Severe Storms

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Wed Aug 16 2023 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR THE EASTERN HALF OF MINNESOTA...NORTHWEST WISCONSIN...FAR WESTERN PART OF THE UPPER PENINSULA OF MICHIGAN... ...SUMMARY... Thunderstorms capable of damaging winds and hail are expected this afternoon and evening across parts Minnesota, Wisconsin, and western Upper Michigan. ...Discussion... No appreciable change was made to the previous convective outlook. ..Smith.. 08/16/2023 .PREV DISCUSSION... /ISSUED 1109 AM CDT Wed Aug 16 2023/ ...MN/WI/Western Upper MI... Latest surface analysis shows a strong cold front surging southeastward across ND. Southerly low-level winds ahead of the front, along with shallow vertical mixing below a capping inversion, have resulted in a corridor of low-mid 60s dewpoints across much of MN. Strong daytime heating and steep mid-level lapse rates will yield afternoon MLCAPE values around 2500 J/kg. The cap will likely focus thunderstorm development to immediately along or even slightly behind the cold front, but given the strong winds aloft and focused convergence, a few intense bowing structures are expected. Damaging winds and hail appear to be the main threats. Storms will likely persist a few hours after dark and track into parts of northern/central WI and western Upper MI before weakening. ...southern GA/SC/FL... A very moist/unstable air mass will be present again today ahead of a cold front sagging into the southeast states. Winds aloft and large scale forcing are weak, suggesting convection will be relatively disorganized. Nevertheless, steep low-level lapse rates and water-loading will contribute to isolated instances of damaging wind gusts in the stronger cells. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0214 PM CDT Wed Aug 16 2023 Valid 171200Z - 181200Z ...CRITICAL FIRE WEATHER AREA FOR COLUMBIA BASIN... ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE NORTHERN ROCKIES... No changes to the ongoing forecast. ..Wendt.. 08/16/2023 .PREV DISCUSSION... /ISSUED 0159 AM CDT Wed Aug 16 2023/ ...Synopsis... Mid-level high pressure is forecast to continue building as it shifts eastward over the southern Rockies/Plains through the forecast period. To the west, a Pacific trough will overspread the Northwest, increasing mid-level flow into the Northern Rockies. Dry and windy conditions will favor elevated to critical fire-weather conditions across the Northwest and northern Rockies. Monsoon moisture will also support shower and thunderstorm chances over southern parts of the Pacific Northwest. ...Northwest and northern Rockies... As the upper ridge shifts eastward, flow aloft will turn westerly as a Pacific trough begins to approach. While initially modest, winds are forecast to gradually increase through the day. At the same time, a thermally induced surface pressure trough/weak lee cyclone will bolster low-level pressure gradients in the lee of the Cascades, through the Columbia Basin and into northern MT. This will result in downslope winds of 20-25 mph, along with afternoon RH values of 15-20%. Widespread elevated and critical conditions are likely over the Northwest and parts of the northern Rockies where fuels are quite dry. Confidence in critical conditions is highest across the western Columbia Basin where RH is forecast to be lower and winds slightly stronger. To the south, monsoon moisture will linger over parts of southern OR and northern CA, supporting scattered afternoon showers and thunderstorms. A mixed mode of wet and dry storms is expected with PWATS climbing above 1 inch and only modest storm speeds. However, area fuels remain very dry and receptive to lightning ignitions. While storms will tend to be come more efficient with wetting rains through the day, sufficient coverage should exist for isolated dry strikes outside of heavier cores across parts of southern OR and far northern CA. ...Central Texas... As the upper ridge rebuilds, very hot temperatures are expected across parts of TX and the southern Plains. Winds are forecast to remain weak, but temperatures well over 100F and exceptionally dry fuels may support a risk for locally elevated fire-weather conditions. Especially across central portions of the state, local winds may occasionally reach 10-15 mph. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0649 Status Updates
