Severe Storms

No watches are valid as of Tue Aug 30 17:57:01 UTC 2022.

MD 1751 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR VA..MD
Mesoscale Discussion 1751 NWS Storm Prediction Center Norman OK 1255 PM CDT Tue Aug 30 2022 Areas affected...VA..MD Concerning...Severe potential...Watch unlikely Valid 301755Z - 302000Z Probability of Watch Issuance...5 percent SUMMARY...Isolated damaging wind gusts are possible this afternoon. DISCUSSION...Surface observations reveal temperatures have climbed into the low 90s amid low 70s dewpoints across much of MD and VA. This heating has helped erode convective inhibition across the region ahead of the approaching shortwave trough and attendant surface trough. Thunderstorms have developed along the leading edge of the large-scale forcing for ascent (as evidenced by the relatively sharp gradient in cloud cover). Given the downstream destabilization, the ongoing storms are expected to persist eastward into more of VA and MD. Even so, relatively warm thermodynamic profiles will temper instability, likely keeping storms near their current intensity. Primary risk with any of these storms is expected to be damaging wind gusts associated with water-loaded downbursts. ..Mosier/Thompson.. 08/30/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PHI...AKQ...LWX...RNK... LAT...LON 37308053 39537840 39567631 38847597 37907669 36687858 36628063 37308053 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Tue Aug 30 2022 Valid 311200Z - 011200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS... ...SUMMARY... Isolated strong to severe wind gusts may occur with thunderstorms across parts of the central Plains Wednesday afternoon and evening. ...Central Plains... On the east side of a prominent upper ridge over the western CONUS, a weak mid-level perturbation should move southeastward across parts of the central Plains on Wednesday. Modest low-level moisture is forecast to return northward through the day across the central High Plains on the western periphery of a surface high centered over eastern KS and MO. Scattered thunderstorms should develop from northeastern CO into NE Wednesday afternoon along and south of a weak boundary. Strong daytime heating will act to deeply mix the boundary layer across these regions, with forecast soundings showing inverted-v type soundings. Even though instability should remain fairly weak, with MLCAPE generally 500-1000 J/kg, substantial DCAPE should promote a risk for isolated strong to severe wind gusts with convective downdrafts as thunderstorms spread southeastward through the early evening. Around 20-30 kt of deep-layer shear should also foster some convective organization, with loosely organized clusters possible. ...Western New York... An amplified upper trough will continue eastward over the Northeast and eastern Canada on Wednesday. A mid-level shortwave embedded within this upper trough should overspread Ontario, southern Quebec, and NY through the day. Enhanced mid-level winds will accompany this feature, with strong deep-layer shear also present. Most guidance shows a band of thunderstorms developing and spreading quickly eastward across parts of western/northern NY Wednesday afternoon. Some risk for strong/gusty winds may accompany this convection, but instability is forecast to remain rather weak. Given the potential thermodynamic limitations, have opted to not include low severe wind probabilities at this time. But, trends will be monitored. ..Gleason.. 08/30/2022 Read more

MD 1750 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR EASTERN NY...EASTERN PA...NORTHWEST NJ
Mesoscale Discussion 1750 NWS Storm Prediction Center Norman OK 1201 PM CDT Tue Aug 30 2022 Areas affected...Eastern NY...Eastern PA...Northwest NJ Concerning...Severe potential...Watch unlikely Valid 301701Z - 301900Z Probability of Watch Issuance...20 percent SUMMARY...Isolated damaging wind gusts are possible as thunderstorm coverage increases this afternoon. DISCUSSION...Visible satellite imagery shows deepening cumulus from eastern PA and into eastern NY, with a few instances of convective initiation east of BGM. This deepening is occurring in the vicinity of weak surface troughing ahead a broad upper trough still back west over the Upper Great Lakes and the middle OH Valley. Expectation is for this trend to continue