Severe Storms

MD 2148 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR CENTRAL TO NORTHERN ARIZONA
Mesoscale Discussion 2148 NWS Storm Prediction Center Norman OK 0522 PM CDT Wed Sep 13 2023 Areas affected...central to northern Arizona Concerning...Severe potential...Watch unlikely Valid 132222Z - 140015Z Probability of Watch Issuance...5 percent SUMMARY...Instances of large hail will be possible for the next few hours as transient, but robust, thunderstorms continue to develop across central to northern Arizona. Watch issuance is not expected. DISCUSSION...Numerous robust, but short lived (30-60 minutes) thunderstorms continue to develop across central to northern AZ. Deep-layer flow over the region remains very weak (effective bulk shear values on the order of 15 knots), which is contributing to the short duration of most cells. However, MUCAPE over the region is near the 90th percentile for the Flagstaff, AZ region for mid-September. This, combined with mid-level lapse rates near 8 C/km, is likely supporting the robust, but transient updrafts noted in GOES IR and KFSX reflectivity imagery. Severe-hail signatures have been noted in MRMS products with these cells, suggesting that large hail is possible. This activity is largely being driven by a combination of weak low-level theta-e advection over the Mogollon Rim and lift along a composite outflow/weak dryline draped over the region. Both of these factors should continue to support thunderstorm development through sunset before the onset of nocturnal cooling. ..Moore/Edwards.. 09/13/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FGZ... LAT...LON 34151048 34381143 34551251 34791292 35231314 35721313 35881281 35791192 35591127 35301054 34981004 34690981 34510974 34250975 34121004 34151048 Read more

MD 2147 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR THE BIG BEND REGION OF TEXAS
Mesoscale Discussion 2147 NWS Storm Prediction Center Norman OK 0455 PM CDT Wed Sep 13 2023 Areas affected...The Big Bend region of Texas Concerning...Severe potential...Watch unlikely Valid 132155Z - 140000Z Probability of Watch Issuance...5 percent SUMMARY...Sporadic severe hail and wind will be possible over the next couple of hours as thunderstorms continue to mature. However, this threat will remain sufficiently limited to preclude watch issuance. DISCUSSION...Over the past 1-2 hours, GOES IR imagery has shown steadily cooling cloud top temperatures associated with a multicell cluster south of the Fort Stockton, TX area. Although individual cells within the cluster have demonstrated limited longevity and organization so far, the overall trend suggests that the potential for severe wind/hail is increasing for downstream areas. This cluster is expected to continue propagating east/southeast along a low-level theta-e gradient where buoyancy is maximized (MLCAPE up to 1500 J/kg). Furthermore, sufficient shear is present in the 0-5 km layer to support supercell structures, though the observed storm mode will likely continue to modulate this potential. While the severe threat is noted, these limitations will preclude the need for a watch. To the west, a cluster of storms across northern Mexico is undergoing similar intensification per GOES IR imagery, and should cross the TX/Mexico border within the next hour. These cells may intensify further as they move towards the regional buoyancy maximum, and could also pose a severe hail/wind threat along and just north of the Rio Grande. ..Moore/Edwards.. 09/13/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...EWX...MAF... LAT...LON 28990292 28890323 29440441 29720466 30190487 30420495 30610487 30650469 30670442 30520386 30500352 30620314 30760265 30760242 30660213 30410183 29850168 29700174 29750210 29630259 28990292 Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0449 PM CDT Wed Sep 13 2023 Valid 151200Z - 211200Z Mid-level ridging will remain in place over the Northwest through the first part of the extended forecast period. While winds will be weak, warm and dry conditions beneath the ridge may promote localized fire-weather concerns. Into the weekend and early next week, prominent troughing will likely develop over the Northwest, ushering in cooler and wetter conditions for the remainder of the forecast period. Overall fire-weather concerns remain low given the poor overlap of dry and windy conditions with receptive fuels. ...Northwest... As the upper ridge solidifies and shifts eastward late this week and into the weekend, low-level northerly flow is forecast to weaken over much of southern OR and northern CA. At the same