STATUS REPORT ON WW 649 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 S RDU TO 20 SSE RZZ. ..KERR..08/15/23 ATTN...WFO...RAH...GSP...RNK...CAE... STATUS REPORT FOR WS 649 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NCC065-083-101-163-191-195-152340- NC . NORTH CAROLINA COUNTIES INCLUDED ARE EDGECOMBE HALIFAX JOHNSTON SAMPSON WAYNE WILSON 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 649 SEVERE TSTM NC SC VA 151750Z - 160100Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 649 NWS Storm Prediction Center Norman OK 150 PM EDT Tue Aug 15 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Central North Carolina Northern South Carolina South Central Virginia * Effective this Tuesday afternoon and evening from 150 PM until 900 PM EDT. * Primary threats include... Scattered damaging winds likely with isolated significant gusts to 75 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...Thunderstorms will increase in coverage and intensity through the afternoon, with multiple clusters of severe storms possible. Locally damaging wind gusts are the main threat. The severe thunderstorm watch area is approximately along and 45 statute miles north and south of a line from 25 miles west northwest of Charlotte NC to 10 miles northeast of Roanoke Rapids NC. 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 65 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 26030. ...Hart Read more

MD 2003 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF THE FLORIDA PANHANDLE...SOUTHEASTERN ALABAMA AND SOUTHWEST GEORGIA.
Mesoscale Discussion 2003 NWS Storm Prediction Center Norman OK 0451 PM CDT Tue Aug 15 2023 Areas affected...parts of the Florida Panhandle...southeastern Alabama and southwest Georgia. Concerning...Severe potential...Watch unlikely Valid 152151Z - 152345Z Probability of Watch Issuance...20 percent SUMMARY...Scattered thunderstorms have produced occasional damaging gusts this afternoon and will likely remain capable of isolated wind damage into this evening. Given the lack of storm organization, a weather watch is not anticipated. DISCUSSION...Across portions of the Southeast, scattered to numerous thunderstorms were ongoing ahead of a frontal zone across the FL Panhandle, southeast AL and southwest GA. Over the last couple of hours, occasional strong to severe gusts (59 mph at KMAI) have been noted with a few of these storms. A strongly unstable environment, with 3000-4000 J/kg of MLCAPE is supporting, and is expected to continue supporting, strong updrafts through this evening. However, with little vertical shear, storm organization has remained limited to pulse multi-cell clusters. The strong buoyancy and PWATs over 2 inches will support the risk for isolated wet microbursts with the strongest storms. Isolated damaging gusts will remain possible into this evening before nocturnal stabilization begins to limit the potential for strong updrafts. Given the limited potential for storm organizational, and the lack of broader synoptic support, a weather watch is unlikely. ..Lyons/Guyer.. 08/15/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FFC...TAE...BMX...MOB... LAT...LON 30858645 30968642 31348582 31618541 31948486 32048454 32078339 31948295 31818298 31328325 30768386 30488430 30358475 30298536 30438605 30628638 30698642 30858645 Read more

WW 0651 Status Updates
STATUS FOR WATCH 0651 HAS NOT BEEN ISSUED YET Read more

WW 651 SEVERE TSTM NC CW 152145Z - 160500Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 651 NWS Storm Prediction Center Norman OK 545 PM EDT Tue Aug 15 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Eastern North Carolina Coastal Waters * Effective this Tuesday afternoon and Wednesday morning from 545 PM until 100 AM EDT. * Primary threats include... Scattered damaging wind gusts to 65 mph likely SUMMARY...Clusters of storms will continue to progress generally east-northeastward toward eastern North Carolina through the evening, with the stronger storms capable of wind damage and possibly some hail. The severe thunderstorm watch area is approximately along and 50 statute miles north and south of a line from 45 miles south of Fayetteville NC to 35 miles north northeast of Cape Hatteras NC. 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 649...WW 650... AVIATION...A few severe thunderstorms with hail surface and aloft to 1 inch. Extreme turbulence and surface wind gusts to 55 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 25025. ...Guyer Read more

