Severe Storms

MD 1177 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF EASTERN TEXAS AND WESTERN LOUISIANA
Mesoscale Discussion 1177 NWS Storm Prediction Center Norman OK 0343 PM CDT Tue Jun 20 2023 Areas affected...parts of eastern Texas and western Louisiana Concerning...Severe potential...Watch unlikely Valid 202043Z - 202315Z Probability of Watch Issuance...20 percent SUMMARY...Isolated intense thunderstorm development is possible through 5-7 PM CDT. It remains unclear how long any storms that do develop will persist, but they may pose at least a short-lived risk for very large hail and strong downbursts. It does not currently appear that a severe weather watch will be needed, but trends will continue to be monitored. DISCUSSION...Attempts at new thunderstorm development are ongoing near/east-southeast of Longview, TX. This may be supported by forcing for ascent within a focused area of weak low-level warm advection, in the wake of a subtle short wave impulse now digging across Louisiana coastal areas. Due to substantial lingering inhibition associated with warm and dry elevated mixed-layer air, it remains unclear if this convection will be sustained, particularly based on recent model output. However, seasonably moist boundary-layer inflow into the south-southeastward propagating convection appears characterized by very large CAPE. And deep-layer shear beneath moderate northwesterly mid-level flow (on the order of 30 kt) may be marginally sufficient to support supercell structures. So, there appears at least some potential for isolated rapid thunderstorm development and intensification during the next few hours. If this occurs, it probably will be accompanied by a risk for very large hail and occasional strong downbursts as long as it it maintained. ..Kerr/Hart.. 06/20/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LCH...SHV... LAT...LON 32509427 32399408 31739327 30979343 30869387 31029428 32179455 32529452 32509427 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Tue Jun 20 2023 Valid 202000Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF LOUISIANA AND EAST TEXAS...AND ALSO OVER PORTIONS OF EASTERN MONTANA AND THE DAKOTAS... ...SUMMARY... Isolated to scattered severe thunderstorms will be possible late this afternoon into tonight across parts of the northern Plains, and also from east Texas to the Southeast. Damaging winds and large hail should be the main threats. ...20Z Update... The primary outlook change is to trim the northeastern portion of the southern Slight Risk area across parts of southern MS, in the wake of extensive convection that has recently moved into southeast LA. Otherwise, see the previous discussion below for more information, and MCD 1175 for more information regarding the short-term threat across parts of WY. Outside of the Marginal Risk area, elevated storms may develop late tonight across south-central NE into north-central KS. A hail threat cannot be ruled out with the strongest storms, due to the presence of steep midlevel lapse rates and favorable elevated buoyancy. However, with uncertainty regarding storm placement and coverage, and only modest deep-layer shear in place, confidence remains too low to extend severe probabilities into the region at this time. ..Dean.. 06/20/2023 .PREV DISCUSSION... /ISSUED 1124 AM CDT Tue Jun 20 2023/ ...LA/TX... Morning water vapor imagery shows a dominant ridge aloft extending from the southern Plains into the upper Midwest, with a band of relatively fast northwesterly mid-level flow from MO/AR into LA/MS. An extremely moist low-level air mass is present beneath the southwesterly fringe of the strong winds aloft, with dewpoints in the upper 70s to near 80F over parts of east TX and much of LA. Strong heating will yield very large CAPE values this afternoon and promote scattered thunderstorm development. Storms will mainly develop along/ahead of a southwestward sagging surface boundary that currently extends from northern LA into southern MS. A few of the cells will likely be severe, with hail and damaging winds possible through the evening. ...SD/ND... A weak surface cold front currently extends from north central ND into southeast SD. Substantial low-level moisture along and east of the front, coupled with full sunshine, will result in moderate CAPE by afternoon. Large scale forcing for ascent associated with a shortwave trough currently over northwest CO will overspread the area this afternoon, promoting scattered thunderstorms along the front. Low-level winds are relatively weak, but sufficient deep layer shear will promote organized multicell or a few supercell storms capable of large hail and damaging winds. ...Eastern MT/western ND... Model guidance shows a well-defined 60-70kt mid-level jet over northern NV. Forcing associated with this feature is moving across western WY and is expected to result in a scattered thunderstorms over the Big Horn mountains by mid-afternoon. These storms will track northeastward into southeast MT and eventually western ND tonight. A cluster of fast-moving supercells or bowing structures (similar to yesterday) is possible, capable of damaging winds and hail. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0247 PM CDT Tue Jun 20 2023 Valid 211200Z - 221200Z The Elevated region was expanded slightly into northern Arizona to account for Elevated fire weather conditions in the Little Colorado River Valley. In this region, sustained downslope winds around 15-20 will overlap modestly dry fuels and relative humidity reductions to 10-15 percent. Otherwise, the forecast remains on track. See previous discussion below for more information. ..Thornton.. 