Severe Storms

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1149 AM CDT Wed Oct 12 2022 Valid 121700Z - 131200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE NORTHERN PLAINS... Minor adjustments were made with the forecast remaining largely on track. The Critical risk area was expanded into south-central South Dakota where low relative humidity and strong winds will likely lead to more active fire behavior in ongoing fires. Surface observations show sustained winds of 20+ mph and gusts up to 45 mph across portions of the Dakotas. Expect warming and drying through the day, as mid-level cloud cover decreases and boundary-layer deepening/mixing allows relative humidity to decrease to around 20-25 percent. VWP profiles show 50+ mph winds above the surface, which will likely lead to a further increase in the winds as the boundary layer deepens through the afternoon. The Elevated risk was extended southward into Kansas to account for areas where relative humidity may approach 20-25 percent with sustained winds at 15-20 mph. Further east, similar conditions will occur, but rainfall in the last 24 hours may have made fuels less receptive. See the previous discussion for more details. ..Thornton/Weinman.. 10/12/2022 .PREV DISCUSSION... /ISSUED 0157 AM CDT Wed Oct 12 2022/ ...Synopsis... Very strong northwesterly flow will overspread the northern Plains today as a mid-level trough amplifies. Beneath the strongest mid-level jet streak, winds of 30 to 35 mph are expected at the surface. Relative humidity will drop into the upper teens from far northeast Montana across western North Dakota and into northern South Dakota. Elsewhere, relative humidity will likely be too high to warrant a critical delineation. Farther south, across central and eastern Nebraska, some critical conditions may also develop. However, Tuesday night thunderstorms brought some rainfall to this region and therefore, fuels will likely not be as receptive. ...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 1227 PM CDT Tue Oct 11 2022 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE LOWER MS VALLEY TO THE TN AND OH VALLEYS VICINITY... ...SUMMARY... Thunderstorms, a few of which may produce strong/gusty winds and marginal hail, are expected Wednesday across parts of the Ohio/Mid and Lower Mississippi/Tennessee Valleys, and westward to the Arklatex region. ...Synopsis... A large-scale upper trough will develop eastward from the Plains on Wednesday morning, becoming oriented from the Upper Midwest to the Southeast by Thursday morning. Enhanced southwesterly flow ahead of the trough will overspread much of the Midwest, and decreasing with southward extent into the southern U.S. At the surface, a cold front extending from WI southwestward into western OK/northwest TX will sweep eastward during the forecast period. By Thursday morning, the front is expected to extend from western NY/PA toward Middle TN, southwestward toward the TX coast. ...Middle TN into the OH Valley Vicinity... Stronger vertical shear will be in place across the region, closer to the core of the upper trough and within the stronger surface pressure gradient associated with a low over Ontario. South/southwesterly low-level flow will bring a narrow corridor of upper 50s and 60s F surface dewpoints northward ahead of the eastward-advancing cold front. Heating will be limited by cloud cover and possibly early day showers. However, cooling aloft will support modestly steep midlevel lapse rates, and MLCAPE of a few hundred J/kg will be possible amid 30+ kt effective shear magnitudes. Transient supercells and briefly organized clusters could produce isolated strong storms capable of hail and strong gusts. Low-level instability will be limited, but enlarged, favorably curved surface-3 km hodographs suggest a brief tornado also could occur. ...AR into western TN/northern MS Vicinity... Additional thunderstorms are expected to develop along the front during the afternoon across AR and shift east/southeast into western TN and northern MS. Some guidance suggest an increase in hail and strong gust potential will accompany these cells. Stronger heating is expected along this corridor ahead of the front, resulting in steeper low-level lapse rates, while cooling aloft associated with the main upper trough supports steepening mid-level lapse rates. Effective shear magnitudes around 25-35 kt and favorable hodographs suggest some rotating cells will be possible. A narrow corridor of relative greater severe potential may exist within this corridor and an upgrade to Slight risk may be needed in subsequent outlooks if forecast confidence increases. ...Southern MS/AL... A lead shortwave impulse is expected to move across MS/AL during the morning/early afternoon. Scattered thunderstorms are expected in this pre-frontal warm advection regime. However, low-level thermodynamics appear weak given limited heating. Midlevel temperatures also are only forecast to be around -8 to -10 C, resulting in poor midlevel lapse rates. Effective shear magnitudes around 20-30 kt, and somewhat elongated hodographs could result in some briefly organized cells within morning thunderstorm clusters across parts of MS/AL and the FL Panhandle, though severe potential appears limited at this time. By the time the cold front moves into southern MS/AL during the evening/overnight, considerable mid/upper level drying is forecast and thunderstorms are not expected to be severe. ..Leitman.. 10/11/2022 Read more

No watches are valid as of Tue Oct 11 17:31:01 UTC 2022.

