Severe Storms

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0247 PM CDT Tue May 23 2023 Valid 232000Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHEASTERN NEW MEXICO SOUTHEASTWARD INTO CENTRAL TEXAS... ...SUMMARY... Scattered severe thunderstorms will be possible across west to central Texas later this afternoon into tonight. A few intense storms are possible this evening. These will be capable of producing very large hail to around baseball size, severe wind gusts to around 80 mph, and brief tornadoes. ...Discussion... Aside from minor adjustments to the thunder line in a few areas, substantial changes to the outlook do not appear necessary at this time, as the current forecast continues to reflect ongoing and anticipated convective evolution. The most substantial change to the severe risk areas at this time, is to extend the 5% hail probability area northwestward across Florida into the Panhandle, where a few storms have occasionally intensified to levels consistent with hail in excess of 1" in diameter. ..Goss.. 05/23/2023 .PREV DISCUSSION... /ISSUED 1129 AM CDT Tue May 23 2023/ ...Southern High Plains to central TX... With widespread upper 50s to mid 60s surface dew points established and steeper mid-level lapse rates (around 1 C/km greater) sampled in 12Z MAF/AMA soundings compared to yesterday, larger MLCAPE from 2000-3000 J/kg is anticipated at peak heating ahead of the dryline in west to central TX. This will aid in a broader swath of severe thunderstorm potential during the late afternoon and evening relative to yesterday. A trio of minor MCVs are evident in water vapor/radar imagery...over east TX, north-central OK, and northeast NM. The latter impulse in conjunction with terrain enhancement and weak convergence along the dryline should aid in scattered thunderstorms forming towards mid-afternoon from northeast NM to the South Plains, with isolated thunderstorms also over the Trans-Pecos. Despite weak SRH initially, 30-35 kt effective bulk shear with relatively straight-line hodographs should foster outflow-dominated, splitting supercells with a primary threat of very large hail. Morning CAM guidance is varied in the duration of discrete supercell mode but the consensus appears to indicate a quicker transition to upscale growth relative to yesterday's event. The most likely area for MCS occurrence appears to be across the Big Country vicinity, with severe wind gust potential likely lingering longer tonight (wind reports yesterday ending around 02Z) and farther southeast into central TX, owing to the greater buoyancy today. ...FL... An MCV remains anchored over west-central AL with a low-amplitude trough extending south into the northern Gulf. Ahead of this, scattered thunderstorms are ongoing over the northeast Gulf and will also occur in a few hours along the sea breezes across the peninsula. Weak mid-level lapse rates sampled in 12Z soundings will continue to be a limiting factor to more substantial instability, but 20-30 kt effective bulk shear should support multicell clustering with a primary threat of sporadic downbursts producing locally damaging winds. ...Northeast NV/northwest UT and southeast ID... An upper trough with a series of embedded shortwave impulses will remain anchored from the Canadian Rockies south into northern CA. The fringe of enhanced mid-level south-southwesterlies should overlap a weak buoyancy plume characterized by MLCAPE from 250-750 J/kg over the northern Great Basin this afternoon. Scattered multicell clusters are expected in this corridor, with the potential for isolated severe gusts and small hail. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0245 PM CDT Tue May 23 2023 Valid 241200Z - 251200Z Latest ERC guidance suggests fuels may still be marginally dry, especially at lower terrain where less precipitation has fallen, into portions of west-central New Mexico. Therefore, since this is where winds and low relative humidity are expected to be strongest and driest, expanded the Elevated delineation across this region. However, the threat will primarily be at lower elevation in more fine fuels. ..Bentley.. 05/23/2023 .PREV DISCUSSION... /ISSUED 1217 AM CDT Tue May 23 2023/ ...Synopsis... Persistent troughing across the West Coast and the Pacific Northwest will lead to continued dry and windy conditions across much of the Southwest on Wednesday. Many areas within Arizona, southern Nevada, and northern and central New Mexico have received above normal rainfall in the last seven days. This will keep fire concerns low in these regions. Less rainfall was received across portions of far southern New Mexico, where fuels are expected to experience multiple days of windy and dry conditions earlier in the week. Given potential for modest drying of fuels, an Elevated delineation has been included within the region where relative humidity reductions to 10-15 percent amid sustained winds around 15-20 mph. ...