Severe Storms

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0245 AM CDT Tue Aug 13 2019 Valid 161200Z - 211200Z ...DISCUSSION... An area of moderate westerlies aloft will remain over the northern CONUS on Fri/D4 and Sat/D5, but will lift north into Canada during the Sun/D6-Sat/D7 period. During that time, an upper ridge will build over the West with the high centered over AZ. On Fri/D4, the GFS indicates a low-amplitude shortwave trough moving from WY across SD, NE, and into IA, with an associated cold front, but the ECMWF is less amplified with this feature. In addition, there are major discrepancies with latitudinal placement of the larger instability (KS vs NE). As such, predictability is too low for Friday, though severe weather is possible (mainly wind gusts) in this general region. For the period from Sat/D5 into Sun/D6, ample moisture and instability will remain from the central Plains into the mid and upper MS Valley as a larger trough amplification occurs over south-central Canada, extending south into the northern Plains. Aside from timing issues amongst the various models with this trough, daily cycles of thunderstorms further decrease predictability regarding the best threat corridors. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0149 AM CDT Tue Aug 13 2019 Valid 151200Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF THE CENTRAL PLAINS... ...SUMMARY... A few severe storms are possible across much of the central Plains on Thursday. ...Synopsis and Discussion... A belt of 30-40 kt midlevel winds, increasing to 50-60 kt in the upper levels, will stretch from the northern Rockies across the central Plains and into the mid MS Valley on Thursday with various embedded disturbances within the flow. In general, a trough of low pressure is forecast to develop over the central and southern High Plains, with mid to upper 60s F dewpoints to about I-70 in KS. Given relatively cool temperatures aloft, this will result in areas of strong instability over parts of the central Plains. Complicating the forecast will be the possibility of early storms moving across parts of NE and KS, likely situated on the nose of a 20-30 kt low-level jet. Some of these storms may produce locally severe wind gusts. Later in the day, the air mass south and west of any outflow boundaries may serve as a focus for new development, again with an MCS possible with damaging wind potential. At this time, predictability is too low to place a Slight Risk. Farther north, storms are expected to develop by late morning or midday over SD in association with a low-amplitude wave moving out of MT. Here, cold temperatures aloft and long hodographs will favor both hail and wind as storms form along a weak cold front. Finally, isolated storms capable of hail are possible along the Front Range during the peak heating hours, with cold profiles aloft beneath ample westerlies. Parts of the area will likely be upgraded to a Slight Risk in later outlooks when predictability increases. ..Jewell.. 08/13/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0149 AM CDT Tue Aug 13 2019 Valid 151200Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF THE CENTRAL PLAINS... ...SUMMARY... A few severe storms are possible across much of the central Plains on Thursday. ...Synopsis and Discussion... A belt of 30-40 kt midlevel winds, increasing to 50-60 kt in the upper levels, will stretch from the northern Rockies across the central Plains and into the mid MS Valley on Thursday with various embedded disturbances within the flow. In general, a trough of low pressure is forecast to develop over the central and southern High Plains, with mid to upper 60s F dewpoints to about I-70 in KS. Given relatively cool temperatures aloft, this will result in areas of strong instability over parts of the central Plains. Complicating the forecast will be the possibility of early storms moving across parts of NE and KS, likely situated on the nose of a 20-30 kt low-level jet. Some of these storms may produce locally severe wind gusts. Later in the day, the air mass south and west of any outflow boundaries may serve as a focus for new development, again with an MCS possible with damaging wind potential. At this time, predictability is too low to place a Slight Risk. Farther north, storms are expected to develop by late morning or midday over SD in association with a low-amplitude wave moving out of MT. Here, cold temperatures aloft and long hodographs will favor both hail and wind as storms form along a weak cold front. Finally, isolated storms capable of hail are possible along the Front Range during the peak heating hours, with cold profiles aloft beneath ample westerlies. Parts of the area will likely be upgraded to a Slight Risk in later outlooks when predictability increases. ..Jewell.. 