WW 0650 Status Updates
STATUS REPORT ON WW 650 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 10 NE RZZ TO 35 SW DOV TO 20 N TTN. ..KERR..08/15/23 ATTN...WFO...LWX...PHI...AKQ... STATUS REPORT FOR WS 650 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS DEC001-005-152240- DE . DELAWARE COUNTIES INCLUDED ARE KENT SUSSEX MDC011-015-019-037-039-045-047-152240- MD . MARYLAND COUNTIES INCLUDED ARE CAROLINE CECIL DORCHESTER ST. MARYS SOMERSET WICOMICO WORCESTER NJC001-005-007-009-011-015-021-025-029-033-152240- NJ . NEW JERSEY COUNTIES INCLUDED ARE ATLANTIC BURLINGTON CAMDEN CAPE MAY CUMBERLAND GLOUCESTER Read more

WW 650 SEVERE TSTM DC DE MD NC NJ PA VA CW 151810Z - 160100Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 650 NWS Storm Prediction Center Norman OK 210 PM EDT Tue Aug 15 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of District Of Columbia Delaware Eastern Maryland Northeast North Carolina Central and Southern New Jersey Southeast Pennsylvania Eastern Virginia Coastal Waters * Effective this Tuesday afternoon and evening from 210 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 SUMMARY...Scattered thunderstorms will develop this afternoon ahead of an approaching cold front. Some of the storms will become severe, posing a risk of locally damaging wind gusts. The severe thunderstorm watch area is approximately along and 65 statute miles east and west of a line from 20 miles north of Trenton NJ to 15 miles east of Roanoke Rapids NC. 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 649... 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 26030. ...Hart Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0346 PM CDT Tue Aug 15 2023 Valid 171200Z - 231200Z A weak upper low is expected to remain off the California coast perhaps into early next week. Model guidance continues to differ in terms of the evolution of the upper-level pattern late this week into the weekend. At some point, an upper trough in the Northwest is expected to phase with the weak upper low. High pressure at the surface will remain in the Plains through midweek. Thereafter, a cold front is forecast to push southward into parts of the southern Plains late this week. ...Northwest... Dry and windy conditions appear probable on Thursday and Friday from the east side of the Cascades into the Columbia Basin. Temperatures will be higher on Thursday than on Friday. This could lead to a small increase in RH on Friday. However, guidance still suggests both days will reach critically low values. Winds on Thursday will primarily be driven by the thermal pressure trough in the Basin. Mid-level winds will increase on Friday as the mid-level jet overspreads most of Washington. Critical fire weather potential will exist on both days, but the greater potential should exist on Friday given the greater expected coverage of 20-25 mph winds. Thunderstorms are expected to occur each day through the weekend in parts of Oregon. PWAT values will continue to increase and lead to wetting rainfall potential. There is some possibility that storms may be slightly drier on Friday in north-central/northeast Oregon with drier air working in from the south and strong mid-level winds moving in from the north. Coverage of dry thunderstorms should remain low, though lightning away from storm cores could still pose problems. ...Montana... With an upper-level trough approaching the Northwest, a surface low is expected to deepen in Alberta. There is some model disagreement as to the evolution of the surface low late this week, but enhanced downslope winds are expected on both Thursday and Friday in the lee of the northern Rockies. With temperatures expected to be higher on Thursday, greater confidence in critical fire weather exists. Cooler temperatures and the potential for a cold front to limit the duration of fire weather concerns leads to less confidence on Friday. ...Texas... Hot surface temperatures should return to the region by Thursday. The development of thermal pressure troughs may lead to some locally elevated conditions in the presence of extremely dry fuels. There may be some broader increase in surface winds on Friday as a large-scale surface trough develops into the southern Plains. Trends will need to be monitored, but wind speeds continue to look too weak for critical probabilities. In addition, isolated thunderstorms could develop in the surface trough with the extreme heat, but predictability is quite low. ..Wendt.. 