as large-scale forcing for ascent and modest low-level convergence persist. This should result in gradually increasing thunderstorm coverage this afternoon. The expectation is for these thunderstorms to develop within the moist and warm corridor ahead of the thicker cloud band, but to the west of the clearer skies and stronger diurnal heating from the lower Hudson Valley and across much of NJ. Steeper low-level lapse rates are expected in these areas of stronger heating, but this mixing will limit buoyancy and thunderstorm intensity. Expectation is for a predominantly multicellular storm mode, with limited updraft strength. Even so, a few water-loaded downbursts are still possible, particularly with any storms that are able develop strong updrafts. Storm mergers could also result in enough water loading to produce a damaging downburst. ..Mosier/Thompson.. 08/30/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BTV...OKX...ALY...PHI...BGM...CTP... LAT...LON 42647609 43507524 43727479 43797446 43767408 43647383 43457351 43007337 42397357 41067434 40167509 39787618 40017721 41277705 42647609 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1146 AM CDT Tue Aug 30 2022 Valid 301700Z - 311200Z ...NO CRITICAL AREAS... No changes. Fire weather concerns remain limited today. See previous discussion below. ..Bentley.. 08/30/2022 .PREV DISCUSSION... /ISSUED 0113 AM CDT Tue Aug 30 2022/ ...Synopsis... Fire weather concerns will remain limited today across the CONUS. A broad upper ridge will continue to build to the west across the Great Basin today. This will favor warming temperatures and mostly dry conditions across much of the West that will aid in drying fuels. However, this will also result in meager low to mid-level flow, mitigating overall fire weather potential. Localized concerns may emerge across parts of the northern Great Basin and parts of the Pacific Northwest. ...Northern Great Basin into eastern Oregon... Locally breezy winds are possible this afternoon across the northern Great Basin into parts of eastern OR as deep boundary-layer mixing, combined with local terrain enhancements, support occasional gusts to 15-20 mph. Antecedent warm/dry conditions with RH values in the teens will allow for pockets of elevated conditions. Such conditions will likely remain too limited spatially and temporally to require highlights, but may result in local fire weather concerns - especially given the potential for holdover fires from early-morning lightning strikes across portions of northwest NV. Additional isolated showers/thunderstorms are possible this afternoon across eastern OR/western ID as the weak upper disturbance lifts north/northeast, but the probability of thunderstorms remains too limited to introduce lightning-driven highlights. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1118 AM CDT Tue Aug 30 2022 Valid 301630Z - 311200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FROM VA NORTHWARD TO NY AND NORTHERN NEW ENGLAND... ...SUMMARY... Isolated wind damage may occur this afternoon/evening from Virginia northward into New York and northern New England. ...VA to NY and northern New England this afternoon/evening... A midlevel trough over IN/OH will move eastward to the Mid-Atlantic and New England by tonight, along with an associated surface cold front. A thick cloud band precedes the midlevel trough and accompanies the frontal zone, and midlevel lapse rates are poor in the warm sector. Differential heating and ascent along the east edge of the thicker clouds will support thunderstorm development in bands early this afternoon from northern VA northward across central/eastern PA and NY. Surface temperatures warming into the 80s with boundary-layer dewpoints in the upper 60s to lower 70s will support MLCAPE of 500-1500 J/kg, though poor midlevel lapse rates and relatively moist profiles in the zone of storm initiation will tend to mute downdraft potential. Thus, isolated strong outflow gusts and some wind damage may occur with the stronger clusters/line segments this afternoon in an environment with roughly 30 kt midlevel flow, but the potential for severe outflow winds appears to be low enough to maintain 5% wind/Marginal risk. ...Lower MS Valley area this afternoon... Cloud breaks will allow surface temperatures to warm to near or just above 90 F, while boundary-layer dewpoints will be maintained in the low-mid 70s. Forcing for ascent and vertical shear will be weak, but widely scattered thunderstorms will be possible this afternoon as convective inhibition is removed via daytime heating/mixing. Regional 12z soundings revealed the potential for afternoon MLCAPE near 3000 J/kg, but relatively moist profiles will limit the potential for intense downdrafts. Isolated/localized wind damage could occur with precipitation-loaded downdrafts, but the potential for severe outflow winds appears too low to warrant adding an outlook area. ..Thompson/Squitieri.. 08/30/2022 Read more

