Severe Storms

WW 558 SEVERE TSTM DC MD VA WV CW 282045Z - 290300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 558 NWS Storm Prediction Center Norman OK 445 PM EDT Fri Jul 28 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of District Of Columbia Maryland Northern Virginia Eastern West Virginia Coastal Waters * Effective this Friday afternoon and evening from 445 PM until 1100 PM EDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible SUMMARY...A band of thunderstorms with a history of wind damage will move across the higher terrain through the remainder of the afternoon, with additional storm clusters/downbursts expected farther east toward I-95. The severe thunderstorm watch area is approximately along and 45 statute miles east and west of a line from 10 miles east northeast of Hagerstown MD to 35 miles west of Roanoke VA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU8). 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 557... AVIATION...A few severe thunderstorms with hail surface and aloft to 0.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 27025. ...Thompson Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0251 PM CDT Fri Jul 28 2023 Valid 282000Z - 291200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS LATER THIS AFTERNOON INTO EARLY TONIGHT FROM NORTHERN IA TO NORTHERN IN AND VICINITY... ...SUMMARY... Severe storms are most probable from Iowa and southern Minnesota eastward to northern Illinois/southern Wisconsin late this afternoon/evening, and continuing into southwest Lower Michigan and northern Indiana tonight. Damaging winds and large hail are the main threats. ...20Z Update... Minor changes were made to the wind probabilities in the upper Midwest and upper Ohio Valley vicinity. The remainder of the outlook is unchanged as the previous forecast reasoning remains valid. ..Wendt.. 07/28/2023 .PREV DISCUSSION... /ISSUED 1120 AM CDT Fri Jul 28 2023/ ...SD/NE to the Upper Midwest through tonight... Within a largely zonal flow regime, embedded speed maxima will move eastward over the central/northern Plains and the upper MS Valley - the most pronounced of which is now over ND. Convection and an outflow/frontal surge with this ND speed max will eventually interact with the north edge of the more moist/unstable air mass from southeast SD/southern MN into northern IA/southern WI later this afternoon/evening. The timing of convective initiation and details of subsequent storm evolution are both somewhat in question, but effective bulk shear near 50 kt and MLCAPE of 2500-4000 J/kg will conditionally favor splitting supercells initially with very large hail. Convection could then grow upscale into an MCS this evening into tonight, with an attendant threat for damaging winds. ...Upper OH Valley into the Mid-Atlantic this afternoon/evening... A remnant MCV over northern IN will move eastward over OH today, and additional convection expected today along the associated outflow boundary/differential heating zone across central/eastern OH. The stronger flow with the MCV will tend to trail the lead outflow, so multicell storms with occasional downburst winds will be the primary threat this afternoon. Farther east, vertical shear will be weak, but surface heating over the higher terrain and weak convergence along a diffuse baroclinic zone will support scattered thunderstorm development this afternoon from the central Appalachians into parts of the Mid-Atlantic. Isolated strong downburst winds for a few hours this afternoon/evening will be the main concern this area. ...Northern ME this evening... A northern stream shortwave trough and associated surface cold front will cross Quebec and northern ME later this afternoon into this evening. Midlevel lapse rates will not be steep, but MLCAPE near 1000 J/kg and relatively long hodographs will support the potential for wind damage with a band of storms along and just ahead of the cold front. ...Southern MT to northeast CO and vicinity through tonight... Subtle speed maxima will move around the northern periphery of the southern Rockies midlevel high, interacting with terrain circulations and a deepening mixed layer later this afternoon. High-based storm development is expected around mid afternoon from southern MT to southeast WY/northeast CO, where storm clusters will move off the high terrain in response to mid-upper westerlies, and inverted-V profiles will favor isolated strong-severe outflow gusts as the main concerns. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0231 PM CDT Fri Jul 28 2023 Valid 291200Z - 301200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NORTHWEST NEVADA...FAR NORTHEAST CALIFORNIA...AND SOUTH-CENTRAL OREGON...... The previous forecast remains largely on track. The elevated area across north-central Oregon and central Washington was expanded slightly southwestward and northward, based on latest guidance and observations. Otherwise, no additional changes were made to the previous forecast. ..Marsh.. 