Severe Storms

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1044 AM CDT Wed Aug 14 2024 Valid 141700Z - 151200Z The previous forecast remains on track based on morning observations and latest guidance. Isolated thunderstorms remain likely after 00 UTC across far northern CA, spreading into central and eastern OR through 12 UTC Thursday. Pockets of wetting rainfall are possible, but PWAT values around 0.75 inches and storm motions between 20-25 knots should support the potential for sporadic dry lightning strikes over a region with dry fuels. Other forecast concerns outlined in the previous discussion below remain valid. ..Moore.. 08/14/2024 .PREV DISCUSSION... /ISSUED 0126 AM CDT Wed Aug 14 2024/ ...Synopsis... A mid-level shortwave trough is forecast to cross the northern California coast Wednesday evening into Thursday morning, bringing with it forcing for ascent supportive of isolated dry thunderstorms. The greatest chances for dry thunderstorms will be across portions of northern California and southern Oregon. ...Dry Thunderstorms... Forecast sounding profiles still suggest the most unstable/buoyant parcels will originate at temperatures near or colder than 0 C, leaving some uncertainty in charge separation/lightning potential across the Northwest. However, forcing from the shortwave trough should be sufficient enough for at least some thunderstorm development overnight Wednesday into Thursday morning over receptive fuels. ...Dry/Windy... The strongest surface winds supportive of Elevated fire-weather conditions across the Western U.S. will be confined to diurnally/terrain-driven corridors that are too localized for highlights at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1044 AM CDT Wed Aug 14 2024 Valid 141700Z - 151200Z The previous forecast remains on track based on morning observations and latest guidance. Isolated thunderstorms remain likely after 00 UTC across far northern CA, spreading into central and eastern OR through 12 UTC Thursday. Pockets of wetting rainfall are possible, but PWAT values around 0.75 inches and storm motions between 20-25 knots should support the potential for sporadic dry lightning strikes over a region with dry fuels. Other forecast concerns outlined in the previous discussion below remain valid. ..Moore.. 08/14/2024 .PREV DISCUSSION... /ISSUED 0126 AM CDT Wed Aug 14 2024/ ...Synopsis... A mid-level shortwave trough is forecast to cross the northern California coast Wednesday evening into Thursday morning, bringing with it forcing for ascent supportive of isolated dry thunderstorms. The greatest chances for dry thunderstorms will be across portions of northern California and southern Oregon. ...Dry Thunderstorms... Forecast sounding profiles still suggest the most unstable/buoyant parcels will originate at temperatures near or colder than 0 C, leaving some uncertainty in charge separation/lightning potential across the Northwest. However, forcing from the shortwave trough should be sufficient enough for at least some thunderstorm development overnight Wednesday into Thursday morning over receptive fuels. ...Dry/Windy... The strongest surface winds supportive of Elevated fire-weather conditions across the Western U.S. will be confined to diurnally/terrain-driven corridors that are too localized for highlights at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1044 AM CDT Wed Aug 14 2024 Valid 141700Z - 151200Z The previous forecast remains on track based on morning observations and latest guidance. Isolated thunderstorms remain likely after 00 UTC across far northern CA, spreading into central and eastern OR through 12 UTC Thursday. Pockets of wetting rainfall are possible, but PWAT values around 0.75 inches and storm motions between 20-25 knots should support the potential for sporadic dry lightning strikes over a region with dry fuels. Other forecast concerns outlined in the previous discussion below remain valid. ..Moore.. 08/14/2024 .PREV DISCUSSION... /ISSUED 0126 AM CDT Wed Aug 14 2024/ ...Synopsis... A mid-level shortwave trough is forecast to cross the northern California coast Wednesday evening into Thursday morning, bringing with it forcing for ascent supportive of isolated dry thunderstorms. The greatest chances for dry thunderstorms will be across portions of northern California and southern Oregon. ...Dry Thunderstorms... Forecast sounding profiles still suggest the most unstable/buoyant parcels will originate at temperatures near or colder than 0 C, leaving some uncertainty in charge separation/lightning potential across the Northwest. However, forcing from the shortwave trough should be sufficient enough for at least some thunderstorm development overnight Wednesday into Thursday morning over receptive fuels. ...Dry/Windy... The strongest surface winds supportive of Elevated fire-weather conditions across the Western U.S. will be confined to diurnally/terrain-driven corridors that are too localized for highlights at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1044 AM CDT Wed Aug 14 2024 Valid 141700Z - 151200Z The previous forecast remains on track based on morning observations and latest guidance. Isolated thunderstorms remain likely after 00 UTC across far northern CA, spreading into central and eastern OR through 12 UTC Thursday. Pockets of wetting rainfall are possible, but PWAT values around 0.75 inches and storm motions between 20-25 knots should support the potential for sporadic dry lightning strikes over a region with dry fuels. Other forecast concerns outlined in the previous discussion below remain valid. ..Moore.. 08/14/2024 .PREV DISCUSSION... /ISSUED 0126 AM CDT Wed Aug 14 2024/ ...Synopsis... A mid-level shortwave trough is forecast to cross the northern California coast Wednesday evening into Thursday morning, bringing with it forcing for ascent supportive of isolated dry thunderstorms. The greatest chances for dry thunderstorms will be across portions of northern California and southern Oregon. ...Dry Thunderstorms... Forecast sounding profiles still suggest the most unstable/buoyant parcels will originate at temperatures near or colder than 0 C, leaving some uncertainty in charge separation/lightning potential across the Northwest. However, forcing from the shortwave trough should be sufficient enough for at least some thunderstorm development overnight Wednesday into Thursday morning over receptive fuels. ...Dry/Windy... The strongest surface winds supportive of Elevated fire-weather conditions across the Western U.S. will be confined to diurnally/terrain-driven corridors that are too localized for highlights at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1044 AM CDT Wed Aug 14 2024 Valid 141700Z - 151200Z The previous forecast remains on track based on morning observations and latest guidance. Isolated thunderstorms remain likely after 00 UTC across far northern CA, spreading into central and eastern OR through 12 UTC Thursday. Pockets of wetting rainfall are possible, but PWAT values around 0.75 inches and storm motions between 20-25 knots should support the potential for sporadic dry lightning strikes over a region with dry fuels. Other forecast concerns outlined in the previous discussion below remain valid. ..Moore.. 08/14/2024 .PREV DISCUSSION... /ISSUED 0126 AM CDT Wed Aug 14 2024/ ...Synopsis... A mid-level shortwave trough is forecast to cross the northern California coast Wednesday evening into Thursday morning, bringing with it forcing for ascent supportive of isolated dry thunderstorms. The greatest chances for dry thunderstorms will be across portions of northern California and southern Oregon. ...Dry Thunderstorms... Forecast sounding profiles still suggest the most unstable/buoyant parcels will originate at temperatures near or colder than 0 C, leaving some uncertainty in charge separation/lightning potential across the Northwest. However, forcing from the shortwave trough should be sufficient enough for at least some thunderstorm development overnight Wednesday into Thursday morning over receptive fuels. ...Dry/Windy... The strongest surface winds supportive of Elevated fire-weather conditions across the Western U.S. will be confined to diurnally/terrain-driven corridors that are too localized for highlights at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1044 AM CDT Wed Aug 14 2024 Valid 141700Z - 151200Z The previous forecast remains on track based on morning observations and latest guidance. Isolated thunderstorms remain likely after 00 UTC across far northern CA, spreading into central and eastern OR through 12 UTC Thursday. Pockets of wetting rainfall are possible, but PWAT values around 0.75 inches and storm motions between 20-25 knots should support the potential for sporadic dry lightning strikes over a region with dry fuels. Other forecast concerns outlined in the previous discussion below remain valid. ..Moore.. 08/14/2024 .PREV DISCUSSION... /ISSUED 0126 AM CDT Wed Aug 14 2024/ ...Synopsis... A mid-level shortwave trough is forecast to cross the northern California coast Wednesday evening into Thursday morning, bringing with it forcing for ascent supportive of isolated dry thunderstorms. The greatest chances for dry thunderstorms will be across portions of northern California and southern Oregon. ...Dry Thunderstorms... Forecast sounding profiles still suggest the most unstable/buoyant parcels will originate at temperatures near or colder than 0 C, leaving some uncertainty in charge separation/lightning potential across the Northwest. However, forcing from the shortwave trough should be sufficient enough for at least some thunderstorm development overnight Wednesday into Thursday morning over receptive fuels. ...Dry/Windy... The strongest surface winds supportive of Elevated fire-weather conditions across the Western U.S. will be confined to diurnally/terrain-driven corridors that are too localized for highlights at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1044 AM CDT Wed Aug 14 2024 Valid 141700Z - 151200Z The previous forecast remains on track based on morning observations and latest guidance. Isolated thunderstorms remain likely after 00 UTC across far northern CA, spreading into central and eastern OR through 12 UTC Thursday. Pockets of wetting rainfall are possible, but PWAT values around 0.75 inches and storm motions between 20-25 knots should support the potential for sporadic dry lightning strikes over a region with dry fuels. Other forecast concerns outlined in the previous discussion below remain valid. ..Moore.. 