SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0650 AM CST Mon Dec 22 2025 Valid 221300Z - 231200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected today. ...Discussion... The next shortwave trough and associated cold front are expected to advance inland across British Columbia/coastal Washington by this evening. A related plume of steepening mid-level lapse rates will contribute to weak buoyancy and the potential for isolated lightning flashes with low-topped convection. Elsewhere across the West, a few lightning flashes have been noted early this morning across the California Sierra, and this scenario may continue today within a moisture-rich plume with weak buoyancy. A weak mid-level disturbance over the western Gulf and coastal Mexico, along with a moist air mass (reference 12z Brownsville observed sounding) to the south of a slow-moving front, may allow for a few thunderstorms to develop into/across Deep South Texas. Similar to morning RAOB/WSR-88D VWP observations, forecast soundings suggest deep-layer shear will remain quite weak, such that any convection that evolves across this region should remain below severe levels. ..Guyer/Marsh.. 12/22/2025
