Severe Storms

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0240 PM CDT Sat Jul 08 2023 Valid 082000Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN HIGH PLAINS/FRONT RANGE ACROSS THE TX/OK PANHANDLES AND INTO OK...AND THE MID-SOUTH VICINITY... ...SUMMARY... Scattered strong to severe thunderstorms, and one or two organized thunderstorm clusters, are possible east of the Front Range and Sangre de Cristo Mountains through the Texas and Oklahoma Panhandles and Oklahoma. Additional strong to severe thunderstorm development is possible across parts of the lower Mississippi into Ohio Valleys. Minor changes at 20Z including expanding the Slight Risk a bit more across western Nebraska to account for ongoing hail storms now developing. See WW 461 and mesoscale discussion 1462 for more information. Storms will continue to increase in coverage, with an eventual MCS possible tonight into the TX/OK Panhandles and across OK. Elsewhere, sporadic strong storms persist from KY to the Arklatex and into MS and AL. Storms are forecast to concentrate later today into this evening into northern MS and vicinity, with damaging wind threat. ..Jewell.. 07/08/2023 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Jul 08 2023/ ...Front Range of the Central Rockies into TX Panhandle and OK... A moist air mass is already in place across the Front Range, with recent surface observations sampling upper 50s to low 60s dewpoints. Southeasterly low-level flow will help maintain this moist air mass throughout the day. Steep mid-level lapse rates are in place atop this low-level moisture, with recent mesoanalysis estimate max 2-6 km AGL lapse rates around 8 to 8.5 deg C per km. Convective initiation appears most likely first across the high terrain of north-central CO (and maybe adjacent southern WY), with these storms then moving into the destabilizing air mass across the Front Range. Long hodographs, created by moderate low-level southeasterlies veering to moderate northwesterlies aloft, will combine with moderate to strong buoyancy to support supercells capable of all severe hazards, including very large hail greater than 2" in diameter and a tornado or two. These supercells will likely persist into the evening, when a strengthening low-level jet should help promote upscale growth into one or more linear clusters. The resulting convective lines are then expected to progress southeastward across the TX/OK Panhandles into OK overnight and into Sunday morning. Some potential for significant wind gusts exists with these clusters, but uncertainty regarding overall evolution (mostly the strength of the rear-inflow jet) and most likely location for significant gusts precludes delineating any areas in this outlook. ...Mid-South Vicinity... Surface observations show mid-70s dewpoints are already in place across the region, downstream of an MCV related to last night's thunderstorms across OK. As discussed in recently issued MCD #1461, greater thunderstorm strength and coverage is possible as the MCV continues eastward and interacts with the destabilizing air mass over the Mid-South. Mid-level flow throughout the region will be generally modest, contributing to a predominantly multicellular mode. Even so, some localized enhancement of the flow is possible near the vorticity maximum, resulting in the potential for a few more organized updrafts. Storm mergers could also help briefly augment overall updraft strength. These factors, combined with ample moisture and steep low-level lapse rates, result in the potential for a few water-loaded downbursts. ...Middle/Upper OH Valley... Surface analysis places a pair of weak lows over southern Lower MI and western IN. A weak cold front extends between these two lows, and extends back farther southwestward from the western IN low. An area of showers and thunderstorms currently ongoing ahead of this front over western OH. Expectation is for this ongoing activity to continue eastward while gradually weakening over the next few hours. Associated cloud cover may temper daytime heating across IN and OH, but there should be a window for some limited heating/destabilization between the early cloudiness and the approaching cold front. Instability will still be modest, but this region will be on the southern periphery of the cyclonic flow covering eastern Canada, leading to slightly enhanced westerly flow aloft. The resulting combination of instability and shear could support a few stronger storms or bowing segments capable of damaging gusts. