SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1008 AM CST Mon Dec 22 2025 Valid 221630Z - 231200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected today. ...Synopsis... A pronounced midlevel shortwave trough and associated baroclinic zone will move across the WA coast later this afternoon. Low-midlevel lapse rates will contribute to weak buoyancy of sufficient depth (through -20 C at the equilibrium level) for charge separation and isolated lightning flashes with low-topped convection along and behind the front. Shallow, weakly rotating convection will be possible near the WA coast per the KLGX VWP/hodograph, but the threat for severe storms appears too limited to warrant an outlook area. Farther south, the potential for isolated lightning flashes will slowly wane through the day across the northern Sierra Nevada, where weak buoyancy rooted above the surface will likewise diminish. Otherwise, a broad subtropical ridge (with unusually high geopotential heights) covers the southern Plains/Gulf coast. An embedded/weak midlevel trough will rotate slowly north-northwestward around the periphery of the ridge, bringing weak ascent and an associated moisture plume into south TX. Per the observed deepening of the moist layer at BRO in the past 12 hours, pockets of surface heating/destabilization could support isolated thunderstorm development across south TX this afternoon. ..Thompson/Thornton.. 12/22/2025