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 1231 PM CDT Tue May 23 2023 Valid 241200Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHERN HIGH PLAINS AREA... ...SUMMARY... Strong to locally severe thunderstorms are possible from the central and southern High Plains into northwest Texas. ...Central and southern High Plains into central Texas... While Day 1 convection will affect convective potential across portions of the southern Plains for Tuesday, it appears that destabilization of the seasonably moist boundary layer should result in scattered storm development during the afternoon and into the evening. While prior outflows will likely focus some convective development, a favored location for new storm development appears to be along the front range, south to northeastern New Mexico. While potential for locally gusty/damaging winds and hail will be possible across a broad area -- extending as far southeastward as central Texas, the greatest risk appears to exist across the TX/OK Panhandle vicinity. Here, storms are expected to develop over the higher terrain of northeastern New Mexico/southeastern Colorado, and then potentially grow upscale into a southeastward-propagating MCS through late afternoon and into the evening. Aided by low-level southeasterly flow beneath moderate mid-level northwesterlies, potential for damaging winds and hail can be expected as the MCS matures, spreading southeastward toward parts of western North Texas before weakening diurnally. ...Central and southern Florida... With the southern portion of an eastern U.S. trough lingering across Florida, providing both a slightly enhanced flow field aloft, and cool mid-level temperatures/steep lapse rates aloft, scattered, potentially strong afternoon thunderstorms are forecast to once again develop across much of the Florida Peninsula. Storms are expected near both sea-breeze boundaries, with some merging of storms over central portions of the Peninsula expected. Aided by the enhanced mid-level flow, a few of the stronger cells may produce locally strong/damaging wind gusts, and marginal hail into the early evening hours before storms diurnally diminish. ...Parts of the Great Basin into Montana... Modest afternoon destabilization is forecast across portions of the Great Basin/northern Rockies Tuesday, in the vicinity of a surface front associated with mid-level troughing that will remain quasi-stationary across the West. As afternoon convection develops near the front, and over terrain-favored areas, a few stronger/organized storms should evolve -- aided by mid-level south-southwesterlies around 30 kt. Given potential for locally strong/gusty winds with stronger cells through late afternoon/early evening, and potential for hail as well, upgrade to MRGL risk is warranted. ..Goss.. 05/23/2023 Read more

MD 0840 CONCERNING SEVERE THUNDERSTORM WATCH 231... FOR PORTIONS OF THE TX PANHANDLE...SOUTHWEST OK...AND WESTERN NORTH TEXAS
Mesoscale Discussion 0840 NWS Storm Prediction Center Norman OK 0345 PM CDT Mon May 22 2023 Areas affected...portions of the TX Panhandle...southwest OK...and western North Texas Concerning...Severe Thunderstorm Watch 231... Valid 222045Z - 222215Z The severe weather threat for Severe Thunderstorm Watch 231 continues. SUMMARY...Scattered thunderstorms are expected to continue this afternoon and into this evening. An initial threat for hail will likely transition more to damaging winds as cells cluster later this afternoon/evening. DISCUSSION...As of 2040 UTC, regional radar analysis showed scattered thunderstorms ongoing across portions of the TX Panhandle and far southwestern OK within WW231. Over the last couple of hours, storms have intensified with MRMS MESH showing cores supportive of hail in the 1-2" range. While storms have predominately been multi-cellular thus far, transient mid-level rotation has also been noted with area VADs showing effective shear of 25-30 kt. The mixed storm mode should continue this afternoon, with a threat for large hail and isolated damaging wind gusts. Given the number of storms, cells should gradually merge into one or more southeastward-moving clusters as outflow consolidates, similar to what the latest HRRR data suggests. A locally greater threat for damaging winds may then evolve across portions of the southeastern Panhandle where consolidating storms and stronger outflow may support some severe gusts this evening. ..Lyons.. 05/22/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OUN...LUB...AMA... LAT...LON 33510197 34100202 34310193 34590171 34640166 35310111 35490105 35630091 35660060 35389981 35239949 34639934 33749952 33469992 33280024 33060124 33200182 33510197 Read more

