Valid 041300Z – 051200Z
…NO SEVERE THUNDERSTORM AREAS FORECAST…
Isolated thunderstorms may occur today into tonight across parts of
California and the Southwest. Severe thunderstorms are not expected.
…Synopsis and Discussion…
A southern-stream upper trough will move eastward today across parts
of CA and the Southwest while slowly losing amplitude. Strong ascent
preceding the upper trough is contributing to a broad area of
precipitation early this morning across CA. Gradually cooling
mid-level temperatures should support weak, mainly elevated
instability across these areas today and tonight. Isolated
thunderstorms appear possible, and may focus across parts of the
southern/central CA Coast later this morning and early afternoon.
Weak instability is expected to preclude any meaningful severe risk
for this area.
Across the eastern CONUS, large-scale upper troughing will shift
eastward through the period, becoming centered over the Northeast
and adjacent Atlantic waters late tonight. Showery precipitation may
occur this afternoon across parts of the Mid-Atlantic beneath the
upper trough. But, instability is forecast to remain too weak and
shallow to support thunderstorms across this region.