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0232 PM CDT Sat Jul 08 2023 Valid 091200Z - 101200Z ...CRITICAL FIRE WEATHER AREA FOR FAR SOUTHERN NEVADA AND FAR NORTHWEST ARIZONA... The biggest change with this forecast update was to introduce an isolated dry thunderstorm area for portions of the Pacific Northwest. Here, a slight chance of thunderstorms will be possible tomorrow afternoon into the overnight hours. At the same time, however, relative humidity will be increasing, which might limit true dry thunderstorm potential. However, given the likelihood of at least a few lightning strikes over increasing receptive fuels, an isolated dry thunderstorm area was introduced. Elsewhere, the critical fire weather area in the Southwest was expanded slightly to account for increasing confidence in critical conditions. A more thorough meteorological discussion can be found below. ..Marsh.. 07/08/2023 .PREV DISCUSSION... /ISSUED 0158 AM CDT Sat Jul 08 2023/ ...Synopsis... A mid-level speed max will move across portions of the Southwest into the Great Basin on Sunday, with an increase in surface winds and potential for Elevated to near Critical fire weather conditions. ...Winds and RH... Weak moisture return into central and northern Arizona will bring afternoon relative humidity largely just above Critical values. Elevated conditions will remain possible with relative humidity around 20-25 percent and sustained winds 15-20 mph. Further west across portions of southern Nevada and far western Arizona, and southern Utah, afternoon relative humidity reductions to 10-15 percent amid sustained winds 10-20 mph will support Elevated fire weather conditions and occasional spotty near Critical to Critical conditions. Stronger and longer duration sustained Critical winds are more likely across southern Nevada/far western Arizona amid relative humidity reductions to 10-15 percent. Across southern Nevada, ERCs are approaching and exceeding seasonal averages for dryness. Fuels further north into central/northern Nevada are drying but remain more marginal. A small Critical delineation was added where the highest conditional probabilities for Critical meteorological conditions lines up with drying fuels. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0461 Status Updates
STATUS FOR WATCH 0461 HAS NOT BEEN ISSUED YET Read more

WW 461 SEVERE TSTM CO KS NE WY 081910Z - 090300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 461 NWS Storm Prediction Center Norman OK 110 PM MDT Sat Jul 8 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northeast Colorado Far Northwest Kansas Western Nebraska Southeast Wyoming * Effective this Saturday afternoon and evening from 110 PM until 900 PM MDT. * Primary threats include... Scattered large hail likely with 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...Thunderstorm coverage and intensity is expected to increase this afternoon, with some supercells likely. Primary severe risk is large hail, with some isolated very large hail (i.e. 2" in diameter or greater) possible. A few strong gusts and a tornado or two could also occur. The severe thunderstorm watch area is approximately along and 85 statute miles east and west of a line from 50 miles north of Torrington WY to 5 miles southeast of Limon CO. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU1). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && AVIATION...A few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 27035. ...Mosier Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1226 PM CDT Sat Jul 08 2023 Valid 091200Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE ARKLATEX EASTWARD OVER PARTS OF THE GULF COAST STATES...AND OVER PARTS OF THE MID ATLANTIC... ...SUMMARY... Scattered severe storms are forecast from the Arklatex region across the Gulf Coast States, and across the Mid Atlantic on Sunday. Isolated severe storms will be possible over the far northern Plains/Upper Mississippi Valley. ...Synopsis... An upper ridge will develop over the Rockies while a large upper low develops over south-central Canada. Generally low heights aloft will exist over much of the East, with various disturbances moving around the base of this broad trough from the Arklatex across the Southeast and up the East Coast. At the surface, a weak front will extend from NC/VA northward across PA and NY, with a leading midlevel wave and around 35-40 500 mb winds. Southerly winds ahead of this boundary will maintain dewpoints generally in the 65-70 F range. This weak boundary will trail southwestward into the southern Plains, with 70s F dewpoints to the south aiding instability. Here, a disturbance associated with ongoing storms will enhance wind fields aloft from the Arklatex into parts of the central Gulf Coast States, with damaging wind gusts expected. Elsewhere, cool air aloft and cyclonic flow around the