06/20/2023 .PREV DISCUSSION... /ISSUED 0100 AM CDT Tue Jun 20 2023/ ...Synopsis... A similar upper-level pattern to Tuesday will continue into Wednesday. The trough in the West and ridge in the Plains will make little progress. A similarly situated High Plains lee trough will also be present once again during the afternoon. ...Southwest... Dry and windy conditions are expected during the afternoon from southeastern Arizona into northeastern New Mexico. RH of 15-20% will be most common; however, broader areas of RH near 10% may occur as compared to Tuesday. Winds of 15-20 mph will again occur in most areas. Some terrain-enhancement will promote locally stronger winds. Elevated fire weather will occur for a few 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 1232 PM CDT Tue Jun 20 2023 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS... ...SUMMARY... Isolated to scattered severe thunderstorms are possible on Wednesday across portions of the Plains. Large hail and severe gusts will be the main hazards with this activity. Isolated strong storms also will be possible across parts of the Southeast, with an accompanying risk for damaging gusts. ...Synopsis... Little change to the large-scale pattern is expected on Wednesday, with a deep upper trough remaining in place over much of the west into the northern High Plains, an upper ridge from the southern Rockies into parts of the southern High Plains, and a persistent upper low/trough over the Southeast. At the surface, an initially stationary front will extend from the Gulf Coast northwestward toward the ArkLaTex and into the southern High Plains. This front may tend to move westward across the southern Plains Wednesday evening. Another weak cold front will become nearly stationary across the northern Plains. ...CO Front Range into parts of the central/southern Plains... Guidance varies regarding the placement (if any) of ongoing storm clusters Wednesday morning across the central Plains. Some CAM solutions take an ongoing storm cluster and intensify it through the day as it moves south-southeastward along the periphery of the upper ridge, which would potentially result in a notable severe-wind risk across parts of OK into central/east TX as the downstream environment becomes strongly unstable during the afternoon. Other guidance suggests little to no threat in these areas during the day, as the severe threat focuses farther west toward the High Plains by late afternoon/evening. Even if no substantial MCS development occurs during the day, widely scattered strong storms may be possible along the front, and also emerging from a hot and well-mixed environment across parts of southwest TX. Uncertainty remains quite high, but severe probabilities have been expanded southeastward to cover these potential threats. Otherwise, moist post-frontal low-level flow will support thunderstorm development across parts of the central High Plains and the CO Front Range during the afternoon and evening. Midlevel flow will remain rather modest, but favorably veering wind profiles will result in effective shear of 30-40 kt, supporting the potential for a few supercells with an initial threat of large (possibly golfball-size or larger) hail. A tornado or two will also be possible, especially across parts of southeast WY, where a the most favorable overlap of instability and stronger low-level shear is currently forecast. With time, upscale growth into one or more clusters will be possible, with an increasing severe-wind risk. There is some potential for an organized MCS to develop and move southeastward across the southern High Plains Wednesday night, though this scenario will depend in part on the extent of convective overturning that occurs downstream earlier in the day. ...Northern Plains... Some uncertainty remains regarding the convective evolution on Wednesday across the Dakotas, with morning storms potentially leading to a complex evolution later in the day. Stronger midlevel flow will remain displaced well northwest of the effective warm sector, but a few strong storms may develop during the afternoon near a weakening frontal boundary, with a threat of isolated hail and strong gusts. Farther west, a few stronger cells/clusters may develop across parts of northeast WY, within a modestly moist post-frontal regime. Deep-layer flow/shear will be stronger in this area, but buoyancy may tend to remain somewhat limited. Isolated hail and severe gusts cannot be ruled out in this area. One or more clusters may eventually move northeastward into the Dakotas Wednesday night, which could pose a threat of isolated strong/severe gusts, depending on the magnitude of buoyancy in the wake of potential convection earlier in the day. ...Southeast... To the south and east of the persistent upper low across the Southeast, widespread convection is expected during the day on Wednesday, which may persist into Wednesday night near the immediate Gulf Coast. Modest deep-layer flow/shear and moderate buoyancy will support some stronger cells/clusters, with a primary threat of locally damaging gusts. Weak midlevel lapse rates will tend to limit the hail threat, though small to near-severe hail cannot be ruled out with the strongest storms. ..Dean.. 06/20/2023 Read more

MD 1169 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR SOUTHEASTERN LOUISIANA
