MD 2062 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR PORTIONS OF NORTHEASTERN MONTANA AND WESTERN NORTH DAKOTA
Mesoscale Discussion 2062 NWS Storm Prediction Center Norman OK 0458 PM CDT Thu Sep 12 2024 Areas affected...Portions of northeastern Montana and western North Dakota Concerning...Severe potential...Watch likely Valid 122158Z - 122330Z Probability of Watch Issuance...80 percent SUMMARY...The potential for severe gusts and instances of large hail will gradually increase over the next few hours across northeastern Montana and western North Dakota. A severe thunderstorm watch is likely within an hour or so. DISCUSSION...Latest water-vapor imagery and regional VWP data indicate the left-exit region of a midlevel jet streak overspreading portions of north-central WY -- ahead of a deep midlevel low centered over southwestern MT. Over the next few hours, related large-scale ascent will overspread northeastern MT, promoting a gradual increase in convective development. Around 50-60 kt of midlevel south-southwesterly flow is contributing to a long/mostly straight hodograph -- characterized by 45-55 kt of effective shear. Despite somewhat cool post-frontal boundary-layer conditions, and lingering inhibition at the base of a robust EML, the strong deep-layer shear and steep midlevel lapse rates will still favor organized clusters and embedded supercells. These storms will be capable of producing severe gusts and instances of large hail. Significant severe gusts (75-85 mph) will be possible, especially with any congealing cold pools that evolve. A severe thunderstorm watch is likely for portions of the area within an hour or so. ..Weinman/Smith.. 09/12/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BIS...BYZ...GGW... LAT...LON 47170755 47760759 48830747 49030725 49150660 49080371 48920330 47820298 46750333 46590388 46670668 46800734 47170755 Read more

MD 2063 CONCERNING SEVERE THUNDERSTORM WATCH 670... FOR PORTIONS OF NORTHEASTERN WYOMING AND SOUTHEASTERN MONTANA
Mesoscale Discussion 2063 NWS Storm Prediction Center Norman OK 0536 PM CDT Thu Sep 12 2024 Areas affected...portions of northeastern Wyoming and southeastern Montana Concerning...Severe Thunderstorm Watch 670... Valid 122236Z - 130000Z The severe weather threat for Severe Thunderstorm Watch 670 continues. SUMMARY...The risk of severe gusts and isolated large hail continues across portions of Severe Thunderstorm Watch 670. DISCUSSION...Latest radar data from KBLX depicts a north/south-oriented band of organized thunderstorms (including a semi-discrete supercell structures and a small bowing segment) tracking northward across portions of northeastern WY and southeastern MT. One of these supercells produced 2-inch hail near Sheridan WY at around 21Z. A long/straight hodograph (around 60 kt of deep-layer shear per RIW VWP) and weak (albeit sufficient) surface-based buoyancy will continue to support semi-discrete supercells and small bowing structures, capable of producing severe gusts and isolated large hail. As strong large-scale ascent within the left-exit region of a midlevel jet continues to cross the area, there may be some tendency for localized upscale growth and an increasing severe-wind risk (aided by steep midlevel lapse rates and the strong deep-layer flow/shear). Severe gusts of 70-80 mph are possible with any upscale-grown convection. ..Weinman.. 09/12/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...UNR...BYZ... LAT...LON 44620673 45060681 45540654 46310602 46460576 46390538 46160517 45280544 44650599 44570631 44620673 Read more

WW 0672 Status Updates
STATUS FOR WATCH 0672 HAS NOT BEEN ISSUED YET Read more

WW 672 SEVERE TSTM MT ND 122235Z - 130400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 672 NWS Storm Prediction Center Norman OK 435 PM MDT Thu Sep 12 2024 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northeastern and Eastern Montana Western North Dakota * Effective this Thursday afternoon and evening from 435 PM until 1000 PM MDT. * Primary threats include... Scattered damaging winds and isolated significant gusts to 85 mph likely Scattered large hail events to 1.5 inches in diameter possible SUMMARY...Scattered thunderstorms will continue to develop and intensify late this afternoon and evening and spread northeast into the Watch area. The stronger thunderstorms, including a mix of cells and linear clusters, will be potentially capable of a severe threat. Severe gusts will probably be the primary severe hazard (60-85 mph), but large hail may accompany the stronger thunderstorm cores as well (1 to 1.5 inches in diameter). The severe thunderstorm watch area is approximately along and 85 statute miles north and south of a line from 35 miles west southwest of Glasgow MT to 55 miles northeast of Dickinson ND. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU2). 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 670...WW 671... AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 75 knots. A few cumulonimbi with maximum tops to 400. Mean storm motion vector 21050. ...Smith Read more