MD 0839 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF SOUTHWEST INTO CENTRAL MT
Mesoscale Discussion 0839 NWS Storm Prediction Center Norman OK 0341 PM CDT Mon May 22 2023 Areas affected...Parts of southwest into central MT Concerning...Severe potential...Watch unlikely Valid 222041Z - 222245Z Probability of Watch Issuance...20 percent SUMMARY...A threat for isolated hail and localized severe gusts will continue through the rest of the afternoon. Watch issuance remains unlikely. DISCUSSION...At 2030 UTC, a weakly organized storm cluster is moving across west-central MT, with some recent development noted into southwest MT. The cluster approaching Great Falls has mostly only produced subsevere hail and wind thus far, though some increase in severe potential remains possible as it moves into an increasingly unstable environment downstream, where steeper low-level lapse rates may favor an uptick in severe wind potential. However, with generally modest buoyancy and stronger deep-layer flow/shear expected to remain northwest of the strongest convection, the severe threat is still expected to remain isolated at best. Additional cells/clusters may evolve out of developing convection in southwest MT and move northeastward, with a similar risk of isolated hail and localized strong/severe gusts. The overall severe risk still appears too marginal and isolated for watch issuance. ..Dean/Grams.. 05/22/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BYZ...GGW...TFX...MSO... LAT...LON 46660929 45921010 45081136 44511247 44871342 44981347 45391371 45601334 45981264 46401192 48371122 48540994 48570916 47660869 47210890 46660929 Read more

WW 0231 Status Updates
STATUS REPORT ON WW 231 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..LYONS..05/22/23 ATTN...WFO...OUN...AMA...LUB... STATUS REPORT FOR WS 231 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS OKC009-055-057-065-222140- OK . OKLAHOMA COUNTIES INCLUDED ARE BECKHAM GREER HARMON JACKSON TXC011-023-045-075-087-101-107-125-129-153-155-169-179-189-191- 197-263-269-275-303-305-345-433-437-483-487-222140- TX . TEXAS COUNTIES INCLUDED ARE ARMSTRONG BAYLOR BRISCOE CHILDRESS COLLINGSWORTH COTTLE CROSBY DICKENS DONLEY FLOYD FOARD GARZA GRAY HALE HALL HARDEMAN KENT KING KNOX LUBBOCK LYNN MOTLEY STONEWALL SWISHER WHEELER WILBARGER Read more

WW 231 SEVERE TSTM OK TX 221920Z - 230300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 231 NWS Storm Prediction Center Norman OK 220 PM CDT Mon May 22 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Southwest Oklahoma Northwest Texas * Effective this Monday afternoon and evening from 220 PM until 1000 PM CDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2 inches in diameter possible Scattered damaging wind gusts to 70 mph possible A tornado or two possible SUMMARY...Scattered thunderstorms appear to be developing across the southeast Texas Panhandle and Low Rolling Plains. A few lower-end supercells and multicell clusters should develop with an initial threat of large hail transitioning to mainly severe wind during the early evening. The severe thunderstorm watch area is approximately along and 60 statute miles east and west of a line from 60 miles north of Childress TX to 100 miles south southwest of Childress TX. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU1). 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 2 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 450. Mean storm motion vector 30020. ...Grams Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0248 PM CDT Mon May 22 2023 Valid 222000Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHWEST TEXAS VICINITY... ...SUMMARY... Isolated to scattered severe thunderstorms are likely across the Oklahoma/Texas Panhandles into northwest Texas through late evening. Large hail and severe wind gusts will be the primary hazards. ...Southern High Plains... The previous forecast largely remains on track with only minor adjustments needed. Wind probabilities were adjusted slightly to account for where convective initiation is occurring and confidence in the downstream wind threat is correspondingly higher. See MCD #838 for additional details on the near-term forecast. ...MT... Across MT, the initial convection noted in MCD #837 has demonstrated periods of organization with a bowing segment approaching the Great Falls, MT area. However, this segment has not maintained consistent intensity per GOES IR imagery over the past 1-2 hours, and downstream buoyancy remains uncertain. Confidence in a more widespread wind threat remains too limited for higher probabilities, but a few additional strong/severe storms remain probable. ..Moore.. 