Mesoscale Discussion 1169 NWS Storm Prediction Center Norman OK 0503 PM CDT Mon Jun 19 2023 Areas affected...Southeastern Louisiana Concerning...Severe potential...Watch possible Valid 192203Z - 200000Z Probability of Watch Issuance...40 percent SUMMARY...Large hail and damaging winds would be possible should storms develop westward into southeastern Louisiana. A watch is not certain at this time, but convective trends will be monitored. DISCUSSION...Cumulus near Lake Pontchartrain have steadily become more vertically developed late this afternoon. Forcing for ascent remains rather weak with minimal surface convergence and the upper low farther to the northeast. However, temperatures near 100 F and dewpoints in the mid-upper 70s F is supportive of minimal MLCIN. Development along westward-moving outflow from southern Alabama/Mississippi may provide a trigger for additional storm development into southeastern Louisiana. Very large buoyancy and enhanced mid-level northwesterly flow around the upper low (25-35 kts of effective shear) would mean organized supercell structures would be possible. Large hail up to 2 inches and damaging wind gusts would be the main threats. Low-level shear is sufficient for weak low-level rotation (per KLIX VAD). The strongest discrete storms could produce a brief tornado. There is some uncertainty how many storms and how far west development will occur. A watch is possible should convective trends warrant. ..Wendt/Thompson.. 06/19/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LIX... LAT...LON 29769005 30159120 30699135 30809116 30839069 30778990 30608922 30118888 29608922 29769005 Read more

MD 1168 CONCERNING SEVERE THUNDERSTORM WATCH 340... FOR CENTRAL TEXAS
Mesoscale Discussion 1168 NWS Storm Prediction Center Norman OK 0458 PM CDT Mon Jun 19 2023 Areas affected...Central Texas Concerning...Severe Thunderstorm Watch 340... Valid 192158Z - 200000Z The severe weather threat for Severe Thunderstorm Watch 340 continues. SUMMARY...A severe threat is expected to continue into this evening with large hail and wind damage possible across parts of central Texas. As the severe threat moves toward the edge of weather watch, new watch issuance will need to be considered. DISCUSSION...The latest high-resolution radar imagery from San Angelo shows a severe convective cluster over the Texas Hill Country. These storms are located near a thermal axis extending southeastward across central Texas, where surface temperatures are well above 100 F. Large temperature-dewpoint spreads are resulting in high-based storms with damaging outflow potential. The WSR-88D VWP at Fort Hood has a supercell wind profile, with 0-6 km shear near 40 knots. This, combined with 700-500 mb lapse rates near 8.5 C/km, will also support a large hail threat. The severe threat will move toward the edge of weather watch 340 over the next hour, and could affect areas to the east of the watch later this evening. For this reason, a new watch could be needed across central Texas by 00Z. ..Broyles.. 06/19/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FWD...EWX...SJT... LAT...LON 31859793 32129830 32209880 31979921 31479951 30839983 30400008 29939996 29679936 29689900 29889866 30749807 31489781 31859793 Read more

MD 1167 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PORTIONS OF SOUTHEAST MONTANA INTO FAR NORTHEAST WYOMING
Mesoscale Discussion 1167 NWS Storm Prediction Center Norman OK 0351 PM CDT Mon Jun 19 2023 Areas affected...portions of southeast Montana into far northeast Wyoming Concerning...Severe potential...Watch possible Valid 192051Z - 192315Z Probability of Watch Issuance...60 percent SUMMARY...The severe threat is increasing across portions of the northern High Plains. Severe winds and hail are the greatest threats with any of the stronger storms that develop. An organized convective cluster may ultimately materialize and a WW issuance may become necessary at some point this afternoon. DISCUSSION...Several hours of clearing skies have supported surface temperatures to warm into the upper 70s F amid upper 40s to 50s F dewpoints, resulting in 2000+ J/kg SBCAPE/MUCAPE given the presence of 7-8 C/km low- and mid-level lapse rates. Cumulus are increasing in depth and coverage across northeast WY, likely driven by the strong surface heating. However, the approach of the mid-level trough will result in increasing deep-layer ascent and stronger flow aloft, which will also support 60+ kts of effective bulk shear/elongated hodographs. As storms develop, cellular modes are possible, with a mix of severe hail/gusts the hazards of concern. However, as potential upscale growth of an MCS occurs later this afternoon or early evening, severe winds will become the prevalent threat. ..Squitieri/Hart.. 06/19/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BIS...UNR...BYZ...GGW...RIW... LAT...LON 44830940 46360734 47190573 47520432 46950344 46150319 45340368 44920436 44680518 44470625 44090753 44130847 44830940 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Mon Jun 19 2023 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHEAST...NORTHERN PLAINS...AND CENTRAL TEXAS... ...SUMMARY... Severe thunderstorms are possible today over parts of the Southeast, central Texas, Arklatex, and northern Plains. ...20Z Update... The only meaningful change to the outlook has been to introduce a small Slight Risk across parts of central TX. Temperatures have soared into the low to mid 100s