08/15/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0236 PM CDT Tue Aug 15 2023 Valid 152000Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTH CAROLINA TO NEW JERSEY... ...SUMMARY... Damaging to severe thunderstorm gusts should be most common this through this evening from central North Carolina to southern New Jersey. ...20z Update... Only minor adjustments have been made to severe probabilities based on current location of the surface front and ongoing convection. Otherwise, the previous forecast remains on track. Reference ongoing severe thunderstorm watches 649 and 650, and forthcoming MCDs for short term severe storm info. ..Leitman.. 08/15/2023 .PREV DISCUSSION... /ISSUED 1059 AM CDT Tue Aug 15 2023/ ...NC to Mid-Atlantic Region... Morning water vapor imagery shows a large upper low over northwest OH, with a band of 50-60 knot southwesterly mid/upper level winds extending from TN/KY into the Mid-Atlantic region and southern New England. The associated surface cold front runs along/just west of the spine of the Appalachians from PA into east TN. Mostly clear skies ahead of the front will combine with dewpoints in the low-mid 70s to yield a very unstable air mass by mid-afternoon, with forecast soundings showing MLCAPE values of 2000-3000 J/kg. This should result in intensifying clusters of storms from western NC into central VA/southeast PA tracking eastward through the afternoon and early evening. Strong westerly flow aloft, steep low-level lapse rates, and high moisture content will likely result in bowing structures and a few supercells capable of severe wind gusts. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0146 PM CDT Tue Aug 15 2023 Valid 161200Z - 171200Z Only minor changes were made to the dry thunder area in northern California to account for current guidance. The forecast otherwise remains on track. ..Wendt.. 08/15/2023 .PREV DISCUSSION... /ISSUED 0152 AM CDT Tue Aug 15 2023/ ...Synopsis... Mid-level high pressure is forecast to build over the western US while a weak upper low moves off the West Coast. Across the central US, a mid-level trough is forecast to move out of southern Canada with an accompanying surface cold front sweeping southeastward across the northern Rockies. Dry downslope winds are likely to support locally elevated fire-weather concerns over parts of northern MT. Dry thunderstorms are also possible over parts of the Northwest. ...Northwest... Another round of showers and high-based thunderstorms are expected across parts of northern CA and southern OR D2/Wed, as the upper low moves off the West Coast. Monsoon moisture will continue to increase with PWATs exceeding 1 inch. With the low farther offshore, easterly flow aloft will slacken, resulting in gradually diminishing storm speeds. Widely scattered, initially dry, storms are expected, but precipitation efficiency should rise through the day as storms slow down and moisture values increase. While QPF is forecast to increase with time, very dry and receptive fuels, along with initially dry storms, will favor some risk for lightning ignitions. ...Northern Rockies... As the Alberta trough continues to move south into the US, a cold front/wind shift will move through the northern Rockies early D2/Wed. Gusty northwest winds will remain strong through the day with downslope gusts of 15-20 mph possible. While RH values will likely be higher from the cooler air mass behind the front, diurnal minimums below 35% are expected. A few hours of locally elevated fire-weather conditions are possible given dry fuels and breezy conditions across much of northern MT. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Mon Aug 14 22:18:01 UTC 2023.