08/13/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0149 AM CDT Tue Aug 13 2019 Valid 151200Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF THE CENTRAL PLAINS... ...SUMMARY... A few severe storms are possible across much of the central Plains on Thursday. ...Synopsis and Discussion... A belt of 30-40 kt midlevel winds, increasing to 50-60 kt in the upper levels, will stretch from the northern Rockies across the central Plains and into the mid MS Valley on Thursday with various embedded disturbances within the flow. In general, a trough of low pressure is forecast to develop over the central and southern High Plains, with mid to upper 60s F dewpoints to about I-70 in KS. Given relatively cool temperatures aloft, this will result in areas of strong instability over parts of the central Plains. Complicating the forecast will be the possibility of early storms moving across parts of NE and KS, likely situated on the nose of a 20-30 kt low-level jet. Some of these storms may produce locally severe wind gusts. Later in the day, the air mass south and west of any outflow boundaries may serve as a focus for new development, again with an MCS possible with damaging wind potential. At this time, predictability is too low to place a Slight Risk. Farther north, storms are expected to develop by late morning or midday over SD in association with a low-amplitude wave moving out of MT. Here, cold temperatures aloft and long hodographs will favor both hail and wind as storms form along a weak cold front. Finally, isolated storms capable of hail are possible along the Front Range during the peak heating hours, with cold profiles aloft beneath ample westerlies. Parts of the area will likely be upgraded to a Slight Risk in later outlooks when predictability increases. ..Jewell.. 08/13/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0149 AM CDT Tue Aug 13 2019 Valid 151200Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF THE CENTRAL PLAINS... ...SUMMARY... A few severe storms are possible across much of the central Plains on Thursday. ...Synopsis and Discussion... A belt of 30-40 kt midlevel winds, increasing to 50-60 kt in the upper levels, will stretch from the northern Rockies across the central Plains and into the mid MS Valley on Thursday with various embedded disturbances within the flow. In general, a trough of low pressure is forecast to develop over the central and southern High Plains, with mid to upper 60s F dewpoints to about I-70 in KS. Given relatively cool temperatures aloft, this will result in areas of strong instability over parts of the central Plains. Complicating the forecast will be the possibility of early storms moving across parts of NE and KS, likely situated on the nose of a 20-30 kt low-level jet. Some of these storms may produce locally severe wind gusts. Later in the day, the air mass south and west of any outflow boundaries may serve as a focus for new development, again with an MCS possible with damaging wind potential. At this time, predictability is too low to place a Slight Risk. Farther north, storms are expected to develop by late morning or midday over SD in association with a low-amplitude wave moving out of MT. Here, cold temperatures aloft and long hodographs will favor both hail and wind as storms form along a weak cold front. Finally, isolated storms capable of hail are possible along the Front Range during the peak heating hours, with cold profiles aloft beneath ample westerlies. Parts of the area will likely be upgraded to a Slight Risk in later outlooks when predictability increases. ..Jewell.. 08/13/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 AM CDT Tue Aug 13 2019 Valid 141200Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN COLORADO INTO WESTERN NEBRASKA AND KANSAS... ...SUMMARY... Scattered strong to severe storms with damaging hail and wind will be possible over the central High Plains Wednesday afternoon and evening, with isolated severe wind gusts from parts of the Gulf Coast to the eastern Carolinas. ...Synopsis... Northwest flow aloft will stretch from the Pacific Northwest across the northern Rockies and into the central Plains with a low-amplitude shortwave trough entering the northern High Plains late in the day. To the east, another wave will move across northern New England, with relatively cool temperatures aloft remaining over the OH Valley beneath westerly flow. At the surface, relatively dry air will exist from the northern Plains eastward across the Great Lakes and into New England, while a weak surface trough extends from the Mid Atlantic across the northern Gulf Coast and into central TX. Seasonally moist conditions will exist along the southern boundary supporting scattered afternoon storms. To the west, a lee trough will develop over the central High Plains where southeasterly surface winds will maintain moist and unstable conditions beneath moderate northwest winds aloft, favoring severe storms. ...Central High Plains... Southeast surface winds will maintain mid 50s to near 60 F dewpoints to the Front Range as strong heating reduces capping, possibly in the wake of storms the previous night. Storms are expected to initiate around 21Z from eastern WY across the Black Hills, and southward into northeast CO. Relatively long hodographs will favor splitting cells capable of large hail. An MCS is possible by evening into western NE or northwest KS as the low-level jet increases to 30 kt out of the south. A brief tornado cannot be ruled out with any right-moving supercells. ...Gulf Coast States to the Carolinas... Strong heating of a moist air mass will lead to strong instability by afternoon, with MUCAPE in excess of 3000 J/kg from the Sabine River to the eastern Carolinas. Convergence near the boundary will provide a focus for storms, with very weak winds aloft favoring pulse severe capable of localized damaging winds, perhaps with small hail. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% - Slight Hail: 15% - Slight ..Jewell.. 08/13/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 AM CDT Tue Aug 13 2019 Valid 141200Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN COLORADO INTO WESTERN NEBRASKA AND KANSAS... ...SUMMARY... Scattered strong to severe storms with damaging hail and wind will be possible over the central High Plains Wednesday afternoon and evening, with isolated severe wind gusts from parts of the Gulf Coast to the eastern Carolinas. ...Synopsis... Northwest flow aloft will stretch from the Pacific Northwest across the northern Rockies and into the central Plains with a low-amplitude shortwave trough entering the northern High Plains late in the day. To the east, another wave will move across northern New England, with relatively cool temperatures aloft remaining over the OH Valley beneath westerly flow. At the surface, relatively dry air will exist from the northern Plains eastward across the Great Lakes and into New England, while a weak surface trough extends from the Mid Atlantic across the northern Gulf Coast and into central TX. Seasonally moist conditions will exist along the southern boundary supporting scattered afternoon storms. To the west, a lee trough will develop over the central High Plains where southeasterly surface winds will maintain moist and unstable conditions beneath moderate northwest winds aloft, favoring severe storms. ...Central High Plains... Southeast surface winds will maintain mid 50s to near 60 F dewpoints to the Front Range as strong heating reduces capping, possibly in the wake of storms the previous night. Storms are expected to initiate around 21Z from eastern WY across the Black Hills, and southward into northeast CO. Relatively long hodographs will favor splitting cells capable of large hail. An MCS is possible by evening into western NE or northwest KS as the low-level jet increases to 30 kt out of the south. A brief tornado cannot be ruled out with any right-moving supercells. ...Gulf Coast States to the Carolinas... Strong heating of a moist air mass will lead to strong instability by afternoon, with MUCAPE in excess of 3000 J/kg from the Sabine River to the eastern Carolinas. Convergence near the boundary will provide a focus for storms, with very weak winds aloft favoring pulse severe capable of localized damaging winds, perhaps with small hail. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% - Slight Hail: 15% - Slight ..Jewell.. 08/13/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 AM CDT Tue Aug 13 2019 Valid 141200Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN COLORADO INTO WESTERN NEBRASKA AND KANSAS... ...SUMMARY... Scattered strong to severe storms with damaging hail and wind will be possible over the central High Plains Wednesday afternoon and evening, with isolated severe wind gusts from parts of the Gulf Coast to the eastern Carolinas. ...Synopsis... Northwest flow aloft will stretch from the Pacific Northwest across the northern Rockies and into the central Plains with a low-amplitude shortwave trough entering the northern High Plains late in the day. To the east, another wave will move across northern New England, with relatively cool temperatures aloft remaining over the OH Valley beneath westerly flow. At the surface, relatively dry air will exist from the northern Plains eastward across the Great Lakes and into New England, while a weak surface trough extends from the Mid Atlantic across the northern Gulf Coast and into central TX. Seasonally moist conditions will exist along the southern boundary supporting scattered afternoon storms. To the west, a lee trough will develop over the central High Plains where southeasterly surface winds will maintain moist and unstable conditions beneath moderate northwest winds aloft, favoring severe storms. ...Central High Plains... Southeast surface winds will maintain mid 50s to near 60 F dewpoints to the Front Range as strong heating reduces capping, possibly in the wake of storms the previous night. Storms are expected to initiate around 21Z from eastern WY across the Black Hills, and southward into northeast CO. Relatively long hodographs will favor splitting cells capable of large hail. An MCS is possible by evening into western NE or northwest KS as the low-level jet increases to 30 kt out of the south. A brief tornado cannot be ruled out with any right-moving supercells. ...Gulf Coast States to the Carolinas... Strong heating of a moist air mass will lead to strong instability by afternoon, with MUCAPE in excess of 3000 J/kg from the Sabine River to the eastern Carolinas. Convergence near the boundary will provide a focus for storms, with very weak winds aloft favoring pulse severe capable of localized damaging winds, perhaps with small hail. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% - Slight Hail: 15% - Slight ..Jewell.. 08/13/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 AM CDT Tue Aug 13 2019 Valid 141200Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN COLORADO INTO WESTERN NEBRASKA AND KANSAS... ...SUMMARY... Scattered strong to severe storms with damaging hail and wind will be possible over the central High Plains Wednesday afternoon and evening, with isolated severe wind gusts from parts of the Gulf Coast to the eastern Carolinas. ...Synopsis... Northwest flow aloft will stretch from the Pacific Northwest across the northern Rockies and into the central Plains with a low-amplitude shortwave trough entering the northern High Plains late in the day. To the east, another wave will move across northern New England, with relatively cool temperatures aloft remaining over the OH Valley beneath westerly flow. At the surface, relatively dry air will exist from the northern Plains eastward across the Great Lakes and into New England, while a weak surface trough extends from the Mid Atlantic across the northern Gulf Coast and into central TX. Seasonally moist conditions will exist along the southern boundary supporting scattered afternoon storms. To the west, a lee trough will develop over the central High Plains where southeasterly surface winds will maintain moist and unstable conditions beneath moderate northwest winds aloft, favoring severe storms. ...Central High Plains... Southeast surface winds will maintain mid 50s to near 60 F dewpoints to the Front Range as strong heating reduces capping, possibly in the wake of storms the previous night. Storms are expected to initiate around 21Z from eastern WY across the Black Hills, and southward into northeast CO. Relatively long hodographs will favor splitting cells capable of large hail. An MCS is possible by evening into western NE or northwest KS as the low-level jet increases to 30 kt out of the south. A brief tornado cannot be ruled out with any right-moving supercells. ...Gulf Coast States to the Carolinas... Strong heating of a moist air mass will lead to strong instability by afternoon, with MUCAPE in excess of 3000 J/kg from the Sabine River to the eastern Carolinas. Convergence near the boundary will provide a focus for storms, with very weak winds aloft favoring pulse severe capable of localized damaging winds, perhaps with small hail. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% - Slight Hail: 15% - Slight ..Jewell.. 08/13/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1239 AM CDT Tue Aug 13 2019 Valid 131200Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDDLE ATLANTIC... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE TN VALLEY AND OVER THE CENTRAL HIGH PLAINS... ...SUMMARY... Scattered severe thunderstorms are expected across the southern Middle Atlantic into the Tennessee Valley. Severe thunderstorms should also develop across the central High Plains. ...Middle Atlantic/TN Valley... Early-morning water-vapor imagery depicts a mid-level vort max over central IL which appears to be partly responsible for organized deep convection over the lower OH Valley. This feature is forecast to progress east-southeast across the OH Valley and leading edge of affiliated MCS is expected to spread into WV shortly after sunrise. Considerable amount of clouds/precipitation should limit buoyancy across the central Appalachians while models favor stronger boundary-layer heating downstream across the Piedmont. For these reasons will lower severe probs across WV/western VA and orient ENH Risk east of the mountains where renewed thunderstorm development is expected by early afternoon. Damaging winds are the primary severe threat with scattered severe storms as they organize across the Piedmont. While initial convection may be cellular in nature, line segments capable of producing wind should mature across the southern Delmarva into southern VA. Scattered severe thunderstorms are also expected to develop along weak frontal zone as it sags southeast across KY/TN during the afternoon. This activity will evolve along southern fringe of modest northwesterly flow which should contribute to some organization. Strong storms may spread as far south as northern AL by late evening. ...Central High Plains... Weak mid-level height rises are forecast across the Great Basin Tuesday which should maintain modest 500mb flow across the central High Plains along the front side of southwestern U.S. anticyclone. While it's not evident that any meaningful disturbance will approach southern WY/NE, strong boundary-layer heating is forecast across eastern WY/CO. Forecast soundings suggest surface parcels will reach their convective temperatures by 20-21z. Early-evening CAMs aggressively develop convection across this region with supercell structures forecast early in the convective cycle. Local hail algorithm generates hail in excess of 2" and this seems reasonable given the steep lapse rates and seasonally high buoyancy. There is some concern that scattered supercells will merge into an MCS that should propagate southeast across western KS toward northwestern OK during the overnight hours. Wind threat should increase if an organized squall line emerges across this region. ...Upper MS Valley... Notable short-wave trough is beginning to dig southeast across the northern Plains. Large-scale forcing ahead of this feature is forecast to spread across southeast MN/western WI by early afternoon. In response to the short wave, weak surface low will develop over southeast MN which should enhance low-level convergence for isolated thunderstorm development. 