WW 245 SEVERE TSTM ID UT WY 111910Z - 120200Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 245 NWS Storm Prediction Center Norman OK 110 PM MDT Sun May 11 2025 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Eastern Idaho Northern Utah Western Wyoming * Effective this Sunday afternoon and evening from 110 PM until 800 PM MDT. * Primary threats include... Scattered damaging winds and isolated significant gusts to 80 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...Thunderstorm intensity and coverage is expected to increase this afternoon across eastern ID, northern UT, and western WY. Environmental conditions support the potential for strong to severe storms capable of strong gusts. Isolated large hail is also possible, particularly in areas of higher terrain. The severe thunderstorm watch area is approximately along and 80 statute miles east and west of a line from 65 miles north northeast of Idaho Falls ID to 40 miles southwest of Salt Lake City UT. 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. && AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 70 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 23035. ...Mosier Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun May 11 2025 Valid 112000Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN ROCKIES/GREAT BASIN AND MONTANA HIGH PLAINS... ...SUMMARY... Scattered severe wind gusts are expected across the northern Rockies/Great Basin and the Montana High Plains from mid-afternoon into the evening. Isolated severe thunderstorms are also possible across the Southeast today through tonight. ...20Z Update... The only noteworthy change with this update was a southwestward expansion of the Slight Risk area into northern UT, driven by 15-percent severe wind probabilities. Here, ample diurnal heating has resulted in a deep/dry boundary layer supportive of scattered severe wind gusts accompanying high-based storms. Reference Severe Thunderstorm Watch #245 for more details. Farther east, isolated severe storms capable of producing locally damaging winds and marginally severe hail remain possible across the Southeast into this evening. Reference MCDs #766/767 for details. ..Weinman.. 05/11/2025 .PREV DISCUSSION... /ISSUED 1119 AM CDT Sun May 11 2025/ ...Northern Rockies/High Plains and northeast Great Basin... Strengthening southwesterly flow aloft is anticipated throughout the day as the upper low off the Pacific Northwest coast progresses eastward and a lead shortwave trough pivots through OR/northern CA into the northern Rockies. Strong heating will help destabilize the airmass downstream from the northern Rockies into the northern High Plains. Large-scale ascent attendant to the approaching shortwave trough, coupled with orographic lift, will help initiate storms across the high terrain during the afternoon within this destabilized airmass. Environmental conditions suggest some supercells are possible with this initial development, with damaging gusts and isolated hail as the primary risk. A low-probability corridor of tornado potential exists across southeast ID. The storms should encounter an increasingly mixed environment with eastern/northeastern extent into central MT, with strong gusts becoming the primary severe hazard as storms trend towards more outflow-dominant linear structures. ...Southeast States... Recent satellite imagery and surface observations continue to show the vertically stacked low over the Lower MS Valley, with broad swath of southwesterly flow extending south and east of this low from the central Gulf into FL. Surface features have become increasingly diffuse across the Southeast and FL over the past two days given the persistence of this low and associated precipitation, but recent surface analysis shows a weak and wavy stationary boundary extending from the low over the ArkLaMiss southeastward to the AL/FL Panhandle border before arcing back northeastward across southern GA. Scattered thunderstorms are ongoing and the general expectation is for scattered to numerous thunderstorms to persist across much of the region throughout the day. Widespread cloudiness should limit heating, but ample low-level moisture will still support modest buoyancy. Shear will gradually increase as the low to mid-level flow strengthens this afternoon and evening, which could lead to some transient storm organization, but in general convection is expected to be disorganized, outflow-dominated multicells. Even so, isolated damaging gusts are possible. Some low-probability tornado potential exists as well, particularly along the stationary boundary across southern GA around 00Z. Farther northwest across AL/MS and into eastern AR, the airmass is forecast to destabilize this afternoon as heating occurs beneath cool temperatures aloft. Even with the cooler temperature aloft, overall buoyancy will be modest given the somewhat cool low to mid-level thermodynamic profile. Even so, a nearly unidirectional southeasterly wind profile with moderate deep-layer speed shear could support brief updraft organization. As a result, a few cells may briefly produce marginally severe hail and locally strong gusts, and possibly some funnel/brief tornado potential, from late afternoon through early/mid-evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun May 11 2025 Valid 112000Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN ROCKIES/GREAT BASIN AND MONTANA HIGH PLAINS... ...SUMMARY... Scattered