Severe Storms

No watches are valid as of Sat Sep 16 21:31:02 UTC 2023.

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0356 PM CDT Sat Sep 16 2023 Valid 181200Z - 241200Z ...Days 3-4/Monday-Tuesday... Within the base of a large-scale trough over western Canada, several embedded midlevel perturbations accompanied by strong westerly flow aloft will overspread the northwestern CONUS on Days 3-4/Monday-Tuesday. Related downslope trajectories off the northern Cascades and northern Rockies will favor dry/breezy conditions across the Columbia Basin (on Day 3/Monday) and the northern Plains (on Days 3-4/Monday-Tuesday). Given dry fuels across both areas, elevated to locally critical fire-weather conditions are expected. ...Days 5-8/Wednesday-Saturday... A substantial mid/upper-level jet streak will advance southward along the West Coast, resulting in the development of a midlevel cut-off low over the western CONUS. Along the northwestern periphery of this feature, strong north-northeasterly surface winds will overspread Washington and Oregon. However, current indications are that increasing low/mid-level moisture and related cloud coverage may limit RH reductions and the overall fire-weather risk. Along the southern and eastern peripheries of the cut-off low, an expansive area of strong surface winds and low RH are expected across portions of the Southwest into the southern/central Rockies. While the dry/windy conditions will result in increasing fire-weather concerns, recent rainfall and generally unreceptive fuels cast uncertainty on the overall risk -- precluding Critical probabilities at this time. ..Weinman.. 09/16/2023 ...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 0245 PM CDT Sat Sep 16 2023 Valid 162000Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHEASTERN TEXAS...AND OVER PORTIONS OF THE CENTRAL PLAINS AND MID-MISSISSIPPI VALLEY... ...SUMMARY... A few strong thunderstorms remain possible across a portion of southeastern Texas, and will continue over parts of the central Plains into the Mid-Mississippi Valley this afternoon and evening. ...Discussion... Few changes appear necessary to the ongoing outlook at this time, as current and anticipated evolution of convection remains in line with prior expectations. The primary changes in this outlook will trimming the MRGL risk area and removal of hail probability in southeastern Texas, in line with current convection evolution and motion, and also a slight northwestward expansion of MRGL risk over the southeastern Minnesota vicinity, where convection continues to develop just to the west of the existing outlook area. Otherwise, prior reasoning remains valid, across the CONUS. ..Goss.. 09/16/2023 .PREV DISCUSSION... /ISSUED 1101 AM CDT Sat Sep 16 2023/ ...TX... A long-lived MCS continues to track slowly southeastward across central TX. These storms produced occasional strong-severe wind gusts earlier this morning near/northwest of SJT. However, more recent trends have shown a general decreasing trend. At least remnants of the MCS are expected to persist through the day and track southeastward toward the coast. However, given the relatively weak winds aloft and lack of a more focused forcing mechanism, it is likely that the overall severe threat will remain rather marginal. Locally strong-damaging wind gusts will be the main risk. ...Central Plains into Mid MS Valley... A relatively strong upper trough and associated surface cold front is moving southeastward across parts of MN/WI/IA. By mid/late afternoon, this front will extend from near the KS/NE border into southern IA and southern WI. Scattered thunderstorm development will occur along/ahead of the front, in a moderately unstable air mass. Cool mid-level temperatures (-16 to -18C at 500mb) coupled with dewpoints in the 60s may result in sufficiently favorable thermodynamics for hail in the stronger updrafts. Steep low-level lapse rates could also promote gusty winds. However, the overall severe threat appears rather marginal at this time. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0149 PM CDT Sat Sep 16 2023 Valid 171200Z - 181200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NORTH-CENTRAL MONTANA... The primary change with this update was to add an Isolated Dry Thunderstorm area over portions of northern California into south-central Oregon -- where fuels are modestly receptive. Similar to Day 1/Saturday, sufficient midlevel moisture and diurnal heating will support isolated thunderstorms over the higher terrain during the afternoon/evening hours -- aided by weak large-scale ascent preceding a mid/upper-level low off the California coast. Inverted-V thermodynamic profiles and 0.5-0.8 inch PW will favor a mix of dry/wet storms (mostly dry), with an attendant risk of isolated lightning-induced ignitions. Elsewhere, the previous forecast (see below) remains on track, with only minor changes made based on the latest high-resolution guidance. ..Weinman.. 