amid upper 60s to low 70s surface dewpoints to the east of a dryline. Recent visible satellite imagery shows convective initiation occurring east of San Angelo TX. Even though large-scale ascent will remain weak, any thunderstorms that can form and be sustained may become supercellular given 35-40 kt of deep-layer shear due to modestly enhanced mid/upper-level northwesterly winds. An associated threat for very large hail should exist given the presence of very strong instability and steep mid-level lapse rates. Severe downdraft winds may also occur. For more details, see recently issued Mesoscale Discussion 1166 and Severe Thunderstorm Watch 340. Across the Southeast, tornado potential will likely remain focused along/very near the Gulf Coast in MS/AL and the FL Panhandle. Multiple areas of low-level rotation, with occasional debris signatures, have been noted with convection occurring across these areas given favorable low-level shear noted on recent VWPs from KMOB/KEVX, etc... In the wake of earlier thunderstorms, a separate area of convection has also developed this afternoon across south-central AL. This activity may pose an isolated threat for damaging winds and hail through the rest of the afternoon into this evening as the boundary layer attempts to re-destabilize. See Mesoscale Discussion 1165 for more details on the near-term severe threat across the central Gulf Coast states. No changes have been made to the Slight Risk across parts of eastern MT into ND. ..Gleason.. 06/19/2023 .PREV DISCUSSION... /ISSUED 1112 AM CDT Mon Jun 19 2023/ ...Southern MS/AL to FL Panhandle... A large upper trough is present today over much of the eastern states, with a corridor of 30-40 knot mid-level winds extending from AR into the central Gulf Coast region. Ample low-level moisture remains across much of the southeast, but multiple bouts of convection have pushed the main outflow boundary southward into southern MS/AL and the FL Panhandle. Strong afternoon heating will help to establish moderate to strong instability along this axis where re-development of widely scattered strong/severe storms are expected. Weak forcing mechanisms suggest limited coverage of intense storms, but sufficient deep-layer vertical shear and proximity to boundaries may result in isolated supercells capable of hail, damaging wind gusts, and perhaps a tornado. ...Southeast GA/Northeast FL... A persistent linear MCS continues to track eastward across southern GA and northern FL. Strong heating ahead of the line has resulted in moderate CAPE values and sufficient westerly flow aloft to pose a risk of locally gusty/damaging winds for a few more hours until the line moves offshore. Cooler temperatures in the wake of the line should limit the redevelopment of severe storms later today. ...MT/ND... Fast southwesterly flow aloft extends across the northern Rockies and High Plains today. A band of mid/high clouds lies from northern WY into eastern MT and western ND. A consensus of morning model solutions indicate that strong heating along and east of the eastern edge of this cloud cover will result in a corridor of steep low-level lapse rates and sufficient CAPE for scattered thunderstorm development. Fast-moving supercell and bowing structures appear likely this afternoon and evening as storms track from eastern MT into western ND. Damaging winds and hail are the main risks. ...Central TX... Hot/humid conditions along the surface dryline over central TX will pose some risk of isolated thunderstorms by mid/late afternoon. While coverage of these storms may be quite limited, any storm that forms in the extremely unstable air will pose a risk of large hail and damaging winds. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Mon Jun 19 2023 Valid 201200Z - 211200Z ...CRITICAL FIRE WEATHER AREA FOR OF NORTHEASTERN AZ AND NORTHWESTERN NM... The current D2 Fire Weather Outlook remains on track with no updates needed. See previous discussion for more information. ..Thornton.. 06/19/2023 .PREV DISCUSSION... /ISSUED 0133 AM CDT Mon Jun 19 2023/ ...Synopsis... The overall weather pattern will remain fairly stationary on Tuesday as a large trough and associated mid-level speed maximum rotate through the western U.S. Farther east, a cutoff mid-level low will develop over the Southeast, yielding a narrow blocking pattern throughout the Central Plains. A smaller zone of mid-level flow is forecast to move through the Desert Southwest Tuesday afternoon and evening. This is expected to contribute to critical fire-weather conditions across portions of AZ and NM on Tuesday. At the surface, sustained winds of 15-20 mph are expected across the Elevated area by late morning. This will be associated with deep boundary-layer mixing, yielding relative humidities below 15 percent across the region. Single-digit humidities are expected in northeastern AZ and northwestern NM which -- along with locally stronger flow around 20 mph -- should contribute to critical fire-weather conditions. Sustained drying and critical-level fuels in this area will contribute to a higher threat for large fire attack and spread. A second belt of stronger surface flow is expected in the lee of the Sandia and Sacramento Mountains, where ERCs in the 90-95th percentiles will support broad elevated, and perhaps locally critical, fire-weather conditions. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0340 Status Updates
STATUS FOR WATCH 0340 HAS NOT BEEN ISSUED YET Read more