Canadian cyclone will affect parts of ND and northern MN, providing cool air aloft and steep lapse rates. ...OK/TX into the lower MS Valley... Models indicate a likely MCS will exist early in the day over OK, and will move east/southeastward across AR, LA, MS and western AL during the day. Given the very moist air mass and corridor of 2000+ J/kg MUCAPE, areas of wind damage will remain possible as the system evolves, and/or new storms form on the existing outflow. Confidence is low with both timing and placement of the greatest risk corridor given the nature of these regimes, but statistically the best corridor appears to stretch from the Arklatex into central MS. ...Carolinas northward into southern New England... The uncapped, moist air mass combined with minimal heating will result in relatively early development of storms centered over VA, MD, eastern PA and NY. MUCAPE of 1500-2000 J/kg as well as deep-layer mean winds over 30 kt should support a few clusters of damaging outflow winds. Isolated marginal hail appears most likely over northern areas where temperatures aloft will be cooler, and hodographs a bit more favorable with gradually increasing speeds aloft. ...ND/MN... Heating will result in a well-mixed boundary layer during the afternoon, while sufficient moisture contributes to 500-750 J/kg MUCAPE. Scattered storms may develop within the surface trough, with marginal hail or locally strong gusts possible. Storm mode may remain cellular despite the deep mixed layer as deep-layer shear increases to around 35 kt along with around 100 m2/s2 effective SRH. ..Jewell.. 07/08/2023 Read more

MD 1457 CONCERNING SEVERE THUNDERSTORM WATCH 459... FOR WEST TEXAS...OKLAHOMA PANHANDLE
Mesoscale Discussion 1457 NWS Storm Prediction Center Norman OK 0520 PM CDT Fri Jul 07 2023 Areas affected...West Texas...Oklahoma Panhandle Concerning...Severe Thunderstorm Watch 459... Valid 072220Z - 080015Z The severe weather threat for Severe Thunderstorm Watch 459 continues. SUMMARY...A severe threat will continue across parts of west Texas over the next couple of hours. Wind-damage and isolated large hail will continue to be possible with the stronger storms. An isolated severe threat will also be possible to the northwest of Lubbock early this evening, where the severe thunderstorm watch has been extended in area. DISCUSSION...The latest water vapor imagery shows a subtle shortwave trough moving through the central High Plains. The southern end of the shortwave trough is located in northeast New Mexico, just to the west of a maximum in instability where the RAP is analyzing MLCAPE in the 3000 to 3500 J/kg range. The lift and instability will continue to support thunderstorm development over the next few hours. Two line segments are currently ongoing with one in the northwest Texas Panhandle, and the other located about 70 statute miles to the northwest of Lubbock. Some bowing structure is evident in each of these lines. The MCS is moving to the east at around 40 knots. This should be favorable for wind damage along the leading edge of the stronger parts of the line. The strong instability, combined with 700-500 mb lapse rates near 7.5 C/km, will also support an isolated large-hail threat. ..Broyles.. 07/07/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LUB...AMA... LAT...LON 34030286 34750263 35860250 36250243 36600213 36700138 36520073 35970035 34770052 33880115 33350186 33290266 33700300 34030286 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Fri Jul 07 2023 Valid 072000Z - 081200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE OK/NORTHERN TX PANHANDLES INTO FAR NORTHWEST OK... ...SUMMARY... Scattered severe thunderstorms are expected late this afternoon through tonight across portions of the central and southern Plains. Large to very large hail and severe/damaging winds should be the primary risks, with the greatest potential for significant (75+ mph) winds across parts of the Oklahoma/Texas Panhandles into western Oklahoma late this afternoon and evening. ...20Z Update... The primary change with this outlook is to trim parts of the Marginal Risk across parts of the northern and central Plains, generally behind a cold front across parts of ND/MN, and in the wake of earlier convection across parts of the central Plains. Otherwise, isolated supercells will be possible this afternoon across eastern CO into northeast NM, with upscale growth into a severe-wind producing MCS expected across parts of the TX/OK Panhandles by this evening. See MCD 1455 for more information regarding the short-term threat across the southern High Plains, MCD 1454 for more information across northern New England, and MCD 1456 for more information