05/22/2023 .PREV DISCUSSION... /ISSUED 1129 AM CDT Mon May 22 2023/ ...TX/OK Panhandles to the Lower Pecos Valley... An MCV over southwest KS will drift quite slowly east-southeast through tonight. Modestly enhanced westerly mid-level flow (25-30 kts at 500 mb) will be displaced to the south of this MCV, centered across the southern TX Panhandle to the Permian Basin. Cloud coverage is most pronounced close to the MCV, with robust boundary-layer heating expected from the central/southern TX Panhandle southward towards the Pecos Valley. This heating will be coincident with the northwest extent of upper 50s to lower 60s surface dew points and the eastern extent of the elevated mixed layer, supporting moderate buoyancy with MLCAPE of 1500-2000 J/kg. Scattered thunderstorms should develop towards mid-afternoon across the eastern Panhandles into the South Plains, with more isolated activity into the Trans-Pecos. Within the belt of enhanced mid-level flow, adequate effective bulk shear (from 30-35 kts) and 0-3 km SRH should exist for a few slow-moving supercells. Flow will largely remain neutral to decreasing with height above the mid-levels north of the Permian Basin. A mix of transient supercells and multicell clusters can be expected, with a tendency for upscale growth along consolidating outflows by early evening as a modest increase in low-level warm theta-e advection occurs. Overall setup should favor isolated to scattered large hail from quarter to golf ball size and 50-70 mph wind gusts. Any MCS this evening in the western north TX vicinity should weaken after sunset as it impinges on increasing MLCIN to its southeast. ...MT... An upper-level trough will largely remain anchored over the Canadian to the northern U.S. Rockies during the period, with an embedded shortwave impulse rotating through north ID/northwest MT to the southern British Columbia/Alberta region this afternoon. An attendant surface cold front will push eastward across western MT and serve as a focus for isolated to scattered high-based thunderstorm development. Boundary-layer dew points from the mid to upper 40s suggest MLCAPE will remain weak from 500-1000 J/kg. Stronger mid to upper-level flow will be displaced west of the front, and as convection develops it will further outpace the better flow given the track of the embedded shortwave impulse. As such, isolated severe hail is possible mainly early. A few outflow-dominated multicell clusters should become the predominant mode with a primary threat of scattered strong to isolated severe wind gusts. ...FL and Northeast Gulf Coast... A minor mid-level impulse will drift slowly east over MS/AL, with a diffuse west/east-oriented quasi-stationary front to its southeast. Scattered thunderstorms are already ongoing along and just north of this front across south GA into extreme north FL. Additional thunderstorms will develop shortly along the sea breezes down the Peninsula, with numerous colliding convective outflows expected later this afternoon. Mid-level lapse rates will remain weak south, and more moderate to the north, with lower-level winds also remaining weak area wide. Pockets of scattered to broken cloud coverage in the Peninsula and separately over the FL Panhandle into south AL will support steeper low-level lapse rates that will favor sporadic strong to severe outflow gusts of 45-60 mph. Isolated, marginally severe hail will also be possible, mainly with any cells that can be rooted on southwest to south-moving outflows. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0248 PM CDT Mon May 22 2023 Valid 222000Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHWEST TEXAS VICINITY... ...SUMMARY... Isolated to scattered severe thunderstorms are likely across the Oklahoma/Texas Panhandles into northwest Texas through late evening. Large hail and severe wind gusts will be the primary hazards. ...Southern High Plains... The previous forecast largely remains on track with only minor adjustments needed. Wind probabilities were adjusted slightly to account for where convective initiation is occurring and confidence in the downstream wind threat is correspondingly higher. See MCD #838 for additional details on the near-term forecast. ...MT... Across MT, the initial convection noted in MCD #837 has demonstrated periods of organization with a bowing segment approaching the Great Falls, MT area. However, this segment has not maintained consistent intensity per GOES IR imagery over the past 1-2 hours, and downstream buoyancy remains uncertain. Confidence in a more widespread wind threat remains too limited for higher probabilities, but a few additional strong/severe storms remain probable. ..Moore.. 