MD 1742 CONCERNING SEVERE THUNDERSTORM WATCH 527... FOR NORTHERN ILLINOIS AND INDIANA...SOUTHWEST LOWER MICHIGAN
Mesoscale Discussion 1742 NWS Storm Prediction Center Norman OK 1253 PM CDT Mon Aug 29 2022 Areas affected...northern Illinois and Indiana...southwest Lower Michigan Concerning...Severe Thunderstorm Watch 527... Valid 291753Z - 292000Z The severe weather threat for Severe Thunderstorm Watch 527 continues. SUMMARY...Strong to severe wind gusts remain possible across watch 527, and an additional watch may be needed downstream into parts of Lower Michigan and northern Indiana. DISCUSSION...A complex of storms with northern and southern outflow bulges has gradually strengthened this afternoon, with gusts generally 40-50 kt across northern IL. The northern section of this line is now crossing into Lake MI, and will eventually emerge into southwest Lower MI where strong instability is in place. The southern half of the complex also remains strong, and may become dominant as it moves down the 3000+ MLCAPE instability axis into IN later this afternoon. As such, an additional watch could be needed prior to 19Z. ..Jewell.. 08/29/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...IWX...GRR...IND...LOT...ILX...DVN... LAT...LON 42318797 42128799 41918800 41678831 41678879 41498894 41178910 40988926 40828908 40648860 40498825 40478723 40518562 41088497 41798477 42208489 42488539 42588603 42458783 42318797 Read more

WW 0527 Status Updates
STATUS REPORT ON WW 527 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 NNW MLI TO 25 NE MLI TO 45 ENE MLI TO 35 WNW MMO TO 30 NNW MMO TO 30 SSE RFD TO 25 E JVL. ..JEWELL..08/29/22 ATTN...WFO...DVN...LOT...ILX... STATUS REPORT FOR WS 527 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC011-031-037-043-053-063-071-073-075-089-091-093-095-097-099- 105-111-123-131-143-155-161-175-187-195-197-203-291840- IL . ILLINOIS COUNTIES INCLUDED ARE BUREAU COOK DE KALB DUPAGE FORD GRUNDY HENDERSON HENRY IROQUOIS KANE KANKAKEE KENDALL KNOX LAKE LA SALLE LIVINGSTON MCHENRY MARSHALL MERCER PEORIA PUTNAM ROCK ISLAND STARK WARREN WHITESIDE WILL WOODFORD INC007-073-089-111-127-291840- IN . INDIANA COUNTIES INCLUDED ARE BENTON JASPER LAKE NEWTON PORTER Read more

WW 527 SEVERE TSTM IA IL LM 291510Z - 292100Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 527 NWS Storm Prediction Center Norman OK 1010 AM CDT Mon Aug 29 2022 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Extreme southeastern Iowa Northern Illinois Lake Michigan * Effective this Monday morning and afternoon from 1010 AM until 400 PM CDT. * Primary threats include... Scattered damaging wind gusts to 70 mph likely Isolated large hail events to 1 inch in diameter possible SUMMARY...Developing storms near the Mississippi River are expected to growth into a larger cluster through late morning into the afternoon, with an increase in the potential for damaging winds and isolated large hail across northern Illinois. The severe thunderstorm watch area is approximately along and 55 statute miles north and south of a line from Moline IL to 65 miles east northeast of Marseilles IL. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU7). 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 1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 27035. ...Thompson Read more

MD 1741 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR NORTHERN OK...FAR SOUTHEAST KS...FAR SOUTHWEST MO