severe wind gusts are expected across the northern Rockies/Great Basin and the Montana High Plains from mid-afternoon into the evening. Isolated severe thunderstorms are also possible across the Southeast today through tonight. ...20Z Update... The only noteworthy change with this update was a southwestward expansion of the Slight Risk area into northern UT, driven by 15-percent severe wind probabilities. Here, ample diurnal heating has resulted in a deep/dry boundary layer supportive of scattered severe wind gusts accompanying high-based storms. Reference Severe Thunderstorm Watch #245 for more details. Farther east, isolated severe storms capable of producing locally damaging winds and marginally severe hail remain possible across the Southeast into this evening. Reference MCDs #766/767 for details. ..Weinman.. 05/11/2025 .PREV DISCUSSION... /ISSUED 1119 AM CDT Sun May 11 2025/ ...Northern Rockies/High Plains and northeast Great Basin... Strengthening southwesterly flow aloft is anticipated throughout the day as the upper low off the Pacific Northwest coast progresses eastward and a lead shortwave trough pivots through OR/northern CA into the northern Rockies. Strong heating will help destabilize the airmass downstream from the northern Rockies into the northern High Plains. Large-scale ascent attendant to the approaching shortwave trough, coupled with orographic lift, will help initiate storms across the high terrain during the afternoon within this destabilized airmass. Environmental conditions suggest some supercells are possible with this initial development, with damaging gusts and isolated hail as the primary risk. A low-probability corridor of tornado potential exists across southeast ID. The storms should encounter an increasingly mixed environment with eastern/northeastern extent into central MT, with strong gusts becoming the primary severe hazard as storms trend towards more outflow-dominant linear structures. ...Southeast States... Recent satellite imagery and surface observations continue to show the vertically stacked low over the Lower MS Valley, with broad swath of southwesterly flow extending south and east of this low from the central Gulf into FL. Surface features have become increasingly diffuse across the Southeast and FL over the past two days given the persistence of this low and associated precipitation, but recent surface analysis shows a weak and wavy stationary boundary extending from the low over the ArkLaMiss southeastward to the AL/FL Panhandle border before arcing back northeastward across southern GA. Scattered thunderstorms are ongoing and the general expectation is for scattered to numerous thunderstorms to persist across much of the region throughout the day. Widespread cloudiness should limit heating, but ample low-level moisture will still support modest buoyancy. Shear will gradually increase as the low to mid-level flow strengthens this afternoon and evening, which could lead to some transient storm organization, but in general convection is expected to be disorganized, outflow-dominated multicells. Even so, isolated damaging gusts are possible. Some low-probability tornado potential exists as well, particularly along the stationary boundary across southern GA around 00Z. Farther northwest across AL/MS and into eastern AR, the airmass is forecast to destabilize this afternoon as heating occurs beneath cool temperatures aloft. Even with the cooler temperature aloft, overall buoyancy will be modest given the somewhat cool low to mid-level thermodynamic profile. Even so, a nearly unidirectional southeasterly wind profile with moderate deep-layer speed shear could support brief updraft organization. As a result, a few cells may briefly produce marginally severe hail and locally strong gusts, and possibly some funnel/brief tornado potential, from late afternoon through early/mid-evening. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Sun May 11 2025 Valid 121200Z - 131200Z ...Southwest... An accelerating subtropical jet across the Desert Southwest atop a deep, dry boundary layer will support breezy afternoon winds across southeastern Arizona and southwestern New Mexico, where fuels remain relatively dry amid ongoing severe/extreme drought. Expanded area of elevated fire weather conditions to account for higher expected winds across south-central Arizona for Monday. ...Northern Plains and Upper-Midwest... A broad area of dry, southerly return flow amid fuels with ERC values above the 97th percentile will support elevated fire weather conditions across the Northern Plains and Upper-Midwest. Record setting temperatures in the lower to upper 90s are again expected across the region. Locally critical fire weather conditions are most likely from a corridor of enhanced south winds from north-central Nebraska to northwestern Minnesota. Model guidance is still somewhat inconsistent with overlapping low relative humidity so continued uncertainty precluded adding Critical highlights at this time. ..Williams.. 