Severe Storms

WW 611 SEVERE TSTM CO WY 212045Z - 220300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 611 NWS Storm Prediction Center Norman OK 245 PM MDT Wed Aug 21 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Eastern Colorado Southeast Wyoming * Effective this Wednesday afternoon and evening from 245 PM until 900 PM MDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2 inches in diameter possible Isolated damaging wind gusts to 70 mph possible SUMMARY...Isolated severe storms, in the form of sustained multicells and a few transient supercells, are expected to develop along the foothills/I-25 corridor of eastern Colorado into southeast Wyoming. Isolated large hail will be the primary risk as storms drift east-southeastward through late afternoon/evening, although localized severe-caliber winds could also occur, particularly across east-central Colorado. The severe thunderstorm watch area is approximately along and 45 statute miles east and west of a line from 75 miles north northeast of Laramie WY to 30 miles southeast of Pueblo CO. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU1). 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 609...WW 610... AVIATION...A few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 450. Mean storm motion vector 32020. ...Guyer Read more

MD 1830 CONCERNING SEVERE THUNDERSTORM WATCH 611... FOR CENTRAL COLORADO THROUGH SOUTHEAST WYOMING
Mesoscale Discussion 1830 NWS Storm Prediction Center Norman OK 0539 PM CDT Wed Aug 21 2019 Areas affected...central Colorado through southeast Wyoming Concerning...Severe Thunderstorm Watch 611... Valid 212239Z - 220015Z The severe weather threat for Severe Thunderstorm Watch 611 continues. SUMMARY...A few instances of hail and locally strong wind gusts remain possible from central CO through southeast WY through 00Z, but overall threat is expected to become increasingly marginal with onset of nocturnal cooling. DISCUSSION...Isolated storms continue over the higher terrain, but coverage has remained sparse across most of CO into southeast WY. With upper ridging aloft, the primary forcing mechanism has been heating and upslope component over the higher terrain. While the downstream atmosphere is moderately unstable with 2000 J/kg MLCAPE, westerly winds aloft remain modest with generally 15-20 kt in the 700-400 mb layer. Limited storm coverage with low confidence that storms will be able to consolidate, along with weak flow aloft and increasing convective inhibition, all lower confidence that activity will be able to move off the higher terrain. Nevertheless, what storms that do develop will remain capable of producing a few instances of hail and locally strong wind gusts next couple hours. ..Dial.. 08/21/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PUB...BOU...CYS... LAT...LON 42140512 40220442 38200424 38080505 40140558 42080591 42140512 Read more

WW 0610 Status Updates
STATUS REPORT ON WW 610 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 SSW DCA TO 15 WSW BWI TO 30 NE BWI TO 15 SSW TTN TO 5 E EWR. ..NAUSLAR..08/21/19 ATTN...WFO...LWX...PHI...CTP... STATUS REPORT FOR WS 610 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS DEC001-003-005-212340- DE . DELAWARE COUNTIES INCLUDED ARE KENT NEW CASTLE SUSSEX MDC003-009-011-017-029-033-035-041-212340- MD . MARYLAND COUNTIES INCLUDED ARE ANNE ARUNDEL CALVERT CAROLINE CHARLES KENT PRINCE GEORGES QUEEN ANNE'S TALBOT NJC001-005-007-009-011-015-025-029-033-212340- NJ . NEW JERSEY COUNTIES INCLUDED ARE ATLANTIC BURLINGTON CAMDEN CAPE MAY CUMBERLAND GLOUCESTER Read more