MD 1995 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR SOUTHERN INDIANA
Mesoscale Discussion 1995 NWS Storm Prediction Center Norman OK 0356 PM CDT Mon Aug 14 2023 Areas affected...Southern Indiana Concerning...Severe potential...Watch unlikely Valid 142056Z - 142300Z Probability of Watch Issuance...20 percent SUMMARY...Thunderstorms developing along a cold front may pose an isolated hail and wind risk this afternoon and evening. However, watch issuance is not expected. DISCUSSION...Thunderstorms developing along a cold front across the Midwest have been slow to mature over the past few hours, but imagery from KIND has shown improving organization of a few cells over the past 30-60 minutes. Temperatures warming into the low 80s ahead of the cold front have allowed MLCAPE values to increase to around 1000 J/kg, and recent forecast soundings and KIND VWP observations show elongated, nearly straight hodographs with effective bulk shear near 45 knots. The strongly sheared environment may compensate for the otherwise marginal buoyancy and support sufficient storm organization for a large hail/severe wind threat. Initially discrete cells have shown a tendency for slow upscale growth, and this trend should continue into the evening hours, which may modulate the severe threat to some degree. Storms moving into central IN they will likely encounter a noted buoyancy gradient along a warm front, which should limit the northward extent of the severe threat. Watch issuance is not currently anticipated given modest downstream buoyancy and lackluster storm organization thus far. ..Moore/Hart.. 08/14/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ILN...LMK...IND...PAH...ILX... LAT...LON 38038831 39118739 39778695 40098660 40058573 39858490 39498478 38868518 38298585 38028649 37858709 37788762 37788802 38038831 Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0349 PM CDT Mon Aug 14 2023 Valid 161200Z - 221200Z The upper-level ridge will shift east through the period. Along the West Coast, a weak upper low will continue to the north and slightly west. Toward the weekend, model guidance suggests that this feature will phase with a trough that will move southward into the Northwest. ...Northwest... Both thunderstorm and wind/RH concerns will be present during the extended period. Thunderstorms are possible on Wednesday, but coverage will likely be rather isolated. Storm coverage will begin to increase Thursday into the weekend with a general trend for storms to occur farther north each day. The overall potential for lightning ignitions remains uncertain as PWAT values will also be on the increase over time. There may be, however, a period of time where a few drier storms are possible. Mid-level winds increase with northward extent. As thunderstorms move into the Blue Mountain vicinity on Thursday would be the area and time of greatest concern. Model trends will need to be monitored, but confidence remains too low for highlights. Dry and windy conditions will also increase in the coming days. The thermal pressure trough in the Columbia Basin will continue to develop most afternoons. Westerly mid-level winds will also increase as a trough moves toward the Northwest. These features will drive strong surface winds through the Cascades into the Columbia Basin. Some potential for critical fire weather will exist on Thursday and Friday. ...Montana... Critical fire weather is probable on Thursday as westerly winds aloft increase across the northern Rockies. A surface low will also deepen to the north of the region. These factors will promote strong downslope winds within and to the lee of the terrain in parts of western Montana. Ahead of the cold front passage on Friday, strong westerly winds may persist within the same areas. Confidence on critically low RH is less than on Thursday, however. ...Northern California... Thunderstorms will be possible in the region each day through the weekend. PWAT values will generally come up quickly, however. With time, guidance does show a signal for dry air being pulled northward. A few drier storms may occur during the weekend, but the degree of fire weather risk is unclear as storms will have occurred on previous days over the same areas. ...Texas... Cooler conditions are expected to persist through Wednesday. Thereafter, hot conditions will likely return for parts of western/central Texas. With a surface trough/low developing, some increase in surface winds can be expected. Winds still appear too light for critical fire weather, but trends will need to be monitored given the very dry fuels. Furthermore, thunderstorms could develop. Some risk of lightning ignitions would exist with this activity. ..Wendt.. 