No Mesoscale Discussions are in effect as of Tue Oct 11 17:31:01 UTC 2022.

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1201 PM CDT Tue Oct 11 2022 Valid 111700Z - 121200Z A southward-advancing surface cold front will continue across the Plains this afternoon. Winds gusting 40-50 mph have been observed in surface observations across Wyoming and Montana this morning. Strong west to southwest surface winds will overlap with low relative humidity ahead of the cold front across much of the central Plains this afternoon. Dry northerly flow will be possible behind the frontal passage. Within the central High Plains Elevated area, brief periods of near-critical fire-weather conditions may be possible across the Nebraska Panhandle southward into northeastern Colorado and northwestern Kansas. ..Thornton/Weinman.. 10/11/2022 .PREV DISCUSSION... /ISSUED 0155 AM CDT Tue Oct 11 2022/ ...Synopsis... A strong upper-level trough will continue to amplify across the central CONUS today. Meanwhile a surface low will continue to deepen as it moves east across the Canadian Prairie. ...Portions of the central Plains and central High Plains... A cold front will move through the Plains today. In its wake, dry and breezy conditions will develop with winds of 15 to 25 mph and relative humidity of 10 to 25 percent expected from southeast Wyoming/northeast Colorado into Nebraska and northwest Kansas. Some critical conditions are likely, but are not expected to persist for long enough as cooler air moves in behind the front and relative humidity improves as a result. ...Portions of the Northern Plains... Very windy conditions (25 to 30 mph sustained winds) are expected in the wake of the cold front across the northern Plains. Relative humidity may be too high to support fire weather concerns in some locations, but relative humidity of 20-30 percent is expected from southeast Montana to north-central South Dakota where elevated to locally critical conditions are possible. ...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 1128 AM CDT Tue Oct 11 2022 Valid 111630Z - 121200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TONIGHT FROM THE UPPER MIDWEST INTO PARTS OF THE CENTRAL PLAINS... ...SUMMARY... Isolated severe wind and hail will be possible across parts of the Upper Midwest to the central Great Plains tonight through early Wednesday morning. ...KS to WI tonight... A northern stream shortwave trough will continue to dig southeastward and amplify over the northern Plains, as a lower latitude trough and moisture plume eject northeastward from OK/KS/MO toward IL today. A few (mainly elevated) thunderstorms will be possible within the low-midlevel moisture plume from eastern OK across MO into IL this afternoon and Lower MI by this evening. To the west of the thicker clouds and in advance of a cold front associated with the amplifying northern Plains midlevel trough, a modest increase in low-level moisture will occur today from OK to IA and WI. Though the richer low-level moisture will be confined much farther south into the Gulf of Mexico along a remnant frontal zone and with a developing tropical system in the Bay of Campeche, boundary-layer dewpoints in the mid 50s to lower 60s will spread northeastward in advance of the cold front. Regional 12z soundings revealed a relatively warm elevated mixed layer over the central/northern Plains, which will act to cap the boundary layer through this afternoon. By late evening, ascent atop the frontal surface should be sufficient for thunderstorm development across MN/western WI where the cap will be weaker, with subsequent storm development later tonight and farther southwest into KS/MO/IA. Lingering steep midlevel lapse rates and modest cloud-layer shear will support the potential for isolated large hail and strong surface wind gusts with bands of convection slightly behind the surface cold front (better chance for strong winds farther south toward KS/MO/IA). ...Southwest TX and interior southern CA this afternoon... An isolated strong storm may form this afternoon over the high terrain near Fort Stockton, where deep-layer vertical shear and buoyancy could support low-end supercell potential. However, storm coverage will be isolated at best and warming is expected in the mid levels, so any severe threat should remain too low to warrant an outlook area. Otherwise, isolated strong outflow gusts may occur in the higher terrain across southern CA this afternoon, where deeper mixing results in inverted-v profiles. The threat for severe storms appears to be low enough to preclude an outlook area. ..Thompson/Wendt.. 10/11/2022 Read more

No watches are valid as of Mon Oct 10 17:27:02 UTC 2022.