time, the ridge aloft will promote dry and warm surface conditions across much of the Pacific Northwest. The warm and dry surface conditions, combined with only modest mid-level stability, may support some plume-dominated fire activity into the first part of the weekend. The strong heating and terrain effects may also support the development of a low-level thermal pressure trough, occasionally enhancing local winds to 10-15 mph across parts of the Columbia Basin and southern OR. However, given the lack of stronger synoptic flow, confidence in sustained fire-weather conditions is low. As the upper ridge shifts eastward, a weak, upper low will meander toward the CA coast from the eastern Pacific. At the same time, a broad upper trough and stronger flow aloft are forecast to move onshore across western BC. Ascent and weak mid-level moisture transport ahead of the upper-level systems may support isolated showers and thunderstorms across parts of southern OR and northern CA D4/D5 Sat/Sun. Modest storm speeds and a relatively dry sub-cloud layer could support a risk for a few dry lightning strikes over receptive fuels through the weekend. Considerable uncertainty exists regarding storm coverage and mode given the relatively modest forcing for ascent. Storm coverage appears greatest D5/Sun, but may shift eastward toward areas of less receptive fuels. Confidence lessens considerably heading into next week as various model solutions exist with the BC trough shifting eastward. ...Northern Rockies... Late in the weekend and into early next week, stronger westerly flow may emerge from the Northwest troughing into parts of the northern Rockies/Plains. There remains considerable model difference in the medium range. The GFS and some ensemble members are much stronger and more amplified with the overall upper air pattern. With the more amplified solutions, a strong cold front accompanying the upper trough may promote dry and breezy conditions over parts of Columbia Basin, eastern MT and western ND early next week. It remains uncertain if this will occur, but it may favor some potential for elevated fire-weather conditions next week. ..Lyons.. 09/13/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Wed Sep 13 2023 Valid 132000Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN NEW ENGLAND...PARTS OF THE SOUTHEAST...AND THE SOUTHWEST INTO WEST TEXAS... ...SUMMARY... Isolated severe thunderstorms remain possible across parts of southern New England, the Southwest into West Texas, and from Georgia to the South Atlantic coast this afternoon into this evening. ...20Z Update... A few thunderstorms have developed this afternoon across CT into Long Island Sound, in the wake of earlier morning convection. Wind profiles (as noted in VWPs from KOKX and KBOX) continue to be somewhat favorable for organized convection, and locally damaging gusts and/or a brief tornado remain possible through the remainder of the afternoon and potentially into the early evening. The Marginal Risk has been trimmed slightly from the west, but otherwise maintained across parts of southern New England. See MCD 2146 for more information. Elsewhere, the Marginal Risks across parts of the Southeast and Southwest/West TX remain unchanged. See the previous discussion below for more information. ..Dean.. 09/13/2023 .PREV DISCUSSION... /ISSUED 1144 AM CDT Wed Sep 13 2023/ ...Southern New England... A cluster of generally weakening thunderstorms is currently ongoing across the region and could still pose some continued strong/localized severe storm risk. For additional short-term information (through early afternoon), see Mesoscale Discussion 2145. Weak lapse rates and modest overall heating/buoyancy, along with marginal low-level shear, may keep the overall severe risk low. While uncertain, various short-term guidance is insistent that additional redevelopment could occur this afternoon in the wake of this morning's thunderstorm cluster, with renewed development potentially across southwest New England in proximity to the weak surface wave and eastward-advancing front. Should this happen, some severe risk could redevelop as diurnal destabilization occurs across a somewhat broader part of southern New England this afternoon. ...Arizona/New Mexico to West Texas... A low-amplitude mid-level disturbance over the southern Rockies will continue eastward toward west/north Texas through tonight. Conditionally, the most favorable area for a few supercells should be over the Permian Basin and Trans-Pecos of West Texas. Despite near moist-adiabatic mid-level lapse rates, including a lower hail