08/14/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0232 PM CDT Mon Aug 14 2023 Valid 142000Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE TENNESSEE VALLEY INTO THE MID-ATLANTIC... ...SUMMARY... Strong/locally severe thunderstorms are expected through this evening across portions of the Midwest, Kentucky and Tennessee, and extending eastward to the Mid-Atlantic Region. ...20z Update... The Marginal (level 1 of 5) risk has been expanded northwest across parts of eastern IA along the occluded surface front. While instability remains modest across this area, low-level vorticity is maximized along the boundary and beneath the cold core upper trough/low. 3 km MLCAPE is around 100-125 J/kg, though 0-1 km SRH is expected to remain modest. A couple of funnel clouds and/or a brief tornado will be possible the remainder of the afternoon with this activity. Some gusty winds or small hail also could accompany stronger cores. Reference MCD 1994 for more short term details. The Slight risk (level 2 of 5) as been removed from portions of northern KY into southern OH and southwest PA. Earlier day convection and persistent cloud cover has precluded much destabilization this afternoon. While some airmass recovery will continue into the evening in low-level warm advection ahead of the synoptic cold front, overall conditions appear only marginally favorable for isolated strong storms. Otherwise, modest adjustments have been made to the Marginal (level 1 of 5) risk across western KY/TN and northeast OH/western PA based on latest observed data and model forecast guidance. ..Leitman.. 08/14/2023 .PREV DISCUSSION... /ISSUED 1101 AM CDT Mon Aug 14 2023/ ...TN Valley into Mid-Atlantic... Morning water vapor loop shows an upper low moving from IA into northern IL, with a relatively strong mid/upper level jet max rotating into the lower OH and TN Valleys. Widespread remnant clouds from overnight storms cover much of the OH/TN Valleys into the central Appalachians, which is limiting heating/destabilization. Despite rather strong westerly flow aloft and ample low-level moisture, muted heating will keep any severe risk rather low/localized through mid-afternoon. Some intensification of this activity may occur as it spreads east of the mountains into parts of PA/VA/NC, where strong heating is occurring. But this scenario is also relatively low confidence. Later this afternoon and evening, slow clearing/heating will eventually likely result in a pocket of rather strong CAPE from parts of middle/east TN into southeast KY. This area is probably the highest confidence in at least widely scattered strong to severe storms as the cold front approaches. Forecast soundings show sufficient deep-layer shear for a few bowing structures capable of damaging wind gusts. Time-of-day would be a negative, but there is some risk of storms maintaining some intensity as they move into the mountains of WV/western VA/western NC tonight. ...PA/NJ after dark... Most 12z CAM solutions continue to indicate that low-level winds will intensify after dark over parts of eastern PA as a shortwave trough rotates into the area. Favorable low-level shear profiles suggest some risk of rotating cells and tornado or two, although weak lapse rates and time-of-day will be unfavorable for robust updrafts. ...Northern IL... An occluded surface front extends northwestward from central IN into northern IL. Persistent clouds are limited heating in this area, but a zone of low-level convergence/vorticity will be present through the afternoon. A few rotating storms cannot be ruled out by mid/late afternoon, with a non-zero risk of a tornado or hail. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0217 PM CDT Mon Aug 14 2023 Valid 151200Z - 161200Z Minor modifications were made to the dry thunder area in the Northwest based on updated guidance. An area of dry conditions also appears probable in parts of central/eastern Texas behind the cold front. Winds however, will remain rather light at 10-15 mph which should mitigate some fire spread potential within the very dry fuels. ..Wendt.. 