raton Mesa region, Front Range/Sangre de Cristo, and/or Palmer Divide, with some contribution from the lee trough as well. Though far south and east of the stronger flow aloft, sufficient veering of wind with height is expected to result in effective-shear magnitude in the 30-40-kt range, indicating potential for some organized convection. The boundary layer will remain well-heated/ mixed and deep, with very steep lapse rates, even as moisture/ buoyancy increase eastward. With surface dewpoints in the mid 50s to mid 60s F, peak/preconvective MLCAPE should reach 1500-2000 J/kg (locally higher) in a corridor near and just east of the longitude of the CO/KS line. This will foster pulses of strong to isolated severe gusts in initially discrete to semi-discrete activity atop a drier boundary layer, becoming better-organized with potential cold-pool aggregation eastward toward east-central/northeastern CO and adjoining portions of KS/NE into the higher CAPE. While specific shape, size, and track(s) of this clustering still depend on mesoscale details, enough consensus/confidence is now apparent in the general area of greatest severe-wind potential to ratchet up unconditional probabilities a level. With MLCINH increasing eastward from about the KS/CO border longitude and nocturnal near-surface cooling, the severe threat should weaken eastward from northwestern KS and southwestern NE tonight. ...Eastern Great Basin and vicinity... Widely scattered to scattered thunderstorms are possible this afternoon into early evening, offering strong to isolated severe gusts and marginally severe hail. After the shortwave trough and related precip now over parts of this region shifts northeastward, most of the day should remain for diabatic heating/destabilization of the higher terrain across the region, with airmass recovery furthered by warm/theta-e advection from the south. In concert with available monsoonal moisture, a roughly meridional plume of essentially uninhibited MLCAPE in the 500-1500 J/kg range should develop. This will be superimposed under the southeastern rim of stronger upper flow related to the West Coast troughing/cyclone. The result should be strengthening cloud-layer shear and some potential for storm organization, as activity moves generally northeastward over well-mixed boundary layers. ...Upper Midwest... A large area of clouds and precip -- with widely scattered embedded thunderstorms -- should proceed eastward today across the remainder of eastern ND and parts of northern MN near the international border. Though the associated lead perturbation now over ND should be past the area before this afternoon, cyclonic flow aloft should continue in response to the stronger perturbation farther north, moving into MB. As such, little if any hindrance to convective potential is expected from large-scale subsidence, while the low-level airmass destabilizes diabatically from surface heating behind the morning activity. Isolated to widely scattered thunderstorms may develop along/ahead of the cold front, within a narrow plume of 1000-2000 J/kg MLCAPE supported by 60s F surface dewpoints. Modest low/middle-level flow is expected, through enough veering with height should develop to support effective-shear magnitudes locally near 35 kt. The strongest cells may produce marginally severe hail or gusts, before convection weakens this evening. ..Edwards/Mosier.. 08/22/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0754 AM CDT Thu Aug 22 2024 Valid 221300Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... The greatest threat for severe gusts and hail appears to be over parts of the central High Plains this afternoon and evening. ...Synopsis... A highly amplified pattern in mid/upper levels will persist through the period, but with some weakening noted for both mean troughing near the East Coast, and a central CONUS ridge extending northward from a high over west TX. Southwest flow over the Intermountain West will strengthen and back somewhat in response to slow southeastward movement of an intense cyclone -- now centered west of the northern OR Coast --- while a strong shortwave trough pivots through its southern semicircle and onshore the northern CA coast by the end of the period. Farther east, on the periphery of that southwest flow, a shortwave trough (with some incorporation of a Sonoran MCV from 24 hours earlier) was apparent in moisture-channel imagery over northern AZ and southern UT. This perturbation should eject northeastward over western CO by 00Z, then into the central Plains overnight, perhaps with some further convective-vorticity reinforcement then. To the north, closely spaced shortwave troughs now over south-central SK and parts of ND/southeastern SK should pivot eastward across the rest of ND, northern MN and southern/central MB through the period. At the surface, a quasistationary frontal zone from northern FL across the northern Gulf Coast, east/north TX and the TX Panhandle should remain near that position through the period, with the richest low-level moisture remaining to its south. However, gradual moisture return of more incompletely modified (yet still convectively sufficient) character is apparent up the High Plains from the Panhandles across western NE to the central Dakotas. This is east of a lee trough over eastern parts of WY/CO, and a weak cold front analyzed from north-central ND to western SD. The latter front should proceed eastward across the Dakotas and into northwestern MN through this evening. ...Central High Plains... Highly variable thunderstorm