risk than typical supercell situations, favorable speed shear will exist above 700 mb to support an elongated mid to upper hodograph. Nevertheless, timing of large-scale ascent attendant to the impulse appears to be early relative to peak heating, and boundary-layer warming will be the key driver to the degree of instability today. Accordingly, will continue to maintain a broad corridor of relatively low severe probabilities at this time, while still acknowledging some potential for storm clustering across west/southwest Texas later this afternoon/evening that could semi-focus a wind-related severe risk. Otherwise, isolated, marginal severe hail/wind will be possible from late afternoon to mid-evening over the southeast part of Arizona and southwest into east-central New Mexico. ...South Atlantic coast... Isolated to scattered thunderstorms should develop along the coastal sea breeze and across the Savannah Valley in association with a remnant MCV. While 0-3 km winds will be light, 20-25 kt 500-mb west-southwesterlies could support loose multicell clustering with locally strong gusts from 45-60 mph, with a peak threat in the late afternoon. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0254 PM CDT Wed Sep 13 2023 Valid 141200Z - 151200Z ...NO CRITICAL AREAS... The previous forecast remains valid with no changes. Localized dry and breezy conditions are possible over parts of the southern Cascades and northern Central valley of CA. Otherwise, fire-weather concerns over much of the CONUS are low. ..Lyons.. 09/13/2023 .PREV DISCUSSION... /ISSUED 0157 AM CDT Wed Sep 13 2023/ ...Synopsis... A mid-level trough will traverse the Northern Plains/international border while a cold front surges southward across eastern Montana into North Dakota tomorrow/Thursday. Behind this cold front, 15+ mph sustained northwesterly surface winds will coincide with 25-35 percent RH during the afternoon hours. Since RH and fuel receptiveness will be marginally supportive of widespread wildfire potential, fire weather highlights have been withheld. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Tue Sep 12 22:32:02 UTC 2023.

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0439 PM CDT Tue Sep 12 2023 Valid 141200Z - 201200Z In the wake of earlier troughing, prominent mid-level ridging is forecast to remain over the Pacific Northwest through much of the extended forecast period. Beneath the ridge, dry and warm conditions are expected, albeit with weaker winds. To the east, persistent troughing and cooler than average temperatures are forecast for much of the central and eastern CONUS. Given the lack of overlap of strong winds with dry surface conditions, fire-weather concerns will be limited to localized areas. ...Northwest... Dry and breezy conditions are possible across southern OR and northern CA D3/Thur as the upper ridge builds over the eastern Pacific. Northerly flow of 10-20 mph and RH below 30% are possible through the afternoon. A few hours of dry and breezy conditions may overlap areas of dry fuels and ongoing fires, supporting locally elevated fire-weather concerns. However, widespread fire-weather conditions appear unlikely as gradient winds are forecast to weaken quickly into the evening. Through the remainder of the week and first part of next weekend, the building upper ridge will support continued warming and drying over much of the Pacific Northwest. A thermally induced surface pressure trough may support occasional gusty winds in proximity to the low RH, but the lack of stronger synoptic winds will keep fire-weather concerns localized. Through the weekend and end of the forecast period, a series of upper-level troughs will approach the West Coast. Broad ascent ahead of these systems may support isolated thunderstorms D5/D6 Sat/Sun across parts of far southern OR into northern CA. Exact storm coverage is highly uncertain given model timing differences. However, dry sub-cloud layers and modest PWAT values below 1 inch may support some risk for dry lightning strikes over receptive fuels. ..Lyons.. 