07/28/2023 .PREV DISCUSSION... /ISSUED 1256 AM CDT Fri Jul 28 2023/ ...Synopsis... As a mid-level ridge builds across the western CONUS on Saturday, a shortwave will move along the western periphery of this ridge into the Northwest. This will spread moderate mid-level flow over the region. Downslope flow is likely in the lee of the northern Sierra and southern Cascades during this period. In addition, a hot and deeply mixed airmass will be in place, and some of this stronger flow may be transported to the surface. Have added a Critical delineation where 20 to 25 mph winds are most likely with relative humidity around 7 to 10 percent. Some downslope/gap flow is also possible in north-central Oregon and south-central Washington from the Columbia River Gorge and Cascade gaps. This threat may be later, as the surface pressure gradient tightens near 00Z. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Fri Jul 28 2023 Valid 291200Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF SOUTHERN NEW ENGLAND AND THE MID-ATLANTIC...PARTS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Widely scattered to scattered strong to severe thunderstorms are possible over southern New England into the Mid Atlantic states on Saturday. Damaging gusts are the primary hazard. Widely scattered severe storms are also possible over the north-central Great Plains late Saturday into Saturday night. ...Synopsis... The upper-level ridge centered over the Divide will amplify on Saturday. Some amplification of the cyclonic flow aloft over the Northeast is also expected. At the surface, a frontal boundary will continue to sag southward within the Plains into the Northeast. This front will likely become more diffuse with time, however. Farther west, modest moist upslope flow will occur in the central/northern High Plains behind the boundary. ...Mid-Atlantic into southern New England... Widely scattered to scattered storms are expected to develop by afternoon either along the front or along a surface trough near the Blue Ridge. Despite modest mid-level lapse rates, strong surface heating and a very moist boundary layer will support moderate to strong buoyancy (2000-3000 J/kg MLCAPE). The greatest values will likely occur within central/eastern Virginia into perhaps the Delmarva. Farther north, more limited heating and weaker mid-level lapse rates will limit overall destabilization. With the amplifying upper-level pattern, moderate mid-level winds will exist as far south as the northern Mid-Atlantic and decrease fairly rapidly to the south. That being said, the overlap of the most buoyant air and the greater deep-layer shear will not be spatially broad. Given the degree of buoyancy, damaging downburst winds are the expected primary threat with isolated large hail possible with initial storm development. A complicating factor in the forecast will be the timing and location of an MCV moving out of the Great Lakes region. Depending on where this feature is located, an area of greater mesoscale shear and storm coverage could develop within a zone from central Virginia into the Delmarva. Confidence remains too low for an increase in wind probabilities. ...Black Hills Vicinity... An uncertain forecast is evident for the region. Storms associated with a MCV moving out of Montana could be ongoing early in the period. While these storms would likely be elevated, strong deep-layer shear and adequate elevated buoyancy would promote some risk for large hail and perhaps a strong/severe wind gusts. Outflow from this early activity could also provide the focus for additional convective development farther south into northwest Nebraska. Model spread remains high in terms of the expected evolution. The Slight risk will be maintained this outlook cycle, though confidence in any one eventual scenario is low. ...Mid-Mississippi and Lower Ohio Valleys... Moderate to strong buoyancy is anticipated south of the surface front. Models suggest the MCV moving into the central Plains will likely provide lift for eventual development of a cluster of thunderstorms. Deep-layer shear will not be overly strong, particularly farther south from the boundary, but should be sufficient for modest storm organization. The timing and location of development is uncertain, but intensification could occur within northern/eastern Missouri. Damaging wind gusts would be the primary threat, though isolated large hail could also occur. ...Northern Plains... Storm coverage will likely be limited given the amplification of the ridge aloft. However, enough low-level moisture flowing into the terrain should allow a few storms to develop in the northern Rockies. Guidance also suggests development is possible in southern Alberta with eventual movement into northeast Montana and far western North Dakota. Shear profiles would support supercells capable of large hail and strong/severe wind gusts. ..Wendt.. 07/28/2023 Read more

