Severe Storms

No watches are valid as of Mon Sep 5 17:40:02 UTC 2022.

No Mesoscale Discussions are in effect as of Mon Sep 5 17:40:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1200 PM CDT Mon Sep 05 2022 Valid 061200Z - 071200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for severe thunderstorms is expected to be relatively low on Tuesday. ...Synopsis... An upper ridge is forecast to amplify further across the western CONUS on Tuesday. A broad, positively tilted mid/upper-level trough will persist over the East, as several embedded vorticity maxima move through the mean trough position. A weak surface low is forecast to develop near a remnant baroclinic zone over the Mid Atlantic during the morning and then move offshore by the end of the period. Scattered to widespread convection is expected within a seasonably moist environment from the ArkLaTex into the Mid South, though weak deep-layer shear is expected to limit the organized severe-thunderstorm threat. Extensive convection is also expected from coastal NC into the Mid Atlantic within a slightly stronger flow regime, though any severe potential across quite uncertain across that region. ...Mid Atlantic... Guidance varies somewhat regarding the timing and intensity of surface cyclone development across the Mid Atlantic Tuesday morning. The stronger solutions depict a modest increase in low-level flow/shear during the first part of the day near the cyclone track and surface boundary, which could potentially support a threat of locally damaging wind gusts and/or a brief tornado as substantial convection moves through the region. However, given the uncertainty regarding this scenario and the relatively limited areal extent of any potential threat before convection moves offshore, no probabilities have been introduced at this time. ..Dean.. 09/05/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1127 AM CDT Mon Sep 05 2022 Valid 051630Z - 061200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS CENTRAL TEXAS... ...SUMMARY... Isolated marginally severe thunderstorms are possible across a portion of central Texas centered on 3 to 7 PM CDT. ...Central Texas... A mid-level low will drift southwestward across far southeast Oklahoma and northeast Texas through tonight. The western fringe of relatively cooler mid-level temperatures in conjunction with a belt of 15-25 kt mid-level northerlies should overlap a confined corridor of low to mid 60s surface dew points near the intersection of a diffuse surface front and dryline. Within this regime, isolated to scattered thunderstorms should develop in the mid to late afternoon. Marginally severe hail and localized strong to severe gusts will be possible until convection begins to weaken by around sunset. ...Midwest to Appalachians... Cloud breaks and a moist air mass (near 70F dewpoints) will be conducive for moderate destabilization across the Lower Ohio Valley, although weak wind profiles should keep any stronger storms of a pulse-type character with limited severe potential. Farther east, modestly stronger low/mid-level southwesterly winds will reside near and in the windward side of the Appalachians through tonight. However, insolation will be limited by the generally prevalent nature of existing cloud cover and precipitation. A bit more insolation/destabilization could occur across northern/eastern Georgia into South Carolina/western North Carolina this afternoon. A few stronger storms could occur in this region, but organized severe potential is currently expected to remain low. ..Guyer/Bentley.. 09/05/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon Sep 05 2022 Valid 051700Z - 061200Z No changes to the ongoing forecast. ..Wendt.. 09/05/2022 .PREV DISCUSSION... /ISSUED 0105 AM CDT Mon Sep 05 2022/ ...Synopsis... Fire weather concerns will linger across the northern Rockies for today as a winds increase within a hot/dry boundary layer. A belt of strong mid-level flow is expected to shift from the Pacific Northwest into the northern Rockies over the next 24 hours as a low-amplitude upper wave shifts into western Canada. This will support a breezy and dry downslope wind regime across parts of ID into central/northern MT where fuels continue to cure after several days of hot conditions. ...Northern Montana to North Dakota... Elevated fire weather conditions are expected from north-central MT into far western ND this afternoon. A surface low/lee trough is evident across the northern High Plains and Canadian Prairies in early-morning surface observations/analyses. This feature will shift east through the day in tandem with the upper disturbance, establishing a westerly downslope wind regime across much of MT. Diurnal heating/boundary-layer mixing will help downward transfer of strengthening mid-level flow as RH values fall into the teens and low 20s. Sustained winds near 15 mph will be accompanied by frequent gusts between 20-30 mph. Brief periods of critical conditions are possible, but confidence in the duration/coverage of 20+ mph winds remains low. Recent fire activity across the region indicates that fuels remain receptive and will support the fire weather threat. A cold front is expected to push across north/northeast MT during the overnight hours, bringing a wind shift to the north/northwest. ...Idaho... The 00 UTC BOI sounding sampled a very dry boundary layer with 0-1 km mean RH near 12%. With little moisture flux into the region expected over the next 24 hours, similar low-level thermodynamic conditions are anticipated for this afternoon. Strong diurnal heating through the Snake River Plain will support deep boundary-layer mixing and RH reductions into the low teens (and possibly single digits) by mid afternoon. Sustained winds near 15-20 mph may occasionally gust to 25 mph. Elevated conditions appear likely, and brief/localized periods of critical conditions are possible. ...Northwest NV into southern OR... Localized elevated conditions are possible this afternoon from far northeast CA/northwest NV into southern OR. Widespread RH reductions below 15% are likely with pockets of breezy winds between 15-20 mph. With the stronger synoptic pressure gradients shifting to the east away from the region through the day, such winds will most likely be confined to the vicinity of terrain features, limiting confidence in a more widespread fire weather concern. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Sun Sep 4 17:38:02 UTC 2022.

