SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1126 PM CST Sat Nov 15 2025 Valid 161200Z - 171200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms are possible across the Four Corners states and along the California coast late tonight. Severe storms are not expected. ...Western U.S... Large-scale pattern does not appear particularly favorable for robust convection across the CONUS Sunday. Even so, isolated thunderstorms are expected across a few areas of the western U.S., primarily ahead of two strong troughs. The lead midlevel trough will eject across the lower CO River Valley early in the period with high-level diffluent flow spreading across the Four Corners region during the afternoon. This feature will eject as a negative-tilted trough resulting in cool midlevel temperatures and steep lapse rates. Forecast soundings exhibit meager instability, but likely adequate for lightning in the strongest updrafts. A secondary trough is forecast to approach the northern CA Coast during the latter half of the period. 500mb speed max will dig toward the back side of this feature, but not advance inland until later in the day2 period. At this time it appears the synoptic front will approach the northern CA Coast around 17/12z, along with a bit more instability beneath the approaching trough. Most lightning activity should remain offshore, but isolated storms may approach the Coast by the end of the period. ..Darrow/Moore.. 11/16/2025