coverage is expected over this region, with the greatest density in the 15%/"slight" area, where upscale evolution of increasingly outflow-driven thunderstorm clusters should support severe-gust potential this afternoon into evening. The primary foci for formation of eventually severe activity should be the northern Raton Mesa region, Front Range/Sangre de Cristo, and/or Palmer Divide, with some contribution from the lee trough as well. Though far south and east of the stronger flow aloft, sufficient veering of wind with height is expected to result in effective-shear magnitude in the 30-40-kt range, indicating potential for some organized convection. The boundary layer will remain well-heated/ mixed and deep, with very steep lapse rates, even as moisture/ buoyancy increase eastward. With surface dewpoints in the mid 50s to mid 60s F, peak/preconvective MLCAPE should reach 1500-2000 J/kg (locally higher) in a corridor near and just east of the longitude of the CO/KS line. This will foster pulses of strong to isolated severe gusts in initially discrete to semi-discrete activity atop a drier boundary layer, becoming better-organized with potential cold-pool aggregation eastward toward east-central/northeastern CO and adjoining portions of KS/NE into the higher CAPE. While specific shape, size, and track(s) of this clustering still depend on mesoscale details, enough consensus/confidence is now apparent in the general area of greatest severe-wind potential to ratchet up unconditional probabilities a level. With MLCINH increasing eastward from about the KS/CO border longitude and nocturnal near-surface cooling, the severe threat should weaken eastward from northwestern KS and southwestern NE tonight. ...Eastern Great Basin and vicinity... Widely scattered to scattered thunderstorms are possible this afternoon into early evening, offering strong to isolated severe gusts and marginally severe hail. After the shortwave trough and related precip now over parts of this region shifts northeastward, most of the day should remain for diabatic heating/destabilization of the higher terrain across the region, with airmass recovery furthered by warm/theta-e advection from the south. In concert with available monsoonal moisture, a roughly meridional plume of essentially uninhibited MLCAPE in the 500-1500 J/kg range should develop. This will be superimposed under the southeastern rim of stronger upper flow related to the West Coast troughing/cyclone. The result should be strengthening cloud-layer shear and some potential for storm organization, as activity moves generally northeastward over well-mixed boundary layers. ...Upper Midwest... A large area of clouds and precip -- with widely scattered embedded thunderstorms -- should proceed eastward today across the remainder of eastern ND and parts of northern MN near the international border. Though the associated lead perturbation now over ND should be past the area before this afternoon, cyclonic flow aloft should continue in response to the stronger perturbation farther north, moving into MB. As such, little if any hindrance to convective potential is expected from large-scale subsidence, while the low-level airmass destabilizes diabatically from surface heating behind the morning activity. Isolated to widely scattered thunderstorms may develop along/ahead of the cold front, within a narrow plume of 1000-2000 J/kg MLCAPE supported by 60s F surface dewpoints. Modest low/middle-level flow is expected, through enough veering with height should develop to support effective-shear magnitudes locally near 35 kt. The strongest cells may produce marginally severe hail or gusts, before convection weakens this evening. ..Edwards/Mosier.. 08/22/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0754 AM CDT Thu Aug 22 2024 Valid 221300Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... The greatest threat for severe gusts and hail appears to be over parts of the central High Plains this afternoon and evening. ...Synopsis... A highly amplified pattern in mid/upper levels will persist through the period, but with some weakening noted for both mean troughing near the East Coast, and a central CONUS ridge extending northward from a high over west TX. Southwest flow over the Intermountain West will strengthen and back somewhat in response to slow southeastward movement of an intense cyclone -- now centered west of the northern OR Coast --- while a strong shortwave trough pivots through its southern semicircle and onshore the northern CA coast by the end of the period. Farther east, on the periphery of that southwest flow, a shortwave trough (with some incorporation of a Sonoran MCV from 24 hours earlier) was apparent in moisture-channel imagery over northern AZ and southern UT. This perturbation should eject northeastward over western CO by 00Z, then into the central Plains overnight, perhaps with some further convective-vorticity reinforcement then. To the north, closely spaced shortwave troughs now over south-central SK and parts of ND/southeastern SK should pivot eastward across the rest of ND, northern MN and southern/central MB through the period. At the surface, a quasistationary frontal zone from northern FL across the northern Gulf Coast, east/north TX and the TX Panhandle should remain near that position through the period, with the richest low-level moisture remaining to its south. However, gradual moisture return of more incompletely modified (yet still convectively sufficient) character is apparent up the High Plains from the Panhandles across