SPC Aug 21, 2019 0730 UTC Day 3 Severe Thunderstorm Outlook

5 years 10 months ago
SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 AM CDT Wed Aug 21 2019 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTH CAROLINA INTO SOUTHERN VIRGINIA... ...SUMMARY... Isolated severe wind gusts are possible Friday over parts of North Carolina and southern Virginia. ...Synopsis... An upper low will pivot northeast across the Canadian Maritimes, with a jet streak sweeping across New England and tail end near the Mid Atlantic. At the surface, high pressure will remain over the Great Lakes, with a cold front moving south toward the VA/NC border. A weak surface low is forecast to develop over eastern VA and NC near the front where 70s F dewpoints and heating will contribute to moderate destabilization. To the west, a leading shortwave trough will eject out of the Dakotas toward western Ontario as a broad upper jet noses into the northern High Plains Friday night. Dewpoints in the 60s F will exist over the Dakotas ahead of a dying front related to the leading wave, and will back westward toward MT by 12Z Saturday. Elsewhere, a loose east-west boundary will remain roughly from KY/TN into north TX, with bouts of mainly non-severe thunderstorms through the period. ...NC into southern VA... Strong heating of a moist air mass will occur south of the cold front approaching the VA/NC border late in the day. Forecast soundings indicate 2000-2500 J/kg MLCAPE developing despite poor midlevel lapse rates, though low-level lapse rates will become steep. With no capping present, the front will provide a focus for scattered storms, which may produce locally severe wind gusts as they propagate southeastward from VA into NC. Models are in good agreement depicting a relatively concentrated area of storms in this area. ...Northern High Plains... Elevated thunderstorms may be ongoing Friday morning over central ND in association with the departing shortwave trough, but will likely lose strength as lift wanes, and due to dry trajectories out of the surface high to the east. As cooling aloft arrives from the west, lapse rates as well as deep shear will increase, conditionally favoring elevated hail into Saturday morning over eastern MT. At this time, storm chances prior to 12Z Saturday appear too low to introduce severe probabilities. ..Jewell.. 08/21/2019 Read more

SPC Aug 21, 2019 0730 UTC Day 3 Severe Thunderstorm Outlook

5 years 10 months ago
SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 AM CDT Wed Aug 21 2019 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTH CAROLINA INTO SOUTHERN VIRGINIA... ...SUMMARY... Isolated severe wind gusts are possible Friday over parts of North Carolina and southern Virginia. ...Synopsis... An upper low will pivot northeast across the Canadian Maritimes, with a jet streak sweeping across New England and tail end near the Mid Atlantic. At the surface, high pressure will remain over the Great Lakes, with a cold front moving south toward the VA/NC border. A weak surface low is forecast to develop over eastern VA and NC near the front where 70s F dewpoints and heating will contribute to moderate destabilization. To the west, a leading shortwave trough will eject out of the Dakotas toward western Ontario as a broad upper jet noses into the northern High Plains Friday night. Dewpoints in the 60s F will exist over the Dakotas ahead of a dying front related to the leading wave, and will back westward toward MT by 12Z Saturday. Elsewhere, a loose east-west boundary will remain roughly from KY/TN into north TX, with bouts of mainly non-severe thunderstorms through the period. ...NC into southern VA... Strong heating of a moist air mass will occur south of the cold front approaching the VA/NC border late in the day. Forecast soundings indicate 2000-2500 J/kg MLCAPE developing despite poor midlevel lapse rates, though low-level lapse rates will become steep. With no capping present, the front will provide a focus for scattered storms, which may produce locally severe wind gusts as they propagate southeastward from VA into NC. Models are in good agreement depicting a relatively concentrated area of storms in this area. ...Northern High Plains... Elevated thunderstorms may be ongoing Friday morning over central ND in association with the departing shortwave trough, but will likely lose strength as lift wanes, and due to dry trajectories out of the surface high to the east. As cooling aloft arrives from the west, lapse rates as well as deep shear will increase, conditionally favoring elevated hail into Saturday morning over eastern MT. At this time, storm chances prior to 12Z Saturday appear too low to introduce severe probabilities. ..Jewell.. 08/21/2019 Read more