05/22/2023 .PREV DISCUSSION... /ISSUED 1129 AM CDT Mon May 22 2023/ ...TX/OK Panhandles to the Lower Pecos Valley... An MCV over southwest KS will drift quite slowly east-southeast through tonight. Modestly enhanced westerly mid-level flow (25-30 kts at 500 mb) will be displaced to the south of this MCV, centered across the southern TX Panhandle to the Permian Basin. Cloud coverage is most pronounced close to the MCV, with robust boundary-layer heating expected from the central/southern TX Panhandle southward towards the Pecos Valley. This heating will be coincident with the northwest extent of upper 50s to lower 60s surface dew points and the eastern extent of the elevated mixed layer, supporting moderate buoyancy with MLCAPE of 1500-2000 J/kg. Scattered thunderstorms should develop towards mid-afternoon across the eastern Panhandles into the South Plains, with more isolated activity into the Trans-Pecos. Within the belt of enhanced mid-level flow, adequate effective bulk shear (from 30-35 kts) and 0-3 km SRH should exist for a few slow-moving supercells. Flow will largely remain neutral to decreasing with height above the mid-levels north of the Permian Basin. A mix of transient supercells and multicell clusters can be expected, with a tendency for upscale growth along consolidating outflows by early evening as a modest increase in low-level warm theta-e advection occurs. Overall setup should favor isolated to scattered large hail from quarter to golf ball size and 50-70 mph wind gusts. Any MCS this evening in the western north TX vicinity should weaken after sunset as it impinges on increasing MLCIN to its southeast. ...MT... An upper-level trough will largely remain anchored over the Canadian to the northern U.S. Rockies during the period, with an embedded shortwave impulse rotating through north ID/northwest MT to the southern British Columbia/Alberta region this afternoon. An attendant surface cold front will push eastward across western MT and serve as a focus for isolated to scattered high-based thunderstorm development. Boundary-layer dew points from the mid to upper 40s suggest MLCAPE will remain weak from 500-1000 J/kg. Stronger mid to upper-level flow will be displaced west of the front, and as convection develops it will further outpace the better flow given the track of the embedded shortwave impulse. As such, isolated severe hail is possible mainly early. A few outflow-dominated multicell clusters should become the predominant mode with a primary threat of scattered strong to isolated severe wind gusts. ...FL and Northeast Gulf Coast... A minor mid-level impulse will drift slowly east over MS/AL, with a diffuse west/east-oriented quasi-stationary front to its southeast. Scattered thunderstorms are already ongoing along and just north of this front across south GA into extreme north FL. Additional thunderstorms will develop shortly along the sea breezes down the Peninsula, with numerous colliding convective outflows expected later this afternoon. Mid-level lapse rates will remain weak south, and more moderate to the north, with lower-level winds also remaining weak area wide. Pockets of scattered to broken cloud coverage in the Peninsula and separately over the FL Panhandle into south AL will support steeper low-level lapse rates that will favor sporadic strong to severe outflow gusts of 45-60 mph. Isolated, marginally severe hail will also be possible, mainly with any cells that can be rooted on southwest to south-moving outflows. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0240 PM CDT Mon May 22 2023 Valid 231200Z - 241200Z ...NO CRITICAL AREAS... No changes. See previous forecast below. ..Bentley.. 05/22/2023 .PREV DISCUSSION... /ISSUED 0125 AM CDT Mon May 22 2023/ ...Synopsis... A trough across the Pacific Northwest will begin to dig southward Tuesday, scouring out remaining moisture across the Southwest. Southwest winds will increase, with potential for areas of Elevated meteorological conditions across the lower elevations of Arizona, southern Nevada, and southern New Mexico. These regions have seen above normal recent rainfall, with unseasonably moist fuels, precluding the need to include any areas. ...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 0240 PM CDT Mon May 22 2023 Valid 231200Z - 241200Z ...NO CRITICAL AREAS... No changes. See previous forecast below. ..Bentley.. 05/22/2023 .PREV DISCUSSION... /ISSUED 0125 AM CDT Mon May 22 2023/ ...Synopsis... A trough across the Pacific Northwest will begin to dig southward Tuesday, scouring out remaining moisture across the Southwest. Southwest winds will increase, with potential for areas of Elevated meteorological conditions across the lower elevations of Arizona, southern Nevada, and southern New Mexico. These regions have seen above normal recent rainfall, with unseasonably moist fuels, precluding the need to include any areas. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No Mesoscale Discussions are in effect as of Sun May 21 21:45:07 UTC 2023.