WW 610 SEVERE TSTM DC DE MD NJ PA VA CW 211925Z - 220200Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 610 NWS Storm Prediction Center Norman OK 325 PM EDT Wed Aug 21 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of District Of Columbia Delaware Eastern Maryland New Jersey Eastern Pennsylvania Northern Virginia Coastal Waters * Effective this Wednesday afternoon and evening from 325 PM until 1000 PM EDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...Thunderstorms will continue to develop and intensify, initially along and west of the I-95 corridor this afternoon. The strongest of these storms will be capable of damaging winds and possibly severe hail as they spread east-northeastward through early evening. The severe thunderstorm watch area is approximately along and 75 statute miles east and west of a line from 35 miles northeast of Allentown PA to 25 miles southeast of Washington DC. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU0). 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 609... AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 25020. ...Guyer Read more

WW 0609 Status Updates
340- STATUS REPORT ON WW 609 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 NNE NEL TO 5 W EWR TO 25 NNW EWR TO 30 SSE MSV TO 20 NE MSV TO 35 N POU TO 10 WNW PSF TO 30 W EEN TO 25 WSW LCI. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1829 ..NAUSLAR..08/21/19 ATTN...WFO...OKX...BOX...ALY...GYX... STATUS REPORT FOR WS 609 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS CTC001-003-005-007-009-011-013-015-212340- CT . CONNECTICUT COUNTIES INCLUDED ARE FAIRFIELD HARTFORD LITCHFIELD MIDDLESEX NEW HAVEN NEW LONDON TOLLAND WINDHAM MEC031-212340- ME . MAINE COUNTIES INCLUDED ARE YORK MAC001-003-005-007-009-011-013-015-017-019-021-023-025-027- 212340- Read more

WW 609 SEVERE TSTM CT MA ME NH NJ NY RI VT CW 211750Z - 220100Z
0- URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 609 NWS Storm Prediction Center Norman OK 150 PM EDT Wed Aug 21 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Connecticut Massachusetts Far southern Maine Southern New Hampshire Northern New Jersey Southeast New York Rhode Island Southern Vermont Coastal Waters * Effective this Wednesday afternoon and evening from 150 PM until 900 PM EDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1.5 inches in diameter possible A tornado or two possible SUMMARY...Storms will continue to develop and intensify particularly across far eastern New York and southern New England, near and south of a warm front that will continue to spread slowly northward. Some supercells with a hail/tornado risk aside from damaging winds are most probable across southern New England, with damaging winds otherwise expected with the strongest storms. The severe thunderstorm watch area is approximately along and 85 statute miles north and south of a line from 30 miles west northwest of Poughkeepsie NY to 40 miles east of Boston MA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU9). 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. && AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 24025. ...Guyer Read more

MD 1829 CONCERNING SEVERE THUNDERSTORM WATCH 609... FOR PORTIONS OF NEW ENGLAND
Mesoscale Discussion 1829 NWS Storm Prediction Center Norman OK 0520 PM CDT Wed Aug 21 2019 Areas affected...portions of New England Concerning...Severe Thunderstorm Watch 609... Valid 212220Z - 220015Z The severe weather threat for Severe Thunderstorm Watch 609 continues. SUMMARY...The severe threat continues across much of WW609 with severe wind as the primary threat. Large hail and a brief, weak tornado or two are possible as well. DISCUSSION...Storms continue to move and develop eastward across New England ahead of an upper-level shortwave trough. A mixed storm mode is evident with a broken line of storms stretching from southwest Maine to south of Albany along a surface pressure trough and discrete cells developing within the warm sector ahead of the line. MLCAPE 1000-1500 J/kg and 30-40 knots of effective bulk shear will support some weaker supercells and a few of those have been observed across New England in the last hour. While damaging wind is the main severe threat, marginally large hail and a brief, weak tornado are possible with any of the stronger, especially discrete, cells. Areas with more of a easterly component in the surface wind will increase hodograph curvature/low-level SRH and be the favored location for these stronger storms. The severe threat will diminish from west to east as storms moves eastward into the evening. ..Nauslar/Grams.. 08/21/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GYX...BOX...OKX...ALY...PHI...BGM... LAT...LON 40567452 41907438 42657348 43327210 43687143 43747075 43517023 42937018 42177022 41647024 41367036 41167058 41047099 40607338 40467409 40567452 Read more

