Severe Storms

MD 2034 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF SOUTHEASTERN SOUTH DAKOTA INTO FAR SOUTHWESTERN MINNESOTA AND EXTREME NORTHWESTERN IOWA
Mesoscale Discussion 2034 NWS Storm Prediction Center Norman OK 0456 PM CDT Thu Sep 04 2025 Areas affected...portions of southeastern South Dakota into far southwestern Minnesota and extreme northwestern Iowa Concerning...Severe potential...Watch unlikely Valid 042156Z - 042330Z Probability of Watch Issuance...5 percent SUMMARY...Storms may continue to intensify over the next few hours and produce isolated severe gusts. DISCUSSION...Multicellular convection is developing along a low-level confluence zone, immediately ahead of a mid-level trough and associated 120 kt 300 mb jet streak. These storms are developing amid a strongly sheared/forced environment, characterized by strong vertical flow fields. The FSD VAD profiler shows show up to 50 kts of of west-northwesterly flow at or just below 700 mb. As such, any efficient downward momentum may support strong surface wind gusts, a few of which could approach severe limits. The primary limitation for a more robust severe threat is scant buoyancy, and given the expected isolated nature of the severe threat, a WW issuance is not expected. ..Squitieri/Mosier.. 09/04/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MPX...DMX...FSD...ABR... LAT...LON 43429771 44389741 44989690 45109634 44929507 44469431 43859408 43369419 42969486 42889555 42919652 43029707 43429771 MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH Read more

MD 2033 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF EASTERN MARYLAND...EASTERN VIRGINIA...AND NORTHERN NORTH CAROLINA
Mesoscale Discussion 2033 NWS Storm Prediction Center Norman OK 0439 PM CDT Thu Sep 04 2025 Areas affected...portions of eastern Maryland...eastern Virginia...and northern North Carolina Concerning...Severe potential...Watch unlikely Valid 042139Z - 042315Z Probability of Watch Issuance...5 percent SUMMARY...A few damaging gusts may accompany the stronger storms for a few more hours, before storms weaken with the onset of nocturnal cooling. DISCUSSION...Multiple strong thunderstorms persist ahead of a surface cold front over northern North Carolina into eastern Virginia/Maryland. With diurnal heating continuing along the East Coast, temperatures are in the 80s F, amid low to upper 60s F dewpoints, yielding 500-1000 J/kg MLCAPE despite poor mid-level lapse rates (per 21Z mesoanalysis). The current thinking is that these storms may persist for a few more hours, accompanied by strong to occasionally damaging wind gusts, and an instance or two of hail cannot be ruled out. With time, storms should begin to weaken as nocturnal cooling increases convective inhibition and CAPE weakens. ..Squitieri/Mosier.. 09/04/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PHI...AKQ...CTP...LWX...RAH...RNK... LAT...LON 38157599 36547748 35887854 35717910 35747958 35867976 36087968 37487846 39357715 39577683 39777612 39557577 38967570 38157599 MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0334 PM CDT Thu Sep 04 2025 Valid 061200Z - 121200Z A negatively-tilted upper-level shortwave trough will continue to track slowly northward across the Northwest Day 3/Saturday into Day 4/Sunday. A larger upper low will move into the Northwest late Day 4/Sunday through Day 6/Tuesday, with upper-level troughing likely deepening over the West Coast through mid-next week. Upper-level troughing may develop over most of the West mid to late next week, but forecast uncertainty remains high on the progression of the upper-level trough over the West/West Coast. Isolated to scattered mixed wet/dry thunderstorms are likely in portions of the Northwest and northern Rockies/Great Basin on Day 3/Saturday - Day 4/Sunday, with the Cascades having the best chances. Onshore flow will bring showers, higher RH, and cooler temperatures to the Northwest and eventually the northern Rockies and northwest California beginning late Day 4/Sunday and likely lasting through much of the outlook period. This pattern change and potential preceding wetting rain in areas on Day 1/Thursday - Day 2/Friday will limit the impacts of potential ignitions on Day 3/Saturday - Day 4/Sunday and slow fire activity across the northwestern US. However, if the upper-level trough slows or changes track in the coming days, areas may need to be introduced. Dry/windy conditions are likely to develop across portions of the central/southern Intermountain West on Day 4/Sunday - Day 7/Wednesday as upper-level troughing moves into the West. Fuel conditions are vastly improved after the last monsoonal surge. However, the environment will be monitored, especially in areas that received less wetting rain with the last monsoon surge, for potential overlap of critical winds/RH and receptive fuels. ..Nauslar.. 09/04/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0334 PM CDT Thu Sep 04 2025 Valid 061200Z - 121200Z A negatively-tilted upper-level shortwave trough will continue to track slowly northward across the Northwest Day 3/Saturday into Day 4/Sunday. A larger upper low will move into the Northwest late Day 4/Sunday through Day 6/Tuesday, with upper-level troughing likely deepening over the West Coast through mid-next week. Upper-level troughing may develop over most of the West mid to late next week, but forecast uncertainty remains high on the progression of the upper-level trough over the West/West Coast. Isolated to scattered mixed wet/dry thunderstorms are likely in portions of the Northwest and northern Rockies/Great Basin on Day 3/Saturday - Day 4/Sunday, with the Cascades having the best chances. Onshore flow will bring showers, higher RH, and cooler temperatures to the Northwest and eventually the northern Rockies and northwest California beginning late Day 4/Sunday and likely lasting through much of the outlook period. This pattern change and potential preceding wetting rain in areas on Day 1/Thursday - Day 2/Friday will limit the impacts of potential ignitions on Day 3/Saturday - Day 4/Sunday and slow fire activity across the northwestern US. However, if the upper-level trough slows or changes track in the coming days, areas may need to be introduced. Dry/windy conditions are likely to develop across portions of the central/southern Intermountain West on Day 4/Sunday - Day 7/Wednesday as upper-level troughing moves into the West. Fuel conditions are vastly improved after the last monsoonal surge. However, the environment will be monitored, especially in areas that received less wetting rain with the last monsoon surge, for potential overlap of critical winds/RH and receptive fuels. ..Nauslar.. 