No Mesoscale Discussions are in effect as of Sun Sep 4 17:38:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1200 PM CDT Sun Sep 04 2022 Valid 051200Z - 061200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms potential appears low on Monday. ...Synopsis and Discussion... An upper anticyclone will persist over much of the western CONUS on Monday. Compared to prior days, weak large-scale ascent should limit overall convective potential to mainly terrain-driven circulations across the Four Corners region to the Mogollon Rim, and parts of the Sierra Mountains into the Coastal Ranges of southern CA. While strong/gusty winds may occur with any convection that can develop, overall sparse thunderstorm coverage precludes any severe wind probabilities. Thunderstorms will be possible across a broad portion of the central and eastern states extending from parts of the southern Plains to the Northeast, mainly Monday afternoon and evening. Weak upper troughing should extend from the ArkLaTex region northeastward to the OH Valley and Great Lakes. Generally weak mid-level flow and related deep-layer shear is anticipated east of this feature across the warm sector, which should limit thunderstorm organization. Poor mid-level lapse rates should also temper instability across much of these regions, with moderate to perhaps strong instability developing along/south of a weak front that should be draped across parts of north/central TX. While occasional strong/gusty winds may occur with any convection that develops, the threat for organized severe thunderstorms still appears low. ..Gleason.. 09/04/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Sun Sep 04 2022 Valid 041630Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE DESERT SOUTHWEST AND THE SOUTHERN GREAT PLAINS... ...SUMMARY... Isolated severe wind gusts are possible during the late afternoon to early evening over parts of the Desert Southwest along with southeast Oklahoma and North Texas. ...Desert Southwest... With a moist air mass remaining across the region, strong boundary layer heating and orographic influences will again yield isolated thunderstorm development late this afternoon into evening. This will include a corridor from northwest Arizona, far southern Nevada into interior southern California. A belt of moderately strong easterly winds will persist on the southern periphery of the Great Basin-centered upper ridge, which will support a west-southwestward movement of some potentially semi-organized storms. A well-mixed boundary layer will support a threat for isolated severe wind gusts from the late afternoon into early/mid-evening. ...Southeast Oklahoma and North Texas... A southward-sagging front along with different heating/outflow will focus renewed thunderstorm development this afternoon. With 15-25 kt mid-level north/northwesterly winds, weakly organized clusters may congeal and spread south in north Texas with a threat for locally strong to severe wind gusts given surface temperatures in the 90s F. Storms will weaken towards/after sunset as the boundary layer cools and MLCIN increases. ..Guyer/Bentley.. 09/04/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1104 AM CDT Sun Sep 04 2022 Valid 041700Z - 051200Z ...CRITICAL FIRE WEATHER AREA FOR FAR NORTHWESTERN GREAT BASIN... No changes to the ongoing forecast. ..Wendt.. 09/04/2022 .PREV DISCUSSION... /ISSUED 0153 AM CDT Sun Sep 04 2022/ ...Synopsis... Two upper-level shortwave troughs are forecast to move over the ridge centered in the Great Basin today, acting to deamplify the upper-level high pressure. The first small and compact shortwave over northwestern Montana this morning is forecast to weaken and move eastward across northern Montana and North Dakota throughout the day. The second shortwave, currently off the Pacific Northwest coast, is forecast to move into British Columbia and Washington state by the end of the day. In response at the surface, a low-pressure trough is forecast to develop over the northern High Plains. Ahead of these shortwave troughs, a broad area of elevated fire weather conditions is expected from northeastern California east-northeastward across Montana. The environment across this region will be characterized by hot, dry, and well-mixed boundary layers yielding critical RH values in the presence of enhanced flow aloft. The best overlap of strong winds (>20 mph) and critical RH values is in the vicinity of the California/Nevada/Oregon border, so a focused critical area has been delineated across that region. Farther east ahead of the surface pressure trough, critical south-southeasterly winds are likely across the western Dakotas, but RH values may be a limiting factor with surface dewpoints only mixing into the mid-to-upper 40s F. Nevertheless, this different fire-weather regime compared to areas farther west should also lead to elevated fire-weather concerns. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Sat Sep 3 17:40:02 UTC 2022.