00z NAM suggests strong boundary-layer heating will be noted into this feature which will result in convective temperatures being breached by 20-21z. Will maintain 5% severe probs across this region due to the expected isolated nature of convection. ..Darrow/Cook.. 08/13/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1239 AM CDT Tue Aug 13 2019 Valid 131200Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDDLE ATLANTIC... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE TN VALLEY AND OVER THE CENTRAL HIGH PLAINS... ...SUMMARY... Scattered severe thunderstorms are expected across the southern Middle Atlantic into the Tennessee Valley. Severe thunderstorms should also develop across the central High Plains. ...Middle Atlantic/TN Valley... Early-morning water-vapor imagery depicts a mid-level vort max over central IL which appears to be partly responsible for organized deep convection over the lower OH Valley. This feature is forecast to progress east-southeast across the OH Valley and leading edge of affiliated MCS is expected to spread into WV shortly after sunrise. Considerable amount of clouds/precipitation should limit buoyancy across the central Appalachians while models favor stronger boundary-layer heating downstream across the Piedmont. For these reasons will lower severe probs across WV/western VA and orient ENH Risk east of the mountains where renewed thunderstorm development is expected by early afternoon. Damaging winds are the primary severe threat with scattered severe storms as they organize across the Piedmont. While initial convection may be cellular in nature, line segments capable of producing wind should mature across the southern Delmarva into southern VA. Scattered severe thunderstorms are also expected to develop along weak frontal zone as it sags southeast across KY/TN during the afternoon. This activity will evolve along southern fringe of modest northwesterly flow which should contribute to some organization. Strong storms may spread as far south as northern AL by late evening. ...Central High Plains... Weak mid-level height rises are forecast across the Great Basin Tuesday which should maintain modest 500mb flow across the central High Plains along the front side of southwestern U.S. anticyclone. While it's not evident that any meaningful disturbance will approach southern WY/NE, strong boundary-layer heating is forecast across eastern WY/CO. Forecast soundings suggest surface parcels will reach their convective temperatures by 20-21z. Early-evening CAMs aggressively develop convection across this region with supercell structures forecast early in the convective cycle. Local hail algorithm generates hail in excess of 2" and this seems reasonable given the steep lapse rates and seasonally high buoyancy. There is some concern that scattered supercells will merge into an MCS that should propagate southeast across western KS toward northwestern OK during the overnight hours. Wind threat should increase if an organized squall line emerges across this region. ...Upper MS Valley... Notable short-wave trough is beginning to dig southeast across the northern Plains. Large-scale forcing ahead of this feature is forecast to spread across southeast MN/western WI by early afternoon. In response to the short wave, weak surface low will develop over southeast MN which should enhance low-level convergence for isolated thunderstorm development. 00z NAM suggests strong boundary-layer heating will be noted into this feature which will result in convective temperatures being breached by 20-21z. Will maintain 5% severe probs across this region due to the expected isolated nature of convection. ..Darrow/Cook.. 08/13/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1239 AM CDT Tue Aug 13 2019 Valid 131200Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDDLE ATLANTIC... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE TN VALLEY AND OVER THE CENTRAL HIGH PLAINS... ...SUMMARY... Scattered severe thunderstorms are expected across the southern Middle Atlantic into the Tennessee Valley. Severe thunderstorms should also develop across the central High Plains. ...Middle Atlantic/TN Valley... Early-morning water-vapor imagery depicts a mid-level vort max over central IL which appears to be partly responsible for organized deep convection over the lower OH Valley. This feature is forecast to progress east-southeast across the OH Valley and leading edge of affiliated MCS is expected to spread into WV shortly after sunrise. Considerable amount of clouds/precipitation should limit buoyancy across the central Appalachians while models favor stronger boundary-layer heating downstream across