09/04/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0334 PM CDT Thu Sep 04 2025 Valid 061200Z - 121200Z A negatively-tilted upper-level shortwave trough will continue to track slowly northward across the Northwest Day 3/Saturday into Day 4/Sunday. A larger upper low will move into the Northwest late Day 4/Sunday through Day 6/Tuesday, with upper-level troughing likely deepening over the West Coast through mid-next week. Upper-level troughing may develop over most of the West mid to late next week, but forecast uncertainty remains high on the progression of the upper-level trough over the West/West Coast. Isolated to scattered mixed wet/dry thunderstorms are likely in portions of the Northwest and northern Rockies/Great Basin on Day 3/Saturday - Day 4/Sunday, with the Cascades having the best chances. Onshore flow will bring showers, higher RH, and cooler temperatures to the Northwest and eventually the northern Rockies and northwest California beginning late Day 4/Sunday and likely lasting through much of the outlook period. This pattern change and potential preceding wetting rain in areas on Day 1/Thursday - Day 2/Friday will limit the impacts of potential ignitions on Day 3/Saturday - Day 4/Sunday and slow fire activity across the northwestern US. However, if the upper-level trough slows or changes track in the coming days, areas may need to be introduced. Dry/windy conditions are likely to develop across portions of the central/southern Intermountain West on Day 4/Sunday - Day 7/Wednesday as upper-level troughing moves into the West. Fuel conditions are vastly improved after the last monsoonal surge. However, the environment will be monitored, especially in areas that received less wetting rain with the last monsoon surge, for potential overlap of critical winds/RH and receptive fuels. ..Nauslar.. 09/04/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0334 PM CDT Thu Sep 04 2025 Valid 061200Z - 121200Z A negatively-tilted upper-level shortwave trough will continue to track slowly northward across the Northwest Day 3/Saturday into Day 4/Sunday. A larger upper low will move into the Northwest late Day 4/Sunday through Day 6/Tuesday, with upper-level troughing likely deepening over the West Coast through mid-next week. Upper-level troughing may develop over most of the West mid to late next week, but forecast uncertainty remains high on the progression of the upper-level trough over the West/West Coast. Isolated to scattered mixed wet/dry thunderstorms are likely in portions of the Northwest and northern Rockies/Great Basin on Day 3/Saturday - Day 4/Sunday, with the Cascades having the best chances. Onshore flow will bring showers, higher RH, and cooler temperatures to the Northwest and eventually the northern Rockies and northwest California beginning late Day 4/Sunday and likely lasting through much of the outlook period. This pattern change and potential preceding wetting rain in areas on Day 1/Thursday - Day 2/Friday will limit the impacts of potential ignitions on Day 3/Saturday - Day 4/Sunday and slow fire activity across the northwestern US. However, if the upper-level trough slows or changes track in the coming days, areas may need to be introduced. Dry/windy conditions are likely to develop across portions of the central/southern Intermountain West on Day 4/Sunday - Day 7/Wednesday as upper-level troughing moves into the West. Fuel conditions are vastly improved after the last monsoonal surge. However, the environment will be monitored, especially in areas that received less wetting rain with the last monsoon surge, for potential overlap of critical winds/RH and receptive fuels. ..Nauslar.. 09/04/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0334 PM CDT Thu Sep 04 2025 Valid 061200Z - 121200Z A negatively-tilted upper-level shortwave trough will continue to track slowly northward across the Northwest Day 3/Saturday into Day 4/Sunday. A larger upper low will move into the Northwest late Day 4/Sunday through Day 6/Tuesday, with upper-level troughing likely deepening over the West Coast through mid-next week. Upper-level troughing may develop over most of the West mid to late next week, but forecast uncertainty remains high on the progression of the upper-level trough over the West/West Coast. Isolated to scattered mixed wet/dry thunderstorms are likely in portions of the Northwest and northern Rockies/Great Basin on Day 3/Saturday - Day 4/Sunday, with the Cascades having the best chances. Onshore flow will bring showers, higher RH, and cooler temperatures to the Northwest and eventually the northern Rockies and northwest California beginning late Day 4/Sunday and likely lasting through much of the outlook period. This pattern change and potential preceding wetting rain in areas on Day 1/Thursday - Day 2/Friday will limit the impacts of potential ignitions on Day 3/Saturday - Day 4/Sunday and slow fire activity across the northwestern US. However, if the upper-level trough slows or changes track in the coming days, areas may need to be introduced. Dry/windy conditions are likely to develop across portions of the central/southern Intermountain West on Day 4/Sunday - Day 7/Wednesday as upper-level troughing moves into the West. Fuel conditions are vastly improved after the last monsoonal surge. However, the environment will be monitored, especially in areas that received less wetting rain with the last monsoon surge, for potential overlap of critical winds/RH and receptive fuels. ..Nauslar.. 09/04/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0334 PM CDT Thu Sep 04 2025 Valid 061200Z - 121200Z A negatively-tilted upper-level shortwave trough will continue to track slowly northward across the Northwest Day 3/Saturday into Day 4/Sunday. A larger upper low will move into the Northwest late Day 4/Sunday through Day 6/Tuesday, with upper-level troughing likely deepening over the West Coast through mid-next week. Upper-level troughing may develop over most of the West mid to late next week, but forecast uncertainty remains high on the progression of the upper-level trough over the West/West Coast. Isolated to scattered mixed wet/dry thunderstorms are likely in portions of the Northwest and northern Rockies/Great Basin on Day 3/Saturday - Day 4/Sunday, with the Cascades having the best chances. Onshore flow will bring showers, higher RH, and cooler temperatures to the Northwest and eventually the northern Rockies and northwest California beginning late Day 4/Sunday and likely lasting through much of the outlook period. This pattern change and potential preceding wetting rain in areas on Day 1/Thursday - Day 2/Friday will limit the impacts of potential ignitions on Day 3/Saturday - Day 4/Sunday and slow fire activity across the northwestern US. However, if the upper-level trough slows or changes track in the coming days, areas may need to be introduced. Dry/windy conditions are likely to develop across portions of the central/southern Intermountain West on Day 4/Sunday - Day 7/Wednesday as upper-level troughing moves into the West. Fuel conditions are vastly improved after the last monsoonal surge. However, the environment will be monitored, especially in areas that received less wetting rain with the last monsoon surge, for potential overlap of critical winds/RH and receptive fuels. ..Nauslar.. 