SPC Aug 21, 2019 0730 UTC Day 3 Severe Thunderstorm Outlook

5 years 10 months ago
SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 AM CDT Wed Aug 21 2019 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTH CAROLINA INTO SOUTHERN VIRGINIA... ...SUMMARY... Isolated severe wind gusts are possible Friday over parts of North Carolina and southern Virginia. ...Synopsis... An upper low will pivot northeast across the Canadian Maritimes, with a jet streak sweeping across New England and tail end near the Mid Atlantic. At the surface, high pressure will remain over the Great Lakes, with a cold front moving south toward the VA/NC border. A weak surface low is forecast to develop over eastern VA and NC near the front where 70s F dewpoints and heating will contribute to moderate destabilization. To the west, a leading shortwave trough will eject out of the Dakotas toward western Ontario as a broad upper jet noses into the northern High Plains Friday night. Dewpoints in the 60s F will exist over the Dakotas ahead of a dying front related to the leading wave, and will back westward toward MT by 12Z Saturday. Elsewhere, a loose east-west boundary will remain roughly from KY/TN into north TX, with bouts of mainly non-severe thunderstorms through the period. ...NC into southern VA... Strong heating of a moist air mass will occur south of the cold front approaching the VA/NC border late in the day. Forecast soundings indicate 2000-2500 J/kg MLCAPE developing despite poor midlevel lapse rates, though low-level lapse rates will become steep. With no capping present, the front will provide a focus for scattered storms, which may produce locally severe wind gusts as they propagate southeastward from VA into NC. Models are in good agreement depicting a relatively concentrated area of storms in this area. ...Northern High Plains... Elevated thunderstorms may be ongoing Friday morning over central ND in association with the departing shortwave trough, but will likely lose strength as lift wanes, and due to dry trajectories out of the surface high to the east. As cooling aloft arrives from the west, lapse rates as well as deep shear will increase, conditionally favoring elevated hail into Saturday morning over eastern MT. At this time, storm chances prior to 12Z Saturday appear too low to introduce severe probabilities. ..Jewell.. 08/21/2019 Read more

SPC Aug 21, 2019 0730 UTC Day 3 Severe Thunderstorm Outlook

5 years 10 months ago
SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 AM CDT Wed Aug 21 2019 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTH CAROLINA INTO SOUTHERN VIRGINIA... ...SUMMARY... Isolated severe wind gusts are possible Friday over parts of North Carolina and southern Virginia. ...Synopsis... An upper low will pivot northeast across the Canadian Maritimes, with a jet streak sweeping across New England and tail end near the Mid Atlantic. At the surface, high pressure will remain over the Great Lakes, with a cold front moving south toward the VA/NC border. A weak surface low is forecast to develop over eastern VA and NC near the front where 70s F dewpoints and heating will contribute to moderate destabilization. To the west, a leading shortwave trough will eject out of the Dakotas toward western Ontario as a broad upper jet noses into the northern High Plains Friday night. Dewpoints in the 60s F will exist over the Dakotas ahead of a dying front related to the leading wave, and will back westward toward MT by 12Z Saturday. Elsewhere, a loose east-west boundary will remain roughly from KY/TN into north TX, with bouts of mainly non-severe thunderstorms through the period. ...NC into southern VA... Strong heating of a moist air mass will occur south of the cold front approaching the VA/NC border late in the day. Forecast soundings indicate 2000-2500 J/kg MLCAPE developing despite poor midlevel lapse rates, though low-level lapse rates will become steep. With no capping present, the front will provide a focus for scattered storms, which may produce locally severe wind gusts as they propagate southeastward from VA into NC. Models are in good agreement depicting a relatively concentrated area of storms in this area. ...Northern High Plains... Elevated thunderstorms may be ongoing Friday morning over central ND in association with the departing shortwave trough, but will likely lose strength as lift wanes, and due to dry trajectories out of the surface high to the east. As cooling aloft arrives from the west, lapse rates as well as deep shear will increase, conditionally favoring elevated hail into Saturday morning over eastern MT. At this time, storm chances prior to 12Z Saturday appear too low to introduce severe probabilities. ..Jewell.. 08/21/2019 Read more

SPC Day 2 Fire Weather Outlook

5 years 10 months ago
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0143 AM CDT Wed Aug 21 2019 Valid 221200Z - 231200Z ...Synopsis... An upper-level shortwave trough will continue to move east-northeast across the northern Intermountain West tomorrow. An associated surface cold front will continue to move south and east into the Great Basin and through much of the northern Rockies and northern California. With a pre-frontal surface pressure trough running parallel and ahead of the cold front, the surface pressure gradient will strengthen across the Intermountain West along and ahead of the cold front. Elevated conditions are expected from northern Arizona/southern Nevada stretching northeastward into central Wyoming along/ahead of the surface cold front. Southwest-westerly sustained surface winds of 15-20 mph and RH values of 8-20% are likely to develop during tomorrow afternoon and evening across this area. High clouds may drift into northern Arizona, which could limit the southern extent of the current elevated area. Elevated conditions are also likely to develop across central/eastern portions of the Snake River Plain and vicinity tomorrow afternoon. The cold front will have passed through the area, but daytime heating should warm temperatures and mix the boundary layer enough to result in west-southwest winds of 15-25 mph and RH values of 15-20%. ..Nauslar.. 08/21/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook

5 years 10 months ago
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0143 AM CDT Wed Aug 21 2019 Valid 221200Z - 231200Z ...Synopsis... An upper-level shortwave trough will continue to move east-northeast across the northern Intermountain West tomorrow. An associated surface cold front will continue to move south and east into the Great Basin and through much of the northern Rockies and northern California. With a pre-frontal surface pressure trough running parallel and ahead of the cold front, the surface pressure gradient will strengthen across the Intermountain West along and ahead of the cold front. Elevated conditions are expected from northern Arizona/southern Nevada stretching northeastward into central Wyoming along/ahead of the surface cold front. Southwest-westerly sustained surface winds of 15-20 mph and RH values of 8-20% are likely to develop during tomorrow afternoon and evening across this area. High clouds may drift into northern Arizona, which could limit the southern extent of the current elevated area. Elevated conditions are also likely to develop across central/eastern portions of the Snake River Plain and vicinity tomorrow afternoon. The cold front will have passed through the area, but daytime heating should warm temperatures and mix the boundary layer enough to result in west-southwest winds of 15-25 mph and RH values of 15-20%. ..Nauslar.. 08/21/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook

5 years 10 months ago
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0143 AM CDT Wed Aug 21 2019 Valid 221200Z - 231200Z ...Synopsis... An upper-level shortwave trough will continue to move east-northeast across the northern Intermountain West tomorrow. An associated surface cold front will continue to move south and east into the Great Basin and through much of the northern Rockies and northern California. With a pre-frontal surface pressure trough running parallel and ahead of the cold front, the surface pressure gradient will strengthen across the Intermountain West along and ahead of the cold front. Elevated conditions are expected from northern Arizona/southern Nevada stretching northeastward into central Wyoming along/ahead of the surface cold front. Southwest-westerly sustained surface winds of 15-20 mph and RH values of 8-20% are likely to develop during tomorrow afternoon and evening across this area. High clouds may drift into northern Arizona, which could limit the southern extent of the current elevated area. Elevated conditions are also likely to develop across central/eastern portions of the Snake River Plain and vicinity tomorrow afternoon. The cold front will have passed through the area, but daytime heating should warm temperatures and mix the boundary layer enough to result in west-southwest winds of 15-25 mph and RH values of 15-20%. ..Nauslar.. 08/21/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook

5 years 10 months ago
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0143 AM CDT Wed Aug 21 2019 Valid 221200Z - 231200Z ...Synopsis... An upper-level shortwave trough will continue to move east-northeast across the northern Intermountain West tomorrow. An associated surface cold front will continue to move south and east into the Great Basin and through much of the northern Rockies and northern California. With a pre-frontal surface pressure trough running parallel and ahead of the cold front, the surface pressure gradient will strengthen across the Intermountain West along and ahead of the cold front. Elevated conditions are expected from northern Arizona/southern Nevada stretching northeastward into central Wyoming along/ahead of the surface cold front. Southwest-westerly sustained surface winds of 15-20 mph and RH values of 8-20% are likely to develop during tomorrow afternoon and evening across this area. High clouds may drift into northern Arizona, which could limit the southern extent of the current elevated area. Elevated conditions are also likely to develop across central/eastern portions of the Snake River Plain and vicinity tomorrow afternoon. The cold front will have passed through the area, but daytime heating should warm temperatures and mix the boundary layer enough to result in west-southwest winds of 15-25 mph and RH values of 15-20%. ..Nauslar.. 08/21/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

5 years 10 months ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0136 AM CDT Wed Aug 21 2019 Valid 211200Z - 221200Z ...NO CRITICAL AREAS... ...Synopsis... An upper-level shortwave trough will move into the Pacific Northwest and northern Rockies today with an associated surface cold front sweeping east and south through the Pacific Northwest. Hot/dry/unstable conditions are expected to continue across much of the Intermountain West ahead of the cold front and north/west of the subtropical moisture in the Southwest and Rocky Mountains. Elevated conditions may develop just ahead of the cold front across eastern Washington/Oregon, but conditions should be short-lived and followed by cooler, moist air. Isolated thunderstorms are possible along the cold front across portions of the inland Pacific Northwest. Additionally, isolated dry thunderstorms may form across portions of the northern Rockies. However, the forecast airmass change and marginal fuel conditions where storms may develop preclude an isolated dry thunderstorm area. ..Nauslar.. 08/21/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

5 years 10 months ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0136 AM CDT Wed Aug 21 2019 Valid 211200Z - 221200Z ...NO CRITICAL AREAS... ...Synopsis... An upper-level shortwave trough will move into the Pacific Northwest and northern Rockies today with an associated surface cold front sweeping east and south through the Pacific Northwest. Hot/dry/unstable conditions are expected to continue across much of the Intermountain West ahead of the cold front and north/west of the subtropical moisture in the Southwest and Rocky Mountains. Elevated conditions may develop just ahead of the cold front across eastern Washington/Oregon, but conditions should be short-lived and followed by cooler, moist air. Isolated thunderstorms are possible along the cold front across portions of the inland Pacific Northwest. Additionally, isolated dry thunderstorms may form across portions of the northern Rockies. However, the forecast airmass change and marginal fuel conditions where storms may develop preclude an isolated dry thunderstorm area. ..Nauslar.. 08/21/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

