SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0147 PM CST Wed Dec 17 2025 Valid 172000Z - 181200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms will continue across portions of the Intermountain West and Texas/Louisiana coasts through this evening. The overall threat for organized severe thunderstorms appears low. ...20z Update... The Marginal Risk across southern Idaho/northern Utah has been removed with this outlook. Thunderstorm activity has shown gradual weakening with only meager MLCAPE remaining. Occasional strong gradient winds will continue with the upper-level wave but the overall convective severe threat appears to be waning. ..Thornton.. 12/17/2025 .PREV DISCUSSION... /ISSUED 1022 AM CST Wed Dec 17 2025/ ...Interior Northwest and Northern Great Basin/Rockies... A powerful mid-level shortwave trough and associated sub-980 mb surface low will move quickly eastward today across the interior Northwest/northern Rockies and adjacent western Canada. A strong surface cold front will likewise translate east-southeastward over the northern Intermountain/Great Basin region late this morning into the afternoon. Widespread cloud cover remains prevalent ahead of the front across southern ID into northern UT and vicinity, with cool surface temperatures and very limited low-level moisture also present. MUCAPE is expected to remain only barely sufficient to support convection. But, given the enhanced flow at low levels noted on recent VWPs from KCBX/KSFX, it is not entirely out of the question that convectively augmented gusts may exceed the already strong background gradient winds on a localized basis. The Marginal Risk has therefore been maintained for parts of southern ID/northern UT and vicinity, even though the overall threat for organized severe thunderstorms will remain low.