09/12/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0439 PM CDT Tue Sep 12 2023 Valid 141200Z - 201200Z In the wake of earlier troughing, prominent mid-level ridging is forecast to remain over the Pacific Northwest through much of the extended forecast period. Beneath the ridge, dry and warm conditions are expected, albeit with weaker winds. To the east, persistent troughing and cooler than average temperatures are forecast for much of the central and eastern CONUS. Given the lack of overlap of strong winds with dry surface conditions, fire-weather concerns will be limited to localized areas. ...Northwest... Dry and breezy conditions are possible across southern OR and northern CA D3/Thur as the upper ridge builds over the eastern Pacific. Northerly flow of 10-20 mph and RH below 30% are possible through the afternoon. A few hours of dry and breezy conditions may overlap areas of dry fuels and ongoing fires, supporting locally elevated fire-weather concerns. However, widespread fire-weather conditions appear unlikely as gradient winds are forecast to weaken quickly into the evening. Through the remainder of the week and first part of next weekend, the building upper ridge will support continued warming and drying over much of the Pacific Northwest. A thermally induced surface pressure trough may support occasional gusty winds in proximity to the low RH, but the lack of stronger synoptic winds will keep fire-weather concerns localized. Through the weekend and end of the forecast period, a series of upper-level troughs will approach the West Coast. Broad ascent ahead of these systems may support isolated thunderstorms D5/D6 Sat/Sun across parts of far southern OR into northern CA. Exact storm coverage is highly uncertain given model timing differences. However, dry sub-cloud layers and modest PWAT values below 1 inch may support some risk for dry lightning strikes over receptive fuels. ..Lyons.. 09/12/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 2141 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF SOUTHERN ARIZONA AND SOUTHERN NEW MEXICO
Mesoscale Discussion 2141 NWS Storm Prediction Center Norman OK 0428 PM CDT Tue Sep 12 2023 Areas affected...portions of southern Arizona and southern New Mexico Concerning...Severe potential...Watch unlikely Valid 122128Z - 122300Z Probability of Watch Issuance...20 percent SUMMARY...Some uptick in severe potential may occur over the next few hours. Isolated bouts of severe hail/wind may accompany the strongest storms and a WW is not anticipated. DISCUSSION...Storms near the AZ/NM/international border area have been percolating in intensity over the last couple of hours, with MRMS mosaic radar imagery showing an increase in 1 inch MESH tracks with some of the strongest storms. Recently, robust convective initiation has taken place in far western Pinal County, AZ, where slightly elongated hodographs and 1000+ J/kg MLCAPE support supercell structures capable of severe hail. A severe gust or two also cannot be ruled out with the stronger storms. Overall, the severe threat should be isolated and a WW issuance is not expected. ..Squitieri.. 09/12/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ABQ...EPZ...TWC...FGZ...PSR... LAT...LON 32921274 33661157 33930973 33380717 32890615 32430621 31990665 31810744 31560790 31270838 31340938 31361045 31541104 32111247 32921274 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Tue Sep 12 2023 Valid 131200Z - 141200Z ...NO CRITICAL AREAS... ...20z Update... Breezy northwest winds are forecast to develop over portions of the southern OR Cascades into the far northern Central Valley of CA. While occasional 15-25 mph gusts are possible, surface conditions are not expected to be overly dry with RH values generally above 30%. Occasional lower RH values may overlap locally with breezy conditions through the afternoon, but the limited coverage should keep fire-weather concerns localized. Thus, confidence remains too low to include elevated probabilities. ..Lyons.. 09/12/2023 .PREV DISCUSSION... /ISSUED 0121 AM CDT Tue Sep 12 2023/ ...Synopsis... Relatively zonal flow is expected across much of the central U.S. tomorrow/Wednesday. Nonetheless, some surface lee troughing is likely along the High Plains, which will encourage the northward transport of a moist low-level airmass. At the same time, more beneficial rainfall may occur across portions of the southern Plains (mainly Texas). As such, wildfire-spread concerns are relatively minimal, with no highlights introduced. ...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 0300 PM CDT Tue Sep 12 2023 Valid 131200Z - 141200Z ...NO CRITICAL AREAS... ...20z Update... Breezy northwest winds are forecast to develop over portions of the southern OR Cascades into the far northern Central Valley of CA. While occasional 15-25 mph gusts are possible, surface conditions are not expected to be overly dry with RH values generally above 30%. Occasional lower RH values may overlap locally with breezy conditions through the afternoon, but the limited coverage should keep fire-weather concerns localized. Thus, confidence remains too low to include elevated probabilities. ..Lyons.. 