5 years 10 months ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0136 AM CDT Wed Aug 21 2019 Valid 211200Z - 221200Z ...NO CRITICAL AREAS... ...Synopsis... An upper-level shortwave trough will move into the Pacific Northwest and northern Rockies today with an associated surface cold front sweeping east and south through the Pacific Northwest. Hot/dry/unstable conditions are expected to continue across much of the Intermountain West ahead of the cold front and north/west of the subtropical moisture in the Southwest and Rocky Mountains. Elevated conditions may develop just ahead of the cold front across eastern Washington/Oregon, but conditions should be short-lived and followed by cooler, moist air. Isolated thunderstorms are possible along the cold front across portions of the inland Pacific Northwest. Additionally, isolated dry thunderstorms may form across portions of the northern Rockies. However, the forecast airmass change and marginal fuel conditions where storms may develop preclude an isolated dry thunderstorm area. ..Nauslar.. 08/21/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

5 years 10 months ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0136 AM CDT Wed Aug 21 2019 Valid 211200Z - 221200Z ...NO CRITICAL AREAS... ...Synopsis... An upper-level shortwave trough will move into the Pacific Northwest and northern Rockies today with an associated surface cold front sweeping east and south through the Pacific Northwest. Hot/dry/unstable conditions are expected to continue across much of the Intermountain West ahead of the cold front and north/west of the subtropical moisture in the Southwest and Rocky Mountains. Elevated conditions may develop just ahead of the cold front across eastern Washington/Oregon, but conditions should be short-lived and followed by cooler, moist air. Isolated thunderstorms are possible along the cold front across portions of the inland Pacific Northwest. Additionally, isolated dry thunderstorms may form across portions of the northern Rockies. However, the forecast airmass change and marginal fuel conditions where storms may develop preclude an isolated dry thunderstorm area. ..Nauslar.. 08/21/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Severe Thunderstorm Watch 608 Status Reports

5 years 10 months ago
WW 0608 Status Updates
STATUS REPORT ON WW 608 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 E CYS TO 30 NW SNY TO 10 WSW AIA TO 15 SSE CDR. ..DEAN..08/21/19 ATTN...WFO...LBF...CYS... STATUS REPORT FOR WS 608 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NEC005-009-013-017-031-033-041-049-069-075-091-101-105-111-113- 115-117-123-135-161-171-210740- NE . NEBRASKA COUNTIES INCLUDED ARE ARTHUR BLAINE BOX BUTTE BROWN CHERRY CHEYENNE CUSTER DEUEL GARDEN GRANT HOOKER KEITH KIMBALL LINCOLN LOGAN LOUP MCPHERSON MORRILL PERKINS SHERIDAN THOMAS 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

SPC MD 1823

5 years 10 months ago
MD 1823 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR CENTRAL INTO SOUTHEAST NE
Mesoscale Discussion 1823 NWS Storm Prediction Center Norman OK 0122 AM CDT Wed Aug 21 2019 Areas affected...Central into southeast NE Concerning...Severe potential...Watch unlikely Valid 210622Z - 210815Z Probability of Watch Issuance...20 percent SUMMARY...Storms capable of large hail will be possible overnight. Watch issuance for the ongoing storms is currently not anticipated. DISCUSSION...Elevated convection that rapidly developed across portions of central NE around 05Z has evolved into more of a discrete mode as of 06Z, with a couple of potentially severe cells noted just west and southeast of Grand Island. This activity is likely being sustained by low-level warm advection, given the strongly veering wind profiles noted in area VWPs. Steep midlevel lapse rates (noted on 00Z soundings) and relatively rich low-level moisture are supporting strong elevated buoyancy across the region, with MUCAPE in excess of 3000 J/kg per recent mesoanalyses. With generally weak midlevel flow across this area, effective shear is generally in the 20-30 kt range, so longevity of any one particular cell may be relatively limited. However, given very favorable instability noted above, a large hail threat will continue with the strongest storms. The coverage and duration of the hail threat should remain relatively limited, so watch issuance is currently not anticipated for the ongoing storms. However, watch issuance may be needed later this morning if the ongoing MCS across the NE Panhandle begins to threaten this area. ..Dean/Edwards.. 08/21/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OAX...GID... LAT...LON 41489914 41319814 40739603 40329603 40189686 40199732 40269781 40349838 40539877 40869915 41489914 Read more

