Severe Storms

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

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0454 PM CDT Sun Sep 10 2023 Valid 121200Z - 181200Z Generally quiescent fire-weather conditions are expected across the CONUS through the extended forecast period. Pacific Northwest troughing is forecast to remain in place through the first part of next week before mid-level ridging builds over the West. Cooler and breezy conditions will give way to warmer and drier weather, with generally poor overlap of critical fire-weather conditions and dry fuels expected across the western states. ...Northwest... Through the first part of next week, the persistent mid-level trough over the Pacific Northwest will remain in place, subtly enhancing west/southwest flow over the Pacific Northwest and northern Rockies. Ensemble forecasts suggest winds will likely be strongest D3/Tues into D4/Wed east of the Cascades and across the Snake River Valley. Isolated thunderstorms may also develop with the passage of the main trough, though coverage is expected to remain low. While surface winds may occasionally reach 15 mph on a localized basis, widespread dry and windy conditions, supporting critical fire-weather concerns, are not expected. Fire-weather concerns shift toward warm, dry and unstable conditions late next week into the first part of next weekend, as a mid-level ridge is forecast to build over the eastern Pacific. With the main ridge axis offshore, weak offshore flow is possible over parts of the Cascades and West Coast. Localized fire-weather concerns are possible, but widespread coverage is not anticipated through the remainder of the extended forecast period. ..Lyons.. 09/10/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0680 Status Updates
STATUS FOR WATCH 0680 HAS NOT BEEN ISSUED YET Read more

WW 680 SEVERE TSTM CO KS OK 102055Z - 110400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 680 NWS Storm Prediction Center Norman OK 355 PM CDT Sun Sep 10 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Southeast Colorado Western Kansas Oklahoma Panhandle * Effective this Sunday afternoon and evening from 355 PM until 1100 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 strong to severe thunderstorms will continue to develop across the region through late afternoon and early evening. The severe thunderstorm watch area is approximately along and 110 statute miles east and west of a line from 70 miles northeast of Lamar CO to 20 miles west of Guymon OK. 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 2 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 29025. ...Guyer Read more