WW 0670 Status Updates
STATUS REPORT ON WW 670 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 45 NE CPR TO 25 SW GCC TO 25 WNW GCC TO 30 ESE SHR TO 10 SSE SHR TO 25 W SHR TO 55 WNW SHR TO 40 SSE BIL. ..JEWELL..09/12/24 ATTN...WFO...BYZ...RIW...UNR... STATUS REPORT FOR WS 670 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS MTC003-011-017-025-075-087-103-122240- MT . MONTANA COUNTIES INCLUDED ARE BIG HORN CARTER CUSTER FALLON POWDER RIVER ROSEBUD TREASURE WYC005-033-122240- WY . WYOMING COUNTIES INCLUDED ARE CAMPBELL SHERIDAN 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 670 SEVERE TSTM MT WY 121855Z - 130100Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 670 NWS Storm Prediction Center Norman OK 1255 PM MDT Thu Sep 12 2024 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Southeast Montana Northeast Wyoming * Effective this Thursday afternoon and evening from 1255 PM until 700 PM MDT. * Primary threats include... Scattered damaging winds likely with isolated significant gusts to 75 mph possible Scattered large hail events to 1.5 inches in diameter possible A tornado or two possible SUMMARY...At least widely scattered severe storms including supercells will initially develop generally near the Montana/Wyoming border vicinity this afternoon, spreading northeastward through the afternoon. The severe thunderstorm watch area is approximately along and 80 statute miles east and west of a line from 60 miles east southeast of Worland WY to 25 miles north of Miles City MT. 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. && 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 450. Mean storm motion vector 22040. ...Guyer Read more

WW 0671 Status Updates
STATUS FOR WATCH 0671 HAS NOT BEEN ISSUED YET Read more

WW 671 TORNADO AL 122135Z - 130300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 671 NWS Storm Prediction Center Norman OK 435 PM CDT Thu Sep 12 2024 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Central Alabama * Effective this Thursday afternoon and evening from 435 PM until 1000 PM CDT. * Primary threats include... A couple tornadoes possible SUMMARY...A convective band within a moist and strongly sheared environment will feature embedded quasi-discrete updrafts late this afternoon into the evening. Several supercells will potentially pose a tornado risk before instability wanes late this evening. The tornado watch area is approximately along and 55 statute miles north and south of a line from 55 miles northwest of Selma AL to 45 miles northeast of Montgomery AL. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU1). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Tornado Watch means conditions are favorable for tornadoes and 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. && OTHER WATCH INFORMATION...CONTINUE...WW 670... AVIATION...Tornadoes and a few severe thunderstorms with hail surface and aloft to 0 inches. Extreme turbulence and surface wind gusts to 50 knots. A few cumulonimbi with maximum tops to 400. Mean storm motion vector 20020. ...Smith Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0333 PM CDT Thu Sep 12 2024 Valid 141200Z - 201200Z In general, fire weather concerns will be on a downward trend across most areas. Upper-level zonal flow will begin to amplify this weekend. A series of troughs will impact the West while ridging will generally remain across the East through the period. Precipitation and cooler temperatures over a broad area of what have been dry fuels should moderate the fire environment for many areas west of the Divide and into some of the Plains. ...Great Basin... As the trough approaches the region this weekend into early next week, some areas of dry and windy conditions are possible both along the Sierra Front as well as into the southern/eastern Basin. Ongoing large fire activity near the Sierra could experience stronger winds, but RH may also be higher along with the winds on Sunday. Further complicating