09/12/2023 .PREV DISCUSSION... /ISSUED 0121 AM CDT Tue Sep 12 2023/ ...Synopsis... Relatively zonal flow is expected across much of the central U.S. tomorrow/Wednesday. Nonetheless, some surface lee troughing is likely along the High Plains, which will encourage the northward transport of a moist low-level airmass. At the same time, more beneficial rainfall may occur across portions of the southern Plains (mainly Texas). As such, wildfire-spread concerns are relatively minimal, with no highlights introduced. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Tue Sep 12 2023 Valid 122000Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE EAST AND SOUTHWEST... ...SUMMARY... Isolated severe thunderstorms remain possible this afternoon into tonight, across parts of the southern Appalachians to Mid-Atlantic States, south Georgia to central Florida, and southern Arizona to southwest New Mexico. ...20Z Update... Some minor adjustments have been made to the general thunderstorm lines, but no changes have been made to the severe probabilities. See the previous discussion below for more information, and MCD 2140 regarding the short-term threat for northeast GA into parts of the Carolinas and southern VA. ..Dean.. 09/12/2023 .PREV DISCUSSION... /ISSUED 1129 AM CDT Tue Sep 12 2023/ ...Appalachians/Mid-Atlantic States... Broad height falls will occur regionally in advance of the upper trough centered near the Great Lakes/northern Ontario. Moderate differential diabatic heating will occur today ahead of a weak southwest/northeast-oriented baroclinic zone. This will aid the development of scattered thunderstorms through early/mid afternoon from the Tennessee Valley to the central Appalachians. Poor mid-level lapse rates will limit overall buoyancy and updraft vigor, but at least weak buoyancy coupled with 25-35 kt effective bulk shear should support multicell clusters and an attendant threat for sporadic damaging winds this afternoon through early evening. While a spatial decrease in the severe threat is expected after sunset, some uptick in severe risk may occur tonight as greater mid-level height falls overspread richer low-level moisture over the Chesapeake and Delmarva regions. With weak surface low development expected, low-level mass response and low-level shear/SRH may be adequate for a few transient supercells. These supercells should generally remain weak, but could potentially pose a low-probability brief tornado threat aside from localized wind damage. ...Florida/southern Georgia... A minor mid-level trough over the north-central Gulf will slowly progress east and remain well offshore through the period. Downstream of this feature, 500-mb west-southwesterly winds of 15-25 kt will persist and support short-duration/transient storm organization. As surface temperatures warm into the upper 80s to low 90s, isolated to scattered thunderstorms will develop along the sea breezes and collide inland. Ample buoyancy with MLCAPE of 2000-2500 J/kg will support vigorous downdrafts and sporadic wind gusts from 45-65 mph, along with the possibility of marginally severe hail from 0.75 to 1.25 inches. ...Southern Arizona/southwest New Mexico... A belt of confluent mid-level westerlies will yield a swath of 30-35 kt flow across the region, supporting potential for isolated severe thunderstorms from late afternoon through tonight. Mid-level lapse rates will be modest and timing/extent of large-scale ascent appears nebulous with multiple rounds of thunderstorm development from this morning through tonight. Although somewhat tempered by lingering early day clouds and precipitation, a plume of weak to moderate buoyancy should become established this afternoon south of the Mogollon Rim, with the strongest regional destabilization across parts of southwest into south-central Arizona. Scattered thunderstorms seem most likely during the late afternoon and evening within the buoyancy gradient and across the higher terrain. Sporadic occurrences of 50-60 mph wind gusts along with marginally severe hail around 1 inch will be possible through the period. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Tue Sep 12 2023 Valid 122000Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE EAST AND SOUTHWEST... ...SUMMARY... Isolated severe thunderstorms remain possible this afternoon into tonight, across parts of the southern Appalachians to Mid-Atlantic States, south Georgia to central Florida, and southern Arizona to southwest New Mexico. ...20Z Update... Some minor adjustments have been made to the general thunderstorm lines, but no changes have been made to the severe probabilities. See the previous discussion below for more information, and MCD 2140 regarding the short-term threat for northeast GA into parts of the Carolinas and southern VA. ..Dean.. 09/12/2023 .PREV DISCUSSION... /ISSUED 1129 AM CDT Tue Sep 12 2023/ ...Appalachians/Mid-Atlantic States... Broad height falls will occur regionally in advance of the upper trough centered near the Great Lakes/northern Ontario. Moderate differential diabatic heating will occur today ahead of a weak southwest/northeast-oriented baroclinic zone. This will aid the development of scattered thunderstorms through early/mid afternoon from the Tennessee Valley to the central Appalachians. Poor mid-level lapse rates will limit overall buoyancy and updraft vigor, but at least weak buoyancy coupled with 25-35 kt effective bulk shear should support multicell clusters and an attendant threat for sporadic damaging winds this afternoon through early evening. While a spatial decrease in the severe threat is expected after sunset, some uptick in severe risk may occur tonight as greater mid-level height falls overspread richer low-level moisture over the Chesapeake and Delmarva regions. With weak surface low development expected, low-level mass response and low-level shear/SRH may be adequate for a few transient supercells. These supercells should generally remain weak, but could potentially pose a low-probability brief tornado threat aside from localized wind damage. ...Florida/southern Georgia... A minor mid-level trough over the north-central Gulf will slowly progress east and remain well offshore through the period. Downstream of this feature, 500-mb west-southwesterly winds of 15-25 kt will persist and support short-duration/transient storm organization. As surface temperatures warm into the upper 80s to low 90s, isolated to scattered thunderstorms will develop along the sea breezes and collide inland. Ample buoyancy with MLCAPE of 2000-2500 J/kg will support vigorous downdrafts and sporadic wind gusts from 45-65 mph, along with the possibility of marginally severe hail from 0.75 to 1.25 inches. ...Southern Arizona/southwest New Mexico... A belt of confluent mid-level westerlies will yield a swath of 30-35 kt flow across the region, supporting potential for isolated severe thunderstorms from late afternoon through tonight. Mid-level lapse rates will be modest and timing/extent of large-scale ascent appears nebulous with multiple rounds of thunderstorm development from this morning through tonight. Although somewhat tempered by lingering early day clouds and precipitation, a plume of weak to moderate buoyancy should become established this afternoon south of the Mogollon Rim, with the strongest regional destabilization across parts of southwest into south-central Arizona. Scattered thunderstorms seem most likely during the late afternoon and evening within the buoyancy gradient and across the higher terrain. Sporadic occurrences of 50-60 mph wind gusts along with marginally severe hail around 1 inch will be possible through the period. Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1227 PM CDT Tue Sep 12 2023 Valid 131200Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF SOUTHERN NEW ENGLAND...COASTAL CAROLINAS...SOUTHERN HIGH PLAINS... ...SUMMARY... Marginally severe thunderstorms are possible in parts of the southern High Plains, southern New England, and the Carolinas on Wednesday. ...Synopsis... An upper-level trough will move from the Great Lakes/Ohio Valley toward New England on Wednesday. Multiple vorticity maxima will be embedded within the midlevel southwesterly flow ahead of this trough. At the surface, a cold front will move across parts of the Northeast and Mid Atlantic into the southern Appalachians, with a weak frontal wave potentially moving from the Mid Atlantic into New England through the day. Farther west, a broad upper-level trough will remain in place across parts of the western/central CONUS, with one notable shortwave trough expected to move eastward from the southern Rockies into the southern Plains. ...Northern NJ/Southeast NY into southern New England... A band of convection will likely be ongoing at the start of the forecast period somewhere across southeast NY/northern NJ into western parts of southern New England, aided by low-level warm advection and midlevel vorticity maxima ejecting northeastward ahead of the primary upper trough. Instability will generally remain weak, but moderate deep-layer shear, favorable moisture, and some enhancement of low-level shear/SRH