MD 1828 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR CENTRAL NORTH CAROLINA
Mesoscale Discussion 1828 NWS Storm Prediction Center Norman OK 0516 PM CDT Wed Aug 21 2019 Areas affected...central North Carolina Concerning...Severe potential...Watch unlikely Valid 212216Z - 220015Z Probability of Watch Issuance...5 percent SUMMARY...Storms may produce a few instances of strong but mostly sub-severe wind gusts as they move through central North Carolina next couple of hours. DISCUSSION...Storms that developed over the mountains of western NC earlier this afternoon have consolidated into a squall line as they approach central NC. The downstream atmosphere is weakly capped and moderately unstable with temperatures around 90F supporting 2000 J/kg MCLAPE. Multicell storms are expected to continue through central NC next couple hours and might eventually interact with the seabreeze which could support brief intensification, before subsequently diminishing as they continue into eastern NC. Isolated strong wind gusts should remain the primary threat next couple hours. ..Dial/Grams.. 08/21/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...RAH...GSP... LAT...LON 36227910 36327853 36047764 35507810 35017902 34887982 35168043 35787962 36227910 Read more

No Mesoscale Discussions are in effect as of Wed Aug 21 21:56:02 UTC 2019.

WW 0609 Status Updates
240- STATUS REPORT ON WW 609 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 NNE TTN TO 10 E MSV TO 40 SW ALB TO 30 ENE ALB TO 10 SSE LEB. ..NAUSLAR..08/21/19 ATTN...WFO...OKX...BOX...ALY...GYX... STATUS REPORT FOR WS 609 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS CTC001-003-005-007-009-011-013-015-212240- CT . CONNECTICUT COUNTIES INCLUDED ARE FAIRFIELD HARTFORD LITCHFIELD MIDDLESEX NEW HAVEN NEW LONDON TOLLAND WINDHAM MEC031-212240- ME . MAINE COUNTIES INCLUDED ARE YORK MAC001-003-005-007-009-011-013-015-017-019-021-023-025-027- 212240- MA . MASSACHUSETTS COUNTIES INCLUDED ARE Read more

WW 0610 Status Updates
STATUS REPORT ON WW 610 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 WSW DCA TO 20 NW DCA TO 25 WNW BWI TO 30 NNE BWI TO 35 NW ILG TO 35 E CXY TO 25 WNW ABE TO 15 SW AVP. ..NAUSLAR..08/21/19 ATTN...WFO...LWX...PHI...CTP... STATUS REPORT FOR WS 610 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS DEC001-003-005-212240- DE . DELAWARE COUNTIES INCLUDED ARE KENT NEW CASTLE SUSSEX DCC001-212240- DC . DISTRICT OF COLUMBIA COUNTIES INCLUDED ARE DISTRICT OF COLUMBIA MDC003-009-011-015-017-025-027-029-031-033-035-041-510-212240- MD . MARYLAND COUNTIES INCLUDED ARE ANNE ARUNDEL CALVERT CAROLINE CECIL CHARLES HARFORD HOWARD KENT MONTGOMERY Read more

WW 0611 Status Updates
STATUS REPORT ON WW 611 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..DIAL..08/21/19 ATTN...WFO...BOU...PUB...CYS... STATUS REPORT FOR WS 611 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS COC001-005-013-014-025-031-035-039-041-059-069-089-101-119-123- 212240- CO . COLORADO COUNTIES INCLUDED ARE ADAMS ARAPAHOE BOULDER BROOMFIELD CROWLEY DENVER DOUGLAS ELBERT EL PASO JEFFERSON LARIMER OTERO PUEBLO TELLER WELD WYC001-015-021-031-212240- WY . WYOMING COUNTIES INCLUDED ARE ALBANY GOSHEN LARAMIE PLATTE 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 0611 Status Updates
STATUS FOR WATCH 0611 HAS NOT BEEN ISSUED YET Read more