No Mesoscale Discussions are in effect as of Sat Sep 3 17:40:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1222 PM CDT Sat Sep 03 2022 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE DESERT SOUTHWEST... ...SUMMARY... There is a Marginal Risk of severe thunderstorms across portions of the Desert Southwest Sunday afternoon/evening. ...Synopsis... The upper-level ridge across the western CONUS will deamplify somewhat tomorrow as a mid-level shortwave traverses the northern Rockies and northern Plains. Farther east, a slow-moving upper-level low will continue to slowly drift east through the Ohio Valley. Thunderstorms are expected in much of the moist sector, extending from most of Texas and the Southeast through the Ohio Valley and into the Northeast. An even greater concentration of thunderstorms is likely near and east of the upper-level low across the Ohio Valley. However, wind shear will remain weak across the warm sector. Therefore, storm organization should be minimal. ...Portions of the Desert Southwest... Some thunderstorms will likely develop and move off the higher terrain across portions of Northwest Arizona Sunday afternoon/evening. Weak to moderate instability amid 30 knots of mid-level easterly flow should provide an environment favorable for a few strong to severe storms. The primary threat will be damaging winds, particularly with any clusters which may develop and move across the Colorado River Valley. ...Northern/Central Texas... There is some signal in convective allowing guidance for a potential cluster/southward moving line of storms across central Texas. A cold front will be moving south through this region which could provide the focus for more concentrated convection, and forecast MLCAPE will be around 2000-2500 J/kg. However, wind shear will be very weak and therefore, organized severe convection is not anticipated. ..Bentley.. 09/03/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1129 AM CDT Sat Sep 03 2022 Valid 031630Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF THE DESERT SOUTHWEST...SOUTHERN GREAT PLAINS...AND THE MID-SOUTH... ...SUMMARY... Isolated severe thunderstorms are possible across a portion of the Desert Southwest, the southern Great Plains, and the Mid-Mississippi and Lower Ohio River Valleys, mainly during the late afternoon and early evening. ...Interior Southern CA to northwest AZ... Isolated thunderstorm development is anticipated over interior southern CA and northwest AZ along the northern edge of a deep moisture plume. Although the stronger midlevel flow will reside farther south near the international border, slightly stronger mid-level easterly flow averaging 25 kts and steep low-level lapse rates will result in an environment conducive for isolated strong/severe wind gusts. ...Northern/west-central OK to far southern KS... Increasing frontal convergence and minimal CINH will contribute to isolated thunderstorm development by early evening along a slow-moving surface front. RAP/NAM forecast soundings depict a deep/well-mixed atmosphere and 1000-1500 J/kg MLCAPE by late afternoon. Within this environment, an isolated stronger storm will be capable of producing strong/potentially severe gusts. ...Mid-MS/Lower OH River Valleys... An increase in thunderstorm coverage is expected this afternoon/early evening east of a weak midlevel trough. Despite poor lapse rates, a very moist environment and modestly enhanced mid-level flow (20-25 kts) may yield a few storms capable of wet microbursts, especially where breaks in cloud cover result in locally greater buoyancy. Storms should diminish in intensity as the evening progresses. ..Bunting/Gleason.. 09/03/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1100 AM CDT Sat Sep 03 2022 Valid 031700Z - 041200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EXTREME NORTHEAST CALIFORNIA INTO SOUTHEAST OREGON...FAR NORTHWESTERN NEVADA AND FAR SOUTHWESTERN IDAHO... The previous forecast remains on track, with only minor changes made to the ongoing highlights to reflect the latest guidance consensus. Please see the previous outlook below for more details. ..Squitieri.. 