SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0653 AM CST Sun Dec 21 2025 Valid 211300Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected today. ...Discussion... A progressive/zonal upper-flow pattern will continue over the CONUS. A low-amplitude shortwave trough will move inland across the Pacific Northwest by tonight. Weak buoyancy and cooling temperatures aloft may become sufficient for isolated lightning flashes, particularly near the Washington coast. Farther south, a moisture-rich plume and a marginally favorable thermodynamic environment may allow for some lighting flashes across northern California. Elsewhere, a relatively moist airmass near/south of a southward-moving front, along with continued weak warm/moist advection, will probably be conducive for isolated thunderstorms mainly across southern portions of Louisiana and Mississippi today. ..Guyer/Marsh.. 12/21/2025