across the northern Plains. Also see the previous discussion below for more information. ..Dean.. 07/07/2023 .PREV DISCUSSION... /ISSUED 1123 AM CDT Fri Jul 07 2023/ ...Southern/Central Plains...Southern/Central High Plains... Ongoing MCS across central OK is expected to continue weakening over the next few hours as it moves into the more stable conditions downstream in the Arklatex vicinity. A large ACCAS field has developed in the wake of the this MCS across the TX Panhandle, supported by modest isentropic ascent atop the MCS outflow. A few elevated storms are possible within this environment this morning, but warming and drying mid-levels should lead to their dissipation before this afternoon. The evolution of this MCS and additional elevated storms this morning have helped to reinforce a subtle surface boundary extending across the western TX Panhandle through far northeast NM and into southeast CO, where it intersects the lee troughing. Additionally, a cold front is forecast to continue pushing southward/southeastward across eastern CO and the adjacent central Plains. This front will likely be through much of eastern CO by the late afternoon, with post-frontal upslope in place across southeast CO. Afternoon thunderstorm development is anticipated along the higher terrain of northeast NM and southern CO, with an initially supercellular mode possible over southeast CO. Very large hail is the primary severe risk with these supercells, but the high surface vorticity environment suggests a tornado or two is possible as well. Highest storm coverage is anticipated south of the Palmer Divide. An isolated storm or two capable of hail is possible north of the divide. These supercells are then expected to move downstream, interacting with the now modified boundary farther east across the northern TX/OK Panhandles. Convergence along this boundary will likely provide a favored corridor for upscale growth. High storm bases coupled with steep low-level lapse rates will support strong outflow, with significant severe winds of 75+ mph possible with this complex as it moves quickly eastward. Other supercells may form in the strengthening warm advection regime across south-central KS/northern OK this evening. Steep mid-level lapse rates and moderate deep-layer shear will support the potential for very large hail. Some threat for severe/damaging winds may eventually develop with this convection if it can grow upscale into one or more small clusters while spreading generally southeastward tonight. ...Central Plains into the Mid MS Valley... Decaying MCS continues to push eastward across western IA/northern MO, with a few thunderstorms ongoing along its southern periphery across far northwest MO. Redevelopment/restrengthening appears possible downstream of theses storms over northern and east-central MO/west-central IL as the air mass destabilizes. This area will be on the southern periphery of the stronger mid-level flow, supporting the potential for a few strong to severe storms capable of damaging gusts. Additional redevelopment is possible farther west over the southeast NE/northeast KS vicinity as outflow for the IA/MO MCS as well as outflow from the elevated cluster over central KS moves into the region. However, ongoing cloud cover may limit destabilization, precluding this potential redevelopment until later this evening. ...Northeast/Mid-Atlantic... Daytime heating of a moist low-level airmass should encourage the development of weak to moderate instability by this afternoon across parts of the Northeast and Mid-Atlantic. Glancing ascent associated with a shortwave trough over Quebec and weak low-level convergence along a surface trough extending from northern NY southward through central VA will likely foster at least scattered thunderstorm coverage this afternoon and evening. Deep-layer shear is forecast to remain fairly modest, generally 25 kt or less, and weakening with southward extent across the Mid-Atlantic. Still, some loosely organized thunderstorm clusters capable of producing damaging gusts are possible, particularly from central NY into northern ME where shear is strongest. Read more

WW 0459 Status Updates
STATUS FOR WATCH 0459 HAS NOT BEEN ISSUED YET Read more