09/16/2023 .PREV DISCUSSION... /ISSUED 0103 AM CDT Sat Sep 16 2023/ ...Synopsis... ...North-central Montana... A shortwave trough will move across southern Alberta on Sunday, this will overspread stronger mid-level flow across northern Montana and lead to lee cyclogenesis east of the Canadian Rockies with a tightening pressure gradient. The combination of deep mixing beneath this stronger mid-level flow, downslope flow, and a tightening surface pressure gradient, will lead to strong winds across northern Montana on Sunday. In addition, relative humidity will be very dry (9 to 16 percent). Much of this area has received less than half an inch of precipitation in the past 2 weeks. Therefore, given the weather conditions and dry fuels, there will be critical fire weather concerns across north-central Montana on Sunday. Farther west, some dry and breezy conditions are expected in the Columbia Basin as moderate mid-level flow remains in a region of deep boundary-layer mixing. Therefore, some elevated fire weather concerns are possible during the afternoon on Sunday. ...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 1232 PM CDT Sat Sep 16 2023 Valid 171200Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF SOUTHEASTERN GEORGIA AND THE COASTAL CAROLINAS... ...SUMMARY... Isolated severe thunderstorms are possible Sunday afternoon and evening over parts of southeast Georgia and the Carolina Coastal Plain. A mid-level trough initially extending from the Upper Great Lakes south-southwestward to the central Gulf Coast area will advance steadily toward the Appalachians through Monday morning. Elsewhere, ridging aloft will prevail across much of the country. At the surface, a weak/diffuse front will progress eastward across the Appalachians, and then become a bit better-organized -- reaching the East Coast overnight. A weak frontal wave is forecast to evolve over southeastern Georgia during the day, and then move northeastward along the Carolina Coast through the second half of the period. ...Southeast... Daytime heating/weak destabilization is forecast over parts of Georgia and South Carolina Sunday, in the vicinity of the developing frontal wave. This should support development of showers and isolated thunderstorms, which would then spread northeastward in the vicinity of the North Carolina coast later in the period. With enhanced shear in the vicinity of the frontal wave, a few stronger storms/storm clusters may evolve with time, accompanied by risk for locally gusty winds. A brief tornado cannot be ruled out, particularly near or just off the Carolina coast through the second half of the period. ..Goss.. 09/16/2023 Read more

No watches are valid as of Fri Sep 15 22:16:02 UTC 2023.

No Mesoscale Discussions are in effect as of Fri Sep 15 22:16:02 UTC 2023.

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0406 PM CDT Fri Sep 15 2023 Valid 171200Z - 231200Z The greatest potential for critical fire-weather conditions will generally be confined to portions of the northern Plains (particularly northern Montana) and the Northwest during the extended forecast period. ...Days 3-4/Sunday-Monday - Northern Montana... Strong westerly flow aloft accompanying a series of midlevel shortwave troughs will overspread the northern Rockies and adjacent northern Plains on Days 3-4/Sunday-Monday. On Day 3/Sunday, downslope-related warming/drying will yield 10-15 percent RH across northern Montana. Deep boundary-layer mixing into the strong flow aloft, coupled with a tightening pressure gradient, will support 20+ mph sustained westerly surface winds (with higher gusts) in the lee of the northern Rockies in Montana. Given dry fuels across this area, critical fire-weather conditions are expected on Day 3/Sunday. Critical conditions will also be possible across the area on Day 4/Monday, though confidence in the overlap of 20 mph sustained surface winds and 20 percent RH is lower than Day 3/Sunday -- precluding 70-percent probabilities at this time. ...Day 3/Sunday - Northwest... Similar to the northern Rockies, strong westerly flow across the northern Cascades will promote dry/breezy conditions -- primarily across the Columbia Basin on Day 3/Sunday. 15-20 mph sustained westerly surface winds and 10-15 percent minimum RH will favor elevated to locally critical fire-weather conditions. Currently, these conditions appear too localized to terrain features to add 70-percent Critical probabilities. Late in the extended forecast period, strong offshore winds could develop across the Northwest, though large differences amongst the global model guidance regarding the evolution of a midlevel low casts uncertainty on where the fire-weather threat will be maximized. ..Weinman.. 09/15/2023 ...