08/14/2024 .PREV DISCUSSION... /ISSUED 0126 AM CDT Wed Aug 14 2024/ ...Synopsis... A mid-level shortwave trough is forecast to cross the northern California coast Wednesday evening into Thursday morning, bringing with it forcing for ascent supportive of isolated dry thunderstorms. The greatest chances for dry thunderstorms will be across portions of northern California and southern Oregon. ...Dry Thunderstorms... Forecast sounding profiles still suggest the most unstable/buoyant parcels will originate at temperatures near or colder than 0 C, leaving some uncertainty in charge separation/lightning potential across the Northwest. However, forcing from the shortwave trough should be sufficient enough for at least some thunderstorm development overnight Wednesday into Thursday morning over receptive fuels. ...Dry/Windy... The strongest surface winds supportive of Elevated fire-weather conditions across the Western U.S. will be confined to diurnally/terrain-driven corridors that are too localized for highlights at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0729 AM CDT Wed Aug 14 2024 Valid 141300Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EASTERN NEBRASKA...SOUTHWEST IOWA...NORTHEAST KANSAS...AND NORTHWEST MISSOURI... ...SUMMARY... Scattered severe thunderstorms capable of all hazards are possible late this afternoon through the evening across adjacent portions of the mid and lower Missouri Valley. ...Synopsis... Water-vapor imagery this morning shows a mid- to upper-level shortwave trough over WY/CO moving east-northeast. This upper feature is forecast to rotate through the base of a larger-scale trough and move into the eastern ND/northern MN vicinity by daybreak Thursday. In its wake, an upstream perturbation will move from southeast OR/southern ID into NE by late tonight. Consequently, an upper ridge will shift eastward from the lower-mid MO Valley through the mid MS Valley during the period. At the surface, weak/broad low pressure initially over the High Plains is forecast to gradually consolidate as it shifts eastward across the central Plains, in tandem with the advance of the upper trough. As this occurs, a cool front will shift southeastward across the central Plains through the afternoon and evening. Overnight, further consolidation of the surface low is expected as it moves slowly northeastward into southern Minnesota, while the trailing front sharpens, extending from the low southwestward across Kansas and into New Mexico by the end of the period. ...Mid to lower Missouri Valley... Mid morning radar/IR satellite mosaic shows an MCS over northern MO/IA with a well-developed MCV moving east-northeast over northeast NE. This activity will continue to weaken this morning and become increasingly displaced from KS/NE where a renewed focus for thunderstorm development will occur later today. The remnant outflow boundary will likely persist into the afternoon across the southeastern Nebraska/northwestern Missouri/southwestern Iowa area and modify as heating occurs to the west edge of the MCS cirrus canopy. Rich low-level moisture was sampled this morning on the Topeka, KS 12 UTC raob (16.7 g/kg lowest 100-mb mean mixing ratio). Southerly low-level flow will aid in moistening the airmass as insolation contributes to moderate to strong buoyancy (2000-4000 J/kg MLCAPE) by peak heating. By late afternoon as low pressure and the cold front shifts eastward into this area, the low/front and remnant outflow should all provide low-level foci for storm initiation. With enhanced southerly low-level flow ahead of the advancing mid-level trough beneath moderate (30 to 40 kt) mid-level westerlies, resulting shear suggests that initial storms will likely be supercells capable of producing large hail (1 to 2.5 inches in diameter). Enlarged hodographs along and north of the modified outflow boundary suggest a tornado risk will probably accompany a couple of the more intense supercells, where surface to 0.5 km flow remains relatively backed beneath a belt of 30-40 700-mb flow. Given modest flow above 300 mb, upscale growth into a cluster is forecast to occur relatively quickly during the early evening with a band further consolidating into a eastward-moving line by mid to late evening. Coincident with the transition to upscale growth, the tornado risk will gradually wane and severe gusts capable of wind damage will become the primary concern. This activity will likely persist as a linear MCS but the severe threat should lessen with east extent towards the MS River late. ...Wyoming and vicinity eastward across the northern and central Plains... As the upper trough -- comprised of several vorticity maxima embedded in the broader cyclonic flow field -- shifts across the Rockies toward/into the Plains, daytime heating beneath cooler air at mid levels will support modest destabilization across a broad area. Ascent -- focused near favored higher terrain areas and near various weak surface boundaries -- will contribute to widely scattered thunderstorm development during the afternoon. Moderate mid-level westerlies will contribute to shear sufficient for a few stronger storms -- and attendant risks for hail and locally strong/severe wind gusts into the evening hours. ..Smith.. 08/14/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0729 AM CDT Wed Aug 14 2024 Valid 141300Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EASTERN NEBRASKA...SOUTHWEST IOWA...NORTHEAST KANSAS...AND NORTHWEST MISSOURI... ...SUMMARY... Scattered severe thunderstorms capable of all hazards are possible late this afternoon through the evening across adjacent portions of the mid and lower Missouri Valley. ...Synopsis... Water-vapor imagery this morning shows a mid- to upper-level shortwave trough over WY/CO moving east-northeast. This upper feature is forecast to rotate through the base of a larger-scale trough and move into the eastern ND/northern MN vicinity by daybreak Thursday. In its wake, an upstream perturbation will move from southeast OR/southern ID into NE by late tonight. Consequently, an upper ridge will shift eastward from the lower-mid MO Valley through