MD 2133 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PARTS OF NORTHEASTERN NEW MEXICO...SOUTHEASTERN COLORADO...AND THE TEXAS AND OKLAHOMA PANHANDLES INTO SOUTHWESTERN KANSAS
Mesoscale Discussion 2133 NWS Storm Prediction Center Norman OK 0313 PM CDT Sun Sep 10 2023 Areas affected...parts of northeastern New Mexico...southeastern Colorado...and the Texas and Oklahoma Panhandles into southwestern Kansas Concerning...Severe potential...Watch possible Valid 102013Z - 102245Z Probability of Watch Issuance...60 percent SUMMARY...Isolated to widely scattered strong thunderstorm development is possible through 5-6 PM CDT. This may include an isolated supercell or two, posing a risk for severe hail, locally strong surface gusts and perhaps a brief tornado. DISCUSSION...Low-level moistening is still ongoing within weak, but slowly deepening surface troughing to the lee of the southern Rockies. This is occurring beneath warm and capping elevated mixed-layer, and mid-level ridging to the north of a still fairly prominent subtropical high centered over the northwestern Mexican Plateau. In response to a series of short wave perturbations progressing around the periphery of the ridge in the near term, and, later, digging mid-level troughing across the northern Great Plains, mid-level heights are gradually beginning to fall. It appears that large-scale forcing for ascent will lead to increasing convective development spreading off the Front Range into the destabilizing boundary layer across and east of northeastern New Mexico and southeastern Colorado by early this evening. Potential for the initiation of sustained thunderstorm development in advance of this activity, through late afternoon, remains more unclear. Based on objective analysis, mixed-layer CAPE remains fairly modest to the north of the Texas Panhandle vicinity, currently maximized around 1000 J/kg near the Colorado/Kansas border. However, shear for boundary-layer based thunderstorm development is sufficient for supercells beneath 30 kt west-northwesterly mid-level flow (around 500 mb). Farther south, mixed-layer CAPE is more substantive, but shear remains weaker. With additional surface heating, it appears possible that weakening of lingering mid-level inhibition may become sufficient for at least widely scattered thunderstorm development. A zone of enhanced lower/mid-tropospheric warm advection, currently centered to the west/northwest of Garden City KS, may provide one potential focus for thunderstorm initiation during the next hour or two. As this activity acquires increasing inflow of destabilizing boundary-layer, it may rapidly intensify and organize, accompanied by increasing potential for severe hail and perhaps some risk for a tornado through 22-23Z. ..Kerr/Guyer.. 09/10/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OUN...DDC...GLD...LUB...AMA...PUB...ABQ... LAT...LON 37350277 38420253 38800174 38540046 38029982 36909958 33770062 34030194 34280395 35780381 37350277 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Sun Sep 10 2023 Valid 102000Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTH-CENTRAL PLAINS... ...SUMMARY... Scattered severe thunderstorms are expected through this evening across eastern Colorado and western Kansas into the Oklahoma/Texas Panhandles. Large hail and severe wind gusts will be the main threats. ...20z Update... The previous outlook remains on track and no changes have been made with the 20z update. See previous discussion below for more details. ..Leitman.. 09/10/2023 .PREV DISCUSSION... /ISSUED 1138 AM CDT Sun Sep 10 2023/ ...Central High Plains southward to west Texas... A nearly zonal belt of moderately strong westerlies will exist from the central Rockies into the south-central Plains. Weak surface cyclogenesis will occur across southeast Colorado/far southwest Kansas as a cold front shifts southward across the south-central High Plains. A confined plume of modified Gulf air will be maintained across a portion of west Texas into southwest Kansas near and ahead of the front. Robust boundary-layer heating is expected especially to the west/southwest of convection that persists across the region into midday, netting a corridor of moderate buoyancy mainly from northwest Texas into southwest Kansas later today. Afternoon thunderstorm development should be focused within three regimes. One being high-based storms emanating off the southern Rockies, two being along the front and buoyancy plume intersection in west Kansas, and three near the dryline/remnant outflow intersection in the Texas Panhandle. For the latter two, low-level veering of the wind profile with height beneath mid to upper level speed shear should favor at least a few discrete supercells with a primary threat of large hail. Upstream high-based activity should overtake slower-moving supercells and Kansas supercells will also be undercut from north to south by the accelerating cold front. This should yield broader cluster development towards early evening with some uptick in severe wind potential anticipated. ...Southern New England... A weak mid-level disturbance and warm/moist conveyor appears to be influencing a corridor of recently increased thunderstorms at late morning. A moist air mass and cloud breaks/additional heating will lead to modest destabilization, although updraft accelerations will be somewhat tempered by poor mid-level lapse rates. A few microbursts could occur, but overall severe potential should be tempered by the marginal thermodynamic environment and effective shear of 20-25 kt or less. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0244 PM CDT Sun Sep 10 2023 Valid 111200Z - 121200Z ...NO CRITICAL AREAS... ...20z Update... Generally quiet fire-weather conditions are again expected over much of the western CONUS D2/Monday. Locally breezy winds will be possible over parts of the Columbia Gorge and lee of the Cascades coincident with periodic drier surface conditions. However, widespread dry and windy conditions are not expected over the West, precluding broader fire-weather concerns. ..Lyons.. 09/10/2023 .PREV DISCUSSION... /ISSUED 0143 AM CDT Sun Sep 10 2023/ ...Synopsis... A surface cold front will continue to sweep across the southern Plains as a mid-level trough becomes situated over the central U.S. tomorrow/Monday. Cooler, moist conditions will usher in behind the cold front and will overspread much of the Plains states, limiting widespread, significant wildfire-spread potential. Dry conditions should also persist across the western U.S. However, the lack of stronger surface winds should keep wildfire-spread potential localized. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 2126 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PORTIONS OF EASTERN WYOMING INTO FAR SOUTHWESTERN SOUTH DAKOTA AND NORTHWESTERN NEBRASKA PANHANDLE
Mesoscale Discussion 2126 NWS Storm Prediction Center Norman OK 0519 PM CDT Sat Sep 09 2023 Areas affected...portions of eastern Wyoming into far southwestern South Dakota and northwestern Nebraska Panhandle Concerning...Severe potential...Watch possible Valid 092219Z - 092345Z Probability of Watch Issuance...40 percent SUMMARY...The severe threat may be increasing across portions of the northern High Plains. The strongest storms may produce a few bouts of severe hail or wind. A Severe Thunderstorm Watch issuance may be needed if more widespread convective coverage becomes evident. DISCUSSION...Convective initiation has occurred along the lee of the Rockies in eastern WY while multicells/transient supercells have become established across southwestern SD. The SD storms are expected to remain confined to the more favorable terrain, with a persistent but sparse severe wind/hail threat. However, the storms should intensify and move off of the higher terrain in WY as a weak mid-level impulse crests the synoptic ridge and ejects into the central High Plains. Boundary-layer moisture is meager. However, steep low and mid-level lapse rates are contributing to 1000+ J/kg MLCAPE, which is adequate to support some severe wind/hail with supercells that can develop given elongated hodographs and 40-50 kts of effective bulk shear. Nonetheless, discrete storms and their severe threat should be isolated, so convective trends are being closely monitored for greater storm coverage and the need for a Severe Thunderstorm Watch issuance. ..Squitieri/Thompson.. 09/09/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...UNR...CYS...BYZ...RIW... LAT...LON 41550500 43390680 44680696 44980582 44820466 44300337 43710285 43220272 42680299 41760401 41550500 Read more

WW 0677 Status Updates
STATUS REPORT ON WW 677 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..SPC..09/09/23 ATTN...WFO...LWX...PHI...OKX...BGM...CTP... STATUS REPORT FOR WS 677 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS DCC001-092340- DC . DISTRICT OF COLUMBIA COUNTIES INCLUDED ARE DISTRICT OF COLUMBIA MDC003-005-013-015-021-025-027-031-033-043-510-092340- MD . MARYLAND COUNTIES INCLUDED ARE ANNE ARUNDEL BALTIMORE CARROLL CECIL FREDERICK HARFORD HOWARD MONTGOMERY PRINCE GEORGES WASHINGTON MARYLAND INDEPENDENT CITIES INCLUDED ARE BALTIMORE CITY NJC005-007-015-019-021-027-031-035-037-041-092340- Read more