western NE to the central Dakotas. This is east of a lee trough over eastern parts of WY/CO, and a weak cold front analyzed from north-central ND to western SD. The latter front should proceed eastward across the Dakotas and into northwestern MN through this evening. ...Central High Plains... Highly variable thunderstorm coverage is expected over this region, with the greatest density in the 15%/"slight" area, where upscale evolution of increasingly outflow-driven thunderstorm clusters should support severe-gust potential this afternoon into evening. The primary foci for formation of eventually severe activity should be the northern Raton Mesa region, Front Range/Sangre de Cristo, and/or Palmer Divide, with some contribution from the lee trough as well. Though far south and east of the stronger flow aloft, sufficient veering of wind with height is expected to result in effective-shear magnitude in the 30-40-kt range, indicating potential for some organized convection. The boundary layer will remain well-heated/ mixed and deep, with very steep lapse rates, even as moisture/ buoyancy increase eastward. With surface dewpoints in the mid 50s to mid 60s F, peak/preconvective MLCAPE should reach 1500-2000 J/kg (locally higher) in a corridor near and just east of the longitude of the CO/KS line. This will foster pulses of strong to isolated severe gusts in initially discrete to semi-discrete activity atop a drier boundary layer, becoming better-organized with potential cold-pool aggregation eastward toward east-central/northeastern CO and adjoining portions of KS/NE into the higher CAPE. While specific shape, size, and track(s) of this clustering still depend on mesoscale details, enough consensus/confidence is now apparent in the general area of greatest severe-wind potential to ratchet up unconditional probabilities a level. With MLCINH increasing eastward from about the KS/CO border longitude and nocturnal near-surface cooling, the severe threat should weaken eastward from northwestern KS and southwestern NE tonight. ...Eastern Great Basin and vicinity... Widely scattered to scattered thunderstorms are possible this afternoon into early evening, offering strong to isolated severe gusts and marginally severe hail. After the shortwave trough and related precip now over parts of this region shifts northeastward, most of the day should remain for diabatic heating/destabilization of the higher terrain across the region, with airmass recovery furthered by warm/theta-e advection from the south. In concert with available monsoonal moisture, a roughly meridional plume of essentially uninhibited MLCAPE in the 500-1500 J/kg range should develop. This will be superimposed under the southeastern rim of stronger upper flow related to the West Coast troughing/cyclone. The result should be strengthening cloud-layer shear and some potential for storm organization, as activity moves generally northeastward over well-mixed boundary layers. ...Upper Midwest... A large area of clouds and precip -- with widely scattered embedded thunderstorms -- should proceed eastward today across the remainder of eastern ND and parts of northern MN near the international border. Though the associated lead perturbation now over ND should be past the area before this afternoon, cyclonic flow aloft should continue in response to the stronger perturbation farther north, moving into MB. As such, little if any hindrance to convective potential is expected from large-scale subsidence, while the low-level airmass destabilizes diabatically from surface heating behind the morning activity. Isolated to widely scattered thunderstorms may develop along/ahead of the cold front, within a narrow plume of 1000-2000 J/kg MLCAPE supported by 60s F surface dewpoints. Modest low/middle-level flow is expected, through enough veering with height should develop to support effective-shear magnitudes locally near 35 kt. The strongest cells may produce marginally severe hail or gusts, before convection weakens this evening. ..Edwards/Mosier.. 08/22/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0400 AM CDT Thu Aug 22 2024 Valid 251200Z - 301200Z ...DISCUSSION... ...Sunday/Day 4 to Tuesday/Day 6... Heights within an upper-level ridge over the Mississippi Valley will continue to rise on Sunday, as an upper-level trough moves through the western U.S. The ridge is forecast to move into the western Great Lakes from Monday into Tuesday, as the upper-level trough moves across the north-central U.S. Ahead of the approaching trough, thunderstorm development will be possible each day, from the northern Plains into the upper Mississippi Valley. For the three days, the greatest chance of severe storms appears to be in the Dakotas on Sunday and in the upper Mississippi Valley on Monday. Strong instability and moderate deep-layer shear, combined with increasing large-scale ascent, should result in a severe threat each afternoon and evening. Large hail and severe gusts will likely be the primary threats. ...Wednesday/Day 7 and Thursday/Day 8... On Wednesday and Thursday, the upper-level trough is forecast to move across the upper Mississippi Valley and into southern Canada, as a second trough moves through the northern Plains. At the surface, a moist airmass is forecast to remain in place over the Great Lakes region and Upper Midwest. Scattered to widely scattered thunderstorms will be possible across much of this moist airmass on both days. Although an isolated severe threat will be possible each afternoon and evening, the threat is expected to remain marginal due to a large area of mid-level high pressure that is forecast to be in place over much of the eastern half of the nation. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0400 AM CDT Thu Aug 22 2024 Valid 251200Z - 301200Z ...DISCUSSION... ...Sunday/Day 4 to Tuesday/Day 6... Heights within an upper-level ridge over the Mississippi Valley will continue to rise on Sunday, as an upper-level trough moves through the western U.S. The ridge is forecast to move into the western Great Lakes from Monday into Tuesday, as the upper-level trough moves across the north-central U.S. Ahead of the approaching trough, thunderstorm development will be possible each day, from the northern Plains into the upper Mississippi Valley. For the three days, the greatest chance of severe storms appears to be in the Dakotas on Sunday and in the upper Mississippi Valley on Monday. Strong instability and moderate deep-layer shear, combined with increasing large-scale ascent, should result in a severe threat each afternoon and evening. Large hail and severe gusts will likely be the primary threats. ...Wednesday/Day 7 and Thursday/Day 8... On Wednesday and Thursday, the upper-level trough is forecast to move across the upper Mississippi Valley and into southern Canada, as a second trough moves through the northern Plains. At the surface, a moist airmass is forecast to remain in place over the Great Lakes region and Upper Midwest. Scattered to widely scattered thunderstorms will be possible across much of this moist airmass on both days. Although an isolated severe threat will be possible each afternoon and evening, the threat is expected to remain marginal due to a large area of mid-level high pressure that is forecast to be in place over much of the eastern half of the nation. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0400 AM CDT Thu Aug 22 2024 Valid 251200Z - 301200Z ...DISCUSSION... ...Sunday/Day 4 to Tuesday/Day 6... Heights within an upper-level ridge over the Mississippi Valley will continue to rise on Sunday, as an upper-level trough moves through the western U.S. The ridge is forecast to move into the western Great Lakes from Monday into Tuesday, as the upper-level trough moves across the north-central U.S. Ahead of the approaching trough, thunderstorm development will be possible each day, from the northern Plains into the upper Mississippi Valley. For the three days, the greatest chance of severe storms appears to be in the Dakotas on Sunday and in the upper Mississippi Valley on Monday. Strong instability and moderate deep-layer shear, combined with increasing large-scale ascent, should result in a severe threat each afternoon and evening. Large hail and severe gusts will likely be the primary threats. ...Wednesday/Day 7 and Thursday/Day 8... On Wednesday and Thursday, the upper-level trough is forecast to move across the upper Mississippi Valley and into southern Canada, as a second trough moves through the northern Plains. At the surface, a moist airmass is forecast to remain in place over the Great Lakes region and Upper Midwest. Scattered to widely scattered thunderstorms will be possible across much of this moist airmass on both days. Although an isolated severe threat will be possible each afternoon and evening, the threat is expected to remain marginal due to a large area of mid-level high pressure that is forecast to be in place over much of the eastern half of the nation. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0400 AM CDT Thu Aug 22 2024 Valid 251200Z - 301200Z ...DISCUSSION... ...Sunday/Day 4 to Tuesday/Day 6... Heights within an upper-level ridge over the Mississippi Valley will continue to rise on Sunday, as an upper-level trough moves through the western U.S. The ridge is forecast to move into the western Great Lakes from Monday into Tuesday, as the upper-level trough moves across the north-central U.S. Ahead of the approaching trough, thunderstorm development will be possible each day, from the northern Plains into the upper Mississippi Valley. For the three days, the greatest chance of severe storms appears to be in the Dakotas on Sunday and in the upper Mississippi Valley on Monday. Strong instability and moderate deep-layer shear, combined with increasing large-scale ascent, should result in a severe threat each afternoon and evening. Large hail and severe gusts will likely be the primary threats. ...Wednesday/Day 7 and Thursday/Day 8... On Wednesday and Thursday, the upper-level trough is forecast to move across the upper Mississippi Valley and into southern Canada, as a second trough moves through the northern Plains. At the surface, a moist airmass is forecast to remain in place over the Great Lakes region and Upper Midwest. Scattered to widely scattered thunderstorms will be possible across much of this moist airmass on both days. Although an isolated severe threat will be possible each afternoon and evening, the threat is expected to remain marginal due to a large area of mid-level high pressure that is forecast to be in place over much of the eastern half of the nation. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0400 AM CDT Thu Aug 22 2024 Valid 251200Z - 301200Z ...DISCUSSION... ...Sunday/Day 4 to Tuesday/Day 6... Heights within an upper-level ridge over the Mississippi Valley will continue to rise on Sunday, as an upper-level trough moves through the western U.S. The ridge is forecast to move into the western Great Lakes from Monday into Tuesday, as the upper-level trough moves across the north-central U.S. Ahead of the approaching trough, thunderstorm development will be possible each day, from the northern Plains into the upper Mississippi Valley. For the three days, the greatest chance of severe storms appears to be in the Dakotas on Sunday and in the upper Mississippi Valley on Monday. Strong instability and moderate deep-layer shear, combined with increasing large-scale ascent, should result in a severe threat each afternoon and evening. Large hail and severe gusts will likely be the primary threats. ...Wednesday/Day 7 and Thursday/Day 8... On Wednesday and Thursday, the upper-level trough is forecast to move across the upper Mississippi Valley and into southern Canada, as a second trough moves through the northern Plains. At the surface, a moist airmass is forecast to remain in place over the Great Lakes region and Upper Midwest. Scattered to widely scattered thunderstorms will be possible across much of this moist airmass on both days. Although an isolated severe threat will be possible each afternoon and evening, the threat is expected to remain marginal due to a large area of mid-level high pressure that is forecast to be in place over much of the eastern half of the nation. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0400 AM CDT Thu Aug 22 2024 Valid 251200Z - 301200Z ...DISCUSSION... ...Sunday/Day 4 to Tuesday/Day 6... Heights within an upper-level ridge over the Mississippi Valley will continue to rise on Sunday, as an upper-level trough moves through the western U.S. The ridge is forecast to move into the western Great Lakes from Monday into Tuesday, as the upper-level trough moves across the north-central U.S. Ahead of the approaching trough, thunderstorm development will be possible each day, from the northern Plains into the upper Mississippi Valley. For the three days, the greatest chance of severe storms appears to be in the Dakotas on Sunday and in the upper Mississippi Valley on Monday. Strong instability and moderate deep-layer shear, combined with increasing large-scale ascent, should result in a severe threat each afternoon and evening. Large hail and severe gusts will likely be the primary threats. ...Wednesday/Day 7 and Thursday/Day 8... On Wednesday and Thursday, the upper-level trough is forecast to move across the upper Mississippi Valley and into southern Canada, as a second trough moves through the northern Plains. At the surface, a moist airmass is forecast to remain in place over the Great Lakes region and Upper Midwest. Scattered to widely scattered thunderstorms will be possible across much of this moist airmass on both days. Although an isolated severe threat will be possible each afternoon and evening, the threat is expected to remain marginal due to a large area of mid-level high pressure that is forecast to be in place over much of the eastern half of the nation. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0400 AM CDT Thu Aug 22 2024 Valid 251200Z - 301200Z ...DISCUSSION... ...Sunday/Day 4 to Tuesday/Day 6... Heights within an upper-level ridge over the Mississippi Valley will continue to rise on Sunday, as an upper-level trough moves through the western U.S. The ridge is forecast to move into the western Great Lakes from Monday into Tuesday, as the upper-level trough moves across the north-central U.S. Ahead of the approaching trough, thunderstorm development will be possible each day, from the northern Plains into the upper Mississippi Valley. For the three days, the greatest chance of severe storms appears to be in the Dakotas on Sunday and in the upper Mississippi Valley on Monday. Strong instability and moderate deep-layer shear, combined with increasing large-scale ascent, should result in a severe threat each afternoon and evening. Large hail and severe gusts will likely be the primary threats. ...Wednesday/Day 7 and Thursday/Day 8... On Wednesday and Thursday, the upper-level trough is forecast to move across the upper Mississippi Valley and into southern Canada, as a second trough moves through the northern Plains. At the surface, a moist airmass is forecast to remain in place over the Great Lakes region and Upper Midwest. Scattered to widely scattered thunderstorms will be possible across much of this moist airmass on both days. Although an isolated severe threat will be possible each afternoon and evening, the threat is expected to remain marginal due to a large area of mid-level high pressure that is forecast to be in place over much of the eastern half of the nation. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0213 AM CDT Thu Aug 22 2024 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS...AND IN THE FOUR CORNERS REGION... ...SUMMARY... Marginally severe storms will be possible on Saturday across parts of the central and northern High Plains, and near the Four Corners. ...Central and Northern High Plains... Heights associated with a Great Plains upper-level ridge will rise on Saturday, as the ridge moves slowly eastward. A north-to-south corridor of maximized low-level moisture is forecast to the west of the ridge across the central and northern Plains. Moderate instability will likely develop across much of this airmass by afternoon, with isolated thunderstorms forming along the western edge of the instability corridor from west-central Nebraska into the western Dakotas. With the moist airmass, 0-6 km shear is forecast to be in the 20 to 30 knot range in most areas. This, combined with steep lapse rates, will likely be sufficient for an isolated threat for severe gusts and hail. Due to the presence of the ridge, any severe threat is expected to be marginal. ...Four Corners... An upper-level trough is forecast to move across the Intermountain West on Saturday, as southwest mid-level flow remains over the Four Corners and Rocky Mountains. At the surface, an axis of maximized low-level moisture is forecast over the Four Corners, where destabilization will take place during the day. Scattered thunderstorms will likely develop throughout the Four Corners region Saturday afternoon. Forecast soundings at 21Z in the Four Corners vicinity have MLCAPE peaking between 500 and 1000 J/kg, with 0-6 km shear in most areas between 30 and 40 knots. Lapse rates are also forecast to become steep from the surface to 700 mb. This environment should support an isolated severe threat with marginally severe gusts and hail possible. ..Broyles.. 