SPC Aug 21, 2019 0600 UTC Day 2 Convective Outlook

5 years 10 months ago
SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1219 AM CDT Wed Aug 21 2019 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE NORTHERN HIGH PLAINS...AND FROM OKLAHOMA EASTWARD ACROSS THE OHIO VALLEY... ...SUMMARY... Isolated severe wind gusts are possible Thursday from Oklahoma eastward across the Ohio Valley, with hail or wind over the northern High Plains. ...Synopsis... Strong southwest flow aloft will remain over the Northeast, with an upper low over Quebec. At the surface, a cold front will move across New England with dry air spreading southeast across the Great Lakes. South of the stronger winds aloft, a front will become nearly stationary roughly from MD across the OH Valley and into OK, with a moist and unstable air mass in the vicinity supporting clusters of storms throughout the period. To the west, a shortwave trough with 30-40 kt midlevel winds will move east across AB, SK and MT, with attendant cold front. Sufficiently moist southeast low-level winds ahead of this system will result in destabilization from MT into the western Dakotas, supporting a few strong to severe storms. ...Northern High Plains... A shortwave trough and cold front will move across eastern MT and WY during the day, and into the western Dakotas during the evening. Southeast surface winds ahead of the front will bring mid to upper 50s F dewpoints westward beneath steep lapse rates aloft, resulting in MLCAPE in excess of 2000 J/kg. Cells or line segments are expected to form along this front, with a hail and wind threat. Winds will initially be weak in the low levels, but southeast 850 mb winds may aid storms as they continue into the western Dakotas where CIN will slowly erode. Overall, shear will not be particularly strong, but sufficient for isolated mixed-mode severe storms. ...OK northeastward to the OH River... Scattered thunderstorms will be ongoing Thursday morning, from parts of KS eastward across the OH Valley. Models differ with placement and timing of these clusters, but in general, there will be an east/southeastward translation of the active zone as heating occurs to the south and new storms develop. The most unstable air will stretch from I-40 in TX/OK toward the OH River, with 2000-3000 J/kg MLCAPE possible. Westerly winds aloft and only weak low-level winds will favor east/southeastward propagating storms capable of localized wind damage or marginal hail. ...Northern VA...MD...southeast PA and NJ... A moist air mass will remain south of an east-west oriented front which will move very little during the day. Winds aloft will remain nearly parallel to this front, and will be strongest to the north where the air mass is less unstable. Convergence near this front may be sufficient for a few thunderstorms during the afternoon, and perhaps into the evening as height falls occur. If destabilization occurs farther north than currently expected, severe probabilities may be needed in later updates. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Jewell.. 08/21/2019 Read more

SPC Aug 21, 2019 0600 UTC Day 2 Convective Outlook

5 years 10 months ago
SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1219 AM CDT Wed Aug 21 2019 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE NORTHERN HIGH PLAINS...AND FROM OKLAHOMA EASTWARD ACROSS THE OHIO VALLEY... ...SUMMARY... Isolated severe wind gusts are possible Thursday from Oklahoma eastward across the Ohio Valley, with hail or wind over the northern High Plains. ...Synopsis... Strong southwest flow aloft will remain over the Northeast, with an upper low over Quebec. At the surface, a cold front will move across New England with dry air spreading southeast across the Great Lakes. South of the stronger winds aloft, a front will become nearly stationary roughly from MD across the OH Valley and into OK, with a moist and unstable air mass in the vicinity supporting clusters of storms throughout the period. To the west, a shortwave trough with 30-40 kt midlevel winds will move east across AB, SK and MT, with attendant cold front. Sufficiently moist southeast low-level winds ahead of this system will result in destabilization from MT into the western Dakotas, supporting a few strong to severe storms. ...Northern High Plains... A shortwave trough and cold front will move across eastern MT and WY during the day, and into the western Dakotas during the evening. Southeast surface winds ahead of the front will bring mid to upper 50s F dewpoints westward beneath steep lapse rates aloft, resulting in MLCAPE in excess of 2000 J/kg. Cells or line segments are expected to form along this front, with a hail and wind threat. Winds will initially be weak in the low levels, but southeast 850 mb winds may aid storms as they continue into the western Dakotas where CIN will slowly erode. Overall, shear will not be particularly strong, but sufficient for isolated mixed-mode severe storms. ...OK northeastward to the OH River... Scattered thunderstorms will be ongoing Thursday morning, from parts of KS eastward across the OH Valley. Models differ with placement and timing of these clusters, but in general, there will be an east/southeastward translation of the active zone as heating occurs to the south and new storms develop. The most unstable air will stretch from I-40 in TX/OK toward the OH River, with 2000-3000 J/kg MLCAPE possible. Westerly winds aloft and only weak low-level winds will favor east/southeastward propagating storms capable of localized wind damage or marginal hail. ...Northern VA...MD...southeast PA and NJ... A moist air mass will remain south of an east-west oriented front which will move very little during the day. Winds aloft will remain nearly parallel to this front, and will be strongest to the north where the air mass is less unstable. Convergence near this front may be sufficient for a few thunderstorms during the afternoon, and perhaps into the evening as height falls occur. If destabilization occurs farther north than currently expected, severe probabilities may be needed in later updates. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Jewell.. 08/21/2019 Read more