08/14/2023 .PREV DISCUSSION... /ISSUED 0156 AM CDT Mon Aug 14 2023/ ...Synopsis... Across the western US, mid-level ridging is forecast to intensify as a weak upper low moves offshore across western CA. Predominantly weak mid-level flow should keep winds light over much of the western US. Monsoon moisture drawn northward with the upper low may support showers and thunderstorms into parts of northern CA and southern OR. ...Northwest... As the upper low continues to move offshore, easterly mid-level flow will overspread northern CA and southern OR late D1/Mon into early D2/Tues. Showers, and a few thunderstorms, are possible through the early morning hours, and again with additional storms possible in the afternoon and evening. Storm coverage remains very uncertain with hi-res model guidance varying widely in the possible solutions. With weak elevated buoyancy and broad synoptic ascent from the passing low, isolated storms do appear possible. The dry low levels would also favor drier storms with the potential for lightning ignitions. Given the dry and receptive fuels, and at least some risk for lightning, an IsoDryT area has been added despite some uncertainty on storm coverage. ...Northern Rockies... A slight increase in mid-level flow from an approaching Alberta low will help bolster downslope surface winds over parts of northern MT late D2/Tues. Downslope gusts of 15-20 mph are possible, along with relatively low RH below 35%. The temporal overlap of dry and windy conditions will be limited by the arrival of the strongest winds overnight. However, a few hours of locally elevated conditions are possible given dry fuels. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0643 Status Updates
STATUS FOR WATCH 0643 HAS NOT BEEN ISSUED YET Read more

WW 643 SEVERE TSTM KS 132205Z - 140400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 643 NWS Storm Prediction Center Norman OK 505 PM CDT Sun Aug 13 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Central into southeast Kansas * Effective this Sunday afternoon and evening from 505 PM until 1100 PM CDT. * Primary threats include... Scattered damaging wind gusts to 70 mph likely Scattered large hail events to 1.5 inches in diameter likely SUMMARY...Scattered supercell development is expected this afternoon and storms will spread east-southeastward through late evening with an attendant threat for large hail up to 1.5 inches in diameter. Some clustering of storms is also expected, which will favor the potential for severe outflow gusts of 60-70 mph. The severe thunderstorm watch area is approximately along and 65 statute miles north and south of a line from 55 miles northwest of Medicine Lodge KS to 20 miles north northeast of Chanute KS. 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. && OTHER WATCH INFORMATION...CONTINUE...WW 640...WW 641...WW 642... 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 550. Mean storm motion vector 29025. ...Thompson Read more

MD 1985 CONCERNING SEVERE THUNDERSTORM WATCH 641... FOR PORTIONS OF NORTHERN AND CENTRAL AL...INTO SOUTHERN TN AND NORTHWEST GA
Mesoscale Discussion 1985 NWS Storm Prediction Center Norman OK 0449 PM CDT Sun Aug 13 2023 Areas affected...portions of northern and central AL...into southern TN and northwest GA Concerning...Severe Thunderstorm Watch 641... Valid 132149Z - 132245Z The severe weather threat for Severe Thunderstorm Watch 641 continues. SUMMARY...The risk for damaging gusts should continue across WW641 this afternoon. Storms may continue farther south and east where a new weather watch is possible, but uncertain. DISCUSSION...As of 2135 UTC, regional radar analysis showed a linear cluster of storms ongoing across portions of the TN Valley. Over the last couple of hours, several reports of damaging gusts have been received with gusty outflow winds from these storms. The environment ahead of these storms remains strongly unstable, with 3000+ J/kg of MLCAPE, but only weak vertical shear. So far storms have been semi-organized along a propagating cold pool. Weak shear balance and the favorable buoyancy should allow for strong updrafts and damaging gust potential to continue across north-central AL and portions of southern TN over the next couple of hours. Farther south, uncertainty on the severe risk is higher as additional storms have resulted in some overturning of the air mass west of Atlanta into central AL. Outflow temperatures have dropped into the upper 70s F, which may limit the potential for stronger updrafts as the cluster moves south/southeast later this evening. If storms are able to retain strength as they move into the cooler air, as suggested by several HRRR runs, damaging gusts would be possible into parts of central AL and western GA. Convective trends will be monitored but it is unclear if a new weather watch is needed farther south. ..Lyons/Thompson.. 08/13/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MRX...FFC...OHX...BMX...HUN...MEG... LAT...LON 35428635 36058538 36028466 35718457 35338456 34988457 34598462 34098474 33598494 33408505 33258532 33198566 33258614 33328649 33458710 33658756 33798782 33958811 34158819 34448816 34708786 34958738 35208676 35428635 Read more