WW 0555 Status Updates
STATUS REPORT ON WW 555 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..BENTLEY..07/27/23 ATTN...WFO...LWX...PHI...CTP... STATUS REPORT FOR WS 555 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS DEC001-003-272340- DE . DELAWARE COUNTIES INCLUDED ARE KENT NEW CASTLE DCC001-272340- DC . DISTRICT OF COLUMBIA COUNTIES INCLUDED ARE DISTRICT OF COLUMBIA MDC001-003-005-013-015-021-023-025-027-029-031-033-035-043-510- 272340- MD . MARYLAND COUNTIES INCLUDED ARE ALLEGANY ANNE ARUNDEL BALTIMORE CARROLL CECIL FREDERICK GARRETT HARFORD HOWARD KENT MONTGOMERY PRINCE GEORGES Read more

WW 555 SEVERE TSTM DC DE MD NJ PA VA WV CW 271915Z - 280300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 555 NWS Storm Prediction Center Norman OK 315 PM EDT Thu Jul 27 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of District Of Columbia Northern Delaware Northern Maryland New Jersey Southern and Eastern Pennsylvania Northern Virginia Eastern Panhandle of West Virginia Coastal Waters * Effective this Thursday afternoon and evening from 315 PM until 1100 PM EDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible SUMMARY...Thunderstorms are expected to become more numerous across the watch area this afternoon, with a few strong to severe storms expected. Locally damaging wind gusts appear to be the main risk. The severe thunderstorm watch area is approximately along and 60 statute miles north and south of a line from 65 miles west of Martinsburg WV to 25 miles north of Lakehurst NJ. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU5). 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 553...WW 554... AVIATION...A few severe thunderstorms with hail surface and aloft to 0.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 27025. ...Hart Read more

MD 1743 CONCERNING SEVERE THUNDERSTORM WATCH 553...555... FOR PORTIONS OF THE MID-ATLANTIC INTO NEW ENGLAND
Mesoscale Discussion 1743 NWS Storm Prediction Center Norman OK 0507 PM CDT Thu Jul 27 2023 Areas affected...Portions of the Mid-Atlantic into New England Concerning...Severe Thunderstorm Watch 553...555... Valid 272207Z - 272330Z The severe weather threat for Severe Thunderstorm Watch 553, 555 continues. SUMMARY...The severe weather threat will continue for a few more hours from the Mid-Atlantic to southern New England. DISCUSSION...Storms have congealed into a southward drifting line from eastern Pennsylvania to eastern Massachusetts. The best severe wind gust potential will likely remain across portions of Massachusetts, Rhode Island, and Connecticut where storms are oriented more normal to the deep-layer shear. Farther west along this line, some isolated damaging wind gusts, but less favorable orientation should result in a more sub-severe threat. Once the storms across southern New England move offshore, expect the severe threat to be more marginal and isolated along the trailing line of storms. ..Bentley.. 07/27/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BOX...OKX...ALY...PHI...BGM...CTP... LAT...LON 41207699 41647505 42297265 42747063 42617037 42337053 42137032 42126997 41796984 41536995 41447022 41047140 40787230 40597344 40587392 40667478 40737560 40757604 40767637 40827667 40937690 41007697 41207699 Read more

WW 0556 Status Updates
STATUS FOR WATCH 0556 HAS NOT BEEN ISSUED YET Read more

WW 556 SEVERE TSTM MI WI LM LS 272150Z - 280400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 556 NWS Storm Prediction Center Norman OK 450 PM CDT Thu Jul 27 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Western Upper Michigan North-central and northeast Wisconsin Lake Michigan Lake Superior * Effective this Thursday afternoon and evening from 450 PM until 1100 PM CDT. * Primary threats include... Scattered damaging winds and isolated significant gusts to 75 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...Congealing clusters should spread east-southeast this evening with a threat for damaging winds and large hail. The severe thunderstorm watch area is approximately along and 80 statute miles east and west of a line from 35 miles north northwest of Marquette MI to 45 miles south southeast of Mosinee WI. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU6). 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 553...WW 554...WW 555... AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 65 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 29030. ...Grams Read more