SPC Aug 21, 2019 0600 UTC Day 2 Convective Outlook

5 years 10 months ago
SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1219 AM CDT Wed Aug 21 2019 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE NORTHERN HIGH PLAINS...AND FROM OKLAHOMA EASTWARD ACROSS THE OHIO VALLEY... ...SUMMARY... Isolated severe wind gusts are possible Thursday from Oklahoma eastward across the Ohio Valley, with hail or wind over the northern High Plains. ...Synopsis... Strong southwest flow aloft will remain over the Northeast, with an upper low over Quebec. At the surface, a cold front will move across New England with dry air spreading southeast across the Great Lakes. South of the stronger winds aloft, a front will become nearly stationary roughly from MD across the OH Valley and into OK, with a moist and unstable air mass in the vicinity supporting clusters of storms throughout the period. To the west, a shortwave trough with 30-40 kt midlevel winds will move east across AB, SK and MT, with attendant cold front. Sufficiently moist southeast low-level winds ahead of this system will result in destabilization from MT into the western Dakotas, supporting a few strong to severe storms. ...Northern High Plains... A shortwave trough and cold front will move across eastern MT and WY during the day, and into the western Dakotas during the evening. Southeast surface winds ahead of the front will bring mid to upper 50s F dewpoints westward beneath steep lapse rates aloft, resulting in MLCAPE in excess of 2000 J/kg. Cells or line segments are expected to form along this front, with a hail and wind threat. Winds will initially be weak in the low levels, but southeast 850 mb winds may aid storms as they continue into the western Dakotas where CIN will slowly erode. Overall, shear will not be particularly strong, but sufficient for isolated mixed-mode severe storms. ...OK northeastward to the OH River... Scattered thunderstorms will be ongoing Thursday morning, from parts of KS eastward across the OH Valley. Models differ with placement and timing of these clusters, but in general, there will be an east/southeastward translation of the active zone as heating occurs to the south and new storms develop. The most unstable air will stretch from I-40 in TX/OK toward the OH River, with 2000-3000 J/kg MLCAPE possible. Westerly winds aloft and only weak low-level winds will favor east/southeastward propagating storms capable of localized wind damage or marginal hail. ...Northern VA...MD...southeast PA and NJ... A moist air mass will remain south of an east-west oriented front which will move very little during the day. Winds aloft will remain nearly parallel to this front, and will be strongest to the north where the air mass is less unstable. Convergence near this front may be sufficient for a few thunderstorms during the afternoon, and perhaps into the evening as height falls occur. If destabilization occurs farther north than currently expected, severe probabilities may be needed in later updates. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Jewell.. 08/21/2019 Read more