WW 0610 Status Updates
STATUS REPORT ON WW 610 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..KERR..08/21/19 ATTN...WFO...LWX...PHI...CTP... STATUS REPORT FOR WS 610 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS DEC001-003-005-212140- DE . DELAWARE COUNTIES INCLUDED ARE KENT NEW CASTLE SUSSEX DCC001-212140- DC . DISTRICT OF COLUMBIA COUNTIES INCLUDED ARE DISTRICT OF COLUMBIA MDC003-005-009-011-013-015-017-021-025-027-029-031-033-035-041- 510-212140- MD . MARYLAND COUNTIES INCLUDED ARE ANNE ARUNDEL BALTIMORE CALVERT CAROLINE CARROLL CECIL CHARLES FREDERICK HARFORD HOWARD KENT MONTGOMERY Read more

WW 0609 Status Updates
140- STATUS REPORT ON WW 609 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..KERR..08/21/19 ATTN...WFO...OKX...BOX...ALY...GYX... STATUS REPORT FOR WS 609 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS CTC001-003-005-007-009-011-013-015-212140- CT . CONNECTICUT COUNTIES INCLUDED ARE FAIRFIELD HARTFORD LITCHFIELD MIDDLESEX NEW HAVEN NEW LONDON TOLLAND WINDHAM MEC031-212140- ME . MAINE COUNTIES INCLUDED ARE YORK MAC001-003-005-007-009-011-013-015-017-019-021-023-025-027- 212140- MA . MASSACHUSETTS COUNTIES INCLUDED ARE BARNSTABLE BERKSHIRE BRISTOL Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Wed Aug 21 2019 Valid 212000Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHEAST AND MID ATLANTIC REGION...AS WELL AS OVER PARTS OF THE COLORADO FRONT RANGE... ...SUMMARY... Severe thunderstorms will continue this afternoon and evening across parts of the Northeast/Mid-Atlantic States, while a few severe storms will be possible across the central high Plains. ...Discussion... The overall outlook remains on track, with respect to prior forecast reasoning. The main changes in this update will be to extend the eastern U.S. SLGT risk a bit farther south across parts of the mid Atlantic region, while removing northern portions of the risk in parts of New England, and to include a small SLGT risk over the Colorado Front Range. In the East, clouds remain dense, and the airmass stable, over northern portions of Vermont and New Hampshire, with the primary severe risk likely to remain south of these areas. Meanwhile, with recently issued WW #610 extending southward to the Chesapeake Bay region, SLGT risk is correspondingly being expanded slightly southward. In Colorado, shear remains modest -- particularly with southward extent. However, with moderate destabilization occurring, and thus risk for locally intense cells within a narrow corridor, potential for hail/wind with a few of the strongest storms warrants upgrade to a small SLGT risk in this area. Otherwise, no major changes to the outlook are required at this time. ..Goss.. 08/21/2019 .PREV DISCUSSION... /ISSUED 1132 AM CDT Wed Aug 21 2019/ ...Northeast/Mid-Atlantic States... A shortwave trough will continue to progress east-northeastward from eastern New York toward northern New England, while a warm front slowly spreads northward across southern New England. With broken cloud cover lingering in most areas, modest overall destabilization is expected along/south of the warm front where low-level/deep-layer shear will be maximized. The environment will support the possibility of supercells/bowing segments particularly across southeast New York and southern New England, with severe hail/wind possible along with some tornado risk. Multicells with damaging winds are possible farther south within the warm sector. For additional short-term details, see Mesoscale Discussion 1825. ...Kansas/Missouri/far southeast Nebraska to Missouri/Illinois... The remnants of overnight convection continue to decay across the region with cloud cover/outflow influencing an effective boundary across southern portions of Kansas/Missouri. Surface-based thunderstorms should develop/intensify later this afternoon particularly across southern/eastern Kansas into western Missouri within a moist/unstable environment. Relatively weak tropospheric winds may limit overall storm organization, but the strongest storms will pose a damaging wind/severe hail risk. ...Wyoming/Colorado Front Range to central High Plains... Isolated to widely scattered thunderstorms should develop this afternoon over the eastern mountains and foothills from northern Wyoming across central/southern Colorado, offering the potential for isolated severe hail and gusts. Activity is expected predominantly in the post-frontal/upslope region where lift is maximized by a combination of upslope flow and diabatic surface heating of the higher terrain (minimizing MLCINH). Mid-level flow is forecast to be modest; however, vertical shear will be stronger than over lower elevations ahead of the front because of the backed boundary-layer winds and relatively extended low-level hodographs. As such, a mixture of supercellular and multicellular structures are possible. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Wed Aug 21 2019 Valid 212000Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHEAST AND MID ATLANTIC REGION...AS WELL AS OVER PARTS OF THE COLORADO FRONT RANGE... ...SUMMARY... Severe thunderstorms will continue this afternoon and evening across parts of the Northeast/Mid-Atlantic States, while a few severe storms will be possible across the central high Plains. ...Discussion... The overall outlook remains on track, with respect to prior forecast reasoning. The main changes in this update will be to extend the eastern U.S. SLGT risk a bit farther south across parts of the mid Atlantic region, while removing northern portions of the risk in parts of New England, and to include a small SLGT risk over the Colorado Front Range. In the East, clouds remain dense, and the airmass stable, over northern portions of Vermont and New Hampshire, with the primary severe risk likely to remain south of these areas. Meanwhile, with recently issued WW #610 extending southward to the Chesapeake Bay region, SLGT risk is correspondingly being expanded slightly southward. In Colorado, shear remains modest -- particularly with southward extent. However, with moderate destabilization occurring, and thus risk for locally intense cells within a narrow corridor, potential for hail/wind with a few of the strongest storms warrants upgrade to a small SLGT risk in this area. Otherwise, no major changes to the outlook are required at this time. ..Goss.. 08/21/2019 .PREV DISCUSSION... /ISSUED 1132 AM CDT Wed Aug 21 2019/ ...Northeast/Mid-Atlantic States... A shortwave trough will continue to progress east-northeastward from eastern New York toward northern New England, while a warm front slowly spreads northward across southern New England. With broken cloud cover lingering in most areas, modest overall destabilization is expected along/south of the warm front where low-level/deep-layer shear will be maximized. The environment will support the possibility of supercells/bowing segments particularly across southeast New York and southern New England, with severe hail/wind possible along with some tornado risk. Multicells with damaging winds are possible farther south within the warm sector. For additional short-term details, see Mesoscale Discussion 1825. ...Kansas/Missouri/far southeast Nebraska to Missouri/Illinois... The remnants of overnight convection continue to decay across the region with cloud cover/outflow influencing an effective boundary across southern portions of Kansas/Missouri. Surface-based thunderstorms should develop/intensify later this afternoon particularly across southern/eastern Kansas into western Missouri within a moist/unstable environment. Relatively weak tropospheric winds may limit overall storm organization, but the strongest storms will pose a damaging wind/severe hail risk. ...Wyoming/Colorado Front Range to central High Plains... Isolated to widely scattered thunderstorms should develop this afternoon over the eastern mountains and foothills from northern Wyoming across central/southern Colorado, offering the potential for isolated severe hail and gusts. Activity is expected predominantly in the post-frontal/upslope region where lift is maximized by a combination of upslope flow and diabatic surface heating of the higher terrain (minimizing MLCINH). Mid-level flow is forecast to be modest; however, vertical shear will be stronger than over lower elevations ahead of the front because of the backed boundary-layer winds and relatively extended low-level hodographs. As such, a mixture of supercellular and multicellular structures are possible. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Wed Aug 21 2019 Valid 212000Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHEAST AND MID ATLANTIC REGION...AS WELL AS OVER PARTS OF THE COLORADO FRONT RANGE... ...SUMMARY... Severe thunderstorms will continue this afternoon and evening across parts of the Northeast/Mid-Atlantic States, while a few severe storms will be possible across the central high Plains. ...Discussion... The overall outlook remains on track, with respect to prior forecast reasoning. The main changes in this update will be to extend the eastern U.S. SLGT risk a bit farther south across parts of the mid Atlantic region, while removing northern portions of the risk in parts of New England, and to include a small SLGT risk over the Colorado Front Range. In the East, clouds remain dense, and the airmass stable, over northern portions of Vermont and New Hampshire, with the primary severe risk likely to remain south of these areas. Meanwhile, with recently issued WW #610 extending southward to the Chesapeake Bay region, SLGT risk is correspondingly being expanded slightly southward. In Colorado, shear remains modest -- particularly with southward extent. However, with moderate destabilization occurring, and thus risk for locally intense cells within a narrow corridor, potential for hail/wind with a few of the strongest storms warrants upgrade to a small SLGT risk in this area. Otherwise, no major changes to the outlook are required at this time. ..Goss.. 08/21/2019 .PREV DISCUSSION... /ISSUED 1132 AM CDT Wed Aug 21 2019/ ...Northeast/Mid-Atlantic States... A shortwave trough will continue to progress east-northeastward from eastern New York toward northern New England, while a warm front slowly spreads northward across southern New England. With broken cloud cover lingering in most areas, modest overall destabilization is expected along/south of the warm front where low-level/deep-layer shear will be maximized. The environment will support the possibility of supercells/bowing segments