08/22/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0213 AM CDT Thu Aug 22 2024 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS...AND IN THE FOUR CORNERS REGION... ...SUMMARY... Marginally severe storms will be possible on Saturday across parts of the central and northern High Plains, and near the Four Corners. ...Central and Northern High Plains... Heights associated with a Great Plains upper-level ridge will rise on Saturday, as the ridge moves slowly eastward. A north-to-south corridor of maximized low-level moisture is forecast to the west of the ridge across the central and northern Plains. Moderate instability will likely develop across much of this airmass by afternoon, with isolated thunderstorms forming along the western edge of the instability corridor from west-central Nebraska into the western Dakotas. With the moist airmass, 0-6 km shear is forecast to be in the 20 to 30 knot range in most areas. This, combined with steep lapse rates, will likely be sufficient for an isolated threat for severe gusts and hail. Due to the presence of the ridge, any severe threat is expected to be marginal. ...Four Corners... An upper-level trough is forecast to move across the Intermountain West on Saturday, as southwest mid-level flow remains over the Four Corners and Rocky Mountains. At the surface, an axis of maximized low-level moisture is forecast over the Four Corners, where destabilization will take place during the day. Scattered thunderstorms will likely develop throughout the Four Corners region Saturday afternoon. Forecast soundings at 21Z in the Four Corners vicinity have MLCAPE peaking between 500 and 1000 J/kg, with 0-6 km shear in most areas between 30 and 40 knots. Lapse rates are also forecast to become steep from the surface to 700 mb. This environment should support an isolated severe threat with marginally severe gusts and hail possible. ..Broyles.. 08/22/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0213 AM CDT Thu Aug 22 2024 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS...AND IN THE FOUR CORNERS REGION... ...SUMMARY... Marginally severe storms will be possible on Saturday across parts of the central and northern High Plains, and near the Four Corners. ...Central and Northern High Plains... Heights associated with a Great Plains upper-level ridge will rise on Saturday, as the ridge moves slowly eastward. A north-to-south corridor of maximized low-level moisture is forecast to the west of the ridge across the central and northern Plains. Moderate instability will likely develop across much of this airmass by afternoon, with isolated thunderstorms forming along the western edge of the instability corridor from west-central Nebraska into the western Dakotas. With the moist airmass, 0-6 km shear is forecast to be in the 20 to 30 knot range in most areas. This, combined with steep lapse rates, will likely be sufficient for an isolated threat for severe gusts and hail. Due to the presence of the ridge, any severe threat is expected to be marginal. ...Four Corners... An upper-level trough is forecast to move across the Intermountain West on Saturday, as southwest mid-level flow remains over the Four Corners and Rocky Mountains. At the surface, an axis of maximized low-level moisture is forecast over the Four Corners, where destabilization will take place during the day. Scattered thunderstorms will likely develop throughout the Four Corners region Saturday afternoon. Forecast soundings at 21Z in the Four Corners vicinity have MLCAPE peaking between 500 and 1000 J/kg, with 0-6 km shear in most areas between 30 and 40 knots. Lapse rates are also forecast to become steep from the surface to 700 mb. This environment should support an isolated severe threat with marginally severe gusts and hail possible. ..Broyles.. 08/22/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0213 AM CDT Thu Aug 22 2024 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS...AND IN THE FOUR CORNERS REGION... ...SUMMARY... Marginally severe storms will be possible on Saturday across parts of the central and northern High Plains, and near the Four Corners. ...Central and Northern High Plains... Heights associated with a Great Plains upper-level ridge will rise on Saturday, as the ridge moves slowly eastward. A north-to-south corridor of maximized low-level moisture is forecast to the west of the ridge across the central and northern Plains. Moderate instability will likely develop across much of this airmass by afternoon, with isolated thunderstorms forming along the western edge of the instability corridor from west-central Nebraska into the western Dakotas. With the moist airmass, 0-6 km shear is forecast to be in the 20 to 30 knot range in most areas. This, combined with steep