09/04/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0334 PM CDT Thu Sep 04 2025 Valid 061200Z - 121200Z A negatively-tilted upper-level shortwave trough will continue to track slowly northward across the Northwest Day 3/Saturday into Day 4/Sunday. A larger upper low will move into the Northwest late Day 4/Sunday through Day 6/Tuesday, with upper-level troughing likely deepening over the West Coast through mid-next week. Upper-level troughing may develop over most of the West mid to late next week, but forecast uncertainty remains high on the progression of the upper-level trough over the West/West Coast. Isolated to scattered mixed wet/dry thunderstorms are likely in portions of the Northwest and northern Rockies/Great Basin on Day 3/Saturday - Day 4/Sunday, with the Cascades having the best chances. Onshore flow will bring showers, higher RH, and cooler temperatures to the Northwest and eventually the northern Rockies and northwest California beginning late Day 4/Sunday and likely lasting through much of the outlook period. This pattern change and potential preceding wetting rain in areas on Day 1/Thursday - Day 2/Friday will limit the impacts of potential ignitions on Day 3/Saturday - Day 4/Sunday and slow fire activity across the northwestern US. However, if the upper-level trough slows or changes track in the coming days, areas may need to be introduced. Dry/windy conditions are likely to develop across portions of the central/southern Intermountain West on Day 4/Sunday - Day 7/Wednesday as upper-level troughing moves into the West. Fuel conditions are vastly improved after the last monsoonal surge. However, the environment will be monitored, especially in areas that received less wetting rain with the last monsoon surge, for potential overlap of critical winds/RH and receptive fuels. ..Nauslar.. 09/04/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0334 PM CDT Thu Sep 04 2025 Valid 061200Z - 121200Z A negatively-tilted upper-level shortwave trough will continue to track slowly northward across the Northwest Day 3/Saturday into Day 4/Sunday. A larger upper low will move into the Northwest late Day 4/Sunday through Day 6/Tuesday, with upper-level troughing likely deepening over the West Coast through mid-next week. Upper-level troughing may develop over most of the West mid to late next week, but forecast uncertainty remains high on the progression of the upper-level trough over the West/West Coast. Isolated to scattered mixed wet/dry thunderstorms are likely in portions of the Northwest and northern Rockies/Great Basin on Day 3/Saturday - Day 4/Sunday, with the Cascades having the best chances. Onshore flow will bring showers, higher RH, and cooler temperatures to the Northwest and eventually the northern Rockies and northwest California beginning late Day 4/Sunday and likely lasting through much of the outlook period. This pattern change and potential preceding wetting rain in areas on Day 1/Thursday - Day 2/Friday will limit the impacts of potential ignitions on Day 3/Saturday - Day 4/Sunday and slow fire activity across the northwestern US. However, if the upper-level trough slows or changes track in the coming days, areas may need to be introduced. Dry/windy conditions are likely to develop across portions of the central/southern Intermountain West on Day 4/Sunday - Day 7/Wednesday as upper-level troughing moves into the West. Fuel conditions are vastly improved after the last monsoonal surge. However, the environment will be monitored, especially in areas that received less wetting rain with the last monsoon surge, for potential overlap of critical winds/RH and receptive fuels. ..Nauslar.. 09/04/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0334 PM CDT Thu Sep 04 2025 Valid 061200Z - 121200Z A negatively-tilted upper-level shortwave trough will continue to track slowly northward across the Northwest Day 3/Saturday into Day 4/Sunday. A larger upper low will move into the Northwest late Day 4/Sunday through Day 6/Tuesday, with upper-level troughing likely deepening over the West Coast through mid-next week. Upper-level troughing may develop over most of the West mid to late next week, but forecast uncertainty remains high on the progression of the upper-level trough over the West/West Coast. Isolated to scattered mixed wet/dry thunderstorms are likely in portions of the Northwest and northern Rockies/Great Basin on Day 3/Saturday - Day 4/Sunday, with the Cascades having the best chances. Onshore flow will bring showers, higher RH, and cooler temperatures to the Northwest and eventually the northern Rockies and northwest California beginning late Day 4/Sunday and likely lasting through much of the outlook period. This pattern change and potential preceding wetting rain in areas on Day 1/Thursday - Day 2/Friday will limit the impacts of potential ignitions on Day 3/Saturday - Day 4/Sunday and slow fire activity across the northwestern US. However, if the upper-level trough slows or changes track in the coming days, areas may need to be introduced. Dry/windy conditions are likely to develop across portions of the central/southern Intermountain West on Day 4/Sunday - Day 7/Wednesday as upper-level troughing moves into the West. Fuel conditions are vastly improved after the last monsoonal surge. However, the environment will be monitored, especially in areas that received less wetting rain with the last monsoon surge, for potential overlap of critical winds/RH and receptive fuels. ..Nauslar.. 09/04/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0334 PM CDT Thu Sep 04 2025 Valid 061200Z - 121200Z A negatively-tilted upper-level shortwave trough will continue to track slowly northward across the Northwest Day 3/Saturday into Day 4/Sunday. A larger upper low will move into the Northwest late Day 4/Sunday through Day 6/Tuesday, with upper-level troughing likely deepening over the West Coast through mid-next week. Upper-level troughing may develop over most of the West mid to late next week, but forecast uncertainty remains high on the progression of the upper-level trough over the West/West Coast. Isolated to scattered mixed wet/dry thunderstorms are likely in portions of the Northwest and northern Rockies/Great Basin on Day 3/Saturday - Day 4/Sunday, with the Cascades having the best chances. Onshore flow will bring showers, higher RH, and cooler temperatures to the Northwest and eventually the northern Rockies and northwest California beginning late Day 4/Sunday and likely lasting through much of the outlook period. This pattern change and potential preceding wetting rain in areas on Day 1/Thursday - Day 2/Friday will limit the impacts of potential ignitions on Day 3/Saturday - Day 4/Sunday and slow fire activity across the northwestern US. However, if the upper-level trough slows or changes track in the coming days, areas may need to be introduced. Dry/windy conditions are likely to develop across portions of the central/southern Intermountain West on Day 4/Sunday - Day 7/Wednesday as upper-level troughing moves into the West. Fuel conditions are vastly improved after the last monsoonal surge. However, the environment will be monitored, especially in areas that received less wetting rain with the last monsoon surge, for potential overlap of critical winds/RH and receptive fuels. ..Nauslar.. 09/04/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0334 PM CDT Thu Sep 04 2025 Valid 061200Z - 121200Z A negatively-tilted upper-level shortwave trough will continue to track slowly northward across the Northwest Day 3/Saturday into Day 4/Sunday. A larger upper low will move into the Northwest late Day 4/Sunday through Day 6/Tuesday, with upper-level troughing likely deepening over the West Coast through mid-next week. Upper-level troughing may develop over most of the West mid to late next week, but forecast uncertainty remains high on the progression of the upper-level trough over the West/West Coast. Isolated to scattered mixed wet/dry thunderstorms are likely in portions of the Northwest and northern Rockies/Great Basin on Day 3/Saturday - Day 4/Sunday, with the Cascades having the best chances. Onshore flow will bring showers, higher RH, and cooler temperatures to the Northwest and eventually the northern Rockies and northwest California beginning late Day 4/Sunday and likely lasting through much of the outlook period. This pattern change and potential preceding wetting rain in areas on Day 1/Thursday - Day 2/Friday will limit the impacts of potential ignitions on Day 3/Saturday - Day 4/Sunday and slow fire activity across the northwestern US. However, if the upper-level trough slows or changes track in the coming days, areas may need to be introduced. Dry/windy conditions are likely to develop across portions of the central/southern Intermountain West on Day 4/Sunday - Day 7/Wednesday as upper-level troughing moves into the West. Fuel conditions are vastly improved after the last monsoonal surge. However, the environment will be monitored, especially in areas that received less wetting rain with the last monsoon surge, for potential overlap of critical winds/RH and receptive fuels. ..Nauslar.. 09/04/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 2032 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF MIDDLE/EASTERN TENNESSEE
Mesoscale Discussion 2032 NWS Storm Prediction Center Norman OK 0119 PM CDT Thu Sep 04 2025 Areas affected...parts of middle/eastern Tennessee Concerning...Severe potential...Watch unlikely Valid 041819Z - 042045Z Probability of Watch Issuance...20 percent SUMMARY...Occasional intensification of thunderstorms posing a risk for severe hail and localized damaging wind gusts may continue through late afternoon. Although the severe threat still appears mostly marginal in nature, and severe weather watch unlikely to be required, trends are continuing to be monitored. DISCUSSION...An initial surface cold front has stalled roughly along the I-40 corridor of middle/eastern Tennessee, near the southern periphery of the stronger cyclonic mid/upper flow associated with the amplified eastern U.S. troughing. Although it appears that an area of better mid/upper forcing for ascent is now shifting to the east of the southern Appalachians, lift aided by low-level warm advection along the frontal zone is maintaining renewed thunderstorm development, as a relatively moist boundary layer characterized by mid/upper 60s surface dew points destabilizes. Aided by modestly steep/steepening lower tropospheric lapse rates, mixed-layer CAPE appears to be peaking around 1500-2000 J/kg. In the presence of weak to modest clockwise curved low-level hodographs, beneath 30-35 kt westerly 500 mb flow, the environment may remain conducive to the occasional development and intensification of supercell structures posing a risk for severe hail and localized damaging wind gusts through the remainder of the afternoon. ..Kerr/Gleason.. 09/04/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GSP...MRX...OHX... LAT...LON 36478574 36548410 36568358 36318281 36038281 35258357 35368478 35448663 36048656 36478574 MOST PROBABLE PEAK WIND GUST...55-70 MPH MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Thu Sep 04 2025 Valid 042000Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF NEW YORK...TO THE MID ATLANTIC...SOUTHERN APPALACHIANS AND MID MISSOURI VALLEY... ...SUMMARY... Isolated damaging gusts remain possible across parts of New York to the Mid-Atlantic and Southern Appalachians through early this evening. Isolated severe gusts are also possible across parts of the mid Missouri Valley late this afternoon and early evening. ...20z Update Mid Atlantic and southern Appalachians... Several clusters of strong to severe thunderstorms have matured and are expected to continue through early this evening along and ahead of the slow-moving cold front from the Mid Atlantic southward. Despite poor mid-level lapse rates, heating of the modestly moist air mass is supporting around 500-1000 J/kg of MLCAPE, sufficient for a few stronger updrafts. As convection gradually increases in coverage through the remainder of this afternoon, clustering and 30-40 kt of mid-level flow will continue to support isolated damaging gust potential into early this evening. Some hail remains possible with the more cellular elements, especially father southwest over the eastern TN Valley where storm coverage should remain more isolated. The primary change was to align the western edge of the MRGL and severe probabilities with current frontal position, and shift them slightly east for ongoing storms on the border of NC and southern VA. ...New York... As the line of showers and weak thunderstorms continues eastward along the front, occasional damaging gusts remain possible owing to mixing of stronger mid-level flow downward this afternoon. Some heating, but marginal surface moisture should keep buoyancy and the resulting updrafts weak. With MLCAPE generally less than 500 J/kg, showers and storms should steadily weaken with the loss of diurnal heating. The MRGL risk area has been trimmed behind the ongoing line. Otherwise, the prior outlook remains unchanged, see the previous discussion. ..Lyons.