WW 340 SEVERE TSTM TX 191950Z - 200300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 340 NWS Storm Prediction Center Norman OK 250 PM CDT Mon Jun 19 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Central Texas * Effective this Monday afternoon and evening from 250 PM until 1000 PM CDT. * Primary threats include... Scattered large hail and isolated very large hail events to 3 inches in diameter possible Isolated significant damaging wind gusts to 75 mph possible SUMMARY...Isolated intense thunderstorms are expected to form this afternoon over the watch area. Very large hail and damaging wind gusts are possible with the strongest cells. The severe thunderstorm watch area is approximately along and 50 statute miles east and west of a line from 15 miles south southwest of Junction TX to 50 miles northwest of Brownwood TX. 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 3 inches. Extreme turbulence and surface wind gusts to 65 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 28025. ...Hart Read more

WW 0339 Status Updates
STATUS REPORT ON WW 339 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 10 ENE CTY TO 10 NNE SGJ TO 40 NE SSI. REMAINING VALID PORTION OF WW MAY BE ALLOWED TO EXPIRE AT 19/18Z. ..KERR..06/19/23 ATTN...WFO...JAX... STATUS REPORT FOR WS 339 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS FLC001-035-041-107-109-191800- FL . FLORIDA COUNTIES INCLUDED ARE ALACHUA FLAGLER GILCHRIST PUTNAM ST. JOHNS AMZ452-454-191800- CW . ADJACENT COASTAL WATERS INCLUDED ARE COASTAL WATERS FROM FERNANDINA BEACH TO ST. AUGUSTINE FL OUT 20 NM COASTAL WATERS FROM ST. AUGUSTINE TO FLAGLER BEACH FL OUT 20 NM THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Mon Jun 19 2023 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL GULF COAST STATES...AND THE NORTHERN PLAINS... ...SUMMARY... Isolated to scattered severe thunderstorms appear possible across parts of the Southeast and northern Plains on Tuesday. Damaging winds and large hail should be the main threats. ...Southeast... A weak closed mid/upper-level low is forecast to be centered over KY/TN Tuesday morning. This feature should move little through the period while remaining over the Southeast. Modestly enhanced mid-level north-northwesterly flow should be in place on the southwest flank of the upper low, and to the east of upper ridging across the southern Plains. Although there are still some differences in guidance, there may be some elevated thunderstorms ongoing Tuesday morning across parts of the ArkLaTex, posing mainly an isolated hail threat. Additional intense thunderstorm development should occur Tuesday morning through early afternoon along/south of a front draped from northern LA into southern MS/AL. Where robust diurnal heating can occur, moderate to strong instability will likely develop, as a very moist low-level airmass remains in place south of the front. Modest low-level winds are forecast to veer and strengthen with height through mid/upper levels. 30-40+ kt of deep-layer shear will support organized convection, with a mix of multicells and supercells possible initially. Isolated large hail may occur with any discrete convection, but most guidance suggests that thunderstorms will quickly form into one or more small bowing clusters as they spreads generally southward across LA and coastal/southern MS/AL through Tuesday afternoon. Accordingly, damaging winds will probably be the main threat with this activity as low-level lapse rates steepen through the day. Isolated strong to severe thunderstorms may occur farther east across south GA/north FL, and much of the FL Peninsula. However, deep-layer shear should be weaker with eastward extent, which should tend to limit the magnitude of the severe threat. ...Northern Plains... An upper trough/low will extend across much of western Canada and the northwest U.S. Tuesday. A 50+ kt southwesterly mid-level jet should be present from the Great Basin to the northern Rockies and adjacent High Plains, with upper ridging located from the southern/central Plains to the Upper Midwest. A surface cold front is forecast to be in place from the Dakotas into central Canada. A narrow corridor of mid to upper 60s dewpoints should exist near this boundary. As daytime heating occurs, a small zone of moderate to strong instability should develop near the front from parts of western/central NE into central SD and central/eastern ND. Various NAM/RAP forecast soundings across this area show steep mid-level lapse rates will contribute to considerable CAPE in the hail growth zone aloft. Even though stronger mid-level winds and related deep-layer shear will likely remain displaced to the west of greater forecast instability, there should be enough overlap to allow for some updraft organization. Mainly multicells should develop and spread generally north-northeastward through Tuesday afternoon/evening, while posing a threat for severe/damaging downdraft winds and some hail. There also appears to be some potential for a supercell and/or small bowing cluster behind the front from northeastern WY and southeastern MT into the western Dakotas. Stronger mid-level flow and deep-layer shear will be present across these regions, but instability is forecast to remain modest. Based on the consensus of high-resolution guidance, have expanded the Marginal Risk for hail/wind westward into these areas to account for this possibility. ..Gleason.. 06/19/2023 Read more

No watches are valid as of Sun Jun 18 22:16:01 UTC 2023.