the mid MS Valley during the period. At the surface, weak/broad low pressure initially over the High Plains is forecast to gradually consolidate as it shifts eastward across the central Plains, in tandem with the advance of the upper trough. As this occurs, a cool front will shift southeastward across the central Plains through the afternoon and evening. Overnight, further consolidation of the surface low is expected as it moves slowly northeastward into southern Minnesota, while the trailing front sharpens, extending from the low southwestward across Kansas and into New Mexico by the end of the period. ...Mid to lower Missouri Valley... Mid morning radar/IR satellite mosaic shows an MCS over northern MO/IA with a well-developed MCV moving east-northeast over northeast NE. This activity will continue to weaken this morning and become increasingly displaced from KS/NE where a renewed focus for thunderstorm development will occur later today. The remnant outflow boundary will likely persist into the afternoon across the southeastern Nebraska/northwestern Missouri/southwestern Iowa area and modify as heating occurs to the west edge of the MCS cirrus canopy. Rich low-level moisture was sampled this morning on the Topeka, KS 12 UTC raob (16.7 g/kg lowest 100-mb mean mixing ratio). Southerly low-level flow will aid in moistening the airmass as insolation contributes to moderate to strong buoyancy (2000-4000 J/kg MLCAPE) by peak heating. By late afternoon as low pressure and the cold front shifts eastward into this area, the low/front and remnant outflow should all provide low-level foci for storm initiation. With enhanced southerly low-level flow ahead of the advancing mid-level trough beneath moderate (30 to 40 kt) mid-level westerlies, resulting shear suggests that initial storms will likely be supercells capable of producing large hail (1 to 2.5 inches in diameter). Enlarged hodographs along and north of the modified outflow boundary suggest a tornado risk will probably accompany a couple of the more intense supercells, where surface to 0.5 km flow remains relatively backed beneath a belt of 30-40 700-mb flow. Given modest flow above 300 mb, upscale growth into a cluster is forecast to occur relatively quickly during the early evening with a band further consolidating into a eastward-moving line by mid to late evening. Coincident with the transition to upscale growth, the tornado risk will gradually wane and severe gusts capable of wind damage will become the primary concern. This activity will likely persist as a linear MCS but the severe threat should lessen with east extent towards the MS River late. ...Wyoming and vicinity eastward across the northern and central Plains... As the upper trough -- comprised of several vorticity maxima embedded in the broader cyclonic flow field -- shifts across the Rockies toward/into the Plains, daytime heating beneath cooler air at mid levels will support modest destabilization across a broad area. Ascent -- focused near favored higher terrain areas and near various weak surface boundaries -- will contribute to widely scattered thunderstorm development during the afternoon. Moderate mid-level westerlies will contribute to shear sufficient for a few stronger storms -- and attendant risks for hail and locally strong/severe wind gusts into the evening hours. ..Smith.. 08/14/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0729 AM CDT Wed Aug 14 2024 Valid 141300Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EASTERN NEBRASKA...SOUTHWEST IOWA...NORTHEAST KANSAS...AND NORTHWEST MISSOURI... ...SUMMARY... Scattered severe thunderstorms capable of all hazards are possible late this afternoon through the evening across adjacent portions of the mid and lower Missouri Valley. ...Synopsis... Water-vapor imagery this morning shows a mid- to upper-level shortwave trough over WY/CO moving east-northeast. This upper feature is forecast to rotate through the base of a larger-scale trough and move into the eastern ND/northern MN vicinity by daybreak Thursday. In its wake, an upstream perturbation will move from southeast OR/southern ID into NE by late tonight. Consequently, an upper ridge will shift eastward from the lower-mid MO Valley through the mid MS Valley during the period. At the surface, weak/broad low pressure initially over the High Plains is forecast to gradually consolidate as it shifts eastward across the central Plains, in tandem with the advance of the upper trough. As this occurs, a cool front will shift southeastward across the central Plains through the afternoon and evening. Overnight, further consolidation of the surface low is expected as it moves slowly northeastward into southern Minnesota, while the trailing front sharpens, extending from the low southwestward across Kansas and into New Mexico by the end of the period. ...Mid to lower Missouri Valley... Mid morning radar/IR satellite mosaic shows an MCS over northern MO/IA with a well-developed MCV moving east-northeast over northeast NE. This activity will continue to weaken this morning and become increasingly displaced from KS/NE where a renewed focus for thunderstorm development will occur later today. The remnant outflow boundary will likely persist into the afternoon across the southeastern Nebraska/northwestern Missouri/southwestern Iowa area and modify as heating occurs to the west edge of the MCS cirrus canopy. Rich low-level moisture was sampled this morning on the Topeka, KS 12 UTC raob (16.7 g/kg lowest 100-mb mean mixing ratio). Southerly low-level flow will aid