Severe Storms

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
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
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
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

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

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 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 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 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 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 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 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 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 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

WW 0607 Status Updates
STATUS REPORT ON WW 607 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 10 SE SNY TO 15 SW CYS TO 25 N CYS TO 30 NE CDR. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1822 ..GLEASON..08/21/19 ATTN...WFO...BOU...CYS... STATUS REPORT FOR WS 607 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NEC007-013-033-045-105-123-157-165-210540- NE . NEBRASKA COUNTIES INCLUDED ARE BANNER BOX BUTTE CHEYENNE DAWES KIMBALL MORRILL SCOTTS BLUFF SIOUX WYC015-021-210540- WY . WYOMING COUNTIES INCLUDED ARE GOSHEN LARAMIE 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 0607 Status Updates
STATUS REPORT ON WW 607 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 10 SE SNY TO 15 SW CYS TO 25 N CYS TO 30 NE CDR. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1822 ..GLEASON..08/21/19 ATTN...WFO...BOU...CYS... STATUS REPORT FOR WS 607 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NEC007-013-033-045-105-123-157-165-210540- NE . NEBRASKA COUNTIES INCLUDED ARE BANNER BOX BUTTE CHEYENNE DAWES KIMBALL MORRILL SCOTTS BLUFF SIOUX WYC015-021-210540- WY . WYOMING COUNTIES INCLUDED ARE GOSHEN LARAMIE 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 0607 Status Updates
STATUS REPORT ON WW 607 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 10 SE SNY TO 15 SW CYS TO 25 N CYS TO 30 NE CDR. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1822 ..GLEASON..08/21/19 ATTN...WFO...BOU...CYS... STATUS REPORT FOR WS 607 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NEC007-013-033-045-105-123-157-165-210540- NE . NEBRASKA COUNTIES INCLUDED ARE BANNER BOX BUTTE CHEYENNE DAWES KIMBALL MORRILL SCOTTS BLUFF SIOUX WYC015-021-210540- WY . WYOMING COUNTIES INCLUDED ARE GOSHEN LARAMIE 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 607 SEVERE TSTM CO NE WY 202100Z - 210500Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 607 NWS Storm Prediction Center Norman OK 300 PM MDT Tue Aug 20 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Extreme northeast Colorado The western Nebraska Panhandle Southeast Wyoming * Effective this Tuesday afternoon and evening from 300 PM until 1100 PM MDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2.5 inches in diameter possible Scattered damaging wind gusts to 70 mph possible SUMMARY...Scattered thunderstorm development is expected late this afternoon/evening from extreme northeast Colorado into southeast Wyoming. The storm environment will favor discrete supercells with isolated very large hail initially, and upscale growth into a cluster is possible late this evening with some damaging wind potential. The severe thunderstorm watch area is approximately along and 50 statute miles east and west of a line from 45 miles west northwest of Chadron NE to 65 miles southeast of Cheyenne WY. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU7). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for 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. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 604...WW 605...WW 606... AVIATION...A few severe thunderstorms with hail surface and aloft to 2.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 29010. ...Thompson Read more

MD 1822 CONCERNING SEVERE THUNDERSTORM WATCH 607... FOR PORTIONS OF FAR SOUTHEASTERN WY...FAR NORTHEASTERN CO...AND WESTERN/CENTRAL NE
Mesoscale Discussion 1822 NWS Storm Prediction Center Norman OK 1134 PM CDT Tue Aug 20 2019 Areas affected...Portions of far southeastern WY...far northeastern CO...and western/central NE Concerning...Severe Thunderstorm Watch 607... Valid 210434Z - 210530Z The severe weather threat for Severe Thunderstorm Watch 607 continues. SUMMARY...An isolated hail/wind threat continues across far southeastern WY into the western NE Panhandle. The need for a downstream watch into more of western NE remains unclear. DISCUSSION...Storms across far southeastern WY have recently strengthened and consolidated into a small cluster, which is entering the far western NE Panhandle at 0430Z. In the absence of an obvious large-scale forcing mechanism, this uptick in convective coverage and intensity may be related to a modest strengthening of southerly winds in the 2-3 km layer noted on recent VWPs from KCYS. Regardless, this convection will soon encounter a more buoyant airmass in western NE, where surface dewpoints gradually increase from the low 60s to the low 70s with eastward extent. Some short-term guidance suggests that this ongoing cluster will maintain its intensity, and perhaps even strengthen as it moves eastward overnight across western and eventually central NE. Isolated severe winds and large hail remain the primary concerns. At this point, the need for a new Severe Thunderstorm Watch downstream of WW 607 remains unclear. But, trends will be closely monitored. ..Gleason.. 08/21/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...BOU...CYS... LAT...LON 41580479 42110417 42570329 42520070 41570021 40600039 40550241 40600376 41020474 41580479 Read more

MD 1821 CONCERNING SEVERE THUNDERSTORM WATCH 607... FOR PORTIONS OF SOUTHEASTERN WY...NORTHEASTERN CO...AND THE FAR WESTERN NE PANHANDLE
Mesoscale Discussion 1821 NWS Storm Prediction Center Norman OK 1005 PM CDT Tue Aug 20 2019 Areas affected...Portions of southeastern WY...northeastern CO...and the far western NE Panhandle Concerning...Severe Thunderstorm Watch 607... Valid 210305Z - 210430Z The severe weather threat for Severe Thunderstorm Watch 607 continues. SUMMARY...An isolated severe threat continues across mainly western portions of Severe Thunderstorm Watch 607. DISCUSSION...Storms have generally weakened this evening along and just east of the higher terrain in southeastern WY and northeastern CO. Even with continued low-level easterly upslope flow across this region, convective inhibition has increased. Convective overturning from storms earlier this afternoon/evening may have also locally reduced mid-level lapse rates. Even so, weak to moderate instability coupled with sufficient shear may continue to support an isolated severe threat across mainly western portions of Severe Thunderstorm Watch 607 in the short term. Large hail remains the primary threat. The potential for clustering of storms later tonight into the western NE Panhandle appears lower due to a general lack of storm organization and intensity across southeastern WY as of 03Z. ..Gleason.. 08/21/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BOU...CYS... LAT...LON 42550523 42910456 42920378 40050380 40090466 42000520 42550523 Read more