WW 0230 Status Updates
STATUS REPORT ON WW 230 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..SMITH..05/21/23 ATTN...WFO...BOI...MSO...OTX...PDT... STATUS REPORT FOR WS 230 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IDC003-035-045-049-061-069-075-085-087-220000- ID . IDAHO COUNTIES INCLUDED ARE ADAMS CLEARWATER GEM IDAHO LEWIS NEZ PERCE PAYETTE VALLEY WASHINGTON ORC001-023-025-045-061-063-220000- OR . OREGON COUNTIES INCLUDED ARE BAKER GRANT HARNEY MALHEUR UNION WALLOWA WAC003-220000- WA . WASHINGTON COUNTIES INCLUDED ARE ASOTIN Read more

WW 230 SEVERE TSTM ID OR WA 212105Z - 220400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 230 NWS Storm Prediction Center Norman OK 205 PM PDT Sun May 21 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Western and Central Idaho Eastern Oregon Southeast Washington * Effective this Sunday afternoon and evening from 205 PM until 900 PM PDT. * Primary threats include... Isolated damaging wind gusts to 70 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...Widely scattered thunderstorms will continue to develop through late afternoon, with sufficient instability and deep-layer winds to support potentially severe storms capable of hail and locally damaging winds. The severe thunderstorm watch area is approximately along and 65 statute miles east and west of a line from 45 miles southwest of Rome OR to 30 miles north northwest of Lowell ID. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU0). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 24025. ...Guyer Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Sun May 21 2023 Valid 212000Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN OREGON AND NORTHEAST WASHINGTON INTO WESTERN AND NORTHERN IDAHO... ...SUMMARY... Scattered severe thunderstorms are possible across portions of the interior Northwest, centered on 2 to 9 PM PDT. Large hail and isolated damaging gusts will be the primary hazards. ...20z Update... Other than trimming the 10 percent general thunderstorm line across parts of GA and the Carolinas, severe probabilities remain unchanged from the previous outlook. A few strong storms remain possible across parts of southeast GA into northern FL. For details on short term severe thunderstorm potential across that area, reference MCD 831. Severe thunderstorms are also expected to develop across parts of eastern OR into northeast WA and western/northern ID from late afternoon through the evening. Large hail and gusty winds are expected with this activity. For info on short term severe potential across the area, reference MCDs 832 and 833. ..Leitman.. 05/21/2023 .PREV DISCUSSION... /ISSUED 1118 AM CDT Sun May 21 2023/ ...Interior Northwest... Around the northwest periphery of a mid-level anticyclone over the Great Basin, a plume of 0.75 to 1 inch PW values will support rounds of convection persisting into early tonight. The threat for scattered afternoon/evening thunderstorms will shift eastward compared to prior days as a shortwave trough off the Pacific Northwest coast shifts inland into WA/OR. A weak 1013 mb surface low over eastern WA and attendant cold front arcing southwest into south-central OR will be the focus for more vigorous thunderstorm development later this afternoon. Low to mid 50s boundary-layer dew points will contribute to a corridor of MLCAPE from 1000-1500 J/kg in an arc ahead of the cold front. This moderate buoyancy along with strengthening speed shear above 700 mb will favor a few high-based supercells with mid-level rotation, especially over eastern OR to the southern ID Panhandle and in far northeast WA/northern ID Panhandle. Large hail should be the primary initial threat. Consolidating cells will yield more multicell clustering into the evening with an isolated mix of severe wind gusts and hail, before convection weakens over the northern Rockies after sunset. ...Southeast GA and the north FL Peninsula... A diffuse front along with colliding sea breezes will support scattered thunderstorms into early evening. 