#LosAngeles #SanDiego #rain #flooding #CAwx

Mesoscale Precipitation Discussion 1230
NWS Weather Prediction Center College Park MD
1053 PM EST Mon Nov 17 2025

Areas affected...portions of southern California

Concerning...Heavy rainfall...Flash flooding possible

Valid 180353Z - 180753Z

Summary...Flash flood potential continues for at least 2-4 more
hours.

Discussion...A warm conveyor continues to spread moderate to heavy
rainfall into portions of southern California near the Los Angeles
basin and adjacent areas of the Transverse Ranges. Recent
observations suggest that 0.5 inch/hr rain rates were falling over
or very near burn scars just north of Los Angeles, suggesting
continued potential for excessive runoff and debris flows.
Mesoanalyses indicate a continued fetch of southwesterly 850mb
flow into the region oriented parallel to the coastal ranges,
supporting continued orographic enhancement of rain rates at
times. PW values near an inch and weak surface-based instability
also continue to support the convective nature of the activity and
locally heavy rain rates.

Models suggest that these rates will continue to impact burn scar
areas over the next 2-4 hours (through 07Z or so) while
translating slowly eastward. Flash flooding will remain a
possibility, though this risk should become more isolated with
time as rain rates are expected to gradually weaken.