particularly across southeast New York and southern New England, with severe hail/wind possible along with some tornado risk. Multicells with damaging winds are possible farther south within the warm sector. For additional short-term details, see Mesoscale Discussion 1825. ...Kansas/Missouri/far southeast Nebraska to Missouri/Illinois... The remnants of overnight convection continue to decay across the region with cloud cover/outflow influencing an effective boundary across southern portions of Kansas/Missouri. Surface-based thunderstorms should develop/intensify later this afternoon particularly across southern/eastern Kansas into western Missouri within a moist/unstable environment. Relatively weak tropospheric winds may limit overall storm organization, but the strongest storms will pose a damaging wind/severe hail risk. ...Wyoming/Colorado Front Range to central High Plains... Isolated to widely scattered thunderstorms should develop this afternoon over the eastern mountains and foothills from northern Wyoming across central/southern Colorado, offering the potential for isolated severe hail and gusts. Activity is expected predominantly in the post-frontal/upslope region where lift is maximized by a combination of upslope flow and diabatic surface heating of the higher terrain (minimizing MLCINH). Mid-level flow is forecast to be modest; however, vertical shear will be stronger than over lower elevations ahead of the front because of the backed boundary-layer winds and relatively extended low-level hodographs. As such, a mixture of supercellular and multicellular structures are possible. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Wed Aug 21 2019 Valid 212000Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHEAST AND MID ATLANTIC REGION...AS WELL AS OVER PARTS OF THE COLORADO FRONT RANGE... ...SUMMARY... Severe thunderstorms will continue this afternoon and evening across parts of the Northeast/Mid-Atlantic States, while a few severe storms will be possible across the central high Plains. ...Discussion... The overall outlook remains on track, with respect to prior forecast reasoning. The main changes in this update will be to extend the eastern U.S. SLGT risk a bit farther south across parts of the mid Atlantic region, while removing northern portions of the risk in parts of New England, and to include a small SLGT risk over the Colorado Front Range. In the East, clouds remain dense, and the airmass stable, over northern portions of Vermont and New Hampshire, with the primary severe risk likely to remain south of these areas. Meanwhile, with recently issued WW #610 extending southward to the Chesapeake Bay region, SLGT risk is correspondingly being expanded slightly southward. In Colorado, shear remains modest -- particularly with southward extent. However, with moderate destabilization occurring, and thus risk for locally intense cells within a narrow corridor, potential for hail/wind with a few of the strongest storms warrants upgrade to a small SLGT risk in this area. Otherwise, no major changes to the outlook are required at this time. ..Goss.. 08/21/2019 .PREV DISCUSSION... /ISSUED 1132 AM CDT Wed Aug 21 2019/ ...Northeast/Mid-Atlantic States... A shortwave trough will continue to progress east-northeastward from eastern New York toward northern New England, while a warm front slowly spreads northward across southern New England. With broken cloud cover lingering in most areas, modest overall destabilization is expected along/south of the warm front where low-level/deep-layer shear will be maximized. The environment will support the possibility of supercells/bowing segments particularly across southeast New York and southern New England, with severe hail/wind possible along with some tornado risk. Multicells with damaging winds are possible farther south within the warm sector. For additional short-term details, see Mesoscale Discussion 1825. ...Kansas/Missouri/far southeast Nebraska to Missouri/Illinois... The remnants of overnight convection continue to decay across the region with cloud cover/outflow influencing an effective boundary across southern portions of Kansas/Missouri. Surface-based thunderstorms should develop/intensify later this afternoon particularly across southern/eastern Kansas into western Missouri within a moist/unstable environment. Relatively weak tropospheric winds may limit overall storm organization, but the strongest storms will pose a damaging wind/severe hail risk. ...Wyoming/Colorado Front Range to central High Plains... Isolated to widely scattered thunderstorms should develop this afternoon over the eastern mountains and foothills from northern Wyoming across central/southern Colorado, offering the potential for isolated severe hail and gusts. Activity is expected predominantly in the post-frontal/upslope region where lift is maximized by a combination of upslope flow and diabatic surface heating of the higher terrain (minimizing MLCINH). Mid-level flow is forecast to be modest; however, vertical shear will be stronger than over lower elevations ahead of the front because of the backed boundary-layer winds and relatively extended low-level hodographs. As such, a mixture of supercellular and multicellular structures are possible. Read more

