Severe Storms

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.

No Mesoscale Discussions are in effect as of Sat Aug 27 17:58:02 UTC 2022.

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1238 PM CDT Sat Aug 27 2022 Valid 281200Z - 291200Z ...NO CRITICAL AREAS... No changes have been made to the outlook. See the previous discussion below for more details. ..Dean.. 08/27/2022 .PREV DISCUSSION... /ISSUED 0145 AM CDT Sat Aug 27 2022/ ...Synopsis... A mid-level trough will eject into the northern Plains while upper ridging gradually builds over the Interior West tomorrow/Sunday. Despite the departing upper trough, up to 40 kts of 500 mb flow should still overspread a dry boundary layer across parts of the central into northern Rockies by afternoon peak heating. At least locally Elevated surface conditions should develop across the Snake River Plain in southern Idaho into eastern Wyoming, with windy, occasionally dry conditions also likely across Montana into the northern High Plains. Spotty fuel receptiveness or the lack of widespread overlapping favorable winds/RH suggest that fire weather highlights are not currently warranted. ...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 Sat Aug 27 2022 Valid 281200Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF MINNESOTA AND WESTERN WISCONSIN... ...SUMMARY... Isolated to scattered severe thunderstorms should occur late Sunday afternoon and evening across parts of the northern/central Plains and Upper Midwest. Severe/damaging wind gusts and large hail should be the main threats, but a tornado or two also appear possible. ...Northern/Central Plains into the Upper Midwest... A well-defined shortwave trough will advance eastward across the northern Plains and Upper Midwest on Sunday. A 40-50 kt west-southwesterly jet will accompany this feature and overspread parts of the Upper Midwest through Sunday evening. The primary surface low should remain in central Canada, with a secondary low forecast to shift eastward across SD and western MN through the day. A cold front will sweep eastward across the Upper Midwest through the period. This front will serve as a focus for lift and related severe convective potential. A seasonably moist low-level airmass will likely be in place ahead of the front, with surface dewpoints generally in the mid 60s to low 70s. Diurnal heating of this airmass, along with the presence of steep mid-level lapse rates, should encourage the development of moderate to strong instability ahead of the front across MN/IA and eastern NE. The strongest instability should be present across southern/central MN and vicinity where better daytime heating is forecast. A low-level cap should inhibit convective development through much of the afternoon. But, robust thunderstorms should eventually initiate along/near the eastward-sweeping cold front across western/central MN by late Sunday afternoon. 30-40 kt of deep-layer shear will support updraft organization, with a mix of supercells and multicells possible initially. Both large hail and severe/damaging wind gusts may occur with this activity. A fairly quick transition to one or more bowing clusters should occur late Sunday afternoon/evening into eastern MN and western WI, with the wind threat becoming the primary severe concern. A tornado or two also appear possible through the early evening, as 0-1 km SRH appears sufficient for some low-level rotation with both cells and embedded QLCS circulations. The severe threat ahead of cold front appears a bit more uncertain and conditional with southward extent into IA and eastern NE. The better large-scale ascent associated with the upper trough will remain mostly to the north of these areas. Still, any thunderstorms that can form across this region Sunday afternoon/evening could become severe, with both an isolated large hail and damaging wind threat. Given the continued uncertainty with overall thunderstorm coverage across these areas, have opted to just expand the Marginal Risk for now, and keep greater severe probabilities focused in MN and western WI where convective coverage appears greater. ..Gleason.. 08/27/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1126 AM CDT Sat Aug 27 2022 Valid 271630Z - 281200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FOR PARTS OF IA/MN/WI... ...SUMMARY... Severe thunderstorm potential appears most concentrated today over parts of Iowa, southeastern Minnesota and western Wisconsin. ...IA/MN/WI this afternoon/evening... A midlevel shortwave trough over the central NE/KS border will continue moving northeastward to western IA by this evening and the upper MS Valley overnight. Clouds and ongoing convection within a deep moisture plume over the central Plains will likewise spread northeastward through the day. Surface heating to the east of the thicker cloud band and relatively steep low-midlevel lapse rates will contribute to MLCAPE of 1500-2500 J/kg, and the likelihood of additional thunderstorm development this afternoon in the zone of differential heating from IA into southern MN (along and south of a warm front). Vertical shear profiles are forecast to be a bit disjointed with substantially backed/weaker flow in the mid levels across IA this afternoon. Low-level shear/clockwise hodograph curvature will be larger this afternoon/evening closer to the warm front across southeast MN/western WI, with a similar weakness in the midlevel flow. Thus, the environment favors a mixed/messy storm mode with clusters and some transient rotating updrafts, with a primary threat for damaging winds and isolated large hail given the moderately large buoyancy/precipitation loading and sufficiently steep low-midlevel lapse rates (DCAPE near 1000 J/kg). ...TX Panhandle into KS this afternoon/evening... Along the southern fringe of the residual monsoonal moisture plume and the ejecting midlevel trough over northern KS, differential heating and weak convergence along a lee trough will support scattered thunderstorm development later this afternoon. Midlevel