the forecast, cooler temperatures and precipitation along with the initial weekend trough and another trough by the middle of next week will reduce fire weather concerns. These areas will continue to be monitored, but the overall pattern suggests critical fire weather potential is too low for highlights at this time. ...Plains... With troughing expected in the West, troughing along the Rockies is expected to persist into at least the middle of next week. Winds across the Plains may increase periodically as the trough/surface lows intensify. At present, the strongest winds are expected on Tuesday when the initial trough ejects into the central/northern Plains. While there are dry fine fuels in place in some areas, there is also precipitation possible. Unlike the previous southerly flow from the last several days, greater surface moisture will already be present and will likely increase to some degree with the persistent flow from the open Gulf. That said, it is not clear where the greatest fire weather concerns will develop. Trends will continue to be monitored in the coming days. ..Wendt.. 09/12/2024 ...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 0252 PM CDT Thu Sep 12 2024 Valid 122000Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND WESTERN NORTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHEAST... ...SUMMARY... A few tornadoes are possible today from northern Florida to north-central Alabama. Scattered large hail and severe wind gusts (some significant) are expected across eastern Montana into western North Dakota this afternoon through early/mid-evening. ...20z... The D1 Convective Outlook remains on track with no updates needed. A narrow corridor of tornado risk associated with Tropical Depression Francine and the mid/upper low across the southeast will continue across central/southern Alabama this afternoon and evening. See MCD#2061 for more information. Across the northern Great Plains, potential for significant damaging winds will increase through the afternoon and evening as ongoing convection across Montana and Wyoming increases in coverage and tend to grow upscale through the evening. See previous discussion for more information on this threat. ..Thornton.. 09/12/2024 .PREV DISCUSSION... /ISSUED 1138 AM CDT Thu Sep 12 2024/ ...Northern Great Plains including eastern MT/western ND... Have upgraded portions of eastern Montana and western North Dakota for a heightened/focused potential for severe storms capable of large hail and potentially significant-caliber severe wind gusts later this afternoon through around mid-evening. Strong-severe thunderstorms are expected, along and behind the front, as early as early/mid-afternoon, with the most probable severe potential arising from activity moving north-northeastward from northern Wyoming and far southern Montana. High-based supercells and multicells are possible, offering large hail and severe wind gusts. These storms may aggregate and grow upscale into one or two bowing clusters, racing north-northeastward accompanied by a swath of better-organized, potentially significant (65+ kt) gust potential. This scenario will be supported by trough-related cooling mid-level temperatures and steep low/mid-level rates atop a modestly moist boundary layer, as the exit region of a strong upper-level jet overspreads the region. MLCAPE of 500-1200 J/kg and 45-55 kt effective-shear magnitudes will support the severe potential including fast-moving and relatively long-lived storms into western North Dakota. The near-surface airmass over the central Dakotas should stabilize with time and eastward extent tonight, limiting duration and eastward shift of the threat. ...Southeast... Current Tropical Depression Francine is forecast to continue moving generally northward over Mississippi, and to lose definition as it interacts more closely with the mid/upper-level low. Associated deep-layer winds will continue to weaken, but low-level shear will remain favorable through most of the day, well to the east-southeast of its center. A destabilizing airmass along and south of the warm/marine front will support a continued, slow inland shift of supercell potential amid enlarged hodographs. The favorable environment will be bounded on the west by a dry slot and veering low-level flow, on the northeast by more stable air in heavy precip north of the front, and on the south by a gradual weakening of low-level winds and shear as the cyclone center pulls away and fills. In the favorable corridor, where inflow parcels are surface-based, expect effective SRH in the 200-500 m2/s2 range, very rich moisture, low LCL, and weak MLCINH. In the shorter term, a tornado threat may persist this afternoon across northern Florida, while potentially increasing later this afternoon through early evening near the warm front across southern into central Alabama. Read more