in moistening the airmass as insolation contributes to moderate to strong buoyancy (2000-4000 J/kg MLCAPE) by peak heating. By late afternoon as low pressure and the cold front shifts eastward into this area, the low/front and remnant outflow should all provide low-level foci for storm initiation. With enhanced southerly low-level flow ahead of the advancing mid-level trough beneath moderate (30 to 40 kt) mid-level westerlies, resulting shear suggests that initial storms will likely be supercells capable of producing large hail (1 to 2.5 inches in diameter). Enlarged hodographs along and north of the modified outflow boundary suggest a tornado risk will probably accompany a couple of the more intense supercells, where surface to 0.5 km flow remains relatively backed beneath a belt of 30-40 700-mb flow. Given modest flow above 300 mb, upscale growth into a cluster is forecast to occur relatively quickly during the early evening with a band further consolidating into a eastward-moving line by mid to late evening. Coincident with the transition to upscale growth, the tornado risk will gradually wane and severe gusts capable of wind damage will become the primary concern. This activity will likely persist as a linear MCS but the severe threat should lessen with east extent towards the MS River late. ...Wyoming and vicinity eastward across the northern and central Plains... As the upper trough -- comprised of several vorticity maxima embedded in the broader cyclonic flow field -- shifts across the Rockies toward/into the Plains, daytime heating beneath cooler air at mid levels will support modest destabilization across a broad area. Ascent -- focused near favored higher terrain areas and near various weak surface boundaries -- will contribute to widely scattered thunderstorm development during the afternoon. Moderate mid-level westerlies will contribute to shear sufficient for a few stronger storms -- and attendant risks for hail and locally strong/severe wind gusts into the evening hours. ..Smith.. 08/14/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0729 AM CDT Wed Aug 14 2024 Valid 141300Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EASTERN NEBRASKA...SOUTHWEST IOWA...NORTHEAST KANSAS...AND NORTHWEST MISSOURI... ...SUMMARY... Scattered severe thunderstorms capable of all hazards are possible late this afternoon through the evening across adjacent portions of the mid and lower Missouri Valley. ...Synopsis... Water-vapor imagery this morning shows a mid- to upper-level shortwave trough over WY/CO moving east-northeast. This upper feature is forecast to rotate through the base of a larger-scale trough and move into the eastern ND/northern MN vicinity by daybreak Thursday. In its wake, an upstream perturbation will move from southeast OR/southern ID into NE by late tonight. Consequently, an upper ridge will shift eastward from the lower-mid MO Valley through the mid MS Valley during the period. At the surface, weak/broad low pressure initially over the High Plains is forecast to gradually consolidate as it shifts eastward across the central Plains, in tandem with the advance of the upper trough. As this occurs, a cool front will shift southeastward across the central Plains through the afternoon and evening. Overnight, further consolidation of the surface low is expected as it moves slowly northeastward into southern Minnesota, while the trailing front sharpens, extending from the low southwestward across Kansas and into New Mexico by the end of the period. ...Mid to lower Missouri Valley... Mid morning radar/IR satellite mosaic shows an MCS over northern MO/IA with a well-developed MCV moving east-northeast over northeast NE. This activity will continue to weaken this morning and become increasingly displaced from KS/NE where a renewed focus for thunderstorm development will occur later today. The remnant outflow boundary will likely persist into the afternoon across the southeastern Nebraska/northwestern Missouri/southwestern Iowa area and modify as heating occurs to the west edge of the MCS cirrus canopy. Rich low-level moisture was sampled this morning on the Topeka, KS 12 UTC raob (16.7 g/kg lowest 100-mb mean mixing ratio). Southerly low-level flow will aid in moistening the airmass as insolation contributes to moderate to strong buoyancy (2000-4000 J/kg MLCAPE) by peak heating. By late afternoon as low pressure and the cold front shifts eastward into this area, the low/front and remnant outflow should all provide low-level foci for storm initiation. With enhanced southerly low-level flow ahead of the advancing mid-level trough beneath moderate (30 to 40 kt) mid-level westerlies, resulting shear suggests that initial storms will likely be supercells capable of producing large hail (1 to 2.5 inches in diameter). Enlarged hodographs along and north of the modified outflow boundary suggest a tornado risk will probably accompany a couple of the more intense supercells, where surface to 0.5 km flow remains relatively backed beneath a belt of 30-40 700-mb flow. Given modest flow above 300 mb, upscale growth into a cluster is forecast to occur relatively quickly during the early evening with a band further consolidating into a eastward-moving line by mid to late evening. Coincident with the transition to upscale growth, the tornado risk will gradually wane and severe gusts capable of wind damage will become the primary concern. This activity will likely persist as a linear MCS but the severe threat should lessen with east extent towards the MS River late. ...Wyoming and vicinity eastward across the northern and central Plains... As the upper trough -- comprised of several vorticity maxima embedded in the broader cyclonic flow field -- shifts across the Rockies toward/into the Plains, daytime heating beneath cooler air at mid levels will support modest destabilization across a broad area. Ascent -- focused near favored higher terrain areas and near various weak surface boundaries -- will contribute to widely scattered thunderstorm development during the afternoon. Moderate mid-level westerlies will contribute to shear sufficient for a few stronger storms -- and attendant risks for hail and locally strong/severe wind gusts into the evening hours. ..Smith.. 