No Mesoscale Discussions are in effect as of Mon Oct 10 17:27:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1220 PM CDT Mon Oct 10 2022 Valid 111200Z - 121200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...MIDWEST...AND CENTRAL/SOUTHERN PLAINS... ...SUMMARY... Thunderstorms capable of isolated hail and strong wind gusts will be possible from parts of upper Mississippi Valley into the Midwest and central/southern Plains, mainly Tuesday evening into the overnight hours. ...Synopsis... A deep mid/upper-level trough initially covering much of western Canada is forecast to amplify and move southeastward on Tuesday, with the southern portion of the trough building into much of the Great Plains and upper Mississippi Valley by early Wednesday morning. A deep surface low is forecast to move eastward across northern Manitoba, as a trailing cold front sweeps through the northern/central Plains and eventually the upper Midwest. ...Upper MS Valley/Midwest into the central/southern Plains... Modest low-level moisture is expected to stream northward into parts of the Plains/Midwest and upper MS Valley during the day on Tuesday, in advance of the cold front. Relatively steep midlevel lapse rates will support the development of weak to locally moderate buoyancy, though a substantial capping inversion will likely limit thunderstorm initiation for much of the day. Large-scale ascent attendant to the cold front and amplifying upper-level trough may allow for thunderstorm development along the front during the evening, initially over parts of the upper Midwest/MS Valley, and then farther southwest into the central and possibly southern Plains by later Tuesday night. Given the anticipated nocturnal timing of larger-scale storm development, initial convection will likely be somewhat elevated, but sufficient buoyancy and effective shear of 25-35 kt will support the potential for organized multicells and perhaps a supercell or two. Isolated hail may be the most prevalent threat, given favorably cool temperatures aloft and relatively steep midlevel lapse rates. However, even with convection likely to become increasingly elevated with time, isolated strong/damaging gusts cannot be ruled out, given the presence of relatively strong low-level flow and a residual well-mixed boundary layer across parts of the warm sector. A broad Marginal Risk has been maintained for this outlook, though higher probabilities may eventually be needed across parts of the upper MS Valley/Midwest, especially if confidence increases in earlier, near-surface-based storm initiation. The threat becomes increasingly conditional with southwestward extent into the southern Plains, where the environment will be favorable for strong elevated storms late Tuesday night, but large-scale ascent will be weaker compared to areas to the northeast. ..Dean.. 10/10/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1127 AM CDT Mon Oct 10 2022 Valid 101630Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS WEST TEXAS... ...SUMMARY... A few thunderstorms with marginally severe hail and locally strong wind gusts are possible over the Trans-Pecos to Permian Basin of west Texas during the late afternoon to early evening. ...West Texas... A weak MCV continues to persist northeastward near the Midland-Odessa vicinity late this morning. Latest thoughts are the MCV-preceding air mass will not appreciably destabilization into the Big Country owing to ongoing cloud cover and scattered precipitation, aside from relatively weak vertical shear (Effective 20-25 kt or less). However, in the wake of the MCV, clouds continue to clear/thin across the Trans-Pecos, where upwards of 500-1000 J/kg MLCAPE is plausible later this afternoon. Weak low-level upslope flow and differential heating will likely influence widely scattered thunderstorm development by late afternoon. Aided by a modestly strong belt of southwesterly mid/high-level winds, effective shear of 25-30 kt across the Trans-Pecos will support some sustained multicells and possibly a few storms with weak mid-level updraft rotation. A few of these storms could produce marginally severe hail and/or severe-caliber wind gusts on a localized basis. ..Guyer/Wendt.. 10/10/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1128 AM CDT Mon Oct 10 2022 Valid 101700Z - 111200Z The forecast remains on track, and no changes were needed with this update. For details, see the previous discussion below. ..Weinman.. 10/10/2022 .PREV DISCUSSION... /ISSUED 1208 AM CDT Mon Oct 10 2022/ ...Synopsis... A mid/upper-level shortwave trough is forecast to amplify and move southeastward across parts of western Canada, with the southern extension of this trough building into the northern Rockies by early Tuesday morning. A deep surface low attendant to the trough is expected to move eastward across the Canadian Northwest Territories, with a surface trough extending southward through the Canadian Prairies into parts of the northern/central High Plains. ...Central NE into southern SD... A modest southerly low-level jet will support sustained winds of 15-20 mph this afternoon from central NE into southern SD, to the east of the surface trough. With an antecedent dry airmass and limited low-level moisture advection during the day, minimum RH values are expected to drop into the 20-25% range, supporting elevated fire-weather conditions as winds increase this afternoon. ...Interior Northwest/northern Rockies... An antecedent dry airmass and a modest surface pressure gradient may support locally elevated fire-weather conditions across terrain-favored areas of the interior Northwest and northern Rockies, but the duration and areal coverage of this threat is expected to be relatively limited, so no elevated delineation appears warranted for these areas. ...AL into the FL Panhandle... Locally elevated conditions will be possible across parts of AL into the FL Panhandle this afternoon, as RH values drop into the 20-30% range by peak heating. At this time, sustained winds are only expected to be around 10 mph, which should tend to limit the areal coverage and duration of elevated conditions. ...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 1250 PM CDT Sun Oct 09 2022 Valid 101200Z - 111200Z ...NO CRITICAL AREAS... In addition to the fire-weather concerns described below, locally elevated conditions are possible across parts of the Southeast (particularly AL and the western FL Panhandle) during the afternoon. Here, a very dry antecedent airmass (lower 20s minimum RH) and 10 mph northerly surface winds will raise some fire-weather concerns given increasingly dry fuels across the area. However, the lack of stronger sustained surface winds precludes an Elevated area. Elsewhere, the previous forecast (see below) remains on track. ..Weinman.. 10/09/2022 .PREV DISCUSSION... /ISSUED 0149 AM CDT Sun Oct 09 2022/ ...Synopsis... A weak trough will move into the northern/central Plains on Monday. This will result in weak lee troughing across the central Plains. Some breezy conditions may develop as a result. However, there remains considerable uncertainty whether these winds will overlap with low relative humidity. In addition, fuels in the region are only marginally dry. Therefore, no elevated delineation seems warranted at this time. Elsewhere, lee-troughing east of the Canadian Rockies will lead to a tightening pressure gradient across the Northwest and Northern Rockies. Some stronger winds are anticipated in the Columbia Basin, Snake River Valley, and in northern Montana, but these winds are not expected to overlap low relative humidity and critically dry fuels in any locations. Therefore, fire weather concerns should remain minimal. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Sun Oct 9 17:52:02 UTC 2022.