lapse rates will not be steep, but surface heating/mixing will steepen low-level lapse rates, and westerly flow aloft will contribute to modest effective bulk shear of 25-30 kt. Somewhat organized cells/clusters will be capable of producing isolated strong-severe outflow gusts and marginally severe hail from mid afternoon into this evening. ...Southern MT and vicinity this afternoon/evening... Within the primary jet, an embedded speed max/shortwave trough over southern BC and WA will progress eastward to MT later this afternoon into tonight. An associated cold front will move into central MT by this evening, with strong surface heating and deep mixing in advance of the front. Some high-based convection is expected to form over the higher terrain of southern MT later this afternoon, and storms will spread eastward into this evening. Though low-level moisture and buoyancy will be limited, deep inverted-v profiles will support isolated strong-severe outflow gusts. ..Thompson/Karstens.. 08/27/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1126 AM CDT Sat Aug 27 2022 Valid 271700Z - 281200Z ...CRITICAL FIRE WEATHER AREA FOR FAR NORTHERN PORTIONS OF THE GREAT BASIN... No significant changes have been made to the Elevated and Critical areas. Critical conditions still appear most likely this afternoon from northeast NV/northwest UT into southern ID, with elevated to locally critical conditions surrounding this area from the northern Sierras into the north-central High Plains. Stronger winds are already noted across parts of southern ID this morning, while winds should increase elsewhere across the region in conjunction with continued heating/mixing and RH reductions. See the previous discussion below for more information. ..Dean.. 08/27/2022 .PREV DISCUSSION... /ISSUED 0144 AM CDT Sat Aug 27 2022/ ...Synopsis... A pronounced mid-level shortwave trough will progress across the northwestern U.S. today, promoting scattered high-based thunderstorms across the northern Rockies and dry/windy conditions across the northern Great Basin. Critically dry and windy surface conditions are most likely across northeast Nevada into southeast Idaho by late afternoon, though locally Critical conditions are also possible anywhere within the broader Elevated highlights, spanning from the northern Sierra to the northern High Plains. Elevated and Critical highlights have been withheld across southern into central Montana since recent rainfall has likely dampened fuels over several locales. The best chance for a couple of dry strikes as well as gusty, erratic thunderstorm winds would also be in central into southern Montana by late afternoon. Again, the lack of more widespread receptive fuels precludes dry thunderstorm highlights. ...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 Aug 26 2022 Valid 271200Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN/CENTRAL PLAINS INTO THE UPPER MIDWEST... ...SUMMARY... Isolated strong to severe thunderstorms will be possible Saturday across the portions of the southern/central Plains into the Upper Midwest. Occasional hail and damaging winds should be the main threats. ...Southern/Central Plains into the Upper Midwest... A low-amplitude upper trough should advance east-northeastward across the northern Plains/Upper Midwest into Canada on Saturday. A separate shortwave trough over the central Plains should likewise develop northeastward into parts of the Upper Midwest through Saturday evening. A seasonably moist low-level airmass should be in place ahead of both of these features, with a weak front/surface trough across the Plains likely delimiting the western extent of any appreciable severe risk. The potential for organized severe thunderstorms across the Upper Midwest, especially MN and vicinity, still appears rather uncertain and conditional. The already modest large-scale ascent associated with the northern shortwave trough should be shifting into Canada through the day, leaving nebulous/unfocused forcing mechanisms for convective initiation. This uncertainty is evident in latest CAM guidance, which shows varying solutions regarding thunderstorm coverage and intensity across MN/WI through Saturday evening. Still, the presence of fairly steep mid-level lapse rates and diurnal heating should lead to a narrow corridor of at least moderate instability developing by late Saturday afternoon. Any thunderstorms that can develop across this region despite lingering weak convective inhibition would be capable of producing both isolated large hail and damaging winds, as effective bulk shear around 35 kt promotes some updraft organization. A better convective signal exists in guidance across IA and vicinity in association with the southern shortwave trough. Similar to locations farther north, moderate instability and sufficient deep-layer shear should support an isolated hail/wind threat with any robust thunderstorms that can develop across the warm sector Saturday afternoon and evening. Across the southern/central High Plains, isolated to scattered thunderstorms may develop along and east of a weak surface front/trough through Saturday afternoon. A deeply mixed boundary layer, with inverted-v type forecast soundings, should support some threat for isolated severe wind gusts. Deep-layer shear this far south appears marginal for any more than loose convective organization, but some hail may occur with initially more cellular convection before clustering occurs. ...Montana... A pronounced upper trough with attendant strong mid-level jet is forecast to move eastward across the Pacific Northwest and northern Rockies on Saturday. Very modest low-level moisture should be in place across MT ahead of this feature. While high-based thunderstorms should develop off the higher terrain and advance eastward across central/eastern MT through Saturday evening, it currently appears that instability will remain quite limited. Accordingly, have opted to not include low severe wind probabilities at this time. ..Gleason.. 08/26/2022 Read more