WW 459 SEVERE TSTM CO KS NM OK TX 071950Z - 080200Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 459 NWS Storm Prediction Center Norman OK 250 PM CDT Fri Jul 7 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Far Southeast Colorado Far Southwest Kansas Far Northeast New Mexico Oklahoma Panhandle Texas Panhandle * Effective this Friday afternoon and evening from 250 PM until 900 PM CDT. * Primary threats include... Scattered damaging winds and isolated significant gusts to 80 mph likely Scattered large hail and isolated very large hail events to 2.5 inches in diameter likely SUMMARY...Thunderstorms are expected to increase in coverage and intensity across northeastern New Mexico and far southeastern Colorado this afternoon before then spreading into the Texas and Oklahoma Panhandle, and perhaps far southwest Kansas, tonight. Very large hail and strong gusts are possible with these storms. Organization into a linear convective system capable of significant severe gusts is probable. The severe thunderstorm watch area is approximately along and 90 statute miles east and west of a line from 30 miles west northwest of Elkhart KS to 45 miles south of Amarillo TX. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU9). 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 2.5 inches. Extreme turbulence and surface wind gusts to 70 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 27030. ...Mosier Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0204 PM CDT Fri Jul 07 2023 Valid 081200Z - 091200Z Only minor adjustments made to ongoing Elevated area. Otherwise, no changes. See previous discussion below. ..Bentley.. 07/07/2023 .PREV DISCUSSION... /ISSUED 0146 AM CDT Fri Jul 07 2023/ ...Synopsis... ...Wind and RH... Continued dry and breezy conditions are expected on Saturday across portions of Arizona, southern Utah, western Colorado, and New Mexico. Gradients appear to relax somewhat from Friday as heights rise within the western US ridge. Only a marginal signal is shown in the HREF conditional probabilities for widespread sustained Critical fire weather conditions. Afternoon relative humidity reductions to 5-15 percent will be likely but stronger winds look to remain localized and largely terrain driven. Given low confidence in a broader region of Critical conditions, an Elevated delineation was maintained with this outlook. Locally Critical conditions will be possible. ...Dry Thunderstorms... High based thunderstorms will be possible across the Oregon Cascades on Saturday. Enough mid-level moisture will remain in place for afternoon thunderstorm development with little to no accumulation expected (given precipitable water <= 0.75"). Drying fuels will support potential for new lightning starts. ...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 1230 PM CDT Fri Jul 07 2023 Valid 081200Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE HIGH PLAINS SOUTHEASTWARD THROUGH OKLAHOMA AND THE LOWER MS/OH VALLEYS... ...SUMMARY... Severe thunderstorms are possible from the central High Plains area southeastward across parts of Kansas and Oklahoma to the Lower Ohio and Lower Mississippi Valley areas on Saturday. ...High Plains vicinity into parts of OK... Relatively moist low-level southeasterly flow will again support moderate destabilization in areas near the higher terrain of WY/CO/NM on Saturday afternoon. Moderate west-northwesterly flow will result in effective shear of 40+ kt, and isolated supercells will be possible from near the Big Horns in WY southward to near/east of the CO Front Range and Raton Mesa in NM. Large hail and possibly a tornado or two will be the primary threats with initial supercell activity. Some upscale growth into one or more southeastward-moving clusters will be possible during the evening, which could spread a severe-wind threat (in addition to hail) into parts of the TX/OK Panhandles and southwest KS. Farther east into a larger part of OK and north TX, the likelihood of morning convection results in uncertainty regarding the severe threat later in the day. However, there will be some potential for isolated diurnal convection along an outflow-reinforced surface boundary, which would pose a threat of isolated hail and severe gusts. Later Saturday night, an MCS could emerge from the High Plains and move southeastward, though the most favored corridor for a late night severe-wind threat remains uncertain. ...Lower MS/OH Valley and vicinity... Strong to potentially severe thunderstorms will be possible from AR into parts of the lower MS and OH Valleys, in conjunction with multiple low-amplitude shortwave troughs and along/ahead of a cold front and any remnant outflows. The details of the potential scenarios remain uncertain, but with favorable low-level moisture and sufficient deep-layer shear, a few organized cells/clusters capable of damaging winds and some hail will be possible. Some threat could spread as far northeast as the lower Great Lakes, though destabilization becomes increasingly uncertain with northeastward extent. ..Dean.. 07/07/2023 Read more

No Mesoscale Discussions are in effect as of Thu Jul 6 22:00:12 UTC 2023.