12Z JAX/TLH observed soundings sampled a belt of enhanced speed shear through the mid to upper-levels, which may be adequate to foster small hail production despite poor mid-level lapse rates. This may yield precip-loaded, locally strong downbursts in the more intense cells as MLCAPE peaks from 1500-2000 J/kg. ...Southern High Plains... Scattered, slow-moving thunderstorms are expected later this afternoon into the evening within a weakly buoyant air mass characterized by MLCAPE of 500-1000 J/kg. Modest mid-level lapse rates (especially compared to late May climo) away from the higher terrain and relatively weak vertical shear suggest that organized severe storms are unlikely. A very low probability of marginally severe hail and wind exists, but appears too minimal to warrant an areal delineation. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0206 PM CDT Sun May 21 2023 Valid 221200Z - 231200Z ...NO CRITICAL AREAS... No changes. See previous discussion below. ..Bentley.. 05/21/2023 .PREV DISCUSSION... /ISSUED 1230 AM CDT Sun May 21 2023/ ...Synopsis... Moisture will gradually decrease across the Southwest into Monday as a weak upper level low meanders back south over the Baja Peninsula with a return to breezy west to southwest winds. Above normal rainfall within this region has left fuels less receptive to fire spread, precluding the need to include any areas. ...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 1217 PM CDT Sun May 21 2023 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF THE TX PANHANDLE AND SOUTH PLAINS INTO FAR WESTERN OKLAHOMA... ...SUMMARY... Severe thunderstorms are possible across portions of the southern High Plains Monday afternoon and evening. Large hail and damaging gusts will be the primary hazards with these storms. Additional strong to isolated severe thunderstorms are possible across portions of Montana, and parts of southern Alabama/Georgia into Florida. ...Southern Plains... Convectively induced vorticity maxima are forecast to float across the southern Plains in the vicinity of the OK/TX Panhandles to western OK on Monday. This will lead to some enhancement of vertical shear in an otherwise weak flow regime. Boundary-layer moisture will remain modest by late-May standards, though some increase in southerly low-level flow will support 50s to low 60s F dewpoints. Thunderstorms will likely develop near the TX/NM border southward into southwest TX along a weak surface trough. This activity will likely remain isolated and only marginally severe on the back side of the MCV. Vertical shear will remain weak, but a deeply mixed boundary-layer will support strong outflow winds. Additional thunderstorms are likely to initiate on the eastern side of the MCV and within low-level convergence across the TX Panhandle/South Plains vicinity. Enhanced shear courtesy of the MCV will allow for some higher-based supercell structures. Midlevel lapse rates will remain on the weaker side, around 6.5-7 C/km, but MLCAPE around 1000-1500 J/kg in conjunction with effective shear magnitudes around 30-35 kt will support some stronger, organized updrafts capable of severe hail. Strong heating will foster steep low-level lapse rates and severe gusts also will be possible, with some potential for upscale growth during the evening near the TX/OK border into western OK. Tornado potential will likely be limited by modest boundary-layer moisture and generally weak low-level shear, but a tornado cannot be entirely ruled out given some enlargement of low-level hodographs toward 00z as a modest low level jet increases. ...Montana... An approaching midlevel trough and increasing midlevel moisture on southwesterly flow aloft will support thunderstorm development over the higher terrain of west-central MT during the afternoon. This initial activity may pose a risk for hail given modestly steep midlevel lapse rates and favorable vertical shear profiles resulting in elongated hodographs. As this activity continues northeast into the adjacent high Plains over central MT, a deeply mixed boundary-layer and light low-level winds will foster potential for strong outflow winds in addition to hail. ...Southern AL/GA into FL... A seasonally moist airmass will support widespread thunderstorm development as a weak midlevel shortwave trough migrates across the region. A weak cold front and sea breeze boundaries will focus stronger development amid modest vertical shear. Multicell clusters may produce sporadic strong/locally damaging gusts. ..Leitman.. 05/21/2023 Read more

No watches are valid as of Sat May 20 21:41:02 UTC 2023.