MD 1155 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR THE CENTRAL FL PENINSULA
Mesoscale Discussion 1155 NWS Storm Prediction Center Norman OK 0454 PM CDT Sun Jun 18 2023 Areas affected...the central FL Peninsula Concerning...Severe potential...Watch unlikely Valid 182154Z - 190000Z Probability of Watch Issuance...5 percent SUMMARY...Isolated thunderstorm development is possible for the next couple hours across the central FL Peninsula. Localized wind gusts and small hail would be the primary threats. DISCUSSION...Isolated cumulonimbi have developed across the central FL Peninsula within a diurnally driven cumulus field. These updrafts are percolating in an environment characterized by around 3000 J/kg MLCAPE and 15 kts of bulk shear. This environment combined with rather weak upper-level forcing has yielded transient initiation attempts thus far (e.g., Marion County). Forcing and bulk shear should gradually increase throughout the afternoon as the main area of mid-level flow overspreads the region. However, general tropospheric flow is expected to remain around 30 kts or lower. This should limit any severe hazards to areas with stronger localized forcing, such as along storm-scale outflow boundaries or sea breezes. If locally stronger updrafts develop, isolated damaging wind gusts and small hail should be the primary threats. ..Flournoy/Grams.. 06/18/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MFL...MLB...TBW...JAX... LAT...LON 27148228 28158252 29328244 29718201 29678145 29178105 28298066 27498031 26878003 26218008 25918043 25848112 25968172 26548209 27148228 Read more

MD 1154 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF EASTERN MONTANA
Mesoscale Discussion 1154 NWS Storm Prediction Center Norman OK 0357 PM CDT Sun Jun 18 2023 Areas affected...portions of eastern Montana Concerning...Severe potential...Watch unlikely Valid 182057Z - 182230Z Probability of Watch Issuance...5 percent SUMMARY...A severe gust or two cannot be ruled out with any of the stronger storms that manages to develop. The severe threat should remain isolated and a WW issuance is not expected. DISCUSSION...Thunderstorm development has recently been noted within a broader rain-band, which precedes a mid-level trough and where stronger forcing for ascent exists. Adequate surface heating has allowed temperatures to warm into the 80s F, supporting a relatively dry boundary layer/inverted-v soundings extending up to 700 mb given modest low-level moisture (shown by some of the latest RAP forecast soundings). Given the dry boundary layer, any of the stronger storms that manages to develop may generate enough evaporative cooling to support a severe gust or two. However, the severe threat should be isolated and a WW issuance is not anticipated. ..Squitieri/Hart.. 06/18/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BYZ...GGW... LAT...LON 45750892 46380846 48230738 49090810 49100508 48220506 46610552 45900585 45330699 45310817 45540880 45750892 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun Jun 18 2023 Valid 182000Z - 191200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE LOWER MISSISSIPPI VALLEY/SOUTHEAST... ...SUMMARY... Damaging winds, large hail, and a few tornadoes are expected this afternoon into tonight from the lower Mississippi Valley region to the east-central Gulf Coast. ...20Z Update... Convective evolution in the wake of thunderstorms this morning and early afternoon across southern AL and the FL Panhandle remains uncertain. A pronounced MCV and related mid-level circulation is clearly evident in visible satellite imagery across MO this afternoon. An outflow boundary from the morning/early afternoon convection is also draped from far east TX across LA into southern MS. This boundary may serve as a focus for renewed severe thunderstorm development this afternoon/evening, especially where it intersects a weak front in far east TX and vicinity. Have expanded the 10% significant hail area westward to include this region in the event a supercells can form and be sustained, as very large hail appears likely with any supercell given the very favorable thermodynamic and kinematic environment. Of potentially greater concern, multiple supercells may form closer to the MCV this evening across far eastern AR into northern/central MS. Both low-level and deep-layer shear appear very favorable for intense supercells capable of producing a few tornadoes, very large hail, and severe/damaging winds. The primary uncertainty remains convective coverage, as destabilization in the wake of earlier activity is still occurring. Based on recent observational and short-term guidance trends (RAP/HRRR, etc..), have adjusted the eastern extent of the Enhanced Risk, and expanded the 5% tornado area to include more of MS, far southwest TN, and western AL. ..Gleason.. 