the Piedmont. For these reasons will lower severe probs across WV/western VA and orient ENH Risk east of the mountains where renewed thunderstorm development is expected by early afternoon. Damaging winds are the primary severe threat with scattered severe storms as they organize across the Piedmont. While initial convection may be cellular in nature, line segments capable of producing wind should mature across the southern Delmarva into southern VA. Scattered severe thunderstorms are also expected to develop along weak frontal zone as it sags southeast across KY/TN during the afternoon. This activity will evolve along southern fringe of modest northwesterly flow which should contribute to some organization. Strong storms may spread as far south as northern AL by late evening. ...Central High Plains... Weak mid-level height rises are forecast across the Great Basin Tuesday which should maintain modest 500mb flow across the central High Plains along the front side of southwestern U.S. anticyclone. While it's not evident that any meaningful disturbance will approach southern WY/NE, strong boundary-layer heating is forecast across eastern WY/CO. Forecast soundings suggest surface parcels will reach their convective temperatures by 20-21z. Early-evening CAMs aggressively develop convection across this region with supercell structures forecast early in the convective cycle. Local hail algorithm generates hail in excess of 2" and this seems reasonable given the steep lapse rates and seasonally high buoyancy. There is some concern that scattered supercells will merge into an MCS that should propagate southeast across western KS toward northwestern OK during the overnight hours. Wind threat should increase if an organized squall line emerges across this region. ...Upper MS Valley... Notable short-wave trough is beginning to dig southeast across the northern Plains. Large-scale forcing ahead of this feature is forecast to spread across southeast MN/western WI by early afternoon. In response to the short wave, weak surface low will develop over southeast MN which should enhance low-level convergence for isolated thunderstorm development. 00z NAM suggests strong boundary-layer heating will be noted into this feature which will result in convective temperatures being breached by 20-21z. Will maintain 5% severe probs across this region due to the expected isolated nature of convection. ..Darrow/Cook.. 08/13/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1239 AM CDT Tue Aug 13 2019 Valid 131200Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDDLE ATLANTIC... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE TN VALLEY AND OVER THE CENTRAL HIGH PLAINS... ...SUMMARY... Scattered severe thunderstorms are expected across the southern Middle Atlantic into the Tennessee Valley. Severe thunderstorms should also develop across the central High Plains. ...Middle Atlantic/TN Valley... Early-morning water-vapor imagery depicts a mid-level vort max over central IL which appears to be partly responsible for organized deep convection over the lower OH Valley. This feature is forecast to progress east-southeast across the OH Valley and leading edge of affiliated MCS is expected to spread into WV shortly after sunrise. Considerable amount of clouds/precipitation should limit buoyancy across the central Appalachians while models favor stronger boundary-layer heating downstream across the Piedmont. For these reasons will lower severe probs across WV/western VA and orient ENH Risk east of the mountains where renewed thunderstorm development is expected by early afternoon. Damaging winds are the primary severe threat with scattered severe storms as they organize across the Piedmont. While initial convection may be cellular in nature, line segments capable of producing wind should mature across the southern Delmarva into southern VA. Scattered severe thunderstorms are also expected to develop along weak frontal zone as it sags southeast across KY/TN during the afternoon. This activity will evolve along southern fringe of modest northwesterly flow which should contribute to some organization. Strong storms may spread as far south as northern AL by late evening. ...Central High Plains... Weak mid-level height rises are forecast across the Great Basin Tuesday which should maintain modest 500mb flow across the central High Plains along the front side of southwestern U.S. anticyclone. While it's not evident that any meaningful disturbance will approach southern WY/NE, strong boundary-layer heating is forecast across eastern WY/CO. Forecast soundings suggest surface parcels will reach their convective temperatures by 20-21z. Early-evening CAMs aggressively develop convection across this region with supercell structures forecast early in the convective cycle. Local hail algorithm generates hail in excess of 2" and this seems reasonable given the steep lapse rates and seasonally high buoyancy. There is some concern that scattered supercells will merge into an MCS that should propagate southeast across western KS toward northwestern OK during the overnight hours. Wind threat should increase if an organized squall line emerges across this region. ...Upper MS Valley... Notable short-wave trough is beginning to dig southeast across the northern Plains. Large-scale forcing ahead of this feature is forecast to spread across southeast MN/western WI by early afternoon. In response to the short wave, weak surface low will develop over southeast MN which should enhance low-level convergence for isolated thunderstorm development. 00z NAM suggests strong boundary-layer heating will be noted into this feature which will result in convective temperatures being breached by 20-21z. Will maintain 5% severe probs across this region due to the expected isolated nature of convection. ..Darrow/Cook.. 08/13/2019 Read more