within the warm-advection regime may support transient rotating cells capable of locally damaging gusts and/or a brief tornado. The primary threat may reside with the initial cluster of convection as it moves eastward across southern New England, though some redevelopment will be possible its wake, depending on timing of early convection and extent of destabilization in its wake. ...Coastal Carolina vicinity... In advance of the large-scale trough to the north, one or more weak midlevel vorticity maxima may move across parts of the Carolinas Wednesday. These may aid in scattered afternoon thunderstorm development within a warm, moist, and moderately unstable environment during the afternoon. Modest westerly midlevel flow will support effective shear of 25-30 kt, sufficient for some storm organization, and a few semi-organized cells/clusters will be possible. A Marginal Risk has been added for parts of near-coastal SC and southern NC, where the best overlap of instability, shear, and storm coverage is currently anticipated. ...Southern High Plains vicinity... Scattered thunderstorms are expected from the southern Rockies into the High Plains Wednesday afternoon/evening, as a midlevel shortwave trough traverses the region. Weak to moderate buoyancy and sufficient deep-layer shear will support a few organized cells/clusters capable of producing localized hail and severe gusts. ...Southeast AZ into southwest NM... Scattered thunderstorm development will again be possible across parts of southern AZ into southwest NM on Wednesday. Moisture/instability may be somewhat weaker than D1/Tuesday, though deep-layer shear will remain marginally sufficient for a few semi-organized storms. Depending on the extent of D1 convection across the region and its potential impact on D2 destabilization, severe probabilities may eventually be needed. ..Dean.. 09/12/2023 Read more

No Mesoscale Discussions are in effect as of Mon Sep 11 22:20:26 UTC 2023.

WW 0682 Status Updates
STATUS FOR WATCH 0682 HAS NOT BEEN ISSUED YET Read more

WW 682 SEVERE TSTM NM TX 112055Z - 120400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 682 NWS Storm Prediction Center Norman OK 355 PM CDT Mon Sep 11 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Eastern New Mexico West Texas * Effective this Monday afternoon and evening from 355 PM until 1100 PM CDT. * Primary threats include... Scattered large hail likely with isolated very large hail events to 2 inches in diameter possible Scattered damaging winds and isolated significant gusts to 75 mph possible A tornado or two possible SUMMARY...Scattered strong to severe thunderstorms will continue to develop through late afternoon and early evening as a front advances southward across the region. The severe thunderstorm watch area is approximately along and 80 statute miles north and south of a line from 50 miles north northwest of Roswell NM to 30 miles northeast of Abilene TX. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU2). 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 65 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 30025. ...Guyer Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0303 PM CDT Mon Sep 11 2023 Valid 131200Z - 191200Z Across the Western US, Pacific troughing is forecast to weaken and shift eastward as mid-level ridging intensifies through the first part of the extended forecast period. Occasional gusty winds may linger across parts of the Columbia Basin and Snake River Plain through D4/Thursday, but widespread gusty winds and low humidity are not anticipated. In response to the building high pressure, flow aloft will turn more northerly and weaken across the Cascades as the main ridge axis remains off shore. As the ridge continues to build through the remainder of the week and into next weekend, a warming and drying trend will develop across parts of northern CA and the Pacific Northwest. While drier and warmer, the lack of stronger flow aloft suggests widespread critical fire-weather concerns are unlikely. This general upper air pattern is forecast to remain fairly stagnant through next weekend with the ridge and weak flow loft dominating the western half of the CONUS. Across the rest of the US, cooler and wetter conditions will prevail, keeping fire-weather concerns low through the extended forecast period. ..Lyons.. 