06/18/2023 .PREV DISCUSSION... /ISSUED 1129 AM CDT Sun Jun 18 2023/ ...AR/LA/MS/TN/AL... Widespread overnight and morning convection has overturned the air mass across much of the lower MS valley into AL. This leads to a very low-confidence forecast for later today and tonight. Morning model guidance shows wide diversity in where the corridors of highest risk of severe storms will develop, but several solutions continue to show potential. What appears to be the most likely scenario is shown by the morning NAM and recent runs of the RAP/HRRR. This suggests storms will redevelop this afternoon over parts of AR and track eastward into portions of TN/MS/AL. This area will see substantial heating by mid-afternoon as clearing arrives from the west. Forecast soundings in this area show a strengthening low-level jet by late-afternoon, promoting supercell and bowing structures capable of damaging winds, large hail, and a few tornadoes. ...Southern AL to FL Panhandle Today... Multiple clusters of strong/severe storms are ongoing early this afternoon over parts of southern AL and southeast MS. The air mass ahead of these storms is becoming very unstable with dewpoints in the 70s and temperatures warming through the 80s. This is near the core of a 40-50 knot mid level jet max, providing sufficient shear for organized multicell and supercell storm structures. There is uncertainty how this activity will evolve through the afternoon, but they could persist/intensity and track across much of southern AL and the FL Panhandle with a risk of damaging wind gusts and large hail. ...East TX... Several morning CAM solutions show at least isolated intense storms forming along a surface boundary extending across northeast TX. Given the ample moisture/CAPE in this area, have extended the SLGT risk farther west. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0127 PM CDT Sun Jun 18 2023 Valid 191200Z - 201200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF SOUTHEASTERN AND NORTHEASTERN ARIZONA...EASTERN NEW MEXICO... The Critical delineation was expanded further into western New Mexico and northeastern Arizona to encompass potential for very strong downslope flow (gusting 40-50 mph) amid relative humidity reductions to around 10 percent. Fuels within this region have experienced several days of persistent warm, windy, and dry conditions. Given strong downslope flow forecast for Monday, fuels will likely respond further.The Elevated was extended further north into the Coconino Plateau to encompass information from local partners on status of fuels. See previous discussion for additional information. ..Thornton.. 06/18/2023 .PREV DISCUSSION... /ISSUED 0145 AM CDT Sun Jun 18 2023/ ...Synopsis... By Monday afternoon, a broad belt of 60+ kt mid-level flow will reside in an elongated trough centered over the Pacific Northwest. Weak surface cyclogenesis will result in the vicinity of northeastern WY. Farther south, a subtle mid-level speed maximum (around 50 kt) will develop over Mexico and portions of southern AZ and NM. At the surface, a local high-pressure system situated along the AZ/NM border will be associated with increasing wind speeds across the Desert Southwest. As a result, Critical fire-weather conditions are expected to develop in portions of southern AZ and NM Monday afternoon and evening. Deep mixing is anticipated throughout the day on Monday, yielding surface temperatures in the upper 80s/lower 90s and relative humidities around 10-15 percent for much of the day. Surface winds should steadily increase throughout the morning to around 15-20 mph by 18-19z. These conditions will overspread fuels supporting large fire spread, including ERCs above the 60-70th percentile. After many days of dry conditions, ERCs in the 90-95th percentile are anticipated in portions of central and eastern NM. The area with strongest surface flow will materialize beneath the developing mid-level speed max, which currently appears most likely across portions of southeastern AZ through central NM. The Critical area delineates the spatial overlap between these two areas -- the surface wind maximum to the west, and fuel dryness to the east -- on Monday afternoon and evening. Stronger surface winds (around 30 mph) are also expected in tandem with single-digit relative humidities in northeastern AZ, but forecast fuel levels in this region warrant an Elevated area there. ...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 Sun Jun 18 2023 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHEAST... ...SUMMARY... Severe thunderstorms capable of producing mainly damaging winds will be possible across parts of the central Gulf Coast states into Georgia and north Florida on Monday. Additional isolated strong to severe thunderstorms also are possible into eastern Tennessee and parts of the Carolinas, central Texas, and the northern Plains. ...Synopsis... A weak upper trough/low centered over the lower OH Valley should advance slowly eastward on Monday. A belt of 35-50 kt west-northwesterly mid-level flow on the south/southwest flank of the upper low is forecast to persist over much of the lower MS Valley and Southeast. An occluded surface low over the lower OH Valley Monday morning should weaken further through the day as it develops towards the TN Valley and southern Appalachians. A very moist low-level airmass should persist from central/east TX into the lower MS Valley and Southeast. ...ArkLaTex into the Southeast... Latest guidance suggests thunderstorms across the Southeast will probably be in a weakening phase Monday morning. Still, this activity will spread southeast into a destabilizing airmass through late morning and early Monday afternoon. Convection should increase in intensity as the boundary layer becomes moderately to strongly unstable as diurnal heating occurs. Severe/damaging gusts will be the main hazard associated