SPC Aug 21, 2019 0600 UTC Day 1 Convective Outlook

5 years 10 months ago
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Wed Aug 21 2019 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN MID ATLANTIC STATES INTO NEW ENGLAND... ...SUMMARY... Severe thunderstorms are possible across parts of the northern Mid Atlantic Coast states into New England today. Additional strong to severe storms are possible in a corridor from the central Plains into the lower Ohio Valley, and near the Rockies. ...Synopsis... A relatively progressive upper pattern is anticipated across the northern third of the CONUS with a pair of deep shortwave troughs advancing eastward and amplified shortwave ridging between them. The eastern shortwave trough is expected to move through the Upper Great Lakes, central/eastern Ontario, and into southern Quebec while the western shortwave trough moves through the Pacific Northwest into the northern Rockies. At the surface, a cold front currently extends from southeast CO northeastward to a low centered near the IA/MN/WI border intersection. A warm front then extends from that low eastward across central Lower MI through northeast PA and central DE. The cold front will likely remain in place through this afternoon before then pushing southward/southeastward into the Lower OH Valley and northern portions of the southern Plains. The eastern portion of the warm front will gradually lift northward throughout the day, placing a warm and moist air mass over much of New England by the late afternoon. ...New England into the northern Mid-Atlantic... While the vertical ascent and enhanced flow aloft with the shortwave described in the synopsis will remain predominantly north of the region, a low-amplitude, lead shortwave trough (currently moving through the OH Valley) is expected to move into New England this afternoon. Warm and unstable air mass will be in place ahead of this shortwave, and the expectation is for multiple bands of convection to move across the region this afternoon. Some modest strengthening of the low-level flow (i.e. around 30-35 kt at 850 mb) is anticipated ahead of this shortwave trough, lengthening hodographs and contributing to 0-1 km SRH around 100-150 m2/s2. Overall, wind profiles support occasional supercell structures within predominantly linear multicells. Primary severe threat will be damaging wind gusts but isolated hail and a tornado or two are also possible. Vertical shear and forcing for ascent decrease with southern extent, but a warm, moist, and diurnally destabilized air mass will support widely scattered to scattered thunderstorm development. Wet downbursts capable of damaging wind gusts are possible within the strongest storms. ...Central High Plains into the Central Plains The MCS currently moving into the NE Panhandle is expected to continue eastward, reaching central NE by 12Z this morning. Isolated threat for hail and strong wind gusts will exist with this system as it continues into eastern NE. Later this afternoon, scattered thunderstorms are expected to develop across KS along the front as it begins to push southward. A deeply mixed air mass characterized by temperatures in the upper 90s/low 100s and dewpoints in the low/mid 60s is anticipated ahead of the front. Given the amount of dry air entrainment expected and the lack of stronger vertical shear, updrafts will likely be short-lived. Even so, isolated strong wind gusts are possible. Hail could occur within the strongest updrafts. At the same time, thunderstorms are expected to develop along the lee trough from south-central CO into central WY. Mid-level flow here will be the same as areas farther east (across the central Plains), but vertical shear will be stronger due to northeasterly surface winds. A few supercells capable of large hail and/or strong wind gusts are possible and a tornado cannot be completely ruled out. Uncertainty regarding severe thunderstorm coverage precludes higher probabilities with this outlook. ...Mid MS Valley into the Southern OH Valley... Outflow from the MCS across NE this morning will likely move into southern MO and western KY this afternoon. A very moist and buoyant air mass will be in place, with dewpoints in the 70s and MLCAPE in excess of 3000 J/kg. Vertical shear will be weak, limiting storm persistence, but updrafts are expected to be strong enough to result in water loading and a resulting threat for isolated strong/damaging wind gusts. ..Mosier/Nauslar.. 08/21/2019 Read more

SPC Aug 21, 2019 0600 UTC Day 1 Convective Outlook

5 years 10 months ago
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Wed Aug 21 2019 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN MID ATLANTIC STATES INTO NEW ENGLAND... ...SUMMARY... Severe thunderstorms are possible across parts of the northern Mid Atlantic Coast states into New England today. Additional strong to severe storms are possible in a corridor from the central Plains into the lower Ohio Valley, and near the Rockies. ...Synopsis... A relatively progressive upper pattern is anticipated across the northern third of the CONUS with a pair of deep shortwave troughs advancing eastward and amplified shortwave ridging between them. The eastern shortwave trough is expected to move through the Upper Great Lakes, central/eastern Ontario, and into southern Quebec while the western shortwave trough moves through the Pacific Northwest into the northern Rockies. At the surface, a cold front currently extends from southeast CO northeastward to a low centered near the IA/MN/WI border intersection. A warm front then extends from that low eastward across central Lower MI through northeast PA and central DE. The cold front will likely remain in place through this afternoon before then pushing southward/southeastward into the Lower OH Valley and northern portions of the southern Plains. The eastern portion of the warm front will gradually lift northward throughout the day, placing a warm and moist air mass over much of New England by the late afternoon. ...New England into the northern Mid-Atlantic... While the vertical ascent and enhanced flow aloft with the shortwave described in the synopsis will remain predominantly north of the region, a low-amplitude, lead shortwave trough (currently moving through the OH Valley) is expected to move into New England this afternoon. Warm and unstable air mass will be in place ahead of this shortwave, and the expectation is for multiple bands of convection to move across the region this afternoon. Some modest strengthening of the low-level flow (i.e. around 30-35 kt at 850 mb) is anticipated ahead of this shortwave trough, lengthening hodographs and contributing to 0-1 km SRH around 100-150 m2/s2. Overall, wind profiles support occasional supercell structures within predominantly linear multicells. Primary severe threat will be damaging wind gusts but isolated hail and a tornado or two are also possible. Vertical shear and forcing for ascent decrease with southern extent, but a warm, moist, and diurnally destabilized air mass will support widely scattered to scattered thunderstorm development. Wet downbursts capable of damaging wind gusts are possible within the strongest storms. ...Central High Plains into the Central Plains The MCS currently moving into the NE Panhandle is expected to continue eastward, reaching central NE by 12Z this morning. Isolated threat for hail and strong wind gusts will exist with this system as it continues into eastern NE. Later this afternoon, scattered thunderstorms are expected to develop across KS along the front as it begins to push southward. A deeply mixed air mass characterized by temperatures in the upper 90s/low 100s and dewpoints in the low/mid 60s is anticipated ahead of the front. Given the amount of dry air entrainment expected and the lack of stronger vertical shear, updrafts will likely be short-lived. Even so, isolated strong wind gusts are possible. Hail could occur within the strongest updrafts. At the same time, thunderstorms are expected to develop along the lee trough from south-central CO into central WY. Mid-level flow here will be the same as areas farther east (across the central Plains), but vertical shear will be stronger due to northeasterly surface winds. A few supercells capable of large hail and/or strong wind gusts are possible and a tornado cannot be completely ruled out. Uncertainty regarding severe thunderstorm coverage precludes higher probabilities with this outlook. ...Mid MS Valley into the Southern OH Valley... Outflow from the MCS across NE this morning will likely move into southern MO and western KY this afternoon. A very moist and buoyant air mass will be in place, with dewpoints in the 70s and MLCAPE in excess of 3000 J/kg. Vertical shear will be weak, limiting storm persistence, but updrafts are expected to be strong enough to result in water loading and a resulting threat for isolated strong/damaging wind gusts. ..Mosier/Nauslar.. 08/21/2019 Read more