No Mesoscale Discussions are in effect as of Sat May 20 21:41:02 UTC 2023.

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0248 PM CDT Sat May 20 2023 Valid 202000Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHWEST...THE RIO GRANDE VALLEY AND THE DEEP SOUTH... ...SUMMARY... Isolated and marginally severe thunderstorms are possible through this evening across parts of the Deep South, the Northwest, and the Rio Grande Valley. ...20z Update... Only minor adjustments have been made to the Marginal risk (level 1 of 5) across Deep South Texas and MS/AL. These changes are based on currently location of ongoing convection and the position of the surface cold front. Otherwise, the previous forecast is on track. For more details, see the 1630z Day 1 discussion below. ..Leitman.. 05/20/2023 .PREV DISCUSSION... /ISSUED 1126 AM CDT Sat May 20 2023/ ...Deep South... A low-amplitude shortwave trough over the Mid-MS Valley will move southeast towards the southern Appalachians, and will be preceded by an MCV currently centered on middle TN. Abundant cloud coverage across northern portions of AL/GA will limit boundary-layer destabilization to the immediate southeast of lingering stratiform rain attendant to the MCV. Amid poor mid-level lapse rates (5-5.5 C/km between 700-500 mb) sampled by the 12Z BMX/BNA soundings, the lack of more robust boundary-layer heating will likely mitigate appreciable severe potential with north/east extent. With more robust insolation underway farther south-southwest and richer boundary-layer moisture, a plume of moderate MLCAPE from 1500-2000 J/kg is anticipated across southern MS to central AL. This should support convective development trailing southwestward along/ahead of a southeast-moving cold front in the next few hours. With a predominant westerly deep-layer wind profile, effective bulk shear should be limited to around 20-25 kts where buoyancy is greater. Given the poor mid-level lapse rates upstream, hail sizes will probably remain small to marginally severe. A threat for isolated damaging winds should be the main hazard with multicell clusters that spread east-southeast and largely weaken after sunset. ...OR/WA... Somewhat greater convective coverage is anticipated relative to yesterday during the late afternoon and evening within a modest south-southwesterly deep-layer flow regime. The most likely corridor for scattered storm development is off the higher terrain in southern OR east of the Cascades, with more isolated activity possible across central WA. Where adequate effective bulk shear is present, largely close to the Cascades, marginally severe hail will be possible. Otherwise, isolated strong gusts will be possible in eastern OR given deeper mixed thermodynamic profiles with eastern extent. ...Southwest NM vicinity... A minor upper low persists near the northwest Sonora/southeast AZ border area and will drift north-northeast today. With low 50s surface dew points having spread west of the Rio Grande following a recent cold front intrusion, a pocket of weak buoyancy should develop with MLCAPE of 500-1000 J/kg. Effective bulk shear will likely remain weak, from only 20-25 kts as stronger speed shear is confined to the very upper portion of the buoyancy profile. Small to marginally severe hail and a few locally strong gusts cannot be ruled out. ...Deep South TX... A few strong storms remain possible later this afternoon as a cold front continues to move slowly southward. Buoyancy should remain moderate owing to broken cloud coverage ahead of the front. 0-6 km winds will remain unremarkable with moderate southwesterlies above that. In addition, mid-level lapse rates peaked this morning and are consistently progged to weaken through the day. Small to marginally severe hail and a few locally strong gusts cannot be ruled out. Read more