lapse rates, will likely be sufficient for an isolated threat for severe gusts and hail. Due to the presence of the ridge, any severe threat is expected to be marginal. ...Four Corners... An upper-level trough is forecast to move across the Intermountain West on Saturday, as southwest mid-level flow remains over the Four Corners and Rocky Mountains. At the surface, an axis of maximized low-level moisture is forecast over the Four Corners, where destabilization will take place during the day. Scattered thunderstorms will likely develop throughout the Four Corners region Saturday afternoon. Forecast soundings at 21Z in the Four Corners vicinity have MLCAPE peaking between 500 and 1000 J/kg, with 0-6 km shear in most areas between 30 and 40 knots. Lapse rates are also forecast to become steep from the surface to 700 mb. This environment should support an isolated severe threat with marginally severe gusts and hail possible. ..Broyles.. 08/22/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0213 AM CDT Thu Aug 22 2024 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS...AND IN THE FOUR CORNERS REGION... ...SUMMARY... Marginally severe storms will be possible on Saturday across parts of the central and northern High Plains, and near the Four Corners. ...Central and Northern High Plains... Heights associated with a Great Plains upper-level ridge will rise on Saturday, as the ridge moves slowly eastward. A north-to-south corridor of maximized low-level moisture is forecast to the west of the ridge across the central and northern Plains. Moderate instability will likely develop across much of this airmass by afternoon, with isolated thunderstorms forming along the western edge of the instability corridor from west-central Nebraska into the western Dakotas. With the moist airmass, 0-6 km shear is forecast to be in the 20 to 30 knot range in most areas. This, combined with steep lapse rates, will likely be sufficient for an isolated threat for severe gusts and hail. Due to the presence of the ridge, any severe threat is expected to be marginal. ...Four Corners... An upper-level trough is forecast to move across the Intermountain West on Saturday, as southwest mid-level flow remains over the Four Corners and Rocky Mountains. At the surface, an axis of maximized low-level moisture is forecast over the Four Corners, where destabilization will take place during the day. Scattered thunderstorms will likely develop throughout the Four Corners region Saturday afternoon. Forecast soundings at 21Z in the Four Corners vicinity have MLCAPE peaking between 500 and 1000 J/kg, with 0-6 km shear in most areas between 30 and 40 knots. Lapse rates are also forecast to become steep from the surface to 700 mb. This environment should support an isolated severe threat with marginally severe gusts and hail possible. ..Broyles.. 08/22/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0213 AM CDT Thu Aug 22 2024 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS...AND IN THE FOUR CORNERS REGION... ...SUMMARY... Marginally severe storms will be possible on Saturday across parts of the central and northern High Plains, and near the Four Corners. ...Central and Northern High Plains... Heights associated with a Great Plains upper-level ridge will rise on Saturday, as the ridge moves slowly eastward. A north-to-south corridor of maximized low-level moisture is forecast to the west of the ridge across the central and northern Plains. Moderate instability will likely develop across much of this airmass by afternoon, with isolated thunderstorms forming along the western edge of the instability corridor from west-central Nebraska into the western Dakotas. With the moist airmass, 0-6 km shear is forecast to be in the 20 to 30 knot range in most areas. This, combined with steep lapse rates, will likely be sufficient for an isolated threat for severe gusts and hail. Due to the presence of the ridge, any severe threat is expected to be marginal. ...Four Corners... An upper-level trough is forecast to move across the Intermountain West on Saturday, as southwest mid-level flow remains over the Four Corners and Rocky Mountains. At the surface, an axis of maximized low-level moisture is forecast over the Four Corners, where destabilization will take place during the day. Scattered thunderstorms will likely develop throughout the Four Corners region Saturday afternoon. Forecast soundings at 21Z in the Four Corners vicinity have MLCAPE peaking between 500 and 1000 J/kg, with 0-6 km shear in most areas between 30 and 40 knots. Lapse rates are also forecast to become steep from the surface to 700 mb. This environment should support an isolated severe threat with marginally severe gusts and hail possible. ..Broyles.. 