ACUS01 KWNS 221958 SWODY1 SPC AC 221956 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Sat Aug 22 2026 Valid 222000Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE OHIO VALLEY INTO THE CENTRAL APPALACHIANS...THE MID SOUTH...AND THE SOUTHERN GREAT PLAINS... ...SUMMARY... Scattered severe thunderstorms are possible over parts of the Mid South and southern Great Plains with 60 to 75 mph gusts being the primary hazard. Scattered damaging winds also remain possible this afternoon across parts of the Ohio Valley into the central Appalachians. ...20z Update... ...Southern Great Plains... The primary change with this outlook update was an upgrade to a Level 2/Slight risk for portions of northwest Texas and the Texas Panhandle driven by the inclusion of 15% wind probabilities based on the latest CAM and time-lagged ensemble guidance. The 5% wind probability and CIG1 were similarly expanded across adjacent portions of the southern Great Plains. See Mesoscale Discussion 2085 for additional short-term details. ...Mid Atlantic... Isolated convective initiation is ongoing across portions of the central Blue Ridge in far northwestern Virginia as of 1955 UTC. Latest CAM/time-lagged ensemble guidance continues to suggest the potential for some upscale growth/clustering of convection downstream across northern Virginia. Some consideration was given to a targeted upgrade to a Level 2/Slight risk (via the inclusion of a 15% wind probability) for this area; however, weak low-level flow sampled by the Sterling (LWX) VWP and cooler downstream temperatures in the upper-70s F lend uncertainty to the coverage of the resultant severe risk and precluded an upgrade at this time. A locally greater risk for damaging wind gusts could materialize should a cluster of storms develop, however. See MCD 2083 for additional details. Elsewhere, only minor adjustments were made based on recent convective/observational trends and the latest forecast guidance. See the text below and Mesoscale Discussions 2084 and 2086 for additional details. ..Chalmers/Moore.. 08/22/2026 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 22 2026/ ...Ohio Valley into the Central Appalachians and Tennessee/Lower Mississippi Valleys... An upper trough continues to dig southeast across the southwest Great Lakes during the midday as a surface front advances slowly east across the southern Great Lakes and OH Valley. Late morning surface analysis places a moist plume (65 to 70 deg F surface dewpoints) extending northeastward ahead of the front from the lower OH Valley into northeast OH. Visible satellite imagery shows a swelling cumulus field across the upper OH Valley where moderate buoyancy has developed. A gradual increase in thunderstorm coverage and intensity is expected, with 20-30 kt of effective bulk shear fostering enough updraft organization for multicell clusters capable of producing scattered damaging winds. See MCD #2081 for short-term details. These thunderstorms will spread eastward from the upper OH Valley into the central Appalachians this afternoon and evening before eventually weakening with eastward extent. Isolated hail may occur with the stronger cores that develop, but the poor mid-level lapse rates present may limit this threat to some extent. There also appears to be some chance for strong to locally severe thunderstorms to develop along/east of the Blue Ridge Mountains this afternoon. If this occurs, then occasional damaging winds would be the main threat with this activity. ...Southern/Central Plains into the Mid South... Satellite imagery late this morning shows a pair of convectively enhanced mid-level vorticity maxima moving southeast over eastern KS/OK on the eastern periphery of upper ridging centered over NM. Weak thunderstorm activity continues to progress southeast over eastern KS towards the Ozarks, where the airmass has heated near 90 deg F to the downstream of greater cloud cover. Surface analysis this morning showed a reservoir of richer moisture (lower 70s deg F surface dewpoints) south of a stalled west-east frontal zone. Additional heating/destabilization ahead of the southeastward-moving thunderstorms and associated MCV will act to pre-condition the environment to support a greater risk for severe gusts and wind damage across parts of the Mid South this afternoon and early evening. CAM model guidance both from a model core and time-lagged ensemble, suggest the eventual development of a linear cluster developing over the Ozarks and moving east-southeast into a hot/unstable airmass featuring very steep 0-3 km lapse rates. Mid to upper-level flow will tend to weaken with southeast extent, but ample cloud-bearing shear for storm organization is evident. Have upgraded a corridor from northern ARK into northern MS where confidence is highest on an MCS developing and an associated risk for severe gusts and wind damage. Additional isolated storm development is expected later today across parts of the southern Great Plains. Moderate to locally strong instability, very steep low-level lapse rates, and moderate northwesterly deep-layer shear should support some clustering/updraft organization. Occasional hail and severe gusts may occur as thunderstorms spread southward this afternoon/evening. ...Central High Plains/Front Range... A separate area of convection is forecast to develop this afternoon along the Front Range/Laramie Mountains in a weak post-frontal low-level upslope regime. While effective bulk shear should be somewhat weaker across this region, a narrow corridor of greater instability is forecast across the central High Plains. This may support loosely organized multicells and marginal supercells with an isolated severe hail/wind threat. ...Great Basin/Northern Rockies into the Northwest... Upper ridging will remain prominent from the Southwest into the northern Rockies/High Plains today. On the western periphery of this ridging, an upper trough/low will move northward along/near the coast of the Pacific Northwest. Enhanced south-southwesterly mid-level flow will overspread parts of the Great Basin, northern Rockies, and Northwest through the period, with the strongest winds forecast over WA/OR. Low-level moisture remains fairly limited over most of these regions, with somewhat greater surface dewpoints present over parts of the Great Basin. Diurnal heating should support modest destabilization and weak instability from the northern Great Basin into the interior Pacific Northwest and northern Rockies. Thunderstorms will develop this afternoon as the large-scale ascent preceding the upper trough/low overspreads these regions in tandem with orographic effects across the higher terrain. Where low-level lapse rates can become sufficiently steepened with a dry/well-mixed sub-cloud layer, isolated severe/damaging winds may occur. The overall severe threat should be limited by weak instability. $$