09/11/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Mon Sep 11 2023 Valid 112000Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN NEW MEXICO AND WEST TEXAS... ...SUMMARY... Scattered severe wind and large hail will be possible across parts of eastern New Mexico and west Texas through mid-evening. A few storms may be significantly severe with wind gusts to 80 mph and hail to tennis ball size. ...20z Update... The previous outlook remains on track, and no changes have been made with the 20z update. Isolated thunderstorms producing locally strong gusts are ongoing near the sea breeze from southeast GA into northeast FL. This activity will continue, with some increase in coverage with southward extent over the next few hours. Further to the west, thunderstorms are beginning to develop to the cool side of a cold front over eastern NM into the TX Panhandle. Additional thunderstorm development is expected over the next couple of hours. Severe potential will increase/persist across parts of eastern NM into west TX into this evening with damaging gusts and large hail possible. Reference MCD 2137 for info on short term severe thunderstorm and watch issuance potential. ..Leitman.. 09/11/2023 .PREV DISCUSSION... /ISSUED 1140 AM CDT Mon Sep 11 2023/ ...Eastern New Mexico/west Texas... No appreciable outlook changes appear warranted for the region. A low-amplitude shortwave trough over the southern High Plains, and associated belt of enhanced (40 kt) mid-level westerlies, will continue generally eastward over the south-central Plains, and toward the Ozarks/ArkLaTex through late tonight. This will be as a relatively strong cold front continues southward and accelerates later this afternoon into tonight. Scattered thunderstorms are most likely to develop off the higher terrain of New Mexico, first along and to the cool side of the surface boundary during the early to mid-afternoon and later into the well-mixed boundary layer over the Permian Basin and Texas South Plains. Isolated thunderstorms may also form near the surface front/dryline intersection in the Low Rolling Plains/Big Country vicinity. For this latter region, a more favorable discrete supercell wind profile and slower undercutting of the surface front may yield a threat for 2-2.5 inch hail amid MLCAPE around 2000 J/kg. Storms farther west should tend to more quickly consolidate into southeast-moving clusters. Those clusters that can anchor along the undercutting front into the deeply mixed air to the south should have the best chance to produce occasional severe wind gusts from 60-80 mph. These threats should gradually weaken after dusk, but may persist on an isolated basis across the Concho Valley/Edwards Plateau vicinity of west-central Texas as a low-level jet strengthens over the Lower Pecos Valley. ...North/central Florida... Ample heating is occurring at midday with temperatures commonly soaring into the lower 90s F, which is contributing to MLCAPE in excess of 2000 J/kg. Isolated thunderstorms should develop along sea breeze boundaries this afternoon and likely collide over the central/eastern portions of the Florida Peninsula. 20-25 kt effective bulk shear could favor loose multicell clustering with a threat of sporadic wind gusts from 40-60 mph and possibly small hail. ...Southern New England... While locally heavy rainfall will likely be the primary scenario, it is possible that adequate buoyancy will exist with modest-strength westerlies for some potential of localized wind damage with a few of the thunderstorms. However, any such potential should remain very limited/localized with the overall risk of organized severe storms remaining low. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0209 PM CDT Mon Sep 11 2023 Valid 121200Z - 131200Z ...NO CRITICAL AREAS... ...Cascades... Troughing over the Pacific Northwest will allow for a slight increase in westerly flow over the Cascades and western Columbia Basin D2/Tuesday afternoon and evening. Gusty west winds may periodically reach 15-20 mph through favored terrain gaps. While surface conditions will not be overly dry, occasional RH values below 30% may support locally elevated fire-weather conditions for a few hours. Currently, confidence in more widespread conditions remains too low to introduce any forecast probabilities. ..Lyons.. 09/11/2023 .PREV DISCUSSION... /ISSUED 0127 AM CDT Mon Sep 11 2023/ ...Synopsis... Cooler, moist surface conditions should overspread much of the central and southern CONUS tomorrow/Tuesday, reinforced by surface high pressure over the region. Dry conditions will persist over the Interior West. However, rainfall tempering fuel receptiveness or weak surface winds should limit significant wildfire-spread potential to localized areas, precluding fire weather highlights. ...Please see www.spc.noaa.gov/fire for graphic product... Read more