WW 0523 Status Updates
STATUS FOR WATCH 0523 HAS NOT BEEN ISSUED YET Read more

WW 523 SEVERE TSTM CT MA ME NH NY RI VT CW 261705Z - 270000Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 523 NWS Storm Prediction Center Norman OK 105 PM EDT Fri Aug 26 2022 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Connecticut Massachusetts Extreme southern Maine Southern New Hampshire Extreme southeastern New York Rhode Island Extreme southern Vermont Coastal Waters * Effective this Friday afternoon and evening from 105 PM until 800 PM EDT. * Primary threats include... Scattered damaging wind gusts to 65 mph possible Isolated large hail events to 1 inch in diameter possible A tornado or two possible SUMMARY...Scattered thunderstorms are developing from eastern New York into southern New England and southern New Hampshire/Vermont. The storm environment will favor a mix of clusters/line segments and potentially some supercell structures, with a primary threat for damaging winds of 60-65 mph. The strongest storms will also be capable of producing isolated large hail near 1 inch in diameter, and an isolated/brief tornado may also occur with the most persistent supercells. The severe thunderstorm watch area is approximately along and 65 statute miles east and west of a line from 15 miles north of Laconia NH to 40 miles south southwest of Windsor Locks CT. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU3). 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 55 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 25030. ...Thompson Read more

MD 1722 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR FAR EASTERN NEW YORK INTO PARTS OF NEW ENGLAND
Mesoscale Discussion 1722 NWS Storm Prediction Center Norman OK 1125 AM CDT Fri Aug 26 2022 Areas affected...far eastern New York into parts of New England Concerning...Severe potential...Watch possible Valid 261625Z - 261830Z Probability of Watch Issuance...60 percent SUMMARY...Scattered strong storms will develop after 17Z, moving from eastern New York into parts of New England. A few damaging gusts are most likely, and a weak/brief tornado cannot be ruled out. DISCUSSION...Surface analysis shows a low developing over far eastern NY, and just south of an early-day cluster of thunderstorms which stretches into VT. Meanwhile, a diffuse warm front extends eastward toward far southern ME, though mixing may lead to a northward repositioning later today. Heating and advection of mid to upper 60s F dewpoints has led to an uncapped and unstable air mass, with CAPE presently in the 1000-2000 J/kg range. The strongest instability currently exists over southern New England where dewpoints are higher. Further, GPS PWAT sensors show a marked increase in overall moisture values through a deeper layer, approaching 1.50" near coastal CT. Convergence near the developing surface low and trailing surface trough and continued heating will lead to increasing storm coverage throughout the afternoon, progressing eastward. Deep-layer shear averaging near 35 kt, as well as veering winds with height suggest a several storms may be severe, producing a combination of damaging gusts and isolated hail. Steepening low-level lapse rates, and moist boundary layer, and weak SRH values could support a brief/weak tornado with the stronger isolated cells. ..Jewell/Thompson.. 08/26/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GYX...BOX...BTV...OKX...ALY... LAT...LON 41427435 42157405 43067354 43377319 43937184 43857078 43587026 42397060 41767172 41427217 41157331 41097393 41427435 Read more