08/14/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Aug 14 2024 Valid 171200Z - 221200Z ...DISCUSSION... Medium-range guidance remains in good agreement that upper ridging will remain prominent, and probably further amplify, over much of the Rockies/Plains this weekend into early next week. An upper trough should progress slowly eastward from the Midwest/OH Valley to the eastern states on Day 4/Saturday. While an isolated severe risk may exist across parts of the Mid-Atlantic into the Southeast ahead of a weak front, the overall environment currently appears too marginal given modest deep-layer shear to warrant inclusion of a 15% severe area for Saturday. Otherwise, an upper trough/low should mostly remain off the coast of the Pacific Northwest through at least early next week, before possibly advancing inland towards the end of the forecast period (around Day 8/Wednesday). There is a fair amount of uncertainty regarding potential suppression of the upper ridge early next week. Regardless, the severe threat across the CONUS may tend to remain fairly isolated in this time frame, with the exception of potential MCS development from parts of the Plains into the Midwest/OH Valley in a northwesterly mid-level flow regime. But, predictability remains far too low to include any areas early next week. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Aug 14 2024 Valid 171200Z - 221200Z ...DISCUSSION... Medium-range guidance remains in good agreement that upper ridging will remain prominent, and probably further amplify, over much of the Rockies/Plains this weekend into early next week. An upper trough should progress slowly eastward from the Midwest/OH Valley to the eastern states on Day 4/Saturday. While an isolated severe risk may exist across parts of the Mid-Atlantic into the Southeast ahead of a weak front, the overall environment currently appears too marginal given modest deep-layer shear to warrant inclusion of a 15% severe area for Saturday. Otherwise, an upper trough/low should mostly remain off the coast of the Pacific Northwest through at least early next week, before possibly advancing inland towards the end of the forecast period (around Day 8/Wednesday). There is a fair amount of uncertainty regarding potential suppression of the upper ridge early next week. Regardless, the severe threat across the CONUS may tend to remain fairly isolated in this time frame, with the exception of potential MCS development from parts of the Plains into the Midwest/OH Valley in a northwesterly mid-level flow regime. But, predictability remains far too low to include any areas early next week. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Aug 14 2024 Valid 171200Z - 221200Z ...DISCUSSION... Medium-range guidance remains in good agreement that upper ridging will remain prominent, and probably further amplify, over much of the Rockies/Plains this weekend into early next week. An upper trough should progress slowly eastward from the Midwest/OH Valley to the eastern states on Day 4/Saturday. While an isolated severe risk may exist across parts of the Mid-Atlantic into the Southeast ahead of a weak front, the overall environment currently appears too marginal given modest deep-layer shear to warrant inclusion of a 15% severe area for Saturday. Otherwise, an upper trough/low should mostly remain off the coast of the Pacific Northwest through at least early next week, before possibly advancing inland towards the end of the forecast period (around Day 8/Wednesday). There is a fair amount of uncertainty regarding potential suppression of the upper ridge early next week. Regardless, the severe threat across the CONUS may tend to remain fairly isolated in this time frame, with the exception of potential MCS development from parts of the Plains into the Midwest/OH Valley in a northwesterly mid-level flow regime. But, predictability remains far too low to include any areas early next week. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Aug 14 2024 Valid 171200Z - 221200Z ...DISCUSSION... Medium-range guidance remains in good agreement that upper ridging will remain prominent, and probably further amplify, over much of the Rockies/Plains this weekend into early next week. An upper trough should progress slowly eastward from the Midwest/OH Valley to the eastern states on Day 4/Saturday. While an isolated severe risk may exist across parts of the Mid-Atlantic into the Southeast ahead of a weak front, the overall environment currently appears too marginal given modest deep-layer shear to warrant inclusion of a 15% severe area for Saturday. Otherwise, an upper trough/low should mostly remain off the coast of the Pacific Northwest through at least early next week, before possibly advancing inland towards the end of the forecast period (around Day 8/Wednesday). There is a fair amount of uncertainty regarding potential suppression of the upper ridge early next week. Regardless, the severe threat across the CONUS may tend to remain fairly isolated in this time frame, with the exception of potential MCS development from parts of the Plains into the Midwest/OH Valley in a northwesterly mid-level flow regime. But, predictability remains far too low to include any areas early next week. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Aug 14 2024 Valid 171200Z - 221200Z ...DISCUSSION... Medium-range guidance remains in good agreement that upper ridging will remain prominent, and probably further amplify, over much of the Rockies/Plains this weekend into early next week. An upper trough should progress slowly eastward from the Midwest/OH Valley to the eastern states on Day 4/Saturday. While an isolated severe risk may exist across parts of the Mid-Atlantic into the Southeast ahead of a weak front, the overall environment currently appears too marginal given modest deep-layer shear to warrant inclusion of a 15% severe area for Saturday. Otherwise, an upper trough/low should mostly remain off the coast of the Pacific Northwest through at least early next week, before possibly advancing inland towards the end of the forecast period (around Day 8/Wednesday). There is a fair amount of uncertainty regarding potential suppression of the upper ridge early next week. Regardless, the severe threat across the CONUS may tend to remain fairly isolated in this time frame, with the exception of potential MCS development from parts of the Plains into the Midwest/OH Valley in a northwesterly mid-level flow regime. But, predictability remains far too low to include any areas early next week. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0228 AM CDT Wed Aug 14 2024 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE GREAT LAKES INTO THE OHIO/TENNESSEE VALLEYS AND MID-SOUTH... ...SUMMARY... At least isolated strong to severe thunderstorms may develop Friday over portions of the Great Lakes into the Ohio/Tennessee Valleys and Mid-South. ...Great Lakes into the Ohio/Tennessee Valleys and Mid-South... As upper ridging remains suppressed across parts of the Southwest and southern Plains, an upper trough should continue to progress slowly eastward over portions of the Great Lakes/Midwest and OH Valley on Friday. A belt of enhanced mid-level flow should be present over parts of the mid MS Valley into the OH Valley, and related deep-layer shear should be sufficient for some updraft organization with thunderstorms that can develop through the period. A weak/occluded surface low beneath the upper cyclone should likewise develop slowly eastward over the Great Lakes and southern Ontario. An ill-defined front/wind shift is forecast to extend south-southwestward from this surface low. Thunderstorms will probably be ongoing Friday morning over parts of the OH Valley. This activity is generally expected to remain sub-severe and further weaken through the morning/early afternoon as it moves eastward into a less unstable airmass. Some recovery is expected to the west of the early-day convection and ahead of the weak front, with a rather moist low-level airmass forecast to be in place from portions of the lower OH Valley into the TN Valley and Mid-South vicinity. While deep-layer shear is forecast to gradually weaken with southward extent, a broad area of at least moderate instability should develop in tandem with daytime heating along and east/southeast of the front. Any thunderstorms that do develop could become strong to severe with mainly a hail/wind threat given the forecast environment, but considerable uncertainty remains concerning details of convective initiation and development. Only weak low-level convergence along the surface front also lends uncertainty in where greater severe thunderstorm coverage may occur. Therefore, for now have included a broad Marginal Risk for Friday. But, higher severe probabilities may eventually be needed if confidence increases in an MCS/cluster occurring. ..Gleason.. 08/14/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0228 AM CDT Wed Aug 14 2024 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE GREAT LAKES INTO THE OHIO/TENNESSEE VALLEYS AND MID-SOUTH... ...SUMMARY... At least isolated strong to severe thunderstorms may develop Friday over portions of the Great Lakes into the Ohio/Tennessee Valleys and Mid-South. ...Great Lakes into the Ohio/Tennessee Valleys and Mid-South... As upper ridging remains suppressed across parts of the Southwest and southern Plains, an upper trough should continue to progress slowly eastward over portions of the Great Lakes/Midwest and OH Valley on Friday. A belt of enhanced mid-level flow should be present over parts of the mid MS Valley into the OH Valley, and related deep-layer shear should be sufficient for some updraft organization with thunderstorms that can develop through the period. A weak/occluded surface low beneath the upper cyclone should likewise develop slowly eastward over the Great Lakes and southern Ontario. An ill-defined front/wind shift is forecast to extend south-southwestward from this surface low. Thunderstorms will probably be ongoing Friday morning over parts of the OH Valley. This activity is generally expected to remain sub-severe and further weaken through the morning/early afternoon as it moves eastward into a less unstable airmass. Some recovery is expected to the west of the early-day convection and ahead of the weak front, with a rather moist low-level airmass forecast to be in place