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 0244 PM CDT Fri Sep 15 2023 Valid 152000Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN NEW MEXICO INTO WEST TEXAS... ...SUMMARY... Scattered large hail, isolated severe wind gusts, and a brief tornado or two are most likely across the southern High Plains into tonight. ...20z Update... The main change with the 20z update is the removal of the Marginal (level 1 of 5) risk across portions of MN/WI. Weak heating due to persistent cloud cover, coupled with modest boundary-layer moisture and weak midlevel lapse rates are resulting in MLCAPE around 500 J/kg or less. Additionally, vertical shear will remain somewhat low. Latest HRRR and RRFS guidance indicates very low storm coverage through this evening. Any stronger cells that do develop may produce small hail, but overall severe potential appears lower than previous expected. The previous outlook remains on track across the southern High Plains vicinity, and severe storms are expected into this evening and tonight. For more details, see previous discussion below. ..Leitman.. 09/15/2023 .PREV DISCUSSION... /ISSUED 1056 AM CDT Fri Sep 15 2023/ ...Eastern NM/West TX.. Visible satellite imagery shows mostly clear skies over eastern NM and west TX this morning, with weak east/northeasterly surface winds across the region. Surface dewpoints in the low/mid 60s are common, which combined with moderately steep mid-level lapse rates should yield MLCAPE values of 1500-2000 J/kg by late afternoon. Present indications are that scattered storms will form off the higher terrain of eastern NM after 21z as large scale forcing for ascent strengthens ahead of a shortwave trough now over the Four Corners region. These storms will track slowly eastward and intensify as they move into west TX this evening. Westerly mid/upper level winds will be sufficiently strong for a few supercells capable of large hail and locally gusty winds. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0222 PM CDT Fri Sep 15 2023 Valid 161200Z - 171200Z Isolated Dry Thunderstorm highlights were introduced for portions of northwest California with this update. Efficient diurnal heating and adequate midlevel moisture will contribute to sufficient (albeit marginal) instability for isolated thunderstorm development over the Klamath Mountains in northwest CA -- aided by weak large-scale ascent preceding a mid/upper-level low. A dry/deeply mixed boundary layer (inverted-V thermodynamic profiles) should favor limited rainfall accumulations with this activity and an associated risk of isolated lightning-induced ignitions. Elsewhere, the previous forecast (see below) remains on track. ..Weinman.. 09/15/2023 .PREV DISCUSSION... /ISSUED 1155 PM CDT Thu Sep 14 2023/ ...Synopsis... Upper-level ridging will continue into Saturday with mostly light surface winds continuing across the western CONUS. Late Saturday afternoon, some stronger mid-level flow may start to overspread the Northwest as the ridge starts to break down. This stronger flow, and a tightening pressure gradient, may result in some brief stronger winds across north-central Montana late Saturday afternoon after peak heating. Therefore, due to this later arrival of stronger winds, fire weather concerns should remain mostly minimal. ...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 0453 PM CDT Thu Sep 14 2023 Valid 161200Z - 221200Z Ridging over the Pacific Northwest will slide eastward and begin to weaken as several Pacific troughs move onshore late this weekend into early next week. Strong mid-level flow will overspread the Cascades and northern Rockies with dry and breezy conditions likely through the weekend. Forecast certainty decreases quickly later in the period, as more significant troughing amplifies over the Northwest next week. While uncertain, fire-weather potential may increase later in the extended forecast period. ...Northwest... The upper-level ridge will begin to shift eastward and de-amplify heading into the weekend as a weak upper low approaches from the west. At the same time, a broader trough will approach portions of western BC, amplifying, and moving southeastward. Gusty west winds will increase through the weekend, potentially supporting dry and breezy conditions over the western Columbia Basin and Cascade gaps. Weak ascent and moisture advection ahead of the upper low and BC trough will also overspread parts of northern CA and southern OR as early as D3/Sat. Thunderstorm chances should slowly increase through the weekend with the greatest storm coverage likely late D4/Sun into early D5/Mon. A mixed mode of wet and dry storms is possible. Some lightning strikes may develop over dry fuels late this weekend into early next week. Medium-range model guidance has shown considerable uncertainty on the progression of the upper low and BC trough late in the weekend and