WW 0575 Status Updates
STATUS REPORT ON WW 575 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 45 SW BMG TO 20 NW BMG TO 30 ENE BMG. ..KERR..08/13/19 ATTN...WFO...LSX...ILX...IND... STATUS REPORT FOR WT 575 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS INC013-027-055-071-083-093-101-105-119-153-130640- IN . INDIANA COUNTIES INCLUDED ARE BROWN DAVIESS GREENE JACKSON KNOX LAWRENCE MARTIN MONROE OWEN SULLIVAN THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 575 TORNADO IL IN MO 130125Z - 130800Z
URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 575 NWS Storm Prediction Center Norman OK 825 PM CDT Mon Aug 12 2019 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Central Illinois Western and central Indiana Extreme eastern Missouri * Effective this Monday night and Tuesday morning from 825 PM until 300 AM CDT. * Primary threats include... A couple tornadoes possible Scattered damaging winds likely with isolated significant gusts to 75 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...Increasingly focus band of convection has formed over central IL, along with isolated, potentially severe convection northwest of STL, all moving into a favorable environment for supercells and bow echoes. Activity should progress east-southeastward over the watch area, with all severe types possible. The tornado watch area is approximately along and 45 statute miles north and south of a line from 60 miles northwest of Alton IL to 30 miles south southeast of Indianapolis IN. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU5). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Tornado Watch means conditions are favorable for tornadoes and severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. && AVIATION...Tornadoes and a few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 65 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 28030. ...Edwards Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1208 AM CDT Tue Aug 13 2019 Valid 141200Z - 151200Z ...NO CRITICAL AREAS... ...Synopsis... The mid/upper synoptic pattern will amplify slightly as a broad trough becomes established across the East and a weak ridge increases across the Southwest. Stronger flow aloft will remain displaced from dry areas across the West (where fuels are cured), and this should keep fire weather concerns minimal throughout the forecast period. ..Cook.. 08/13/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1208 AM CDT Tue Aug 13 2019 Valid 141200Z - 151200Z ...NO CRITICAL AREAS... ...Synopsis... The mid/upper synoptic pattern will amplify slightly as a broad trough becomes established across the East and a weak ridge increases across the Southwest. Stronger flow aloft will remain displaced from dry areas across the West (where fuels are cured), and this should keep fire weather concerns minimal throughout the forecast period. ..Cook.. 08/13/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1208 AM CDT Tue Aug 13 2019 Valid 141200Z - 151200Z ...NO CRITICAL AREAS... ...Synopsis... The mid/upper synoptic pattern will amplify slightly as a broad trough becomes established across the East and a weak ridge increases across the Southwest. Stronger flow aloft will remain displaced from dry areas across the West (where fuels are cured), and this should keep fire weather concerns minimal throughout the forecast period. ..Cook.. 08/13/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1208 AM CDT Tue Aug 13 2019 Valid 141200Z - 151200Z ...NO CRITICAL AREAS... ...Synopsis... The mid/upper synoptic pattern will amplify slightly as a broad trough becomes established across the East and a weak ridge increases across the Southwest. Stronger flow aloft will remain displaced from dry areas across the West (where fuels are cured), and this should keep fire weather concerns minimal throughout the forecast period. ..Cook.. 08/13/2019 ...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 1208 AM CDT Tue Aug 13 2019 Valid 131200Z - 141200Z ...NO CRITICAL AREAS... ...Synopsis... The synoptic pattern will continue to be generally unfavorable for fire weather concerns today. Weak, quasi-zonal flow aloft will extend across the northern tier of the CONUS today. Additionally, flow across dry areas of the West will remain relatively light outside of localized, terrain-favored areas. Given the minimal fire weather concerns, no highlights will be introduced for this outlook. ..Cook.. 08/13/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more