No Mesoscale Discussions are in effect as of Sun Oct 9 17:52:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1159 AM CDT Sun Oct 09 2022 Valid 101200Z - 111200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The severe-thunderstorm threat is expected to be low on Monday. ...Trans-Pecos region into parts of the southern Plains... The persistent upper-level low near the Arizona/Sonora border is expected to weaken on Monday, as one mid/upper-level shortwave trough moves southward from northern CA to offshore of southern CA, and a stronger shortwave moves southeastward and amplifies across the interior Northwest and northern Rockies. As this occurs, multiple embedded vorticity maxima are forecast to eject northeastward from the Southwest into the southern Plains. One vorticity maximum is forecast to emerge over the TX Trans-Pecos region Monday afternoon, accompanied by scattered to widespread thunderstorm development. Another storm cluster may move from northwest TX into OK through the day. Weak to locally moderate buoyancy and modest effective shear (generally peaking at 20-25 kt) will support the potential for a few strong storms capable of gusty winds and small hail, though at this time the magnitude of instability/shear appears too limited for an organized severe-thunderstorm threat. ..Dean.. 10/09/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1119 AM CDT Sun Oct 09 2022 Valid 091700Z - 101200Z ...NO CRITICAL AREAS... The forecast remains on track, and no changes are needed with this update. For details, see the previous discussion below. ..Weinman.. 10/09/2022 .PREV DISCUSSION... /ISSUED 0149 AM CDT Sun Oct 09 2022/ ...Synopsis... Very dry conditions are expected across Alabama and southern Georgia on Sunday, but winds should be light. Therefore, the threat for large fires should be minimal. Elsewhere, no breezy conditions are expected to accompany dry surface conditions and dry fuels. ...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 1115 AM CDT Sun Oct 09 2022 Valid 091630Z - 101200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms appear unlikely today. ...Southwest... The mid/upper low anchored along the AZ/Sonora border will remain nearly stationary through tonight. Scattered afternoon thunderstorms are once again expected ahead of this feature from southeast AZ to the TX Trans-Pecos and north to the Four Corners area. Strong storm potential will be limited by weak effective shear across much of the region. A couple of storms may produce small hail and strong winds over the TX Trans-Pecos where a confined belt of 500-mb winds from 20-25 kts is expected. ...South FL... A plume of moisture characterized by PW values in excess of 2 inches will support isolated to scattered thunderstorms this afternoon from the Treasure Coast to the Paradise Coast and Everglades. Despite generally weak deep-layer winds, veering of the wind profile with height from low-level easterlies to mid-level southwesterlies should result in modest effective shear of 20-25 kt. Diurnal heating should contribute to moderate buoyancy, and a few strong storms may develop containing sub-severe hail and wind. ..Bunting/Wendt.. 10/09/2022 Read more

No watches are valid as of Sat Oct 8 17:34:01 UTC 2022.

No Mesoscale Discussions are in effect as of Sat Oct 8 17:34:01 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1142 AM CDT Sat Oct 08 2022 Valid 091200Z - 101200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The severe-thunderstorm threat is expected to be low on Sunday. ...Southwest... Scattered thunderstorms will be possible on Sunday across parts of the Southwest, in association with a persistent mid/upper-level low centered near the Arizona/Sonora border. A few strong storms capable of gusty winds and small hail cannot be ruled out, especially from southeast AZ into far west TX, where somewhat stronger instability may develop by afternoon. Weak deep-layer shear is expected to limit the organized severe-thunderstorm threat. ...Central/south Florida... Scattered thunderstorms are expected across parts of central/south Florida on Sunday, as deeper tropical moisture returns to the region. Moderate buoyancy may support a few strong storms during the afternoon into early evening, but weak deep-layer flow/shear is expected to limit storm organization. ..Dean.. 10/08/2022 Read more