from portions of the lower OH Valley into the TN Valley and Mid-South vicinity. While deep-layer shear is forecast to gradually weaken with southward extent, a broad area of at least moderate instability should develop in tandem with daytime heating along and east/southeast of the front. Any thunderstorms that do develop could become strong to severe with mainly a hail/wind threat given the forecast environment, but considerable uncertainty remains concerning details of convective initiation and development. Only weak low-level convergence along the surface front also lends uncertainty in where greater severe thunderstorm coverage may occur. Therefore, for now have included a broad Marginal Risk for Friday. But, higher severe probabilities may eventually be needed if confidence increases in an MCS/cluster occurring. ..Gleason.. 08/14/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0228 AM CDT Wed Aug 14 2024 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE GREAT LAKES INTO THE OHIO/TENNESSEE VALLEYS AND MID-SOUTH... ...SUMMARY... At least isolated strong to severe thunderstorms may develop Friday over portions of the Great Lakes into the Ohio/Tennessee Valleys and Mid-South. ...Great Lakes into the Ohio/Tennessee Valleys and Mid-South... As upper ridging remains suppressed across parts of the Southwest and southern Plains, an upper trough should continue to progress slowly eastward over portions of the Great Lakes/Midwest and OH Valley on Friday. A belt of enhanced mid-level flow should be present over parts of the mid MS Valley into the OH Valley, and related deep-layer shear should be sufficient for some updraft organization with thunderstorms that can develop through the period. A weak/occluded surface low beneath the upper cyclone should likewise develop slowly eastward over the Great Lakes and southern Ontario. An ill-defined front/wind shift is forecast to extend south-southwestward from this surface low. Thunderstorms will probably be ongoing Friday morning over parts of the OH Valley. This activity is generally expected to remain sub-severe and further weaken through the morning/early afternoon as it moves eastward into a less unstable airmass. Some recovery is expected to the west of the early-day convection and ahead of the weak front, with a rather moist low-level airmass forecast to be in place from portions of the lower OH Valley into the TN Valley and Mid-South vicinity. While deep-layer shear is forecast to gradually weaken with southward extent, a broad area of at least moderate instability should develop in tandem with daytime heating along and east/southeast of the front. Any thunderstorms that do develop could become strong to severe with mainly a hail/wind threat given the forecast environment, but considerable uncertainty remains concerning details of convective initiation and development. Only weak low-level convergence along the surface front also lends uncertainty in where greater severe thunderstorm coverage may occur. Therefore, for now have included a broad Marginal Risk for Friday. But, higher severe probabilities may eventually be needed if confidence increases in an MCS/cluster occurring. ..Gleason.. 08/14/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0228 AM CDT Wed Aug 14 2024 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE GREAT LAKES INTO THE OHIO/TENNESSEE VALLEYS AND MID-SOUTH... ...SUMMARY... At least isolated strong to severe thunderstorms may develop Friday over portions of the Great Lakes into the Ohio/Tennessee Valleys and Mid-South. ...Great Lakes into the Ohio/Tennessee Valleys and Mid-South... As upper ridging remains suppressed across parts of the Southwest and southern Plains, an upper trough should continue to progress slowly eastward over portions of the Great Lakes/Midwest and OH Valley on Friday. A belt of enhanced mid-level flow should be present over parts of the mid MS Valley into the OH Valley, and related deep-layer shear should be sufficient for some updraft organization with thunderstorms that can develop through the period. A weak/occluded surface low beneath the upper cyclone should likewise develop slowly eastward over the Great Lakes and southern Ontario. An ill-defined front/wind shift is forecast to extend south-southwestward from this surface low. Thunderstorms will probably be ongoing Friday morning over parts of the OH Valley. This activity is generally expected to remain sub-severe and further weaken through the morning/early afternoon as it moves eastward into a less unstable airmass. Some recovery is expected to the west of the early-day convection and ahead of the weak front, with a rather moist low-level airmass forecast to be in place from portions of the lower OH Valley into the TN Valley and Mid-South vicinity. While deep-layer shear is forecast to gradually weaken with southward extent, a broad area of at least moderate instability should develop in tandem with daytime heating along and east/southeast of the front. Any thunderstorms that do develop could become strong to severe with mainly a hail/wind threat given the forecast environment, but considerable uncertainty remains concerning details of convective initiation and development. Only weak low-level convergence along the surface front also lends uncertainty in where greater severe thunderstorm coverage may occur. Therefore, for now have included a broad Marginal Risk for Friday. But, higher severe probabilities may eventually be needed if confidence increases in an MCS/cluster occurring. ..Gleason.. 08/14/2024 Read more