Mesoscale Discussion 1741 NWS Storm Prediction Center Norman OK 1208 PM CDT Mon Aug 29 2022 Areas affected...Northern OK...Far Southeast KS...Far Southwest MO Concerning...Severe potential...Watch unlikely Valid 291708Z - 291915Z Probability of Watch Issuance...20 percent SUMMARY...A few strong to severe thunderstorms capable of isolated damaging wind gusts and/or hail are expected this afternoon. DISCUSSION...A very moist air mass is in place over the region, with recent surface observations sampling dewpoints in the low 70s and recent mesoanalysis estimated precipitable water around 1.9" to 2.0". Thermodynamic profiles are relatively warm, but these moist conditions amid surface temperatures already in the upper 80s to low 90s still result in moderate buoyancy. Recent mesoanalysis estimates MLCAPE is around 2000-2500 J/kg across the region. Large-scale forcing for ascent is nebulous, with much of it focused well north of the region. Even so, low-level convergence along the numerous outflow boundaries has already promoted a few storms, and that trend is expected to continue this afternoon. A few updrafts may be strong enough to produce hail, but the primary severe risk will be damaging wind gusts associated with wet downbursts. Sporadic/isolated nature of the severe risk is expected to preclude the need for a watch. ..Mosier/Thompson.. 08/29/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...SGF...TSA...ICT...OUN... LAT...LON 36199946 36799783 37529529 37449398 36269452 35229826 36199946 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1202 PM CDT Mon Aug 29 2022 Valid 301200Z - 311200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHEAST AND MID-ATLANTIC... ...SUMMARY... Isolated strong to severe thunderstorms may produce occasional wind damage Tuesday afternoon and early evening across parts of the Northeast and Mid-Atlantic. ...Northeast/Mid-Atlantic... An elongated upper trough should extend from central Canada southward over the Upper Midwest, Great Lakes, and OH Valley regions Tuesday morning. This upper trough is forecast to move eastward across much of the Northeast and Mid-Atlantic through the period. Heating of a moist low-level airmass should occur ahead of a cold front that is likewise expected to sweep eastward over these regions. However, persistent cloudiness and poor mid-level lapse rates should limit the degree of instability that develops Tuesday afternoon, with most guidance suggesting MLCAPE stays generally in the 500-1000 J/kg range. The stronger mid-level southwesterly winds attendant to the upper trough should tend to lag the surface warm sector to some extent. But, around 20-30 kt of deep-layer shear should still be present across much of the warm sector Tuesday afternoon. This shear will aid in modest updraft organization, with multicells and loosely organized clusters expected to be the dominant convective mode. Thunderstorms should gradually increase in coverage and intensity Tuesday afternoon along/ahead of the cold front. Isolated damaging winds appear to be the main severe threat with this activity as it spreads eastward across much of the Northeast and Mid-Atlantic through early Tuesday evening, before eventually weakening. The Marginal Risk has been expanded across these regions based on latest model trends, with the southern extent of appreciable severe risk remaining uncertain. There was not enough confidence in a more focused area of damaging wind potential to include greater severe probabilities at this time. ..Gleason.. 08/29/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1145 AM CDT Mon Aug 29 2022 Valid 291700Z - 301200Z ...NO CRITICAL AREAS... No changes. See previous discussion below. ..Bentley.. 08/29/2022 .PREV DISCUSSION... /ISSUED 0152 AM CDT Mon Aug 29 2022/ ...Synopsis... A mid-level trough will deepen across the Great Lakes Region as an upper ridge builds across the western CONUS today, with weak mid-level impulses expected to pivot around the upper ridge. Deep-layer northwesterly dry flow will envelop the Plains states behind the cold front. At the surface, near-Elevated to Elevated dry and windy conditions are forecast, particularly over South Dakota. However, recent rainfall has dampened fuel receptiveness to a degree, so no fire weather highlights have been introduced. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1123 AM CDT Mon Aug 29 2022 Valid 291630Z - 301200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON FROM NORTHERN IL TO NORTHWESTERN IN AND EXTREME SOUTHWESTERN LOWER MI... ...SUMMARY... Severe thunderstorm winds are expected through this evening across parts of the middle Mississippi Valley into the southern Lake Michigan region. ...Northeast MO across IL to Lower MI through late evening... A midlevel trough will move eastward from the upper MS Valley to the Great Lakes, with some modest amplification expected from IA to IL as an embedded mid-upper speed max digs southeastward from the northern Plains. An associated surface cold front will likewise move eastward/southeastward from IA/WI to MO/IL/Lower MI by tonight. Convective clusters are ongoing this morning across northwest IL, apparently in conjunction with an undular bore ahead of the surface cold front. Given an environment with MLCAPE near 3000 J/kg, midlevel lapse rates at or above 8 C/km, DCAPE > 1000 J/kg and 35-45 kt midlevel flow, the ongoing storms should eventually produce a stronger cold pool and there will be and attendant increase in the threat for damaging winds by early afternoon. The ongoing convection will modulate the severe threat area later this afternoon, with potential stabilization across northern IL in the wake of the storms, and outflow to focus the threat a bit farther south by mid-late afternoon. Additional storms that form this afternoon along the front/outflow will have the potential to produce occasional damaging outflow gusts and isolated large hail from northeast MO across central IL into northern IN and southern Lower MI. ...West TX to the OH Valley this afternoon/evening... A few thunderstorm clusters are ongoing from northern OK to southern IL and northern OH in association with subtle midlevel vorticity maxima and within a moisture plume with PW > 1.75 inches. Mid-upper flow weakens with southward and westward extent, but precipitation loading within multicell clusters will support the potential for isolated wind damage this afternoon. Additional storms will likely form along the surface cold front in KS, and in the area of strong surface heating east of a subtle midlevel trough over northeast NM. Relatively deep mixing and moderate-strong buoyancy will support downburst potential this afternoon/evening from west TX into KS. ..Thompson/Mosier.. 08/29/2022 Read more

No watches are valid as of Sun Aug 28 17:59:02 UTC 2022.

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1251 PM CDT Sun Aug 28 2022 Valid 291200Z - 301200Z ...NO CRITICAL AREAS... No changes to the ongoing forecast. A weak shortwave trough is expected to lift northward into northern California and southern Oregon Monday afternoon though early Tuesday morning. Thermodynamic profiles are marginally supportive of elevated thunderstorms, but mid-level moisture will be limited enough to keep coverage very isolated. ..Wendt.. 08/28/2022 .PREV DISCUSSION... /ISSUED 0157 AM CDT Sun Aug 28 2022/ ...Synopsis... A mid-level trough will amplify while traversing the Northern Plains and Great Lakes region, promoting widespread strong northwesterly mid-level flow across the northwest and north-central CONUS Day 2/Monday. Given the presence of a dry boundary layer in the post-cold-frontal environment beneath the strong northwesterly flow across the northern Rockies into the northern and central Plains states, dry and breezy surface conditions are expected. However, RH is not expected to reach Elevated/Critical criterion on a widespread basis, and fuel receptiveness to wildfire spread is expected to be modest at best, warranting the withholding of fire weather highlights. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 1732 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PARTS OF NORTHERN IL...SOUTHERN WI...FAR EASTERN IA
Mesoscale Discussion 1732 NWS Storm Prediction Center Norman OK 1234 PM CDT Sun Aug 28 2022 Areas affected...Parts of northern IL...southern WI...far eastern IA Concerning...Severe potential...Watch possible Valid 281734Z - 281900Z Probability of Watch Issuance...60 percent SUMMARY...Storms capable of damaging wind gusts and potentially a tornado or two will be possible this afternoon. Watch issuance is possible. DISCUSSION...Convection is gradually increasing early this afternoon across far eastern IA into western IL, in advance of a well-defined MCV centered near southeast IA. MLCAPE has increased into the 1500-2000 J/kg range across the region, with some additional destabilization possible through the afternoon, given the relative lack of cloudiness downstream of the