Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
721 PM EST Thu Jan 1 2026
Day 3
Valid 12Z Sat Jan 03 2026 - 12Z Sun Jan 04 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN CALIFORNIA...

...19z Update...
A Slight risk was added across Santa Barbara and Ventura counties
in southern CA with this update. A line of locally heavy rainfall
rates is expected to traverse this corridor between 12z Sat and
00z Sun along/ahead of a cold front. Forecast rainfall amounts have
trended up over this area, with totals of 1-3" now expected,
mostly falling in ~6 hours or less. The quick duration will be a
limiting factor for more significant flood impacts, but with some
weak instability possibly working into the front and low level flow
aligned orthogonal to the terrain...hourly rainfall over 0.5" is
probable on a localized basis. Given the saturated soil over this
area due to recent heavy rainfall, these rates may be high enough
to result in isolated to scattered flash flooding, along with
localized mudslides and debris flows.

Chenard

...Previous Discussion...

A series of upper level disturbances rotating around a large upper
level low will impact much of California and the West Coast this
weekend. With each upper level disturbance, there will be a
commensurate surface front that also makes its way ashore into
northern California. The result will be an almost non-stop rain,
especially for upslope areas on southerly flow, as well as for all
of the coastal ranges. That said, each disturbance will briefly
increase rainfall rates, with those rates decreasing back down in
between disturbances. Thus, Saturday's rain looks to be a long-
duration relatively light (for most areas) rain, rather than there
being big concerns on any one area seeing prolonged heavy rain.
Given the area's good ability to drain rainwater quickly, a
Marginal Risk remains in effect for northern California. The area
will continue to be monitored for a possible Slight Risk upgrade
with future updates.

Wegman

Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt