1PM Day 1 Convective Outlook for Tuesday, January 27. NO SEVERE THUNDERSTORM AREAS FORECAST
SUMMARY
Isolated thunderstorms may occur this evening and tonight across parts of northern California and coastal southwest Oregon. Severe thunderstorms are not forecast.
20Z Update
No changes have been made to the outlook.
Synopsis and Discussion
Persistent mid/upper-level troughing over the central/eastern CONUS and cold/offshore low-level trajectories will keep thunderstorm potential very low today, with one possible exception. A mid-level shortwave trough will move quickly eastward over the eastern Pacific today, and eventually overspread the Pacific Northwest this evening/tonight. Cool temperatures aloft (around -24 to -28C at 500 mb) should support modest MUCAPE and the potential for isolated lightning flashes with a loosely organized band of convection that is expected to approach the coast of northern CA and southwest OR mainly after 28/00Z. But with limited low-level moisture and overall weak instability, severe thunderstorms are not forecast.