MD 2060 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR NORTHERN WYOMING INTO EASTERN MONTANA
Mesoscale Discussion 2060 NWS Storm Prediction Center Norman OK 0112 PM CDT Thu Sep 12 2024 Areas affected...Northern Wyoming into eastern Montana Concerning...Severe potential...Watch likely Valid 121812Z - 122015Z Probability of Watch Issuance...80 percent SUMMARY...Organized thunderstorms are expected to increase in coverage and intensity through the afternoon and evening posing a threat of large hail and damaging wind. A severe thunderstorm watch is likely in the next couple of hours. DISCUSSION...An upper-level jet max evident in water-vapor imagery is currently nosing into southern Montana. The large-scale ascent associated with the approaching upper-level trough is encouraging early thunderstorm initiation in northern Wyoming. Although this development is preceding peak diurnal heating, strong forcing is likely to encourage maintenance and additional development over the next few hours. Continued destabilization across eastern Montana will result in a modestly unstable environment (~1000 J/kg MUCAPE) this afternoon with favorable deep-layer shear (~50 knots) characterized by long, straight hodographs. Convection-allowing models suggest that storms will initially be supercellular posing a threat for severe hail and isolated wind gusts. Over time, the storms are expected to evolve into hybrid bowing clusters as they move to the north-northeast. Eventually, storms are expected to grow upscale further posing a threat for severe winds, including the potential for significant severe gusts (i.e., 65 knots). Thus, a severe thunderstorm watch is likely to address this threat. ..Jirak/Guyer.. 09/12/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...UNR...BYZ...GGW...RIW... LAT...LON 44740870 45980793 46840743 47370657 47510543 47250477 46900428 46190419 45410441 44760524 44270601 43650779 43920852 44740870 Read more

MD 2061 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PARTS OF CENTRAL INTO SOUTH AL
Mesoscale Discussion 2061 NWS Storm Prediction Center Norman OK 0240 PM CDT Thu Sep 12 2024 Areas affected...Parts of central into south AL Concerning...Severe potential...Watch possible Valid 121940Z - 122215Z Probability of Watch Issuance...40 percent SUMMARY...Some tornado threat could evolve this afternoon. DISCUSSION...Persistent cloudiness has thus far limited destabilization north of a warm front draped across south AL. However, some modest destabilization (with MLCAPE approaching or exceeding 500 J/kg) will be possible from south to north this afternoon as the warm front moves slowly northward. One persistent cell is ongoing northeast of Montgomery, and additional low-topped supercell development will be possible along/north of the warm front through the afternoon. Stronger low-level flow/shear will gradually shift northward in conjunction with the warm front through the afternoon, but will generally remain favorable, with 0-1 km SRH generally in the 150-300 m2/s2 range in areas where modest destabilization is possible. Some tornado threat could evolve with time this afternoon, contingent on the development of additional low-topped supercells. Observational trends will be monitored regarding the need for a Tornado Watch. ..Dean/Guyer.. 09/12/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...TAE...BMX...MOB... LAT...LON 32018746 32638764 33078779 33918793 33548696 33218620 32888563 32598540 32088512 31848518 31718528 31708551 31768600 31858669 31958717 32018746 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0225 PM CDT Thu Sep 12 2024 Valid 141200Z - 151200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Saturday. ...Southeast... The remnants of TD Francine will continue to weaken across the Southeast on Saturday. A moist and unstable airmass should be present across northern Florida and into southern Georgia and southeast Alabama. This will likely result in scattered to widespread thunderstorms, particularly during the afternoon. However, the primary threat from these storms should be heavy rain as very weak lapse rates and only marginal deep-layer shear will likely result in mostly sub-severe convection. ...Central to Northern Plains... Widely scattered thunderstorms are possible along the dryline from the central Plains to the northern Plains on Saturday. Initially, low-level moisture will be limited, but better moisture will advect ahead of the dryline by late afternoon to early evening. This may be sufficient for a few thunderstorms to develop along the dryline as a weak mid-level shortwave trough moves into the Plains. The combination of isolated storm coverage and only marginal deep-layer shear precludes the need for a Marginal Risk at this time. ..Bentley.. 