SPC Aug 21, 2019 0600 UTC Day 1 Convective Outlook

5 years 10 months ago
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Wed Aug 21 2019 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN MID ATLANTIC STATES INTO NEW ENGLAND... ...SUMMARY... Severe thunderstorms are possible across parts of the northern Mid Atlantic Coast states into New England today. Additional strong to severe storms are possible in a corridor from the central Plains into the lower Ohio Valley, and near the Rockies. ...Synopsis... A relatively progressive upper pattern is anticipated across the northern third of the CONUS with a pair of deep shortwave troughs advancing eastward and amplified shortwave ridging between them. The eastern shortwave trough is expected to move through the Upper Great Lakes, central/eastern Ontario, and into southern Quebec while the western shortwave trough moves through the Pacific Northwest into the northern Rockies. At the surface, a cold front currently extends from southeast CO northeastward to a low centered near the IA/MN/WI border intersection. A warm front then extends from that low eastward across central Lower MI through northeast PA and central DE. The cold front will likely remain in place through this afternoon before then pushing southward/southeastward into the Lower OH Valley and northern portions of the southern Plains. The eastern portion of the warm front will gradually lift northward throughout the day, placing a warm and moist air mass over much of New England by the late afternoon. ...New England into the northern Mid-Atlantic... While the vertical ascent and enhanced flow aloft with the shortwave described in the synopsis will remain predominantly north of the region, a low-amplitude, lead shortwave trough (currently moving through the OH Valley) is expected to move into New England this afternoon. Warm and unstable air mass will be in place ahead of this shortwave, and the expectation is for multiple bands of convection to move across the region this afternoon. Some modest strengthening of the low-level flow (i.e. around 30-35 kt at 850 mb) is anticipated ahead of this shortwave trough, lengthening hodographs and contributing to 0-1 km SRH around 100-150 m2/s2. Overall, wind profiles support occasional supercell structures within predominantly linear multicells. Primary severe threat will be damaging wind gusts but isolated hail and a tornado or two are also possible. Vertical shear and forcing for ascent decrease with southern extent, but a warm, moist, and diurnally destabilized air mass will support widely scattered to scattered thunderstorm development. Wet downbursts capable of damaging wind gusts are possible within the strongest storms. ...Central High Plains into the Central Plains The MCS currently moving into the NE Panhandle is expected to continue eastward, reaching central NE by 12Z this morning. Isolated threat for hail and strong wind gusts will exist with this system as it continues into eastern NE. Later this afternoon, scattered thunderstorms are expected to develop across KS along the front as it begins to push southward. A deeply mixed air mass characterized by temperatures in the upper 90s/low 100s and dewpoints in the low/mid 60s is anticipated ahead of the front. Given the amount of dry air entrainment expected and the lack of stronger vertical shear, updrafts will likely be short-lived. Even so, isolated strong wind gusts are possible. Hail could occur within the strongest updrafts. At the same time, thunderstorms are expected to develop along the lee trough from south-central CO into central WY. Mid-level flow here will be the same as areas farther east (across the central Plains), but vertical shear will be stronger due to northeasterly surface winds. A few supercells capable of large hail and/or strong wind gusts are possible and a tornado cannot be completely ruled out. Uncertainty regarding severe thunderstorm coverage precludes higher probabilities with this outlook. ...Mid MS Valley into the Southern OH Valley... Outflow from the MCS across NE this morning will likely move into southern MO and western KY this afternoon. A very moist and buoyant air mass will be in place, with dewpoints in the 70s and MLCAPE in excess of 3000 J/kg. Vertical shear will be weak, limiting storm persistence, but updrafts are expected to be strong enough to result in water loading and a resulting threat for isolated strong/damaging wind gusts. ..Mosier/Nauslar.. 08/21/2019 Read more
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5 years 9 months ago
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