MD 1742 CONCERNING SEVERE THUNDERSTORM WATCH 554... FOR PORTIONS OF EASTERN MN INTO NORTHERN/CENTRAL WI AND THE U.P. OF MI
Mesoscale Discussion 1742 NWS Storm Prediction Center Norman OK 0436 PM CDT Thu Jul 27 2023 Areas affected...Portions of eastern MN into northern/central WI and the U.P. of MI Concerning...Severe Thunderstorm Watch 554... Valid 272136Z - 272300Z The severe weather threat for Severe Thunderstorm Watch 554 continues. SUMMARY...The threat for large hail and damaging winds will likely spread eastward over the next couple of hours. Downstream watch issuance will likely be needed. DISCUSSION...Multiple supercells are ongoing this afternoon across parts of northwestern WI and east-central MN. Multiple measured severe hail reports of 1 to 2 inches have occurred with this activity. Recent radar trends show some updraft interactions, and the beginning stages of clustering/upscale growth may continue. Regardless, a continued threat for large to very large hail will persist in the short term, as strong instability (3000-3500+ J/kg of MLCAPE) and 40+ kt of deep-layer shear prove favorable for robust updrafts. A tornado also appears possible in the short term as well, mainly across northwestern WI where low-level shear is maximized in the presence of ongoing supercells. The threat for severe/damaging winds will likely increase this evening as thunderstorm clusters move eastward across northern/central WI and the U.P. of MI. The eastern extent of the severe threat remains somewhat unclear, as less instability is present towards Lake Michigan. Still, downstream Severe Thunderstorm Watch issuance will likely be required for the increasing hail/wind threat. ..Gleason/Grams.. 07/27/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MQT...GRB...DLH...ARX...MPX... LAT...LON 45399286 46119335 46859154 46878924 46508761 46018731 45228747 44478816 44459035 44729160 45399286 Read more

WW 0553 Status Updates
240- STATUS REPORT ON WW 553 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 NE AVP TO 20 ESE MSV TO 15 NNE POU TO 20 W BDL TO 15 W ORH TO 15 N PSM TO 20 SSW AUG TO 20 NNE AUG. ..BENTLEY..07/27/23 ATTN...WFO...OKX...BOX...ALY...GYX...BGM... STATUS REPORT FOR WS 553 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS CTC001-003-005-007-009-011-013-015-272240- CT . CONNECTICUT COUNTIES INCLUDED ARE FAIRFIELD HARTFORD LITCHFIELD MIDDLESEX NEW HAVEN NEW LONDON TOLLAND WINDHAM MEC001-005-011-013-015-023-027-031-272240- ME . MAINE COUNTIES INCLUDED ARE ANDROSCOGGIN CUMBERLAND KENNEBEC KNOX LINCOLN SAGADAHOC WALDO YORK MAC005-009-013-015-017-021-023-025-027-272240- MA Read more

WW 553 SEVERE TSTM CT MA ME NH NY PA RI VT CW 271645Z - 280000Z
0- URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 553 NWS Storm Prediction Center Norman OK 1245 PM EDT Thu Jul 27 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Connecticut Massachusetts Southern Maine Southern New Hampshire Southeast New York Northeast Pennsylvania Rhode Island Southern Vermont Coastal Waters * Effective this Thursday afternoon and evening from 1245 PM until 800 PM EDT. * Primary threats include... Scattered damaging winds likely with isolated significant gusts to 75 mph possible Isolated large hail events to 1 inch in diameter possible A tornado or two possible SUMMARY...Thunderstorms will intensify this afternoon along a cold front and spread eastward across the watch area. Damaging wind gusts will be possible with the strongest cells through the afternoon. A tornado or two cannot be ruled out. The severe thunderstorm watch area is approximately along and 90 statute miles east and west of a line from 5 miles west northwest of Augusta ME to 30 miles south of Poughkeepsie NY. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU3). 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 inch. Extreme turbulence and surface wind gusts to 65 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 26030. ...Hart Read more