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Sep 04 2025/ ...New York into the Mid-Atlantic and Tennessee Valley... A closed mid/upper-level low will remain centered over Ontario today. Multiple mid-level perturbations will rotate around this feature through the period, including a shortwave trough forecast to advance generally east-northeastward across parts of the central Appalachians/Mid-Atlantic into the Northeast. Showers and thunderstorms are ongoing mainly ahead of a surface cold front from parts of western NY southward to the TN Valley in a low/mid-level moisture plume. Generally clear skies ahead of this activity should allow for ample daytime heating of a modestly moistened low-level airmass. Even so, 12Z observed soundings from BUF, IAD, and RNK/GSO show rather poor mid-level lapse rates, which will likely hinder updraft strength even as weak instability develops this afternoon with continued diurnal heating. Modestly enhanced southwesterly low/mid-level flow should still aid in some thunderstorm organization even with the apparent thermodynamic limitations, with multicells the dominant convective mode. Wherever low-level lapse rates can become steepened, a risk for at least isolated damaging winds remains apparent. Some hail may also occur with the strongest cores across parts of the TN Valley/southern Appalachians where locally greater instability should be present this afternoon. The Marginal Risk has been adjusted for ongoing trends, but the potential for a more focused corridor of scattered severe/damaging winds remains unclear. ...Mid Missouri Valley... A mid-level shortwave trough and attendant strong speed maximum will move quickly southeastward today from central Canada and the northern Plains towards the mid MO Valley and vicinity. Pronounced ascent associated with this jet should encourage convection to develop by late this afternoon across parts of eastern SD and vicinity. While low-level moisture and MLCAPE are both expected to remain very limited, enhanced low/mid-level northwesterly flow may still support some risk for severe gusts with any low-topped convection that can develop and spread quickly southeastward before weakening this evening with the loss of daytime heating. ...Kansas... A sharp cold front will sweep southward across the central Plains tonight. Elevated convection should form to the cool side of this boundary late tonight through early Friday morning given sufficient MUCAPE. Locally strong surface gusts and small hail may accompany this activity amid robust low-level northerlies, but the overall severe potential should remain fairly low given the tendency for convection to be mostly elevated. ...Arizona/Lower Colorado River Valley... Thunderstorms should develop again today across parts of central/southern AZ and the lower CO River Valley, beneath weak mid-level flow and on the periphery of increasing mid-level moisture associated with Tropical Storm Lorena. Weak shear should keep thunderstorms mostly disorganized, but occasional strong/gusty winds may occur where low-level lapse rates can become steepened. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Thu Sep 04 2025 Valid 042000Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF NEW YORK...TO THE MID ATLANTIC...SOUTHERN APPALACHIANS AND MID MISSOURI VALLEY... ...SUMMARY... Isolated damaging gusts remain possible across parts of New York to the Mid-Atlantic and Southern Appalachians through early this evening. Isolated severe gusts are also possible across parts of the mid Missouri Valley late this afternoon and early evening. ...20z Update Mid Atlantic and southern Appalachians... Several clusters of strong to severe thunderstorms have matured and are expected to continue through early this evening along and ahead of the slow-moving cold front from the Mid Atlantic southward. Despite poor mid-level lapse rates, heating of the modestly moist air mass is supporting around 500-1000 J/kg of MLCAPE, sufficient for a few stronger updrafts. As convection gradually increases in coverage through the remainder of this afternoon, clustering and 30-40 kt of mid-level flow will continue to support isolated damaging gust potential into early this evening. Some hail remains possible with the more cellular elements, especially father southwest over the eastern TN Valley where storm coverage should remain more isolated. The primary change was to align the western edge of the MRGL and severe probabilities with current frontal position, and shift them slightly east for ongoing storms on the border of NC and southern VA. ...New York... As the line of showers and weak thunderstorms continues eastward along the front, occasional damaging gusts remain possible owing to mixing of stronger mid-level flow downward this afternoon. Some heating, but marginal surface moisture should keep buoyancy and the resulting updrafts weak. With MLCAPE generally less than 500 J/kg, showers and storms should steadily weaken with the loss of diurnal heating. The MRGL risk area has been trimmed behind the ongoing line. Otherwise, the prior outlook remains unchanged, see the previous discussion. ..Lyons.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Sep 04 2025/ ...New York into the Mid-Atlantic and Tennessee Valley... A closed mid/upper-level low will remain centered over Ontario today. Multiple mid-level perturbations will rotate around this feature through the period, including a shortwave trough forecast to advance generally east-northeastward across parts of the central Appalachians/Mid-Atlantic into the Northeast. Showers and thunderstorms are ongoing mainly ahead of a surface cold front from parts of western NY southward to the TN Valley in a low/mid-level moisture plume. Generally clear skies ahead of this activity should allow for ample daytime heating of a modestly moistened low-level airmass. Even so, 12Z observed soundings from BUF, IAD, and RNK/GSO show rather poor mid-level lapse rates, which will likely hinder updraft strength even as weak instability develops this afternoon with continued diurnal heating. Modestly enhanced southwesterly low/mid-level flow should still aid in some thunderstorm organization even with the apparent thermodynamic limitations, with multicells the dominant convective mode. Wherever low-level lapse rates can become steepened, a risk for at least isolated damaging winds remains apparent. Some hail may also occur with the strongest cores across parts of the TN Valley/southern Appalachians where locally greater instability should be present this afternoon. The Marginal Risk has been adjusted for ongoing trends, but the potential for a more focused corridor of scattered severe/damaging winds remains unclear. ...Mid Missouri Valley... A mid-level shortwave trough and attendant strong speed maximum will move quickly southeastward today from central Canada and the northern Plains towards the mid MO Valley and vicinity. Pronounced ascent associated with this jet should encourage convection to develop by late this afternoon across parts of eastern SD and vicinity. While low-level moisture and MLCAPE are both expected to remain very limited, enhanced low/mid-level northwesterly flow may still support some risk for severe gusts with any low-topped convection that can develop and spread quickly southeastward before weakening this evening with the loss of daytime heating. ...Kansas... A sharp cold front will sweep southward across the central Plains tonight. Elevated convection should form to the cool side of this boundary late tonight through early Friday morning given sufficient MUCAPE. Locally strong surface gusts and small hail may accompany this activity amid robust low-level northerlies, but the overall severe potential should remain fairly low given the tendency for convection to be mostly elevated. ...Arizona/Lower Colorado River Valley... Thunderstorms should develop again today across parts of central/southern AZ and the lower CO River Valley, beneath weak mid-level flow and on the periphery of increasing mid-level moisture associated with Tropical Storm Lorena. Weak shear should keep thunderstorms mostly disorganized, but occasional strong/gusty winds may occur where low-level lapse rates can become steepened. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Thu Sep 04 2025 Valid 042000Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF NEW YORK...TO THE MID ATLANTIC...SOUTHERN APPALACHIANS AND MID MISSOURI VALLEY... ...SUMMARY... Isolated damaging gusts remain possible across parts of New York to the Mid-Atlantic and Southern Appalachians through early this evening. Isolated severe gusts are also possible across parts of the mid Missouri Valley late this afternoon and early evening. ...20z Update Mid Atlantic and southern Appalachians... Several clusters of strong to severe thunderstorms have matured and are expected to continue through early this evening along and ahead of the slow-moving cold front from the Mid Atlantic southward. Despite poor mid-level lapse rates, heating of the modestly moist air mass is supporting around 500-1000 J/kg of MLCAPE, sufficient for a few stronger updrafts. As convection gradually increases in coverage through the remainder of this afternoon, clustering and 30-40 kt of mid-level flow will continue to support isolated damaging gust potential into early this evening. Some hail remains possible with the more cellular elements, especially father southwest over the eastern TN Valley where storm coverage should remain more isolated. The primary change was to align the western edge of the MRGL and severe probabilities with current frontal position, and shift them slightly east for ongoing storms on the border of NC and southern VA. ...New York... As the line of showers and weak thunderstorms continues eastward along the front, occasional damaging gusts remain possible owing to mixing of stronger mid-level flow downward this afternoon. Some heating, but marginal surface moisture should keep buoyancy and the resulting updrafts weak. With MLCAPE generally less than 500 J/kg, showers and storms should steadily weaken with the loss of diurnal heating. The MRGL risk area has been trimmed behind the ongoing line. Otherwise, the prior outlook remains unchanged, see the previous discussion. ..Lyons.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Sep 04 2025/ ...New York into the Mid-Atlantic and Tennessee Valley... A closed mid/upper-level low will remain centered over Ontario today. Multiple mid-level perturbations will rotate around this feature through the period, including a shortwave trough forecast to advance generally east-northeastward across parts of the central Appalachians/Mid-Atlantic into the Northeast. Showers and thunderstorms are ongoing mainly ahead of a surface cold front from parts of western NY southward to the TN Valley in a low/mid-level moisture plume. Generally clear skies ahead of this activity should allow for ample daytime heating of a modestly moistened low-level airmass. Even so, 12Z observed soundings from BUF, IAD, and RNK/GSO show rather poor mid-level lapse rates, which will likely hinder updraft strength even as weak instability develops this afternoon with continued diurnal heating. Modestly enhanced southwesterly low/mid-level flow should still aid in some thunderstorm organization even with the apparent thermodynamic limitations, with multicells the dominant convective mode. Wherever low-level lapse rates can become steepened, a risk for at least isolated damaging winds remains apparent. Some hail may also occur with the strongest cores across parts of the TN Valley/southern Appalachians where locally greater instability should be present this afternoon. The Marginal Risk has been adjusted for ongoing trends, but the potential for a more focused corridor of scattered severe/damaging winds remains unclear. ...Mid Missouri Valley... A mid-level shortwave trough and attendant strong speed maximum will move quickly southeastward today from central Canada and the northern Plains towards the mid MO Valley and vicinity. Pronounced ascent associated with this jet should encourage convection to develop by late this afternoon across parts of eastern SD and vicinity. While low-level moisture and MLCAPE are both expected to remain very limited, enhanced low/mid-level northwesterly flow may still support some risk for severe gusts with any low-topped convection that can develop and spread quickly southeastward before weakening this evening with the loss of daytime heating. ...Kansas... A sharp cold front will sweep southward across the central Plains tonight. Elevated convection should form to the cool side of this boundary late tonight through early Friday morning given sufficient MUCAPE. Locally strong surface gusts and small hail may accompany this activity amid robust low-level northerlies, but the overall severe potential should remain fairly low given the tendency for convection to be mostly elevated. ...Arizona/Lower Colorado River Valley... Thunderstorms should develop again today across parts of central/southern AZ and the lower CO River Valley, beneath weak mid-level flow and on the periphery of increasing mid-level moisture associated with Tropical Storm Lorena. Weak shear should keep thunderstorms mostly disorganized, but occasional strong/gusty winds may occur where low-level lapse rates can become steepened. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Thu Sep 04 2025 Valid 042000Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF NEW YORK...TO THE MID ATLANTIC...SOUTHERN APPALACHIANS AND MID MISSOURI VALLEY... ...SUMMARY... Isolated damaging gusts remain possible across parts of New York to the Mid-Atlantic and Southern Appalachians through early this evening. Isolated severe gusts are also possible across parts of the mid Missouri Valley late this afternoon and early evening. ...20z Update Mid Atlantic and southern Appalachians... Several clusters of strong to severe thunderstorms have matured and are expected to continue through early this evening along and ahead of the slow-moving cold front from the Mid Atlantic southward. Despite poor mid-level lapse rates, heating of the modestly moist air mass is supporting around 500-1000 J/kg of MLCAPE, sufficient for a few stronger updrafts. As convection gradually increases in coverage through the remainder of this afternoon, clustering and 30-40 kt of mid-level flow will continue to support isolated damaging gust potential into early this evening. Some hail remains possible with the more cellular elements, especially father southwest over the eastern TN Valley where storm coverage should remain more isolated. The primary change was to align the western edge of the MRGL and severe probabilities with current frontal position, and shift them slightly east for ongoing storms on the border of NC and southern VA. ...New York... As the line of showers and weak thunderstorms continues eastward along the front, occasional damaging gusts remain possible owing to mixing of stronger mid-level flow downward this afternoon. Some heating, but marginal surface moisture should keep buoyancy and the resulting updrafts weak. With MLCAPE generally less than 500 J/kg, showers and storms should steadily weaken with the loss of diurnal heating. The MRGL risk area has been trimmed behind the ongoing line. Otherwise, the prior outlook remains unchanged, see the previous discussion. ..Lyons.