Day 1 Convective Outlook

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Issued:  ·  Valid: –

Summary

Organized severe storms are not expected through Monday, though a few thunderstorms may occur late this afternoon and evening across parts of North Texas and southern Oklahoma. Additionally, elevated thunderstorms are expected overnight from western South Dakota into North Dakota, which could produce isolated hail.

Product Text

000 ACUS01 KWNS 271632 SWODY1 SPC AC 271630 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Sun Sep 27 2026 Valid 271630Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe storms are not expected through early Monday. ...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. ..Thompson/Chalmers.. 09/27/2026 $$