WW 0554 Status Updates
STATUS REPORT ON WW 554 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 WNW BRD TO 25 E BRD TO 10 S DLH TO 30 ENE BFW. ..BENTLEY..07/27/23 ATTN...WFO...DLH...MPX... STATUS REPORT FOR WS 554 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS MNC001-003-009-017-025-035-053-059-065-067-075-093-095-097-115- 123-141-145-153-163-171-272240- MN . MINNESOTA COUNTIES INCLUDED ARE AITKIN ANOKA BENTON CARLTON CHISAGO CROW WING HENNEPIN ISANTI KANABEC KANDIYOHI LAKE MEEKER MILLE LACS MORRISON PINE RAMSEY SHERBURNE STEARNS TODD WASHINGTON WRIGHT WIC003-005-007-013-017-031-033-035-051-093-095-099-107-109-113- 129-272240- WI . WISCONSIN COUNTIES INCLUDED ARE ASHLAND BARRON BAYFIELD BURNETT CHIPPEWA DOUGLAS DUNN EAU CLAIRE IRON PIERCE POLK PRICE Read more

WW 554 SEVERE TSTM MN WI LS 271905Z - 280200Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 554 NWS Storm Prediction Center Norman OK 205 PM CDT Thu Jul 27 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Central and Eastern Minnesota Northwest Wisconsin Lake Superior * Effective this Thursday afternoon and evening from 205 PM until 900 PM CDT. * Primary threats include... Widespread large hail and isolated very large hail events to 3 inches in diameter likely Scattered damaging wind gusts to 70 mph likely A tornado or two possible SUMMARY...Thunderstorms will rapidly develop this afternoon over central Minnesota and track southeastward across the watch area. Very large hail and damaging winds will be possible. The severe thunderstorm watch area is approximately along and 75 statute miles north and south of a line from 40 miles northwest of Brainerd MN to 15 miles south southeast of Ironwood MI. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU4). 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 553... AVIATION...A few severe thunderstorms with hail surface and aloft to 3 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 29030. ...Hart Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0255 PM CDT Thu Jul 27 2023 Valid 272000Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF EASTERN MINNESOTA...WISCONSIN NORTHWOODS...WESTERN UPPER MICHIGAN... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WITHIN THE SOUTHERN NEW ENGLAND INTO THE MID-ATLANTIC... ...SUMMARY... Severe gusts and hail (some potentially significant) are possible the remainder of this afternoon and evening in parts of Minnesota and Wisconsin. Damaging to severe gusts also may occur today with thunderstorms in parts of the Mid-Atlantic/New England regions, and the central High Plains and Rockies. ...20Z Update... A few minor changes to wind probabilities from the Ohio Valley into the Northeast as well as modifications to the general thunder area based on the latest observational trends. The prior forecast reasoning otherwise remains valid. ..Wendt.. 07/27/2023 .PREV DISCUSSION... /ISSUED 1112 AM CDT Thu Jul 27 2023/ ...Northeast... A well-defined shortwave trough is moving across central NY today. Forcing for ascent ahead of this trough will aid in the development of scattered thunderstorms by mid-afternoon from parts of PA and southeast NY into southern and eastern New England. Rich low-level moisture and pockets of strong daytime heating will yield MLCAPE values around 2000 J/kg. Rather strong wind fields will promote relatively fast-moving storms capable of wind damage. Parts of southern New England may also have sufficient low-level vertical shear to pose a risk of a tornado or two. Please refer to MCDs #1736 and #1737 for further details. ...Western Great Lakes/Upper Midwest... Fast zonal flow is present today across the northern Plains, with 50-70 knot westerly winds above 6km noted on forecast soundings. A surface boundary is sagging southward across MN, and should provide the focus for rapid thunderstorm development later this afternoon. A very unstable air mass will develop from central MN into northern WI, along with sufficient deep-layer shear for supercells capable of very large hail. Storms are expected to persist well into the evening as they spread eastward into parts of Upper MI and much of northern/central WI. The risk of rather widespread damaging winds will increase across this area. Given the favorable environment and consistent 12z model signals, have upgraded portions of this area to ENH. ...Rockies and High Plains... Similar to yesterday, scattered high-based showers and thunderstorms are expected to develop over the high terrain of CO northward into much of WY and MT. Fast westerly flow and steep low-level lapse rates will promote a risk of damaging wind gusts in some of these storms. As activity spreads eastward into the Plains, a few more robust updrafts may also produce large hail. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0220 PM CDT Thu Jul 27 2023 Valid 281200Z - 291200Z No major changes will be made to the current outlook. Elevated fire-weather conditions are possible across the northern Great Basin and lee of the cascades with dry and breezy winds. A few thunderstorms are also possible overnight into D3/Saturday. The highest confidence areas for storms will be across parts of eastern OR and WA where weak elevated buoyancy is forecast. Little to no wetting rainfall is expected, but storm coverage should remain low. See the prior discussion for additional information. ..Lyons.. 07/27/2023 .PREV DISCUSSION... /ISSUED 0200 AM CDT Thu Jul 27 2023/ ...Synopsis... A mid-level trough will amplify along the West Coast as upper ridging intensifies over the Interior West tomorrow/Friday. Similar to Day 1, dry downslope flow should continue along the lee of the higher terrain. 15+ mph sustained west-southwesterly surface winds should overlap with 15 percent RH by afternoon peak heating, warranting the introduction of Elevated highlights. Thunderstorms will also be possible ahead of the trough and north of the upper ridge across the northern Rockies. Similar to previous days, any lightning strikes that can occur in dry fuel beds may encourage fire starts, potentially exacerbated by erratic, gusty winds. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 1241 PM CDT Thu Jul 27 2023 Valid 281200Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IOWA INTO THE SOUTHERN GREAT LAKES... CORRECTED FOR SUMMARY ...SUMMARY... Widely scattered severe thunderstorms are possible on Friday and Friday night across a large portion of the Midwest. ...Synopsis... Moderate to strong mid-level winds will remain along the northern periphery of an upper-level ridge. This flow will be confined to the northern Plains into the upper Midwest, though some amplification of the ridge could push moderate mid-level flow into the lower Great Lakes as well. A surface boundary will extend from the northern Plains into parts of the upper Midwest. A surface low is forecast to deepen slightly in the mid-Missouri Valley. Convective outflow and potential MCVs will also be present, but the location of these features is a bit uncertain. ...Lower Great Lakes/Midwest... Convection within the upper Mississippi Valley on Thursday night into Friday morning will play a role in how convection evolves during Friday afternoon. Guidance is variable in the placement of the outflow/MCV from this activity. However, the general consensus places these features within southern Wisconsin into parts of the upper Ohio Valley. South of the outflow, strong buoyancy is expected to develop. Shear will be strongest along and north of the boundary and decrease with southward extent. Forcing for ascent will generally be nebulous outside of areas impacted by the MCV. The expectation is for a cluster or two of storms to develop and progress eastward/southeastward into the MLCAPE reservoir. Large hail would be possible with initial activity before upscale growth occurs and severe/damaging winds would become the primary threat. A corridor of greater severe wind potential could develop given the clustering and strong instability, but uncertainty in the placement of boundaries and the eventual convective evolution precludes an increase in probabilities. Convection developing within parts of Montana may be ongoing at the beginning of the period. This activity and associated MCV could potentially intensify if it is able to progress into the greater buoyancy within South Dakota/Nebraska. This activity would also pose a risk of primarily strong/damaging winds and isolated large hail possible as well. Confidence in this scenario is also too low for any increase in wind probabilities. ...Southwest Montana... Stronger mid-level winds will persist across the northern Rockies. Convection is likely to develop within the higher terrain. Steep low and mid-level lapse rates will allow for strong wind gusts to reach the surface. Marginally severe hail will also be possible. ...Northern Maine... Strong westerly mid to high-level flow accompanying the aforementioned speed max will overspread the region during the day. It appears at least marginal destabilization will occur with surface dewpoints well into the 60s. A band of storms along a frontal zone will probably push eastward into Maine during the afternoon/early evening. Isolated severe gusts are the primary hazard. ..Wendt.. 07/27/2023 Read more

