Day 1 Convective Outlook
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Issued: · Valid: –
Summary
No organized severe thunderstorms are expected through early Monday, though isolated thunderstorms are ongoing across parts of central and north Texas and may continue into Oklahoma this evening. Overnight, elevated thunderstorms are expected to move from western South Dakota into North Dakota, potentially producing isolated hail.
Product Text
000 ACUS01 KWNS 271959 SWODY1 SPC AC 271957 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sun Sep 27 2026 Valid 272000Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe storms are not expected through early Monday. ...20z Update... No changes were made to the existing outlook with this update cycle. Isolated convective development is ongoing across portions of central/north Texas as of 1945 UTC. While an isolated strong/damaging wind gust cannot be ruled out with this activity owing to steep low-level lapse rates and moderate buoyancy, weak lower tropospheric flow (as depicted by regional VWPs), limited effective shear, and poor mid-level lapse rates should largely temper overall convective intensity. Thus, the severe threat continues to appear too low (less than 5%) to warrant the inclusion of severe probabilities. See the discussion below for additional details. ..Chalmers/Guyer.. 09/27/2026 .PREV DISCUSSION... /ISSUED 1137 AM CDT Sun Sep 27 2026/ ...Synopsis... An occluded cyclone will slowly weaken near the northern Mid-Atlantic coast, with lingering potential for elevated convection and isolated lightning flashes to its northeast across southeast New England. Farther west, weak ridging aloft will extend from the southern High Plains toward MN. A few thunderstorms will be possible late this afternoon/evening along a diffuse surface boundary from north TX into southern OK. The strongest storms may produce gusty outflow winds given steep low-level lapse rates with afternoon mixing, but the severe threat appears too low to justify adding severe-wind probabilities. Slightly elevated convection is ongoing across central SD in a zone of weak low-level frontogenesis, coincident with midlevel lapse rates near 8 C/km and MUCAPE close to 1000 J/kg. Deep-layer vertical shear is on the lower margins for storm organization, but it appears this convection has already peaked. Additional elevated thunderstorms are expected overnight from western SD into ND as low-level warm advection increases in association with embedded speed maxima downstream from a midlevel trough moving across CA/NV. While an isolated hail report could occur overnight as far northeast as southwest ND, the overall threat is low and when combined with the questionable threat for diurnal convection across the central High Plains, the MRGL area has been removed. $$