developing storms. The 17Z DVN sounding and recent VWPs from KDVN indicate increasing flow through a deep layer in association with the MCV, supporting sufficient deep-layer shear for organized storm development, including the potential for a couple of supercells as storms mature this afternoon. Favorable low-level moisture/buoyancy and modestly enhanced low-level flow/shear will be sufficient for some tornado threat with any sustained supercells. The strongest cells/clusters will also be capable of producing damaging wind gusts, as low-level lapse rates steepen downstream of the MCV. Rather weak midlevel lapse rates and warm temperatures aloft will temper the hail threat to some extent, though isolated hail cannot be ruled out with any supercell development. Watch issuance is possible by 18-19Z. ..Dean/Thompson.. 08/28/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LOT...ILX...MKX...DVN...ARX... LAT...LON 42199051 42589042 42968995 43218914 43148893 42758848 42298839 41678847 41318864 40998892 40728950 40728999 41389035 42199051 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Sun Aug 28 2022 Valid 291200Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF ILLINOIS/INDIANA INTO FAR SOUTHEASTERN WISCONSIN AND SOUTHWESTERN LOWER MICHIGAN... ...SUMMARY... Strong to severe thunderstorms should occur Monday across parts of the Great Lakes into the Midwest, Ohio Valley, and central Plains. Damaging wind gusts should be the main threat, with some hail also possible. ...Great Lakes into the Midwest/Ohio Valley and Central Plains... An upper trough will continue to progress eastward across the Upper Midwest, Great Lakes, OH Valley, and mid MS Valley on Monday. At the surface, the primary low is forecast to develop eastward across central/eastern Canada through the period, with a trailing cold front expected to sweep east-southeastward from the Upper Midwest into the Great Lakes and OH Valley. The stronger mid-level winds associated with the upper trough are forecast to lag behind the cold front to some extent. Even so, upper 60s to at least low 70s surface dewpoints should be in place ahead of the front. Daytime heating of this moist low-level airmass should contribute to the development of moderate to strong instability arcing from parts of Lower MI into the Midwest, mid MS Valley, and KS by Monday afternoon. A plume of steep mid-level lapse rates should also be present across parts of KS/MO into IL, and locally very strong instability, with MLCAPE around 3500-4500 J/kg, may develop in a narrow corridor across these regions along and just ahead of the cold front. There is still a fair amount of uncertainty regarding convective development and evolution across the Great Lakes into the Midwest and OH Valley Monday afternoon and evening. The potential for a decaying cluster of thunderstorms related to overnight convection across the Upper Midwest remains apparent in some guidance. If this cluster can maintain itself through the morning, it may shunt greater instability and thunderstorm potential farther south ahead of the front into the OH and mid MS Valleys. Even though these regions will generally be on the southeastern extent of appreciable mid-level flow, loosely organized clusters of convection may still be capable of producing isolated damaging winds as low-level lapse rates become steepened. Have expanded the Marginal Risk to account for this potential. Otherwise, it appears probable that more robust/organized thunderstorms will form along/near the cold front by Monday afternoon. The best combination of strong forecast instability and modest but sufficient deep-layer shear should occur across parts of the Midwest into Lower MI. 15% severe wind probabilities have been introduced across this area where the greatest concentration of thunderstorm clusters may occur based on some convection-allowing guidance. Given the potential for morning convection, some adjustments to the Slight Risk may be needed as mesoscale details and model/convective trends dictate. ..Gleason.. 08/28/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1132 AM CDT Sun Aug 28 2022 Valid 281700Z - 291200Z Dry and windy conditions are most likely to occur just ahead of a cold front in southern Wyoming and western Nebraska. Based on the current position of the front, the elevated area has been adjusted. RH is not likely to fall below critical thresholds for very long within the terrain along the Idaho/Wyoming border. Highlights have been removed from those areas. Locally critical conditions are most likely, for brief periods, within the Snake River Plain and in the lee of the Laramie Range. ..Wendt.. 