05/11/2025 .PREV DISCUSSION... /ISSUED 0149 AM CDT Sun May 11 2025/ ...Synopsis... The partially blocked upper-air pattern over the US will begin to breakdown early in the new week as a trough deepens over the western US. Strong mid-level flow will gradually move into the Plains, as upper ridging moves eastward. Strong lee troughing/cyclogensisis will support gusty south/westerly winds over the High Plains. Fire-weather conditions are expected across the Great Plains and Southwest Monday afternoon and evening. ...Northern Plains and Midwest... Strong southerly low-level flow will continue Monday as the upper trough ejects eastward and the surface low deepens over MT and the western Dakotas. Surface winds of 25-30 mph are again expected across much of MT, the Dakotas and into parts of NE/MN/IA. However, RH values should begin to increase as low-level moisture is advected northward and mid-level cloud cover reduces solar heating. While still relatively dry below 30%, RH values do not appear critical. This will favor widespread elevated and pockets of locally critical conditions Monday afternoon. ...Southwest... As the troughing over the west gradually deepens, strong mid-level flow will begin to move eastward over the southern Rockies and Southwest. Westerly downslope flow is likely across parts of eastern AZ and western NM Monday. With gusts of 15-20 mph and RH below 15%, several hours of elevated fire-weather conditions are likely within dry fuels that have supported recent fire activity. ...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 0252 PM CDT Sun May 11 2025 Valid 121200Z - 131200Z ...Southwest... An accelerating subtropical jet across the Desert Southwest atop a deep, dry boundary layer will support breezy afternoon winds across southeastern Arizona and southwestern New Mexico, where fuels remain relatively dry amid ongoing severe/extreme drought. Expanded area of elevated fire weather conditions to account for higher expected winds across south-central Arizona for Monday. ...Northern Plains and Upper-Midwest... A broad area of dry, southerly return flow amid fuels with ERC values above the 97th percentile will support elevated fire weather conditions across the Northern Plains and Upper-Midwest. Record setting temperatures in the lower to upper 90s are again expected across the region. Locally critical fire weather conditions are most likely from a corridor of enhanced south winds from north-central Nebraska to northwestern Minnesota. Model guidance is still somewhat inconsistent with overlapping low relative humidity so continued uncertainty precluded adding Critical highlights at this time. ..Williams.. 05/11/2025 .PREV DISCUSSION... /ISSUED 0149 AM CDT Sun May 11 2025/ ...Synopsis... The partially blocked upper-air pattern over the US will begin to breakdown early in the new week as a trough deepens over the western US. Strong mid-level flow will gradually move into the Plains, as upper ridging moves eastward. Strong lee troughing/cyclogensisis will support gusty south/westerly winds over the High Plains. Fire-weather conditions are expected across the Great Plains and Southwest Monday afternoon and evening. ...Northern Plains and Midwest... Strong southerly low-level flow will continue Monday as the upper trough ejects eastward and the surface low deepens over MT and the western Dakotas. Surface winds of 25-30 mph are again expected across much of MT, the Dakotas and into parts of NE/MN/IA. However, RH values should begin to increase as low-level moisture is advected northward and mid-level cloud cover reduces solar heating. While still relatively dry below 30%, RH values do not appear critical. This will favor widespread elevated and pockets of locally critical conditions Monday afternoon. ...Southwest... As the troughing over the west gradually deepens, strong mid-level flow will begin to move eastward over the southern Rockies and Southwest. Westerly downslope flow is likely across parts of eastern AZ and western NM Monday. With gusts of 15-20 mph and RH below 15%, several hours of elevated fire-weather conditions are likely within dry fuels that have supported recent fire activity. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0211 PM CDT Sun May 11 2025 Valid 131200Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for severe thunderstorms currently appears low across the U.S. Tuesday through Tuesday night. ...Ohio Valley into the Southeast... The persistent mid/upper low over the Mid-South and attendant trough extending into the Gulf will likely weaken as the system shift east toward the Atlantic coast on Tuesday. While some modest vertical shear will remain over portions of the region, overall wind field is expected to be weaker. Nevertheless, a seasonally moist airmass will modestly destabilize diurnally in pockets of heating. Isolated strong storms producing locally gusty winds and perhaps small hail are possible, though overall severe potential appears less compared to previous days. ...Intermountain West into the Great Plains... A deepening upper trough near the Pacific coast will shift east over the West on Tuesday. A belt of enhanced southwesterly flow will overspread the Rockies to the High Plains. Diurnal thunderstorms may develop over the northern Great Basin and northern Rockies. Instability and heating are expected to remain modest, limiting severe potential across the higher terrain of the Intermountain West. Further east into the Plains, lee troughing along the High Plains will sharpen with the approach of the upper trough. The upper low over the southeastern U.S. will limit northwest moisture return across much of the Plains. Nevertheless, strong heating and steep midlevel lapse rates will support weak to moderate destabilization. However, capping will likely limit much in the way of thunderstorm development. A surface cold front is forecast to move east/southeast across the Dakotas during the evening and overnight. This may allow for a storm or two to develop after peak heating. This activity would likely be either elevated or high-based. If a storm develops, hail would be possible. Uncertainty in storm development/coverage precludes severe probabilities at this time. ..Leitman.. 05/11/2025 Read more