into early next week. With some of the less progressive solutions, thunderstorm chances may linger over the Northwest as late as D6/Tues before a cold front shifts the remaining moisture eastward. Other solutions favor a quicker eastward progression of the cold front, while building strong surface high pressure east of the Cascades by mid week. Should this occur, strong easterly flow may develop over parts of WA, OR and northern CA with dry and windy conditions likely toward the coast. Uncertainty remains high, but the potential for strong offshore pressure gradients, collocated with dry surface conditions and receptive fuels, suggest critical fire-weather conditions are possible midweek next week and beyond. ...Northern Rockies... As the upper ridge begins to slide east and diminish this weekend, stronger westerly flow will move out of the Northwest into the northern Rockies/Plains D4/Sun into D5/Mon. Downslope winds of 15-20 mph are possible along with RH below 30%. While recent rainfall has tempered fuels somewhat, elevated fire-weather conditions are possible across parts MT late in the weekend into early next week. ..Lyons.. 09/14/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Thu Sep 14 21:59:01 UTC 2023.

MD 2149 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR CENTRAL AND INTO SOUTHEASTERN TEXAS
Mesoscale Discussion 2149 NWS Storm Prediction Center Norman OK 0351 PM CDT Thu Sep 14 2023 Areas affected...central and into southeastern Texas Concerning...Severe potential...Watch unlikely Valid 142051Z - 142245Z Probability of Watch Issuance...20 percent SUMMARY...Thunderstorm coverage may increase a bit over the next 1 to 2 hours over central Texas, accompanied by risk for hail and/or strong/gusty winds. WW is not anticipated at this time, due to what appears likely to remain isolated coverage. DISCUSSION...Latest radar and visible satellite loops show isolated convection evolving across portions of central Texas, from the Edwards Plateau to the Hill Country region. Meanwhile, a composite outflow/sea-breeze boundary is evident in the visible satellite loop, surging westward from coastal convection. Within the zone delineated by the developing storms to the west, and the boundary moving inland, an axis of moderate instability (1500 to 2000 J/kg mixed-layer CAPE) is noted, on the southern/western side of the primary surface cold front. Given these factors, it would appear that storms will be sustained over the next few hours, with some additional development of new storms likely. With modest but sufficient shear (0-6km shear near 30 kt) indicated across the area to support organized/rotating storms (and weak supercell characteristics noted in stronger/ongoing storms), hail and gusty/damaging winds will be possible with the most intense updrafts. At this time, isolated storm coverage that is expected, would suggest that WW issuance may not be required. However, we will continue to monitor development, for signs of greater-than-anticipated coverage of stronger storms, which could warrant reconsideration of the need to consider a watch. ..Goss/Hart.. 09/14/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...HGX...FWD...CRP...EWX...SJT... LAT...LON 30669965 31339854 30989738 29849612 28899715 29419904 29800048 30669965 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Thu Sep 14 2023 Valid 142000Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM EASTERN NM TO PARTS OF THE TX GULF COAST... ...SUMMARY... Isolated severe thunderstorm are possible along an axis from eastern New Mexico to the Texas Gulf Coast, mainly from late afternoon through this evening. ...20Z Update... The Marginal Risk has been expanded slightly northeastward along the upper TX Gulf Coast, in advance of a strong storm cluster near and northeast of Houston. These storms have developed within an environment characterized by rich low-level moisture and moderate buoyancy, but also weak midlevel lapse rates and warm temperatures aloft. Within this regime, effective shear of 25-30 kt will support modestly organized storms with a threat of locally damaging gusts until storms reach the coast. Deepening cumulus and recent storm development is ongoing across parts of the TX Hill Country, in the vicinity of a weak surface low/trough. It remains possible that a supercell or two will evolve out of this developing convection and move southeastward later this afternoon into this evening. Weak midlevel lapse rates may tend to limit storm severity, but any sustained supercell could pose a threat of localized severe gusts and hail approaching severe limits. Additional strong to isolated severe storm development will be possible across parts of eastern NM later this afternoon into this evening. See the previous discussion below for more details. ..Dean.. 09/14/2023 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Sep 14 2023/ ...NM/TX... Current visible satellite imagery and surface analysis shows a boundary extending from southeast NM into central TX. A very moist and moderately unstable air mass is present along and south of this boundary, along with mostly clear skies and steepening low level lapse rates. Large scale forcing is weak across this region, but most 12z CAM solutions show isolated thunderstorms developing near the boundary by late afternoon and evening. Forecast soundings suggest sufficient mid/upper level westerly flow for organized multicell or occasional supercell structures capable of hail and gusty winds. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0226 PM CDT Thu Sep 14 2023 Valid 151200Z - 161200Z ...NO CRITICAL AREAS... No changes will be made to the currently valid outlook. Fire-weather concerns should remain localized with hot and dry conditions over parts of the Northwest. See the previous discussion for more information. ..Lyons.. 09/14/2023 .PREV DISCUSSION... /ISSUED 0114 AM CDT Thu Sep 14 2023/ ...Synopsis... Fire weather concerns are expected to remain low for Friday. Warm and very dry conditions (RH in the teens) are expected again Friday afternoon from northern CA and northwest NV through central OR and into southern WA. Locally breezy conditions will remain possible within the Cascades that may support localized elevated fire weather conditions; however, a weak signal in high-res ensemble guidance for sustained winds over 15 mph limits confidence in the overall fire weather threat and precludes highlights at this time. Locally dry/breezy conditions are also possible across the Dakotas within a post-frontal regime, but highlights are withheld due to a combination of low probability for elevated conditions and rain chances over the next 24 hours. ...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 1229 PM CDT Thu Sep 14 2023 Valid 151200Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE SOUTHERN HIGH PLAINS INTO CENTRAL TEXAS... ...SUMMARY... Isolated severe thunderstorms are possible over the southern High Plains eastward into central portions of Texas on Friday and Friday night. ...Synopsis... A mid/upper-level trough is forecast to move eastward across the upper Midwest/Great Lakes region on Friday, as a cold front moves through the northern Plains into parts of MN/WI. Generally zonal mid/upper-level flow will persist across much of the southern CONUS on Friday, in advance of a low-amplitude shortwave trough moving eastward near the Four Corners region. ...Southern High Plains into central TX... Isolated strong to potentially severe storms will be possible across a broad region from the southern High Plains into central TX on Friday, though confidence remains relatively low regarding the details and potential corridors of greater severe potential. Convection will likely be ongoing across parts of west-central/northwest TX Friday morning, though guidance varies regarding the location and intensity of any ongoing convection. If a more organized MCS can develop late in the D1/Thursday period, then it may spread southeastward across central TX during the day on Friday with an isolated severe-wind threat. However, with an already modest low-level jet expected to weaken through the day, confidence in this scenario remains low. Additional diurnal storm development will be possible Friday afternoon near an outflow-reinforced surface boundary that will likely be draped somewhere across central into southwest TX, and also across eastern NM within a favorably moist low-level flow regime in advance of the shortwave trough near the Four Corners region. Modest westerly midlevel flow will provide marginally sufficient effective shear for a few organized storms, including some potential for isolated supercells with initial more discrete development. Some severe hail threat will accompany the stronger discrete storms, especially from eastern NM into parts of the TX Panhandle/South Plains, where midlevel lapse rates will be steeper. With time, some southeastward-moving clusters may evolve and pose a risk of localized severe gusts and perhaps some hail spreading into parts of central and south TX during the evening/overnight. ...Eastern MN into northwest WI... In the wake of weak morning convection, isolated diurnal storm development will be possible along the cold front from eastern MN into northwest WI. While favorably cold temperatures aloft and steepening midlevel lapse rates will spread over the region, limited low-level moisture and buoyancy may tend to limit storm coverage and intensity. If confidence increases in more robust storm development, then hail probabilities may eventually be needed for the region. ..Dean.. 09/14/2023 Read more

No watches are valid as of Wed Sep 13 22:28:02 UTC 2023.

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