MD 1827 CONCERNING SEVERE THUNDERSTORM WATCH 609... FOR HUDSON VALLEY INTO SOUTHERN NEW ENGLAND
Mesoscale Discussion 1827 NWS Storm Prediction Center Norman OK 0255 PM CDT Wed Aug 21 2019 Areas affected...Hudson Valley into southern New England Concerning...Severe Thunderstorm Watch 609... Valid 211955Z - 212130Z The severe weather threat for Severe Thunderstorm Watch 609 continues. SUMMARY...Thunderstorm activity will continue to develop and intensify across the region through 5-7 PM EDT, posing a risk for damaging wind gusts, and perhaps at least some continuing risk for a tornado or two. DISCUSSION...The initial convective band has largely dissipated, but widely scattered, generally discrete vigorous thunderstorms have developed and persisted. This includes one storm which still could take on an increasing supercell structure as it tracks near/northwest of Providence RI during the next hour or so. Convection north of Albany appears to be gradually growing upscale, with potential to produce a swath of damaging winds becoming more apparent. Further intensification and organization appears possible, as it tracks eastward along an effective warm frontal zone near/north of the Massachusetts/Vermont and New Hampshire border area through 21-23Z. Additional new thunderstorm development is ongoing within surface troughing, near/east of the Catskills and Poconos. In the presence of moderate instability and shear, this activity is expected to intensify further and gradually pose increasing potential for strong surface gusts across the lower Hudson Valley into southern New England and Long Island. ..Kerr.. 08/21/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GYX...BOX...BTV...OKX...ALY...PHI...BGM... LAT...LON 43587342 43537203 42807084 41917075 41387192 41027248 40657350 40457445 40657537 41757469 43587342 Read more