No watches are valid as of Sun May 11 17:59:02 UTC 2025.

No Mesoscale Discussions are in effect as of Sun May 11 17:59:02 UTC 2025.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1156 AM CDT Sun May 11 2025 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE TENNESSEE VALLEY AND THE SOUTHEAST... ...SUMMARY... Scattered strong thunderstorms may impact parts of the Southeast on Monday. The strongest activity may pose a risk for a couple of tornadoes, locally strong surface gusts, and isolated hail. ...Southeast... The mid/upper low over the lower MS Valley will pivot northeast toward the TN Valley on Monday. A belt of enhanced south/southwesterly flow aloft will overspread portions of the Southeast. Vertically veering wind profiles, with 30-45 kt of flow between 700-500 mb, will support effective shear magnitude greater than 30 kt across much of the risk area. South/southeasterly low-level flow will maintain a moist airmass. Meanwhile, cool temperatures aloft will support modest midlevel lapse rates. Pockets of stronger daytime heating with aid in modest destabilization, with MLCAPE around 500-1000 J/kg forecast. Similar to the previous couple of days, bands of cells/clusters are expected through the day. This activity will pose an isolated risk for locally damaging gusts, marginal hail, and a tornado or two. ..Leitman.. 05/11/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1156 AM CDT Sun May 11 2025 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE TENNESSEE VALLEY AND THE SOUTHEAST... ...SUMMARY... Scattered strong thunderstorms may impact parts of the Southeast on Monday. The strongest activity may pose a risk for a couple of tornadoes, locally strong surface gusts, and isolated hail. ...Southeast... The mid/upper low over the lower MS Valley will pivot northeast toward the TN Valley on Monday. A belt of enhanced south/southwesterly flow aloft will overspread portions of the Southeast. Vertically veering wind profiles, with 30-45 kt of flow between 700-500 mb, will support effective shear magnitude greater than 30 kt across much of the risk area. South/southeasterly low-level flow will maintain a moist airmass. Meanwhile, cool temperatures aloft will support modest midlevel lapse rates. Pockets of stronger daytime heating with aid in modest destabilization, with MLCAPE around 500-1000 J/kg forecast. Similar to the previous couple of days, bands of cells/clusters are expected through the day. This activity will pose an isolated risk for locally damaging gusts, marginal hail, and a tornado or two. ..Leitman.. 05/11/2025 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1151 AM CDT Sun May 11 2025 Valid 111700Z - 121200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE CENTRAL/NORTHERN PLAINS AND UPPER MIDWEST... Efficient diurnal mixing of a very dry boundary layer under strong south-southwesterly flow aloft and a strengthening lee low will continue to support gusty south-southwest winds through today across the Northern Plains and Upper-Midwest. The winds combined with dry fuels under possible record setting heat will support widespread Elevated to Critical fire weather conditions across the Region. Recent observed soundings and surface observations across the region continue to show minimal upstream boundary layer moisture moving into the region supporting afternoon relative humidity below 20 percent as far north as the North Dakota/Minnesota U.S./Canada border. Critical highlights were extended northward into northeastern North Dakota and northwestern Minnesota. ..Williams.. 05/11/2025 .PREV DISCUSSION... /ISSUED 0147 AM CDT Sun May 11 2025/ ...Synopsis... Mid-level ridging over the Rockies will begin to move eastward as a trough and strong southwesterly flow aloft move over the West. A lee low will aid strong southerly winds over much of the Great Plains and Midwest, while a cutoff low meanders along the Gulf Coast. The dry southerly winds ahead of returning surface moisture will support dry and windy conditions over areas with little recent precipitation. Several hours of critical fire-weather conditions are likely over the Plains today and tonight. ...Plains and Upper Midwest... East of the deepening lee trough/cyclone, strong southerly winds are likely across much of the central/northern Plains and upper Midwest. As flow aloft form the advancing upper trough overspreads the region, diurnal mixing will support widespread winds of 20-30 mph. Afternoon RH values will fall to 20-25%, supporting several hours of dry and windy conditions. As area fuels have continued to dry with little recent rainfall (ERCs in the 80th percentiles), critical fire-weather conditions appear likely today into tonight. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1151 AM CDT Sun May 11 2025 Valid 111700Z - 121200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE CENTRAL/NORTHERN PLAINS AND UPPER MIDWEST... Efficient diurnal mixing of a very dry boundary layer under strong south-southwesterly flow aloft and a strengthening lee low will continue to support gusty south-southwest winds through today across the Northern Plains and Upper-Midwest. The winds combined with dry fuels under possible record setting heat will support widespread Elevated to Critical fire weather conditions across the Region. Recent observed soundings and surface observations across the region continue to show minimal upstream boundary layer moisture moving into the region supporting afternoon relative humidity below 20 percent as far north as the North Dakota/Minnesota U.S./Canada border. Critical highlights were extended northward into northeastern North Dakota and northwestern Minnesota. ..Williams.. 05/11/2025 .PREV DISCUSSION... /ISSUED 0147 AM CDT Sun May 11 2025/ ...Synopsis... Mid-level ridging over the Rockies will begin to move eastward as a trough and strong southwesterly flow aloft move over the West. A lee low will aid strong southerly winds over much of the Great Plains and Midwest, while a cutoff low meanders along the Gulf Coast. The dry southerly winds ahead of returning surface moisture will support dry and windy conditions over areas with little recent precipitation. Several hours of critical fire-weather conditions are likely over the Plains today and tonight. ...Plains and Upper Midwest... East of the deepening lee trough/cyclone, strong southerly winds are likely across much of the central/northern Plains and upper Midwest. As flow aloft form the advancing upper trough overspreads the region, diurnal mixing will support widespread winds of 20-30 mph. Afternoon RH values will fall to 20-25%, supporting several hours of dry and windy conditions. As area fuels have continued to dry with little recent rainfall (ERCs in the 80th percentiles), critical fire-weather conditions appear likely today into tonight. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1119 AM CDT Sun May 11 2025 Valid 111630Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN ROCKIES AND MONTANA HIGH PLAINS... ...SUMMARY... Scattered severe wind gusts are expected across the northern Rockies to Montana High Plains from mid-afternoon into the evening. Isolated severe thunderstorms are also possible across the Southeast today through tonight. ...Northern Rockies/High Plains and northeast Great Basin... Strengthening southwesterly flow aloft is anticipated throughout the day as the upper low off the Pacific Northwest coast progresses eastward and a lead shortwave trough pivots through OR/northern CA into the northern Rockies. Strong heating will help destabilize the airmass downstream from the northern Rockies into the northern High Plains. Large-scale ascent attendant to the approaching shortwave trough, coupled with orographic lift, will help initiate storms across the high terrain during the afternoon within this destabilized airmass. Environmental conditions suggest some supercells are possible with this initial development, with damaging gusts and isolated hail as the primary risk. A low-probability corridor of tornado potential exists across southeast ID. The storms should encounter an increasingly mixed environment with eastern/northeastern extent into central MT, with strong gusts becoming the primary severe hazard as storms trend towards more outflow-dominant linear structures. ...Southeast States... Recent satellite imagery and surface observations continue to show the vertically stacked low over the Lower MS Valley, with broad swath of southwesterly flow extending south and east of this low from the central Gulf into FL. Surface features have become increasingly diffuse across the Southeast and FL over the past two days given the persistence of this low and associated precipitation, but recent surface analysis shows a weak and wavy stationary boundary extending from the low over the ArkLaMiss southeastward to the AL/FL Panhandle border before arcing back northeastward across southern GA. Scattered thunderstorms are ongoing and the general expectation is for scattered to numerous thunderstorms to persist across much of the region throughout the day. Widespread cloudiness should limit heating, but ample low-level moisture will still support modest buoyancy. Shear will gradually increase as the low to mid-level flow strengthens this afternoon and evening, which could lead to some transient storm organization, but in general convection is expected to be disorganized, outflow-dominated multicells. Even so, isolated damaging gusts are possible. Some low-probability tornado potential exists as well, particularly along the stationary boundary across southern GA around 00Z. Farther northwest across AL/MS and into eastern AR, the airmass is forecast to destabilize this afternoon as heating occurs beneath cool temperatures aloft. Even with the cooler temperature aloft, overall buoyancy will be modest given the somewhat cool low to mid-level thermodynamic profile. Even so, a nearly unidirectional southeasterly wind profile with moderate deep-layer speed shear could support brief updraft organization. As a result, a few cells may briefly produce marginally severe hail and locally strong gusts, and possibly some funnel/brief tornado potential, from late afternoon through early/mid-evening. ..Mosier/Wendt.. 05/11/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0754 AM CDT Sun May 11 2025 Valid 111300Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN ROCKIES AND MONTANA HIGH PLAINS... ...SUMMARY... Scattered severe wind gusts are expected across the northern Rockies to Montana High Plains fom mid-afternoon into the evening. Isolated severe thunderstorms are also possible across the Southeast today through tonight. ...Northern Rockies/High Plains and northeast Great Basin... The leading portion of an eastward-transitioning upper-level trough will overspread the northern Rockies and northern Great Basin later today and tonight, with preceding height falls and a regionally strengthening 60-80 kt southwesterly mid-level jet. These trends in conjunction with orographic influences/differential heating will lead to another round of isolated to scattered thunderstorms by mid/late afternoon. Similar to Saturday, severe-caliber wind gusts will be the primary hazard as storms develop in association with deeply mixed boundary layers, especially with eastward extent from southeast Idaho to central/eastern Montana. Corridors of modest buoyancy, coupled with moderate to strong deep-layer southwesterly speed shear, could yield a few high-based supercell structures producing small to marginally severe hail. This should be focused from the Oregon/Washington/Idaho border vicinity into central Montana, and separately over southeast Idaho into Yellowstone. ...Southeast States... A persistent, slow-moving, and essentially vertically stacked low will persist, centered over the ArkLaMiss vicinity, with a preceding belt of moderately strong mid-level winds extending over the northeast Gulf to the coastal Southeast. This will overlie a moderately moist warm sector to the east of the surface cyclone and along/south of the eastward-extending stationary front (or slow-moving warm front). Scattered thunderstorms are ongoing regionally this morning, including semi-extensively over the northeast Gulf. A 30-40 kt southerly low-level jet is expected to sustain adequately enlarged low-level hodographs within this corridor, but especially towards the coast and near the warm front. But convection is expected to be within a messy, outflow-dominated mode at times. Regardless, isolated damaging wind and tornado potential is apparent. While the severe risk does not appear as semi-focused as yesterday, portions of far northern Florida to southern/southeast Georgia in vicinity of the stationary/warm front will be reevaluated for a potential Slight Risk upgrade. Farther west in Alabama and Mississippi, despite somewhat cooler mid-level temperatures closer to the upper cyclone, lapse rates still appear modest. But deep-layer speed shear will be moderately favorable amid a nearly unidirectional southeasterly wind profile. A few cells may briefly produce marginally severe hail and locally strong gusts, and possibly some funnel/brief tornado potential, mainly from late afternoon through early/mid-evening. ..Guyer/Dean.. 05/11/2025 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0400 AM CDT Sun May 11 2025 Valid 141200Z - 191200Z ...DISCUSSION... Latest medium-range output remains generally similar to prior runs concerning the pattern evolution Wednesday into Thursday. A significant short wave trough emerging from the Intermountain West is forecast to support modest cyclogenesis across the central and northern Great Plains through the mid/upper Mississippi Valley vicinity. It appears that this probably will be accompanied by increasing potential for strong to severe thunderstorm development, with severe probabilities maximizing across parts of the Midwest late Thursday into Thursday night, as the stronger large-scale forcing for ascent becomes better coupled with substantive boundary-layer moistening and destabilization. Aided by steep lower/mid-tropospheric lapse rates associated with elevated mixed-layer air, and moderate to strong low-level and deep-layer shear, it appears that the environment will become conducive to the evolution of an upscale growing and organizing convective system. But initial convection may include supercells posing a risk for large hail and a couple of tornadoes, before damaging wind gusts become the predominate severe hazard. Based on the subsequent pattern evolution, it appears that this convection could persist into, or re-intensify, Friday across parts of the mid/upper Ohio Valley, with additional upscale growing convection evolving along a stalling trailing cold front near the southern edge of the stronger westerlies. Into next weekend, renewed cyclogenesis appears possible along the trailing flank of the front across the south central Great Plains, where additional strong to severe thunderstorm development may focus along a developing warm front, and a developing dryline southward through the plains, as the warm sector destabilizes with increasing Gulf moisture return. However, by late Thursday into Friday, and beyond, these developments remain much more unclear, as spread among and within the various medium-range models begins to increase. Substantive differences begin to develop concerning the progressiveness of the lead trough, and a trailing short wave trough emerging from the mid-latitude Pacific. The uncertain impacts of potentially multiple evolving large convective clusters on succeeding days adds to low predictability. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0228 AM CDT Sun May 11 2025 Valid 131200Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for severe thunderstorms currently appears negligible across the U.S. Tuesday through Tuesday night. ...Discussion... It appears that significant mid/upper-level troughing progressing inland of the U.S. Pacific coast may dig as far south as the lower Colorado Valley, and suppress ridging within a belt of westerlies emanating from the subtropical eastern Pacific, across the southwestern international border area. Thereafter, models indicate that the perturbation will turn eastward across the Intermountain West later Tuesday through Tuesday night, with intensifying difluent west-southwesterly mid/upper flow overspreading the southern Rockies by 12Z Wednesday. In lower levels, modestly deep surface troughing to the lee of the Rockies may continue to slowly shift eastward across the Great Plains. However, in the wake of broad, weak negatively tilted mid/upper troughing shifting east of the Mississippi Valley, toward the Atlantic coast at a slower pace than the upstream trough, strengthening low-level flow (up to 30-40 kt around 850 mb) is forecast to maintain a pronounced westerly component across the southern Great Plains into lower Mississippi Valley. This will continue to impede boundary-layer moisture return off the Gulf into the Great Plains, though evapotranspiration may contribute to moistening beneath the leading edge of a plume of warm elevated mixed-layer air advecting eastward across the central and southern Great Plains. Downstream, models indicate that there will be gradual further deepening of broad, weak surface troughing across much of the Southeast. However, the plume of seasonably high moisture content air emanating from the lower latitudes is forecast to generally shift east of the south Atlantic coast during the day Tuesday, though this may be slower to occur across southeast coastal areas of the Florida Peninsula. ...Intermountain West into Great Plains... Models suggest that destabilization beneath an elongated mid-level cold pool, trailing the surface cold front, may contribute to scattered, generally weak/diurnal thunderstorm activity across the northern Rockies and intermountain region, into the vicinity of the northern Sierra Nevada. Near the surface troughing across the Dakotas, it appears that a strongly heated and deeply mixed boundary may become characterized by 40-50 F surface temperature/dew point spreads, but with thermodynamic profiles still supportive of CAPE on the order of 500-1000 J/kg. High-based thunderstorm development appears possible near/after peak heating, which could pose some risk for locally strong surface gusts. However, the extent of this potential remains unclear, and too uncertain to introduce even low severe probabilities at the present time. ...Ohio Valley/Mid Atlantic/Southeast... Scattered, largely diurnal thunderstorm activity will again be possible beneath the weak/weakening mid-level troughing. Stronger convection may focus along the sea breeze near southeastern Florida coastal areas, and perhaps across parts of the mid and southern Atlantic Piedmont, where at least modest boundary-layer destabilization may occur. However, it is not yet clear that this will be accompanied by an appreciable risk for severe weather. ..Kerr.. 05/11/2025 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0228 AM CDT Sun May 11 2025 Valid 131200Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for severe thunderstorms currently appears negligible across the U.S. Tuesday through Tuesday night. ...Discussion... It appears that significant mid/upper-level troughing progressing inland of the U.S. Pacific coast may dig as far south as the lower Colorado Valley, and suppress ridging within a belt of westerlies emanating from the subtropical eastern Pacific, across the southwestern international border area. Thereafter, models indicate that the perturbation will turn eastward across the Intermountain West later Tuesday through Tuesday night, with intensifying difluent west-southwesterly mid/upper flow overspreading the southern Rockies by 12Z Wednesday. In lower levels, modestly deep surface troughing to the lee of the Rockies may continue to slowly shift eastward across the Great Plains. However, in the wake of broad, weak negatively tilted mid/upper troughing shifting east of the Mississippi Valley, toward the Atlantic coast at a slower pace than the upstream trough, strengthening low-level flow (up to 30-40 kt around 850 mb) is forecast to maintain a pronounced westerly component across the southern Great Plains into lower Mississippi Valley. This will continue to impede boundary-layer moisture return off the Gulf into the Great Plains, though evapotranspiration may contribute to moistening beneath the leading edge of a plume of warm elevated mixed-layer air advecting eastward across the central and southern Great Plains. Downstream, models indicate that there will be gradual further deepening of broad, weak surface troughing across much of the Southeast. However, the plume of seasonably high moisture content air emanating from the lower latitudes is forecast to generally shift east of the south Atlantic coast during the day Tuesday, though this may be slower to occur across southeast coastal areas of the Florida Peninsula. ...Intermountain West into Great Plains... Models suggest that destabilization beneath an elongated mid-level cold pool, trailing the surface cold front, may contribute to scattered, generally weak/diurnal thunderstorm activity across the northern Rockies and intermountain region, into the vicinity of the northern Sierra Nevada. Near the surface troughing across the Dakotas, it appears that a