WW 0454 Status Updates
STATUS FOR WATCH 0454 HAS NOT BEEN ISSUED YET Read more

WW 454 SEVERE TSTM CO 062050Z - 070400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 454 NWS Storm Prediction Center Norman OK 250 PM MDT Thu Jul 6 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of North-central and northeast Colorado * Effective this Thursday afternoon and evening from 250 PM until 1000 PM MDT. * Primary threats include... Scattered large hail and isolated very large hail events to 3 inches in diameter likely Isolated damaging wind gusts to 70 mph possible A tornado or two possible SUMMARY...A couple supercells may develop initially along and just east of the Front Range across the I-25 corridor. Additional supercells will likely form later this evening into northeast Colorado and these will have the greatest hail and brief tornado threat. The severe thunderstorm watch area is approximately along and 65 statute miles east and west of a line from 40 miles northeast of Fort Collins CO to 25 miles west southwest of Limon CO. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU4). 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. && OTHER WATCH INFORMATION...CONTINUE...WW 452... AVIATION...A few severe thunderstorms with hail surface and aloft to 3 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 29030. ...Grams Read more

WW 0452 Status Updates
STATUS FOR WATCH 0452 HAS NOT BEEN ISSUED YET Read more

WW 452 SEVERE TSTM WY 062020Z - 070300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 452 NWS Storm Prediction Center Norman OK 220 PM MDT Thu Jul 6 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Eastern Wyoming * Effective this Thursday afternoon and evening from 220 PM until 900 PM MDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2.5 inches in diameter possible Isolated damaging wind gusts to 70 mph possible A tornado or two possible SUMMARY...A few supercells should develop off the higher terrain and move east into this evening, potentially consolidating into a cluster as they approach the South Dakota-Nebraska border area. The severe thunderstorm watch area is approximately along and 60 statute miles east and west of a line from 35 miles east northeast of Sheridan WY to 50 miles east of Laramie WY. 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 2.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 28030. ...Grams Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0246 PM CDT Thu Jul 06 2023 Valid 062000Z - 071200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR NORTHEAST COLORADO INTO SOUTHWEST KANSAS... ...SUMMARY... The most concentrated corridor of severe storms is expected across a portion of eastern Colorado and western Kansas, centered on this evening. These storms will be capable of producing very large hail, a few tornadoes, and significant severe wind gusts as they likely evolve into a cluster tracking towards northwest Oklahoma overnight. ...20Z Update... The primary change to this outlook was to disconnect Marginal risk probabilities from the southern Plains to the Lower MS Valley. The probabilities in the Lower MS Valley were adjusted to address the shorter-term large hail/strong gust threat with storms intensifying over the Arklatex toward MS. Meanwhile, the marginal risk probabilities in the southern Plains were terminated southeast into central OK, where an MCS should be positioned at the end of the period (12Z Friday morning). Finally, the 30 percent hail probabilities (and associated Enhanced Risk line) have been extended slightly northwest into northern CO, where persistent insolation may promote locally higher buoyancy and subsequent supercell hail threat. Otherwise, the previous forecast (see below) remains on track. ..Squitieri.. 07/06/2023 .PREV DISCUSSION... /ISSUED 1130 AM CDT Thu Jul 06 2023/ ...Eastern CO to northwest OK... Decaying remnants of a morning MCS and elevated clusters persist across parts of OK, the far eastern TX Panhandle, and western KS. Abundant cloud coverage from convective debris and a broken stratus canopy will modulate boundary-layer heating, with more robust insolation expected over much of the TX Panhandle and in pockets along the southern Rockies. With a southeasterly component to low-level flow confined to the lowest 1 km and pronounced veering of the wind profile with height to separate confluent belts of enhanced mid-level westerlies centered on the WY/CO border and the CO/NM border, late afternoon thunderstorm development should be focused near the Denver cyclone with capping potentially limiting development over the Raton Mesa. Initial updrafts in northeast CO will likely evolve into one or two slow-moving supercells with very large hail as the main threat early. A strengthening low-level jet this evening should support maintaining these supercells after dusk and/or yield additional development east along the Palmer Divide in east-central CO. Despite increasing MLCIN, low-level hodographs will become quite enlarged, supporting potential for a long-track intense supercell or two moving southeast across a portion of eastern CO