MD 1732 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF CENTRAL WYOMING
Mesoscale Discussion 1732 NWS Storm Prediction Center Norman OK 0446 PM CDT Wed Jul 26 2023 Areas affected...portions of central Wyoming Concerning...Severe potential...Watch unlikely Valid 262146Z - 262315Z Probability of Watch Issuance...5 percent SUMMARY...A few more severe gusts may occur with ongoing storms across central WY. The severe threat should remain isolated and a Severe Thunderstorm Watch issuance is unlikely. DISCUSSION...A semi-organized cluster of pulse-cellular storms have produced measured severe gusts over the past few hours and is poised to progress eastward atop a heated, well-mixed boundary layer. MRMS mosaic radar imagery shows a slight increase in the intensity of storm cores, and 21Z mesoanalysis shows boundary-layer lapse rates exceeding 9.8 C/km in some locales. As such, severe gusts should remain a concern through the rest of the afternoon until boundary-layer stabilization sets in during the evening. Severe gusts should by isolated, so a WW issuance is not expected. ..Squitieri/Grams.. 07/26/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...UNR...CYS...RIW... LAT...LON 43580850 44010820 44230733 44340545 44180486 43500473 42780532 42420630 42310691 42340756 42330789 42520804 43580850 Read more

MD 1731 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF CENTRAL NORTH DAKOTA...SOUTH DAKOTA...AND NEBRASKA
Mesoscale Discussion 1731 NWS Storm Prediction Center Norman OK 0431 PM CDT Wed Jul 26 2023 Areas affected...portions of central North Dakota...South Dakota...and Nebraska Concerning...Severe potential...Watch unlikely Valid 262131Z - 262300Z Probability of Watch Issuance...20 percent SUMMARY...A risk for isolated severe gusts/hail exists this afternoon with the stronger storms that can sustain themselves. A WW issuance is not currently anticipated. DISCUSSION...Strong boundary-layer heating and broad surface lee troughing is supporting the development of isolated, high-based supercells across the northern Plains. 100 F surface temperatures amid low 50s-60s F dewpoints (40-50 F T/Td spreads) preceding the supercells are contributing to 9+ C/km boundary-layer lapse rates. While 7-8 C/km mid-level lapse rates and 40+ kts of effective bulk shear (driven by elongated hodographs) suggest that mid-level updraft rotation and hail potential exists, the deep and hot boundary layer may promote sufficient melting of hail as well as evaporation of rain to support a severe gust threat through the remainder of the afternoon. Given the isolated nature of the storms and their severe threat, a Severe Thunderstorm Watch issuance is not currently expected. ..Squitieri/Grams.. 07/26/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FSD...ABR...GID...BIS...LBF...UNR... LAT...LON 40540075 44300160 46410163 47560055 47700001 47279933 46529886 45329848 43919845 42499860 41539886 40889919 40429954 40540075 Read more

WW 0551 Status Updates
STATUS REPORT ON WW 551 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 WNW MFD TO 35 ESE MTC TO 15 SW OSC. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1728 ..WEINMAN..07/26/23 ATTN...WFO...DTX...CLE... STATUS REPORT FOR WS 551 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS MIC063-151-262240- MI . MICHIGAN COUNTIES INCLUDED ARE HURON SANILAC OHC007-035-043-055-077-085-093-103-262240- OH . OHIO COUNTIES INCLUDED ARE ASHTABULA CUYAHOGA ERIE GEAUGA HURON LAKE LORAIN MEDINA PAC039-049-262240- PA . PENNSYLVANIA COUNTIES INCLUDED ARE Read more