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Sep 04 2025/ ...New York into the Mid-Atlantic and Tennessee Valley... A closed mid/upper-level low will remain centered over Ontario today. Multiple mid-level perturbations will rotate around this feature through the period, including a shortwave trough forecast to advance generally east-northeastward across parts of the central Appalachians/Mid-Atlantic into the Northeast. Showers and thunderstorms are ongoing mainly ahead of a surface cold front from parts of western NY southward to the TN Valley in a low/mid-level moisture plume. Generally clear skies ahead of this activity should allow for ample daytime heating of a modestly moistened low-level airmass. Even so, 12Z observed soundings from BUF, IAD, and RNK/GSO show rather poor mid-level lapse rates, which will likely hinder updraft strength even as weak instability develops this afternoon with continued diurnal heating. Modestly enhanced southwesterly low/mid-level flow should still aid in some thunderstorm organization even with the apparent thermodynamic limitations, with multicells the dominant convective mode. Wherever low-level lapse rates can become steepened, a risk for at least isolated damaging winds remains apparent. Some hail may also occur with the strongest cores across parts of the TN Valley/southern Appalachians where locally greater instability should be present this afternoon. The Marginal Risk has been adjusted for ongoing trends, but the potential for a more focused corridor of scattered severe/damaging winds remains unclear. ...Mid Missouri Valley... A mid-level shortwave trough and attendant strong speed maximum will move quickly southeastward today from central Canada and the northern Plains towards the mid MO Valley and vicinity. Pronounced ascent associated with this jet should encourage convection to develop by late this afternoon across parts of eastern SD and vicinity. While low-level moisture and MLCAPE are both expected to remain very limited, enhanced low/mid-level northwesterly flow may still support some risk for severe gusts with any low-topped convection that can develop and spread quickly southeastward before weakening this evening with the loss of daytime heating. ...Kansas... A sharp cold front will sweep southward across the central Plains tonight. Elevated convection should form to the cool side of this boundary late tonight through early Friday morning given sufficient MUCAPE. Locally strong surface gusts and small hail may accompany this activity amid robust low-level northerlies, but the overall severe potential should remain fairly low given the tendency for convection to be mostly elevated. ...Arizona/Lower Colorado River Valley... Thunderstorms should develop again today across parts of central/southern AZ and the lower CO River Valley, beneath weak mid-level flow and on the periphery of increasing mid-level moisture associated with Tropical Storm Lorena. Weak shear should keep thunderstorms mostly disorganized, but occasional strong/gusty winds may occur where low-level lapse rates can become steepened. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Thu Sep 04 2025 Valid 042000Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF NEW YORK...TO THE MID ATLANTIC...SOUTHERN APPALACHIANS AND MID MISSOURI VALLEY... ...SUMMARY... Isolated damaging gusts remain possible across parts of New York to the Mid-Atlantic and Southern Appalachians through early this evening. Isolated severe gusts are also possible across parts of the mid Missouri Valley late this afternoon and early evening. ...20z Update Mid Atlantic and southern Appalachians... Several clusters of strong to severe thunderstorms have matured and are expected to continue through early this evening along and ahead of the slow-moving cold front from the Mid Atlantic southward. Despite poor mid-level lapse rates, heating of the modestly moist air mass is supporting around 500-1000 J/kg of MLCAPE, sufficient for a few stronger updrafts. As convection gradually increases in coverage through the remainder of this afternoon, clustering and 30-40 kt of mid-level flow will continue to support isolated damaging gust potential into early this evening. Some hail remains possible with the more cellular elements, especially father southwest over the eastern TN Valley where storm coverage should remain more isolated. The primary change was to align the western edge of the MRGL and severe probabilities with current frontal position, and shift them slightly east for ongoing storms on the border of NC and southern VA. ...New York... As the line of showers and weak thunderstorms continues eastward along the front, occasional damaging gusts remain possible owing to mixing of stronger mid-level flow downward this afternoon. Some heating, but marginal surface moisture should keep buoyancy and the resulting updrafts weak. With MLCAPE generally less than 500 J/kg, showers and storms should steadily weaken with the loss of diurnal heating. The MRGL risk area has been trimmed behind the ongoing line. Otherwise, the prior outlook remains unchanged, see the previous discussion. ..Lyons.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Sep 04 2025/ ...New York into the Mid-Atlantic and Tennessee Valley... A closed mid/upper-level low will remain centered over Ontario today. Multiple mid-level perturbations will rotate around this feature through the period, including a shortwave trough forecast to advance generally east-northeastward across parts of the central Appalachians/Mid-Atlantic into the Northeast. Showers and thunderstorms are ongoing mainly ahead of a surface cold front from parts of western NY southward to the TN Valley in a low/mid-level moisture plume. Generally clear skies ahead of this activity should allow for ample daytime heating of a modestly moistened low-level airmass. Even so, 12Z observed soundings from BUF, IAD, and RNK/GSO show rather poor mid-level lapse rates, which will likely hinder updraft strength even as weak instability develops this afternoon with continued diurnal heating. Modestly enhanced southwesterly low/mid-level flow should still aid in some thunderstorm organization even with the apparent thermodynamic limitations, with multicells the dominant convective mode. Wherever low-level lapse rates can become steepened, a risk for at least isolated damaging winds remains apparent. Some