08/28/2022 .PREV DISCUSSION... /ISSUED 0145 AM CDT Sun Aug 28 2022/ ...Synopsis... A mid-level trough will eject into the northern Plains today, promoting downslope flow along the higher terrain of the central/northern Rockies amid a dry boundary layer. In the Plains states, strong surface lee troughing will occur, with a surface cold front poised to sweep across the central and northern High Plains. The net result will be widespread coverage of either dry or windy conditions across much of the north-central CONUS in the post-cold-frontal environment. However, the latest guidance consensus suggests that both dry and windy surface conditions will overlap within a narrow corridor from the Snake River Plain in southern Idaho to the Nebraska Sandhills, where Elevated highlights have been introduced. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Sun Aug 28 2022 Valid 281630Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FOR MN/WESTERN WI...AND NORTHERN IL/SOUTHEASTERN WI... ...SUMMARY... Severe thunderstorms should affect much of Minnesota into western Wisconsin late this afternoon into early tonight, with large to very large hail, damaging gusts, and a couple of tornadoes possible. Damaging winds may also occur this afternoon from northern Illinois into southeastern Wisconsin. ...MN and vicinity this afternoon into early tonight... A well-defined midlevel trough will move eastward from western ND as of mid morning to northwestern MN tonight, and will be preceded by a weakening MCV moving from eastern ND to northwestern MN today. The primary associated surface cyclone will progress eastward across SK/MB, as a trailing cold front/trough likewise moves eastward across the Dakotas to the MN border by this evening. Ahead of the front/trough, a plume of steep midlevel lapse rates of 8-9 C/km sampled in 12z soundings will act to cap a gradually moistening boundary layer (mid-upper 60s dewpoints northern MN to low 70s across southern MN by afternoon), and will allow MLCAPE to increase to near 3000 J/kg. Stratus under the cap and lingering convection in southeastern ND will tend to slow surface heating, but ascent along the boundary will support weakening of convective inhibition and thunderstorm development 21-23z across west central and northwest MN. Storms will then spread eastward through late evening and develop southward toward central MN, with greater uncertainty regarding storm coverage with southward extent into IA/eastern NE this evening. Mixed convective modes are expected along and ahead of the surface front/trough, with a few semi-discrete cells initially, and some upscale growth into clusters/line segments expected by this evening. Vertical shear will become sufficient for supercells as hodographs lengthen and clockwise curvature increases some in the low levels, as reflected by effective bulk shear of 35-45 kt and effective SRH of 100-200 m2/s2. The steep midlevel lapse rates/large CAPE and sufficiently long hodographs will favor isolated very large hail (2-2.5 inch diameter) with the more discrete supercells initially, and the threat will transition more to damaging winds of 60-70 mph with upscale growth of convection. A couple of tornadoes will also be possible with the initial supercells, and with embedded circulations in line segments. ...Northern IL/southeastern WI this afternoon/evening... An MCV will continue to move northeastward from southeastern IA toward southeastern WI through this evening. Midlevel lapse rates are poor, but surface heating in cloud breaks ahead of the MCV will contribute to moderate buoyancy (MLCAPE of 1500-2000 J/kg), and thunderstorm development will be possible by early-mid afternoon near the MS River. A mix of clusters and embedded rotating storms will be possible given modest enhancement of low-level shear ahead of the MCV (effective SRH in excess of 100 m2/s2), with the attendant threat of isolated damaging winds and a tornado or two. ..Thompson/Dean.. 08/28/2022 Read more

No watches are valid as of Sat Aug 27 17:58:02 UTC 2022.