Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1059 AM EST Sun Nov 16 2025
Day 2
Valid 12Z Mon Nov 17 2025 - 12Z Tue Nov 18 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF THE LOS
ANGELES BASIN OF SOUTHERN CALIFORNIA...

The deep and energetic trough that will be centered off the
northern California coast at the start of the period will track
southeast down the coast to over the San Joaquin Valley by early
Tuesday morning. The trough will cut off into a second upper level
low to impact the state by Monday afternoon. The heaviest rains
will be out ahead of this cutoff low, where the overall flow is
onshore out of the southwest. A line of heavy showers with embedded
thunderstorms will move down the coast starting around Point
Conception early Monday morning, reaching the L.A. Basin around
midday. It will take between 2-4 hours for the heavy rain band to
sweep through. During that time, rainfall rates peaking between a
half and 3/4 inch per hour in the thunderstorms may cause widely
scattered instances of flash flooding, especially on the south
facing slopes of the Transverse Ranges down to the L.A. Basin. For
this reason, the inherited Slight Risk remains in place with very
few changes. At least some of the heavy rain will also penetrate
inland into some of the California Deserts, including around Death
Valley N.P. Given how recently the area saw heavy rains from
yesterday, this additional heavy rain may also cause isolated
instances of flash flooding. Thus, the Marginal Risk was expanded
north and east to include a small portion of southern Nevada.

Wegman

Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt