Severe Storms

MD 1722 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR FAR EASTERN NEW YORK INTO PARTS OF NEW ENGLAND
Mesoscale Discussion 1722 NWS Storm Prediction Center Norman OK 1125 AM CDT Fri Aug 26 2022 Areas affected...far eastern New York into parts of New England Concerning...Severe potential...Watch possible Valid 261625Z - 261830Z Probability of Watch Issuance...60 percent SUMMARY...Scattered strong storms will develop after 17Z, moving from eastern New York into parts of New England. A few damaging gusts are most likely, and a weak/brief tornado cannot be ruled out. DISCUSSION...Surface analysis shows a low developing over far eastern NY, and just south of an early-day cluster of thunderstorms which stretches into VT. Meanwhile, a diffuse warm front extends eastward toward far southern ME, though mixing may lead to a northward repositioning later today. Heating and advection of mid to upper 60s F dewpoints has led to an uncapped and unstable air mass, with CAPE presently in the 1000-2000 J/kg range. The strongest instability currently exists over southern New England where dewpoints are higher. Further, GPS PWAT sensors show a marked increase in overall moisture values through a deeper layer, approaching 1.50" near coastal CT. Convergence near the developing surface low and trailing surface trough and continued heating will lead to increasing storm coverage throughout the afternoon, progressing eastward. Deep-layer shear averaging near 35 kt, as well as veering winds with height suggest a several storms may be severe, producing a combination of damaging gusts and isolated hail. Steepening low-level lapse rates, and moist boundary layer, and weak SRH values could support a brief/weak tornado with the stronger isolated cells. ..Jewell/Thompson.. 08/26/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GYX...BOX...BTV...OKX...ALY... LAT...LON 41427435 42157405 43067354 43377319 43937184 43857078 43587026 42397060 41767172 41427217 41157331 41097393 41427435 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1116 AM CDT Fri Aug 26 2022 Valid 261700Z - 271200Z No changes have been made to the outlook. See the previous discussion below for more information. ..Dean.. 08/26/2022 .PREV DISCUSSION... /ISSUED 0103 AM CDT Fri Aug 26 2022/ ...Synopsis... Fire weather concerns will remain limited outside of the northern Great Basin today. An upper-level trough over the northern Rockies is forecast to gradually shift east into the Plains over the next 24 hours, which will support lee troughing along the northern to central High Plains with generally weakening flow over the West. Isolated dry thunderstorms are possible this afternoon across parts of MT under the upper wave, but the overall fire weather threat will remain limited. ...Northern Great Basin... Although stronger mid-level flow will gradually depart the region to the east through the day, continued zonal winds over the northern Sierra Nevada will promote sufficient downslope warming/drying for elevated wind/RH conditions across northern NV this afternoon. RH values, struggling to climb out of the teens/low 20s overnight, will likely fall into the teens (and perhaps single digits) this afternoon as winds increase to around 15 mph. Latest ERC estimates suggests fuels are adequately dry to support at least a low-end fire weather concern. ...Dry Thunderstorms... The 00 UTC TFX and OTX soundings sampled cold temperatures aloft under the northern Rockies upper-level trough. These thermodynamic conditions will persist for today and support modest, but sufficient, instability for convection by late afternoon despite decreasing PWAT values within the dry slot of the upper low. Forecast soundings suggest MUCAPE values may increase to around 250 J/kg with 2-3 km deep sub-cloud layers, favorable for dry lightning potential. Furthermore, storm motions near 20-30 knots may act to limit precipitation accumulations. While a few dry thunderstorms are possible from western to central MT this afternoon, fuel status is questionable after swaths of wetting rainfall over the past 24 hours (per latest MRMS estimates). ...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 1111 AM CDT Fri Aug 26 2022 Valid 261630Z - 271200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FOR PARTS OF NEW ENGLAND... ...SUMMARY... Isolated to widely scattered strong to severe thunderstorms are possible across the Northeast, as well as parts of the northern High Plains. ...Northeast this afternoon/evening... Embedded speed maxima will progress eastward from the lower Great Lakes to New England, within the southern portion of a broad belt of cyclonic mid-upper flow over southeast Canada. Likewise, a weak surface cyclone will move eastward from the Saint Lawrence Valley to ME by early tonight, as a trailing cold front moves southeastward across PA/NY/Southern New England. Scattered, slightly elevated thunderstorms are ongoing this morning over eastern NY in association with a lead shortwave trough. Surface heating and boundary-layer dewpoints in the mid 60s east of this convection and a pre-frontal trough will result in destabilization and will support surface-based thunderstorm development by early afternoon. Clusters and short line segments will subsequently spread eastward across New England in an environment of moderate buoyancy (MLCAPE of 1000-2000 J/kg) and vertical shear (effective bulk shear of 30-35 kt with modest hodograph length/low-level clockwise curvature). Occasional damaging gusts will be the main threat, though marginally severe hail and an isolated tornado will be possible. Isolated strong cells may occur farther west across NY this afternoon, near and east of the cold front, with more veered low-level flow and weaker vertical shear. ...Northern High Plains late this afternoon/evening... A weak midlevel trough will continue moving eastward over MT through this evening, and it will be preceded by a convectively-enhanced trough/MCV moving east-northeastward over SD. The southern fringe of the SD MCV will coincide with a corridor of boundary-layer dewpoints in the 60s along a warm front, but it is not clear that additional (surface-based storms) will form this afternoon across eastern SD. Otherwise, surface heating and residual 55-60 F dewpoints along a weak lee trough (in the zone of ascent downstream from the midlevel trough) will support afternoon/evening thunderstorm development from eastern MT into northeastern WY. Steepening low-midlevel lapse rates and deeper mixing across WY/MT will support the potential for isolated severe outflow winds/hail. Convection will tend to become elevated and will weaken with time while moving eastward into weakening buoyancy and larger convective inhibition across the Dakotas late this evening into tonight. ..Thompson/Jirak.. 08/26/2022 Read more

No watches are valid as of Thu Aug 25 17:47:01 UTC 2022.

No Mesoscale Discussions are in effect as of Thu Aug 25 17:47:01 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Thu Aug 25 2022 Valid 261200Z - 271200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE NORTHEAST... ...SUMMARY... Isolated to widely scattered strong to severe thunderstorms are possible across the Northeast States on Friday. ...Northeast... A broad mid-level trough will shift eastward across southeast Canada and into New England through daybreak Saturday. A mid-level vorticity maximum is forecast to move through the base of the trough and reach the St. Lawrence Valley by late afternoon. An associated surface low will migrate eastward across New England during the day. An attendant cold front will push eastward across New England. A mix of sun/clouds during the morning is expected with isolated to widely scattered showers/few thunderstorms expected closer to the Canadian border. A relatively moist boundary layer will destabilize through midday with surface dewpoints generally in the 60s deg F. Moderate buoyancy coupled with some enhancement to mid-level flow (30-40 kt at 500 mb) will contribute to the potential for storm organization. Scattered to numerous thunderstorms are forecast by the mid afternoon mainly in the form of multicellular clusters and bands of storms. A few transient supercells are possible and some risk for large hail and perhaps a tornado could develop with the most intense storms. This activity will likely diminish during the evening coincident with much of it pushing east of the coast and/or storms encountering convectively overturned air. ...Northern High Plains/Western Dakotas... A slow-moving upper low initially near the MT/Alberta border is expected to evolve into an open wave as it moves into the western Dakotas/southern Saskatchewan. A weak surface low will accompany this shortwave trough, moving ahead of it across southeast MT and into ND. A cluster of showers/storms will likely be ongoing across western SD early Friday morning. The associated cloud cover will probably temper diurnal heating and air mass destabilization over the Dakotas except for the far western part of SD. Models indicate isolated storms will develop by late afternoon in the vicinity of a moist axis extending from near the Black Hills northwestward into eastern MT. Isolated large hail/severe gusts are possible with the stronger storms. ..Smith.. 08/25/2022 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1141 AM CDT Thu Aug 25 2022 Valid 261200Z - 271200Z ...NO CRITICAL AREAS... The previous forecast reasoning (see below) remains on track, and no changes were made with this update. ..Weinman.. 08/25/2022 .PREV DISCUSSION... /ISSUED 0143 AM CDT Thu Aug 25 2022/ ...Synopsis... Mid-level flow is expected to strengthen across the northwestern U.S. as a more pronounced mid-level trough overspreads the Pacific Northwest tomorrow/Friday. While scattered thunderstorms may support a dry strike or two in a locally more receptive fuel bed across the northern Rockies, a slightly more appreciable fire-weather spread threat may exist across the northern Great Basin closer to the mid-level trough. The stronger flow aloft will overspread a dry boundary layer to the lee of the Cascades southeastward into the northern Great Basin, promoting at least locally Elevated dry/windy surface conditions during the afternoon. Highlights have been withheld this outlook given the more localized conditions overlapping spotty fuels. Surface lee troughing will also increase across the central Plains, along with strong southerly surface flow, encouraging locally to widespread Elevated dry and windy conditions. However, recent appreciable rainfall accumulations, especially across central Nebraska into the Dakotas, has likely dampened fuels to a degree, precluding fire weather highlights this outlook. ...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 1141 AM CDT Thu Aug 25 2022 Valid 251700Z - 261200Z ...NO CRITICAL AREAS... There are no changes to the forecast. For details, see the previous discussion below. ..Weinman.. 08/25/2022 .PREV DISCUSSION... /ISSUED 0125 AM CDT Thu Aug 25 2022/ ...Synopsis... Broad cyclonic upper flow will prevail across the eastern U.S. while multiple mid-level impulses will traverse the Northwest into the central Plains today. Scattered thunderstorms are expected to develop amid a modestly buoyant airmass across portions of the northern Rockies. A few of the thunderstorms may be dry initially, before becoming a more wet/dry mix. Fuels, however, are receptive to wildfire spread on a spotty basis. As such, sparse dry strikes into patchy receptive fuels or gusty, erratic winds emanating from storms may support very localized wildfire-spread potential. Locally dry and windy conditions are also possible across parts of the northern Great Basin in association with the passage of a mid-level impulse. ...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 1120 AM CDT Thu Aug 25 2022 Valid 251630Z - 261200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER WESTERN MONTANA AND ACROSS PORTIONS OF THE NORTH-CENTRAL HIGH PLAINS... ...SUMMARY... Isolated severe hail and thunderstorm gusts will be possible across portions of western Montana and the north-central High Plains today. ...Western MT... Slow-moving closed upper low over near the international border in the vicinity of northern ID will begin to move slowly east late today. Diurnal heating of initially 50s surface dew points will result in a deep mixed layer, and steep midlevel lapse rates will contribute to 1000-1500 J/kg MLCAPE this afternoon. Although winds throughout the cloud-bearing layer will be generally modest (30 kts or less), veering low/midlevel flow will contribute to 30-35 kts of effective shear. Widely scattered to scattered thunderstorm development is expected this afternoon across western MT, with multicell/supercell modes possible. Deep mixed layer will result in a risk for isolated severe wind gusts, and large hail will be possible with a few stronger updrafts/supercell structures. ...North-Central High Plains... Midlevel perturbation currently over western WY will continue east, with a region of ascent favorably timed to develop over the Big Horn/Black Hills region during the mid/late afternoon. Despite ongoing cloud cover, heating of mid/upper 50s surface dew points beneath reasonably steep midlevel lapse rates should result in pockets of MLCAPE of 1000-1500 J/kg. Modest midlevel west/northwest flow will contribute to around 30 kts of effective shear which will favor a mixed multicell/transient supercell mode. Isolated stronger storms will be capable of strong/damaging gusts and hail through early evening. ..Bunting/Wendt.. 08/25/2022 Read more

No watches are valid as of Wed Aug 24 17:48:02 UTC 2022.

No Mesoscale Discussions are in effect as of Wed Aug 24 17:48:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1222 PM CDT Wed Aug 24 2022 Valid 251200Z - 261200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms are not forecast across the contiguous United States on Thursday. ...Northern Rockies/Northern High Plains... A slow-moving and weakening mid-level low will move east across the northern Rockies into the northern High Plains. Widely scattered to scattered diurnal thunderstorms are forecast to develop during the afternoon over the higher terrain of western into southern MT and near the Big Horns/Black Hills. Models continue to indicate that heating will be tempered in some areas due to partial cloud cover. However, steepening low-level lapse rates and large directional shear contributing to modest deep-layer shear, will support intermittently organized multicells. Given the marginal character of the potential storm intensity, will defer the highlighting of low wind probabilities for the time being. ..Mid MS Valley... A cold front, associated with a shortwave trough moving through the Upper Great Lakes, is expected to move southward through the Mid MS Valley Thursday afternoon and evening. Dewpoints will likely be in the upper 60s and temperatures in the mid 80s ahead of the front, resulting in moderate buoyancy. Isolated to widely scattered thunderstorms are anticipated across the region near the front. A few stronger updrafts could develop, but weak vertical shear will limit storm intensity. ...Elsewhere... Thunderstorms are also possible within the monsoonal moisture still in place across the Southwest and central Rockies, and in the vicinity of subtle upper low and associated surface low over the Southeast and FL. In each of these regions, weak vertical shear should keep the severe threat low. ..Smith.. 08/24/2022 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1129 AM CDT Wed Aug 24 2022 Valid 251200Z - 261200Z ...NO CRITICAL AREAS... The forecast remains on track, and no changes were made with this update. For details, see the previous discussion below. ..Weinman.. 08/24/2022 .PREV DISCUSSION... /ISSUED 0153 AM CDT Wed Aug 24 2022/ ...Synopsis... A mid-level trough will meander across the northern Rockies tomorrow/Thursday, supporting another day of scattered thunderstorms (a couple of which may be dry) by afternoon. Similar to Day 1, fuels are expected to remain receptive to fire spread on a spotty basis. Given recent rainfall accumulations as well as the potential for appreciable accumulations on Day 1, fuel receptiveness to wildfire spread will likely remain modest, precluding dry thunderstorm highlights this outlook. Also like Day 1, locally Elevated dry and windy conditions may occur in terrain-favoring areas of the northern Great Basin by afternoon. ...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 1126 AM CDT Wed Aug 24 2022 Valid 241700Z - 251200Z ...NO CRITICAL AREAS... The previous forecast reasoning (see below) remains the same, and no changes were needed with this update. ..Weinman.. 08/24/2022 .PREV DISCUSSION... /ISSUED 0153 AM CDT Wed Aug 24 2022/ ...Synopsis... A mid-level trough will traverse the Northwest U.S. as broad but weak cyclonic upper flow remains in place east of the Rockies today. Ahead of the mid-level trough, adequate lift and buoyancy will support scattered thunderstorm development, with at least isolated thunderstorms capable of producing strong to severe wind gusts. Fuel beds are receptive to wildfire spread on a spotty basis. However, the combination of dry strikes away from precipitation cores into dry fuel beds, and strong wind gusts exacerbating ongoing fires suggests that at least localized wildfire-spread concerns exist, especially along the Idaho/Montana border. Farther south across the northern Great Basin, locally Elevated dry and windy conditions are possible by afternoon peak heating. Please see the Day 1 Convective Outlook for more details on the severe threat. ...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 1121 AM CDT Wed Aug 24 2022 Valid 241630Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN ROCKIES TO UPPER THE MISSISSIPPI VALLEY... ...SUMMARY... Marginally severe gusts and/or hail will be possible in a corridor from portions of the northern Rockies to the upper Mississippi Valley. ...Northern Rockies to upper Mississippi Valley... Modest west-northwest mid-level flow will prevail from the Northern Rockies into the upper Great Lakes through tonight. An upper low over WA will drift east, while a low-amplitude impulse over western MN moves slowly southeast. A surface front, extending from the MI Upper Peninsula west/southwest through western NE and southern MT, will serve as a focus for isolated severe potential as thunderstorms develop/intensify this afternoon. Two areas with potentially greater thunderstorm coverage remain evident, over portions of southeast MN/northern IA/southern WI associated with a weak surface low along the front over southern MN, and over western MT in association with the eastward-migrating upper low. Relatively greater boundary-layer moisture exists over IA/southern MN late this morning (surface dew points mid 60s), and this will contribute to pockets of moderate MLCAPE where heating can be maximized. Generally weak low/mid-level wind fields will result in effective shear below 30 kts, though this may support organized multicell structures capable of isolated damaging gusts and hail late this afternoon through early evening. Across western MT, steeper mid-level lapse rates will contribute moderate buoyancy, and effective shear values will average 30-40 kts. Scattered thunderstorms should develop this afternoon, aided by post-frontal upslope flow and ascent with the approaching upper low. A mix of multicell and transient supercell storm modes is possible with a risk for isolated severe wind and hail with the strongest storms. A focused Slight Risk was considered over portions of western MT, however with existing cloud cover some uncertainty remains regarding the degree of destabilization and spatial extent of any greater severe threat. Elsewhere along the front, storm coverage is expected to be more isolated overall, though with perhaps slightly greater coverage in the upslope region of the Black Hills in western SD. A well-mixed boundary layer and marginal low-level moisture will support at least some risk for strong wind gusts. ..Bunting/Wendt.. 08/24/2022 Read more

No watches are valid as of Tue Aug 23 17:41:01 UTC 2022.

No Mesoscale Discussions are in effect as of Tue Aug 23 17:41:01 UTC 2022.

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1235 PM CDT Tue Aug 23 2022 Valid 241200Z - 251200Z ...NO CRITICAL AREAS... The previous forecast (see below) remains on track, and no changes were needed with this update. Isolated dry thunderstorms will also be possible over parts of central into eastern NV during the afternoon, though current indications are that fuels are generally not receptive to wildfire spread over this area. ..Weinman.. 08/23/2022 .PREV DISCUSSION... /ISSUED 0151 AM CDT Tue Aug 23 2022/ ...Synopsis... Broad cyclonic flow will prevail across the eastern U.S., while the western CONUS will remain under the influence of weak upper ridging tomorrow/Wednesday. A weak mid-level cutoff low will also meander around the northern Rockies to the north of the upper ridge. South of this upper low, locally dry and breezy conditions may occur across portions of far southeast Oregon into northern and central Nevada around afternoon peak heating. A greater concentration of dry thunderstorms is also likely across portions of the northern Rockies (particularly central into eastern Idaho) compared to Day 1. As in Day 1 though, dry thunderstorm highlights were withheld given questionable fuel receptiveness to fire spread. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1222 PM CDT Tue Aug 23 2022 Valid 241200Z - 251200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms are not currently forecast for Wednesday across the contiguous United States. ...Synopsis... A flattened mid- to upper-level ridge will reside over the Four Corners while a weak upper low remains over the Pacific Northwest. A subtle shortwave trough is expected to move northeastward in the corridor between the upper ridging and upper low, moving across northern NV/southern ID into southwest MT. ...Northern Rockies/High Plains into the Upper Midwest... A weak area of low pressure will gradually move east across southern MN during the day while an attendant cool front becomes draped from NE and becoming more diffuse over parts of the northern Rockies. Isolated thunderstorms are anticipated across southern MN, northern/central IA, and eastern NE along the cold front. Weak vertical shear will limit storm intensity. Some additional thunderstorm development is possible over eastern WY, where low-level convergence between the post-frontal easterly flow and the lee trough is maximized. Vertical shear will be slightly stronger here compared to areas farther east, largely as a result of low-level easterly flow veering to northwesterly aloft. Model guidance continues to indicate instability will be modest, thereby tempering the risk for strong/locally severe thunderstorms. Perhaps the area with the highest relative concern for a stronger thunderstorm will be over parts of western MT. Strong gusty winds may accompany the more intense thunderstorms during the early evening. ...Southeast... A convectively augmented shortwave trough and attendant surface low will continue to slowly drift eastward across the Southeast states, with numerous thunderstorms expected over the region throughout the day. Uncertainty remains high whether mesoscale enhancement to the wind profile will occur in a very moist airmass. ..Smith.. 08/23/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1120 AM CDT Tue Aug 23 2022 Valid 231700Z - 241200Z ...NO CRITICAL AREAS... The forecast remains on track, and no changes were made with this update. For details, see the previous discussion below. ..Weinman.. 08/23/2022 .PREV DISCUSSION... /ISSUED 0151 AM CDT Tue Aug 23 2022/ ...Synopsis... While broad cyclonic upper flow will prevail east of the Rockies, and a mid-level shortwave trough impinges on the West Coast today, deep-layer winds/forcing should be weak, with dry and windy conditions expected to remain constrained to terrain-favoring areas. While isolated to scattered thunderstorms are possible across parts of the Pacific Northwest into the northern Rockies, several of the storms are expected to be wet. Spotty fuel beds may support isolated lightning-induced ignitions. However, many earlier fire starts have yet to grow rapidly, suggesting that fuels are modestly receptive at best to significant wildfire spread. As such, dry thunderstorm highlights have been withheld this outlook. ...Please see www.spc.noaa.gov/fire for graphic product... Read more