08/22/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Thu Aug 22 2024 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS...AND IN PARTS OF THE INTERMOUNTAIN WEST AND CENTRAL ROCKIES... ...SUMMARY... Marginally severe storms with hail and isolated severe gusts will be possible on Friday across parts of the central and northern High Plains, and in parts of the Intermountain West and central Rockies. ...Central and Northern High Plains... An upper-level ridge will remain over the Great Plains on Friday. At the surface, a north-to-south corridor of maximized low-level moisture will be located across the central and northern Plains, where surface dewpoints will be mostly in the lower to mid 60s F. As temperatures warm during the day, moderate instability is expected to develop throughout much of this moist airmass. Isolated thunderstorms are expected to form during the afternoon over the western edge of the stronger instability, with storm coverage remaining relatively sparse due to subsidence associated with the upper-level ridge. Forecast soundings have directional shear in the low-levels and speed shear aloft over much of the moist airmass. The moderate deep-layer shear combined with steep mid-level lapse rates should support a threat for hail and severe wind gusts. However, the threat should be marginal. ...Intermountain West/Central Rockies... An upper-level low will move to near the coast of Oregon on Friday, as southwest mid-level flow remains over much of the western U.S. A subtle shortwave trough is forecast to move through the Four Corners region, where an axis of moisture and instability will likely be in place. As surface temperatures warm during the day, scattered thunderstorms are expected to develop from parts of eastern Utah into western and central Colorado, and northward into western Wyoming. MLCAPE is forecast to peak in the 500 to 1000 J/kg range, with 0-6 km shear around 35 knots. Low-level lapse rates will also be steep in the afternoon. This environment should support a marginal potential for hail and severe wind gusts during the mid to late afternoon. ..Broyles.. 08/22/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Thu Aug 22 2024 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS...AND IN PARTS OF THE INTERMOUNTAIN WEST AND CENTRAL ROCKIES... ...SUMMARY... Marginally severe storms with hail and isolated severe gusts will be possible on Friday across parts of the central and northern High Plains, and in parts of the Intermountain West and central Rockies. ...Central and Northern High Plains... An upper-level ridge will remain over the Great Plains on Friday. At the surface, a north-to-south corridor of maximized low-level moisture will be located across the central and northern Plains, where surface dewpoints will be mostly in the lower to mid 60s F. As temperatures warm during the day, moderate instability is expected to develop throughout much of this moist airmass. Isolated thunderstorms are expected to form during the afternoon over the western edge of the stronger instability, with storm coverage remaining relatively sparse due to subsidence associated with the upper-level ridge. Forecast soundings have directional shear in the low-levels and speed shear aloft over much of the moist airmass. The moderate deep-layer shear combined with steep mid-level lapse rates should support a threat for hail and severe wind gusts. However, the threat should be marginal. ...Intermountain West/Central Rockies... An upper-level low will move to near the coast of Oregon on Friday, as southwest mid-level flow remains over much of the western U.S. A subtle shortwave trough is forecast to move through the Four Corners region, where an axis of moisture and instability will likely be in place. As surface temperatures warm during the day, scattered thunderstorms are expected to develop from parts of eastern Utah into western and central Colorado, and northward into western Wyoming. MLCAPE is forecast to peak in the 500 to 1000 J/kg range, with 0-6 km shear around 35 knots. Low-level lapse rates will also be steep in the afternoon. This environment should support a marginal potential for hail and severe wind gusts during the mid to late afternoon. ..Broyles.. 08/22/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Thu Aug 22 2024 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS...AND IN PARTS OF THE INTERMOUNTAIN WEST AND CENTRAL ROCKIES... ...SUMMARY... Marginally severe storms with hail and isolated severe gusts will be possible on Friday across parts of the central and northern High Plains, and in parts of the Intermountain West and central Rockies. ...Central and Northern High Plains... An upper-level ridge will remain over the Great Plains on Friday. At the surface, a north-to-south corridor of maximized low-level moisture will be located across the central and northern Plains, where surface dewpoints will be mostly in the lower to mid 60s F. As temperatures warm during the day, moderate instability is expected to develop throughout much of this moist airmass. Isolated thunderstorms are expected to form during the afternoon over the western edge of the stronger instability, with storm coverage remaining relatively sparse due to subsidence associated with the upper-level ridge. Forecast soundings have directional shear in the low-levels and speed shear aloft over much of the moist airmass. The moderate deep-layer shear combined with steep mid-level lapse rates should support a threat for hail and severe wind gusts. However, the threat should be marginal. ...Intermountain West/Central Rockies... An upper-level low will move to near the coast of Oregon on Friday, as southwest mid-level flow remains over much of the western U.S. A subtle shortwave trough is forecast to move through the Four Corners region, where an axis of moisture and instability will likely be in place. As surface temperatures warm during the day, scattered thunderstorms are expected to develop from parts of eastern Utah into western and central Colorado, and northward into western Wyoming. MLCAPE is forecast to peak in the 500 to 1000 J/kg range, with 0-6 km shear around 35 knots. Low-level lapse rates will also be steep in the afternoon. This environment should support a marginal potential for hail and severe wind gusts during the mid to late afternoon. ..Broyles.. 08/22/2024 Read more