09/12/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0225 PM CDT Thu Sep 12 2024 Valid 141200Z - 151200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Saturday. ...Southeast... The remnants of TD Francine will continue to weaken across the Southeast on Saturday. A moist and unstable airmass should be present across northern Florida and into southern Georgia and southeast Alabama. This will likely result in scattered to widespread thunderstorms, particularly during the afternoon. However, the primary threat from these storms should be heavy rain as very weak lapse rates and only marginal deep-layer shear will likely result in mostly sub-severe convection. ...Central to Northern Plains... Widely scattered thunderstorms are possible along the dryline from the central Plains to the northern Plains on Saturday. Initially, low-level moisture will be limited, but better moisture will advect ahead of the dryline by late afternoon to early evening. This may be sufficient for a few thunderstorms to develop along the dryline as a weak mid-level shortwave trough moves into the Plains. The combination of isolated storm coverage and only marginal deep-layer shear precludes the need for a Marginal Risk at this time. ..Bentley.. 09/12/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0207 PM CDT Thu Sep 12 2024 Valid 131200Z - 141200Z ...NO CRITICAL AREAS... No changes to the ongoing forecast. ..Wendt.. 09/12/2024 .PREV DISCUSSION... /ISSUED 0136 AM CDT Thu Sep 12 2024/ ...Synopsis... As the upper trough and the associated cold front continue to the east, high pressure will quickly develop behind them over much of the Great Basin and Intermountain West. A much cooler and quiescent air mass will also develop, keeping winds relatively light with increasing relative humidity. Additionally, precipitation associated with the upper trough should moderate fuels across much of the West and Plains. A few stronger gusts may remain across parts of the southern High Plains and eastern WY. Pockets of lower RH may also remain in place temporarily before moisture increases later tonight. However, the expected duration and coverage of these locally stronger winds and drier conditions should be brief. With only modest overlap of dry and windy conditions atop dry fuels, fire-weather concerns are too localized for any highlights. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0207 PM CDT Thu Sep 12 2024 Valid 131200Z - 141200Z ...NO CRITICAL AREAS... No changes to the ongoing forecast. ..Wendt.. 09/12/2024 .PREV DISCUSSION... /ISSUED 0136 AM CDT Thu Sep 12 2024/ ...Synopsis... As the upper trough and the associated cold front continue to the east, high pressure will quickly develop behind them over much of the Great Basin and Intermountain West. A much cooler and quiescent air mass will also develop, keeping winds relatively light with increasing relative humidity. Additionally, precipitation associated with the upper trough should moderate fuels across much of the West and Plains. A few stronger gusts may remain across parts of the southern High Plains and eastern WY. Pockets of lower RH may also remain in place temporarily before moisture increases later tonight. However, the expected duration and coverage of these locally stronger winds and drier conditions should be brief. With only modest overlap of dry and windy conditions atop dry fuels, fire-weather concerns are too localized for any highlights. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0670 Status Updates
STATUS FOR WATCH 0670 HAS NOT BEEN ISSUED YET Read more

WW 0669 Status Updates