hail may also occur with the strongest cores across parts of the TN Valley/southern Appalachians where locally greater instability should be present this afternoon. The Marginal Risk has been adjusted for ongoing trends, but the potential for a more focused corridor of scattered severe/damaging winds remains unclear. ...Mid Missouri Valley... A mid-level shortwave trough and attendant strong speed maximum will move quickly southeastward today from central Canada and the northern Plains towards the mid MO Valley and vicinity. Pronounced ascent associated with this jet should encourage convection to develop by late this afternoon across parts of eastern SD and vicinity. While low-level moisture and MLCAPE are both expected to remain very limited, enhanced low/mid-level northwesterly flow may still support some risk for severe gusts with any low-topped convection that can develop and spread quickly southeastward before weakening this evening with the loss of daytime heating. ...Kansas... A sharp cold front will sweep southward across the central Plains tonight. Elevated convection should form to the cool side of this boundary late tonight through early Friday morning given sufficient MUCAPE. Locally strong surface gusts and small hail may accompany this activity amid robust low-level northerlies, but the overall severe potential should remain fairly low given the tendency for convection to be mostly elevated. ...Arizona/Lower Colorado River Valley... Thunderstorms should develop again today across parts of central/southern AZ and the lower CO River Valley, beneath weak mid-level flow and on the periphery of increasing mid-level moisture associated with Tropical Storm Lorena. Weak shear should keep thunderstorms mostly disorganized, but occasional strong/gusty winds may occur where low-level lapse rates can become steepened. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Thu Sep 04 2025 Valid 042000Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF NEW YORK...TO THE MID ATLANTIC...SOUTHERN APPALACHIANS AND MID MISSOURI VALLEY... ...SUMMARY... Isolated damaging gusts remain possible across parts of New York to the Mid-Atlantic and Southern Appalachians through early this evening. Isolated severe gusts are also possible across parts of the mid Missouri Valley late this afternoon and early evening. ...20z Update Mid Atlantic and southern Appalachians... Several clusters of strong to severe thunderstorms have matured and are expected to continue through early this evening along and ahead of the slow-moving cold front from the Mid Atlantic southward. Despite poor mid-level lapse rates, heating of the modestly moist air mass is supporting around 500-1000 J/kg of MLCAPE, sufficient for a few stronger updrafts. As convection gradually increases in coverage through the remainder of this afternoon, clustering and 30-40 kt of mid-level flow will continue to support isolated damaging gust potential into early this evening. Some hail remains possible with the more cellular elements, especially father southwest over the eastern TN Valley where storm coverage should remain more isolated. The primary change was to align the western edge of the MRGL and severe probabilities with current frontal position, and shift them slightly east for ongoing storms on the border of NC and southern VA. ...New York... As the line of showers and weak thunderstorms continues eastward along the front, occasional damaging gusts remain possible owing to mixing of stronger mid-level flow downward this afternoon. Some heating, but marginal surface moisture should keep buoyancy and the resulting updrafts weak. With MLCAPE generally less than 500 J/kg, showers and storms should steadily weaken with the loss of diurnal heating. The MRGL risk area has been trimmed behind the ongoing line. Otherwise, the prior outlook remains unchanged, see the previous discussion. ..Lyons.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Sep 04 2025/ ...New York into the Mid-Atlantic and Tennessee Valley... A closed mid/upper-level low will remain centered over Ontario today. Multiple mid-level perturbations will rotate around this feature through the period, including a shortwave trough forecast to advance generally east-northeastward across parts of the central Appalachians/Mid-Atlantic into the Northeast. Showers and thunderstorms are ongoing mainly ahead of a surface cold front from parts of western NY southward to the TN Valley in a low/mid-level moisture plume. Generally clear skies ahead of this activity should allow for ample daytime heating of a modestly moistened low-level airmass. Even so, 12Z observed soundings from BUF, IAD, and RNK/GSO show rather poor mid-level lapse rates, which will likely hinder updraft strength even as weak instability develops this afternoon with continued diurnal heating. Modestly enhanced southwesterly low/mid-level flow should still aid in some thunderstorm organization even with the apparent thermodynamic limitations, with multicells the dominant convective mode. Wherever low-level lapse rates can become steepened, a risk for at least isolated damaging winds remains apparent. Some hail may also occur with the strongest cores across parts of the TN Valley/southern Appalachians where locally greater instability should be present this afternoon. The Marginal Risk has been adjusted for ongoing trends, but the potential for a more focused corridor of scattered severe/damaging winds remains unclear. ...Mid Missouri Valley... A mid-level shortwave trough and attendant strong speed maximum will move quickly southeastward today from central Canada and the northern Plains towards the mid MO Valley and vicinity. Pronounced ascent associated with this jet should encourage convection to develop by late this afternoon across parts of eastern SD and vicinity. While low-level moisture and MLCAPE are both expected to remain very limited, enhanced low/mid-level northwesterly flow may still support some risk for severe gusts with any low-topped convection that can develop and spread quickly southeastward before weakening this evening with the loss of daytime heating. ...Kansas... A sharp cold front will sweep southward across the central Plains tonight. Elevated convection should form to the cool side of this boundary late tonight through early Friday morning given sufficient MUCAPE. Locally strong surface gusts and small hail may accompany this activity amid robust low-level northerlies, but the overall severe potential should remain fairly low given the tendency for convection to be mostly elevated. ...Arizona/Lower Colorado River Valley... Thunderstorms should develop again today across parts of central/southern AZ and the lower CO River Valley, beneath weak mid-level flow and on the periphery of increasing mid-level moisture associated with Tropical Storm Lorena. Weak shear should keep thunderstorms mostly disorganized, but occasional strong/gusty winds may occur where low-level lapse rates can become steepened. Read more