09/03/2022 .PREV DISCUSSION... /ISSUED 1257 AM CDT Sat Sep 03 2022/ ...Synopsis... A progressive shortwave trough, evident in water-vapor imagery moving into northern California, will usher in strong winds to the northern Great Basin this afternoon. This will regionally bolster the fire weather potential after several days of hot/dry weather. Fire weather concerns are also expected to the east across the northern High Plains as gradient winds increase through the day over a region with dry fuels. ...Northern Great Basin... The jet axis associated with the northern CA shortwave trough is expected to shift across the northern Sierra Nevada into central ID through peak heating. The phasing of increasing 800-700 mb winds with deep boundary-layer mixing will support 15-25 mph winds at the surface with frequent gusts between 30-40 mph. Poor overnight RH recovery is noted across the northern Great Basin early this morning, and afternoon highs near 100 F are expected again this afternoon. Consequently, diurnal RH minimums near 5-15% are likely and will support widespread elevated to critical fire weather conditions. Fire activity across the region, supported by recent fuel analyses, lend further credence to the fire weather threat. ...Northern High Plains... Troughing in the lee of the northern Rockies will support increasing southeasterly gradient winds across eastern MT and the western Dakotas. Sustained winds near 15 mph, with occasional gusts to 20-25 mph, are likely. Combined with RH reductions into the low/mid teens, elevated fire weather conditions appear probable across a large swath of the northern High Plains. ...Dry Thunderstorms... Advected PWAT satellite imagery shows a plume of 700-500 mb moisture quickly advancing northward ahead of the northern CA shortwave trough. Strong ascent ahead of the wave will help steepen lapse rates and aid in ascent across WA into far western MT by this afternoon and evening. Forecast soundings hint that adequate buoyancy for convection atop a dry boundary-layer will limit precipitation accumulations and favor isolated dry thunderstorms. Given receptive fuel status across most of the region, a dry-lightning fire weather concern remains likely for today. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Fri Sep 2 17:48:02 UTC 2022.

No Mesoscale Discussions are in effect as of Fri Sep 2 17:48:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1220 PM CDT Fri Sep 02 2022 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHWEST AND WEST-CENTRAL ARIZONA INTO FAR SOUTHERN NEVADA AND SOUTHEASTERN CALIFORNIA... ...SUMMARY... Strong thunderstorms are possible across the higher terrain of western Arizona by late Saturday afternoon, and may spread into parts of the lower Colorado Valley and Mojave Desert Saturday evening. ...AZ into southeast CA and far southern NV... Easterly midlevel flow will persist on Saturday across AZ and adjacent portions of southeast CA and southern NV, to the south of a stout upper ridge over the Great Basin. Some drying is expected across southern AZ (compared to D1/Friday), but low-level moisture may remain sufficient for weak to moderate destabilization from the higher terrain of west-central AZ into parts of the Colorado River Valley and Mojave Desert. Storm coverage remains uncertain during the afternoon/evening, but isolated development will be possible near the western part of the Mogollon Rim. Initial discrete development will pose a threat for strong wind gusts and perhaps isolated hail, with any upscale-growing clusters capable of strong/locally severe gusts into the evening as they spread west-southwestward within the easterly midlevel flow regime. ...Southern Plains... A cold front is forecast to move into parts of the southern Plains on Saturday, though it may tend to weaken and become increasingly ill-defined with time. While large-scale ascent appears nebulous across the region, isolated thunderstorm development will be possible near the front during the afternoon. Moderate instability and modest northerly deep-layer shear could support some organized convection, though uncertainty remains high regarding storm coverage and the primary corridor of any severe threat, so probabilities have not been introduced at this time. ...Parts of the OH/TN Valleys... Widespread convection will be possible across parts of the OH/TN Valleys on Saturday, east of a nearly stationary midlevel trough over the eastern Ozarks region. Isolated downbursts cannot be ruled out during the afternoon, but midlevel lapse rates and deep-layer shear currently appear too weak to support a more organized severe-thunderstorm threat within this regime. ..Dean.. 09/02/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1136 AM CDT Fri Sep 02 2022 Valid 021700Z - 031200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE SOUTHERN CASCADES INTO THE NORTHERN SIERRA... The primary change made to this outlook was to expand Critical highlights further west into south-central Oregon, where the latest guidance consensus has trended more favorably in terms of Critical surface winds/RH overlapping for several hours late this afternoon. Otherwise, the previous forecast (see below) remains on track. ..Squitieri.. 09/02/2022 .PREV DISCUSSION... /ISSUED 1254 AM CDT Fri Sep 02 2022/ ...Synopsis... Great Basin ridging is forecast to remain in place over the next several days, but will deamplify slightly as a shortwave trough impinges on its western periphery late tonight. Ahead of the approaching trough, strengthening flow over the northern Sierra will bolster low-level winds across the northern Great Basin and portions of the Northwest. At the same time, a weak cold front will move into the Plains supporting dry and breezy post-frontal conditions. Elevated to critical fire weather conditions are possible across the Great Basin and central Plains. ...Northern Great Basin to the southern Cascades... Ahead of the trough moving onshore across the West Coast, mid-level flow is forecast to increase late in the day across portions of northern CA/NV, into southern OR. Dry downslope flow from the Sierra, and warm diurnal temperatures will result in afternoon RH values of 10-15%. As flow aloft strengthens, occasional gusts of 15-25 mph should develop within the warm and dry airmass. With area fuels critically dry, spotty critical fire weather conditions appear probable into the evening hours. Farther north, enhanced westerly flow through terrain gaps in the lee of the Cascades may occasionally gust to 15-20 mph through the afternoon. With very warm temperatures expected RH values are forecast to fall to near 30%. Dry and unstable condition may support a few hours of locally elevated fire weather concerns mainly across portions of interior WA where fuels are very dry. ...Central Plains... In the wake of a cold front moving south out of the northern Plains, gusty northwest winds are expected within a modestly dry post-frontal airmass across portions of western NE and northern CO. While RH will be marginally supportive (25-30%) the gusty winds and locally dry fuels should support a few hours of elevated fire weather risk through the afternoon. Fire concerns will decrease quickly this evening and overnight as better humidity recoveries develop within the cooler air behind the front. ...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 1130 AM CDT Fri Sep 02 2022 Valid 021630Z - 031200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF ARIZONA/LOWER COLORADO RIVER VALLEY... ...SUMMARY... Isolated severe thunderstorms are possible late this afternoon and evening over parts of central/southern Arizona and the Lower Colorado River Valley, and from the central Great Plains to the Upper Great Lakes. ...Arizona/Lower Colorado Valley... Visible satellite shows relatively cloud-free skies, which will be conducive for ample insolation/heating coincident with a relatively moist air mass, with prevalent 60s F surface dewpoints in the lower elevations of southern Arizona and middle 50s F dewpoints along the Mogollon Rim as of late morning. An increase in storm coverage as compared to yesterday seems probable. Easterly mid-level/steering winds are and will remain notably strong as the upper high builds to the north over the Great Basin/central Rockies. Upwards of 25-30 kt mid-level winds are plausible across the southern half of Arizona, which would be conducive for storm organization/upscale growth and propagation onto the lower elevations/desert floor and Lower Colorado River Valley. Initial discrete development over the higher terrain/near the Rim will pose a risk for localized severe wind gusts and marginally severe hail. However, a more organized/substantial wind threat may emerge with upscale-growing/MCS development by evening. ...Central Plains to Upper Great Lakes... The primary shortwave trough over northeast Manitoba will shift east across southern Hudson Bay/far northern Ontario, with the trailing part of this trough moving across the Upper Great Lakes. A weak mid-level trough will meander east across the Ozarks. In between these features, deep-layer shear will be enhanced across the central Great Plains owing to 25-35 kt mid-level north-northwesterly winds. Weaker deep-layer shear is anticipated with northeast extent along a cold front pushing southeastward across the Upper Midwest. A greater potential for scattered thunderstorms along the front should exist in the southeast Minnesota/northern Wisconsin/Upper Michigan vicinity given more pronounced low-level convergence and trailing influence of the Ontario trough. Multicell clusters mainly producing isolated damaging winds and perhaps marginally severe hail will be the primary threats. A more isolated thunderstorm coverage is anticipated into southeast Nebraska and northern Kansas, but given the greater vertical shear and nearly perpendicular orientation of mid-level flow with respect to the front, a few transient supercells embedded within a cluster or two may develop. Isolated severe wind and hail will be possible, with increasing MLCIN after dusk being detrimental for sustaining severe potential later into the evening. ..Guyer/Bentley.. 09/02/2022 Read more