strongly heated and deeply mixed boundary may become characterized by 40-50 F surface temperature/dew point spreads, but with thermodynamic profiles still supportive of CAPE on the order of 500-1000 J/kg. High-based thunderstorm development appears possible near/after peak heating, which could pose some risk for locally strong surface gusts. However, the extent of this potential remains unclear, and too uncertain to introduce even low severe probabilities at the present time. ...Ohio Valley/Mid Atlantic/Southeast... Scattered, largely diurnal thunderstorm activity will again be possible beneath the weak/weakening mid-level troughing. Stronger convection may focus along the sea breeze near southeastern Florida coastal areas, and perhaps across parts of the mid and southern Atlantic Piedmont, where at least modest boundary-layer destabilization may occur. However, it is not yet clear that this will be accompanied by an appreciable risk for severe weather. ..Kerr.. 05/11/2025 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0149 AM CDT Sun May 11 2025 Valid 121200Z - 131200Z ...Synopsis... The partially blocked upper-air pattern over the US will begin to breakdown early in the new week as a trough deepens over the western US. Strong mid-level flow will gradually move into the Plains, as upper ridging moves eastward. Strong lee troughing/cyclogensisis will support gusty south/westerly winds over the High Plains. Fire-weather conditions are expected across the Great Plains and Southwest Monday afternoon and evening. ...Northern Plains and Midwest... Strong southerly low-level flow will continue Monday as the upper trough ejects eastward and the surface low deepens over MT and the western Dakotas. Surface winds of 25-30 mph are again expected across much of MT, the Dakotas and into parts of NE/MN/IA. However, RH values should begin to increase as low-level moisture is advected northward and mid-level cloud cover reduces solar heating. While still relatively dry below 30%, RH values do not appear critical. This will favor widespread elevated and pockets of locally critical conditions Monday afternoon. ...Southwest... As the troughing over the west gradually deepens, strong mid-level flow will begin to move eastward over the southern Rockies and Southwest. Westerly downslope flow is likely across parts of eastern AZ and western NM Monday. With gusts of 15-20 mph and RH below 15%, several hours of elevated fire-weather conditions are likely within dry fuels that have supported recent fire activity. ..Lyons.. 05/11/2025 ...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 0149 AM CDT Sun May 11 2025 Valid 121200Z - 131200Z ...Synopsis... The partially blocked upper-air pattern over the US will begin to breakdown early in the new week as a trough deepens over the western US. Strong mid-level flow will gradually move into the Plains, as upper ridging moves eastward. Strong lee troughing/cyclogensisis will support gusty south/westerly winds over the High Plains. Fire-weather conditions are expected across the Great Plains and Southwest Monday afternoon and evening. ...Northern Plains and Midwest... Strong southerly low-level flow will continue Monday as the upper trough ejects eastward and the surface low deepens over MT and the western Dakotas. Surface winds of 25-30 mph are again expected across much of MT, the Dakotas and into parts of NE/MN/IA. However, RH values should begin to increase as low-level moisture is advected northward and mid-level cloud cover reduces solar heating. While still relatively dry below 30%, RH values do not appear critical. This will favor widespread elevated and pockets of locally critical conditions Monday afternoon. ...Southwest... As the troughing over the west gradually deepens, strong mid-level flow will begin to move eastward over the southern Rockies and Southwest. Westerly downslope flow is likely across parts of eastern AZ and western NM Monday. With gusts of 15-20 mph and RH below 15%, several hours of elevated fire-weather conditions are likely within dry fuels that have supported recent fire activity. ..Lyons.. 05/11/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0147 AM CDT Sun May 11 2025 Valid 111200Z - 121200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE CENTRAL AND NORTHERN PLAINS.... ...Synopsis... Mid-level ridging over the Rockies will begin to move eastward as a trough and strong southwesterly flow aloft move over the West. A lee low will aid strong southerly winds over much of the Great Plains and Midwest, while a cutoff low meanders along the Gulf Coast. The dry southerly winds ahead of returning surface moisture will support dry and windy conditions over areas with little recent precipitation. Several hours of critical fire-weather conditions are likely over the Plains today and tonight. ...Plains and Upper Midwest... East of the deepening lee trough/cyclone, strong southerly winds are likely across much of the central/northern Plains and upper Midwest. As flow aloft form the advancing upper trough overspreads the region, diurnal mixing will support widespread winds of 20-30 mph. Afternoon RH values will fall to 20-25%, supporting several hours of dry and windy conditions. As area fuels have continued to dry with little recent rainfall (ERCs in the 80th percentiles), critical fire-weather conditions appear likely today into tonight. ..Lyons.. 05/11/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more