with this activity given its mainly linear/cluster nature and as low-level lapse rates steepen. The Slight Risk has been expanded eastward into more of east/coastal GA and north FL, as most high-resolution models show robust clusters moving across these areas Monday afternoon. Isolated large hail may also occur with the strongest embedded cores. There is still considerable uncertainty regarding the westward extent of severe potential. Some guidance suggests convection may build westward along the weak surface boundary into LA. However, capping also will be stronger to the west, and convection may tend to remain rather isolated. Have opted to expand the Marginal Risk into the ArkLaTex for possible elevated convection late Monday night. As waves of large-scale ascent pivot around the upper low, additional bands of thunderstorms are expected further north and east across eastern TN into the Carolinas. Instability will be weaker with northward extent. However, steepening low-level lapse rates and a high PW environment may support sporadic strong/damaging wind gusts. Additional clusters of strong storms may develop along sea-breeze boundaries across the FL Peninsula. Water-loaded downdrafts may pose a risk for strong gusts here as well, along with occasional hail. ...Central Texas... Upper ridging is expected to remain in place over the southern Plains Monday, with large-scale subsidence generally prevailing. Even so, a dryline is forecast to mix eastward across central TX through late Monday afternoon. Temperatures will likely soar into the 100s via strong daytime heating along the length of the dryline. Most high-resolution guidance continues to show at least isolated thunderstorms initiating along the dryline across central TX by late Monday afternoon. Any convection that can be sustained will have the potential to become a supercell, as northwesterly flow strengthening with height at mid/upper levels will provide 40-50 kt of effective bulk shear. Given the presence of steep mid-level lapse rates and moderate to strong instability, isolated large hail may occur with any supercell. Severe/damaging winds also appear possible, as the boundary layer should be very well mixed, with steepened low-level lapse rates due to the robust diurnal heating. The spatial and temporal extent of the severe threat will likely be constrained by increasing MLCIN with eastward extent and nocturnal cooling of the boundary layer. Given latest trends in high-resolution guidance, have expanded the Marginal Risk a bit. But, confidence in greater coverage of severe thunderstorms remains too low to include higher severe hail/wind probabilities. ...Eastern Montana into North Dakota... A pronounced upper trough/low over the Pacific Northwest and western Canada should undergo some amplification across the western CONUS on Monday. A southwesterly mid-level jet is forecast to overspread parts of the northern High Plains through the period. Low-level moisture should gradually increase through Monday afternoon from eastern MT into ND along/east of a weak front. Large-scale ascent associated with the mid/upper-level jet may encourage isolated thunderstorms to develop across northern WY near the Bighorn Mountains. If it develops, this convection would spread quickly northeastward across eastern MT and into parts of western/central ND through Monday evening. Even though instability should remain fairly weak, deep-layer shear appears strong enough to support supercells with attendant threat for large hail and severe wind gusts. With most high-resolution guidance suggesting 1 or 2 supercells will develop, have added low hail/wind probabilities across this region. ..Gleason.. 06/18/2023 Read more

MD 1132 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR NORTHERN LA AND THE ARK-LA-TEX REGION
Mesoscale Discussion 1132 NWS Storm Prediction Center Norman OK 0513 PM CDT Sat Jun 17 2023 Areas affected...northern LA and the Ark-La-Tex region Concerning...Severe potential...Watch possible Valid 172213Z - 180015Z Probability of Watch Issuance...40 percent SUMMARY...Isolated damaging wind gusts and large hail are possible in the next few hours across northern LA and the Ark-La-Tex region. DISCUSSION...Congested cumulus and isolated areas of deeper convective development are currently observed across the Ark-La-Tex region. A broad effective front is draped from west-northwest to east-southeast through the area, with temperatures generally in the mid-/upper-90s and dewpoints around 80 degrees F. These conditions are contributing to extreme instability with MLCAPE around 5500-6000+ J/kg. As a result, vigorous updraft development could occur in the next hour or two, which could mature into at least transient supercell structures given 45-55 kts of bulk shear. Should this occur, a threat for damaging wind gusts and very large hail would materialize. Such a scenario is captured in some recent high-resolution guidance, but storm strength and lifetimes may be stifled by an approaching mid-level ridge. Ongoing convective trends will continue to be monitored during the next couple of hours. ..Flournoy/Grams.. 06/17/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...JAN...LIX...LCH...SHV... LAT...LON 31209335 31609412 32099470 32599505 33079478 33299424 33229335 32939243 32649175 32179120 31559132 31019170 30969258 31209335 Read more