and western KS. Overnight, elevated convective development should occur downstream of these long-track supercells, which may yield a small bowing MCS focused on southwest KS to northwest OK. The overall tornado and significant severe wind threat should be modulated to an extent by relatively weak low-level lapse rates. But the highly sheared and steep mid-level lapse rate environment renders concern for a narrow swath of significant severe persisting into early morning. ...Lee of the Big Horns to the Black Hills vicinity... Farther north, a separate region of more concentrated thunderstorm development is expected during the late afternoon to evening downstream of a low-amplitude shortwave trough moving east from the northern Rockies towards the Big Horns. Low-level shear will be weak across this area, but an elongated nearly straight-line hodograph will foster a few splitting supercells capable of very large hail. These should consolidate into an east-southeast moving cluster/small MCS across western SD and the NE Panhandle with a threat for severe wind gusts peaking during the mid-late evening and becoming more isolated overnight. ...Ark-La-Tex to Ark-La-Miss vicinity.. An MCV over east-central OK should drift east with regeneration of thunderstorms downstream to its south and southeast impinging on a confined plume of MLCAPE from 2000-3000 J/kg. Despite relatively weak shear, semi-organized multicell clusters should form and offer a risk for isolated damaging winds through this evening. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0205 PM CDT Thu Jul 06 2023 Valid 071200Z - 081200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NORTHERN ARIZONA AND ADJACENT AREAS... The forecast for critical fire-weather conditions on Friday remains unchanged in this update for northern Arizona. Similarly, the forecast for isolated dry thunderstorms remains on track across Oregon with the potential for the greatest number/density of cloud-to-ground lightning flashes across Lake and Klamath Counties in southern Oregon. See the previous discussion below for more details. ..Jirak.. 07/06/2023 .PREV DISCUSSION... /ISSUED 0200 AM CDT Thu Jul 06 2023/ ...Synopsis... ...Wind/RH... Similar to Day 1/Thursday, enhanced west-southwesterly deep-layer flow will persist across the Southwest into the central Rockies -- where a dry antecedent air mass will be in place. Boundary-layer mixing into the enhanced flow aloft will favor 20-25 mph sustained west-southwesterly surface winds (with higher gusts) amid 10-15 percent RH across portions of the Southwest and central Rockies. As a result, critical fire-weather conditions are expected across northern AZ -- where 90th percentile ERCs exist. While critical meteorological conditions may spread northward into southern UT, current indications are that fuels are less receptive here (outside of extreme southern UT). ...Dry Thunderstorms... Midlevel moisture will increase atop a diurnally deepening boundary layer over portions of OR on Day 2/Friday. This will favor isolated high-based thunderstorms along/east of the Cascades in OR from the afternoon into late evening. Inverted-V thermodynamic profiles and around 0.7 inch PW will support dry thunderstorms capable of new fire starts given increasingly dry fuels over the area. ...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 1228 PM CDT Thu Jul 06 2023 Valid 071200Z - 081200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE CENTRAL AND SOUTHERN HIGH PLAINS INTO THE SOUTHERN PLAINS... ...SUMMARY... Severe wind and hail producing storms are expected across the central and southern High Plains into the southern Plains tomorrow/Friday. A couple of damaging gusts are also possible across the Upper Hudson Valley. ...Synopsis... A pronounced mid-level trough will traverse the central CONUS while a secondary mid-level perturbation crosses the southern Rockies and ejects into the southern Plains tomorrow/Friday. Meanwhile, the approach of the mid-level trough over the Midwest will also support weak surface troughing along and to the lee of the central and northern Appalachians during the afternoon hours. Multiple rounds of organized strong to severe storm potential should occur across the central U.S., including at the start of the period. The most robust severe storm development should occur across the southern Plains with the ejection of the mid-level perturbation, with all severe hazards possible. Scattered strong thunderstorm development may also occur across the northeast in tandem with the weak surface lee trough. ...Southern High Plains into the southern Plains... One or more loosely organized MCSs will likely be in progress over portions of the southern Plains at the start of the period (12Z Friday morning), perhaps accompanied by a marginal severe wind threat. With time, as the low-level jet weakens, the MCSs should dissipate through the late morning/early afternoon hours. Similar to Day 1, residual showers and cloud cover will gradually clear, allowing for surface temperatures to rise over 90 F in the TX Panhandle, to over 80F points north. These