STATUS REPORT ON WW 669 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 WSW AAF TO 15 W TLH. WW 669 WILL BE ALLOWED TO EXPIRE AT 121800Z. ..DEAN..09/12/24 ATTN...WFO...MOB...TAE... STATUS REPORT FOR WT 669 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS FLC037-129-121800- FL . FLORIDA COUNTIES INCLUDED ARE FRANKLIN WAKULLA GMZ633-730-755-121800- CW . ADJACENT COASTAL WATERS INCLUDED ARE PERDIDO BAY AREA APALACHEE BAY OR COASTAL WATERS FROM KEATON BEACH TO OCHLOCKONEE RIVER FL OUT TO 20 NM COASTAL WATERS FROM OCHLOCKONEE RIVER TO APALACHICOLA FL OUT TO 20 NM THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1224 PM CDT Thu Sep 12 2024 Valid 131200Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE TN VALLEY TO THE FL PANHANDLE... ...SUMMARY... A couple brief tornadoes and locally damaging winds are possible across a part of the Southeast on Friday morning into the afternoon. ...Synopsis... The remnants of TC Francine will begin the day somewhere across eastern Arkansas and slowly drift east through the day while weakening. A belt of moderate mid-level flow will persist across the southern periphery of this remnant low. Farther west, a strong mid-level trough across the northern Rockies will weaken and move into the Canadian Prairies. A remnant surface cold front will traverse the Northern Plains through the day on Friday. ...Portions of the Southeast... A plume of tropical moisture will remain from the Florida Panhandle into central Tennessee on Friday. A mostly uncapped airmass is expected through the entire convective period. However, some greater instability is likely during the afternoon with some surface heating. However, given the limited inhibition, convective overturning is expected before more substantial instability can develop. Nonetheless, an extended period of 1000 to 1500 J/kg MLCAPE with 25 to 30 knots of effective shear will support some multicell clusters or occasional supercells. This may result in a brief tornado or two and the potential for locally damaging wind gusts, primarily during the afternoon/early evening on Friday. ...Northern Plains into the central Plains... A line of thunderstorms will likely develop along a cold front in North Dakota and South Dakota on Friday. However, instability will be relatively limited and elevated (500-800 J/kg MUCAPE). This weak instability combined with limited upper-level synoptic support, should mitigate any severe weather threat. Farther south, a few thunderstorms are possible in the Texas Panhandle and into western Oklahoma in the vicinity of a dryline/weak surface low where temperatures are expected to warm into the low 90s. While a few storms may develop, significant inhibition/dry air entrainment will likely keep the threat for more robust/severe convection muted. ..Bentley.. 09/12/2024 Read more

MD 2059 CONCERNING TORNADO WATCH 669... FOR PARTS OF THE FL PANHANDLE...SOUTH/CENTRAL AL...FAR SOUTHWEST GA
Mesoscale Discussion 2059 NWS Storm Prediction Center Norman OK 1006 AM CDT Thu Sep 12 2024 Areas affected...Parts of the FL Panhandle...south/central AL...far southwest GA Concerning...Tornado Watch 669... Valid 121506Z - 121730Z The severe weather threat for Tornado Watch 669 continues. SUMMARY...Some tornado threat will persist through late morning, with some northward expansion of the threat into this afternoon. DISCUSSION...Several supercells have moved onshore across parts of the FL Panhandle this morning, before tending to weaken as they move farther inland with time. Some weakening of low-level flow has been noted from the KEVX VWP, and this trend will continue from south to north through the day, as Tropical Depression Francine continues to move north-northeastward and weaken. However, low-level shear/SRH remains favorable for tornadoes with any sustained supercells, and the thermodynamic environment may become more favorable with time, as richer low-level moisture (with dewpoints in the mid 70s F) continues to gradually spread northward. Farther northwest, a pronounced midlevel dry slot is moving over south/central AL. This may allow for some diurnal heating across the region, though it also will tend to suppress deeper convection to some extent. Even if convection remains relatively shallow, a favorable overlap of modest buoyancy (with MLCAPE near 500 J/kg) and rather strong low-level shear/SRH attendant to Francine may support a threat of a couple tornadoes into this afternoon, with some northward expansion of the threat possible with time. With WW 669 expiring at 18Z, additional watch issuance is possible this afternoon. ..Dean/Guyer.. 09/12/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FFC...TAE...BMX...MOB... LAT...LON 30948741 31688761 32958781 32108507 31218461 30868437 30428411 30018399 29648401 29468440 29368519 29608590 29868678 29938733 30948741 Read more