temperatures, along with surface dewpoints into the low to mid 60s F, overspread by 8.5+ C/km mid-level lapse rates, will support strong buoyancy (i.e. 3000+ J/kg SBCAPE), especially in the northern TX Panhandle. By late afternoon into early evening, a 20-30 kt southwesterly low-level jet, overspread by 40-50 kts of 500 mb westerly flow, will support 40-50 kts of effective bulk shear, characterized by hodographs with some low-level curvature and mid-level elongation. Questions remain regarding initial storm coverage (especially north of the TX Panhandle) due to capping. However, at least isolated supercells should initiate by late afternoon with a large hail threat. A few 2+ inch stones and a couple of tornadoes cannot be ruled out. Later in the evening, upscale growth into a severe-wind producing MCS is possible. The overall coverage and severity of this MCS is predicated on the number and intensity of initial merging supercells. The isolated nature of the initial supercells and lack of higher confidence in robust MCS development precludes greater severe wind/hail coverage probabilities this outlook. ...Northern Plains... Behind the progressing mid-level trough, a weak cold front will sag southward across the northern Plains during the day. Insolation and boundary-layer mixing, overspread by 7 C/km mid-level lapse rates, will foster 1000-2000 J/kg SBCAPE by afternoon peak heating. Deep-layer shear will not be overly strong (i.e. generally under 30 kts of effective bulk shear). Nonetheless, enough hodograph curvature/elongation may exist to support stronger pulse-cellular storms or loosely organized multicell clusters with an isolated severe gust threat along with some small hail. ...Midwest... Thunderstorm clusters, potentially in the form of loosely organized MCSs, may be ongoing at the start of the period across eastern portions of the central Plains toward the central MS Valley region. These storms will be supported at the terminus of a 30+ kt low-level jet, accompanied by a marginal severe hail/wind threat. Airmass modification behind the initial storms will be modest and gradual due to lingering clouds and precipitation, limiting instability later during the afternoon. Nonetheless, the passage of the upper trough atop a southward-sagging baroclinic zone may serve as a focus for some renewed convective development by late afternoon. Given modest instability (relatively poor mid-level lapse rates fostering 500-1500 J/kg MUCAPE - most of which may be elevated), later severe potential should not be widespread. Nonetheless, given elongated hodographs (and 40-50 kts of effective bulk/speed shear) multicellular storms (and perhaps a brief, transient supercell) are possible by late afternoon, with a couple of severe gusts/large hail stones possible. ...Upper Hudson Valley... Adequate surface heating of a moist boundary layer will support surface temperatures warming well into the 70s F amid mid to upper 60s F dewpoints, resulting in MLCAPE over 1000 J/kg (perhaps approaching 2000 J/kg in spots). The combination of weak ascent associated with the surface lee trough and insolation will support the initiation of scattered thunderstorms by early afternoon. Deep-layer shear should not be overly strong, though point forecast soundings suggest modest hodograph elongation, especially closer to the international border. As such, a few longer lived multicells and pulse single-cells may organize, capable of supporting wet downbursts, a couple of which may approach severe limits. As such, damaging gusts may accompany the stronger storms, warranting the introduction of Category 1/Marginal risk-driven wind probabilities. ..Squitieri.. 07/06/2023 Read more

MD 1434 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR EASTERN TEXAS PANHANDLE INTO FAR WESTERN OKLAHOMA
Mesoscale Discussion 1434 NWS Storm Prediction Center Norman OK 0355 PM CDT Wed Jul 05 2023 Areas affected...eastern Texas Panhandle into far western Oklahoma Concerning...Severe potential...Watch unlikely Valid 052055Z - 052230Z Probability of Watch Issuance...20 percent SUMMARY...Isolated severe storms will remain possible for a few hours over a small area from the eastern Texas Panhandle into far western Oklahoma. Large hail will be the primary threat. DISCUSSION...Storms persist near the intersection of a modified outflow boundary and surface trough over the northeast TX Panhandle. Other attempts at initiation have failed farther east into OK where capping is a bit stronger. However, additional heating and air mass modification may yield isolated cells into that area as well as backed low-level winds favor rightward propagation. If the zone can destabilize further, a small corridor of damaging hail may materialize. At this time, the overall size and duration of the severe risk appears too short/small for a watch, although trends will continue to be monitored. ..Jewell/Grams.. 07/05/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OUN...AMA... LAT...LON 35210108 35810076 36130050 36170020 36019990 35849975 35269903 34969894 34769946 34770010 34810069 34950102 35210108 Read more