Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
714 PM EST Fri Jan 2 2026
Day 2
Valid 12Z Sat Jan 03 2026 - 12Z Sun Jan 04 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
NORTHERN SIERRA AND SOUTHERN CALIFORNIA...

19z Update: Only minor changes made with this update. The 12z high
res models continue to depict a band of heavy rainfall moving
southward across the Transverse Range between 12z Sat and 00z Sun.
Most high res members depict localized hourly rainfall upwards of
0.5"-1", which should be enough to result in isolated to scattered
flash flooding.

Chenard

...Previous Discussion...

The axis of anomalous 850-700 mb moisture flux values...2 to 4
standard deviations above the mean...along and ahead of the inland
moving frontal boundary at the end of the day 1 period will impact
the upslope areas of the northern Sierra and spread through the
Transverse Ranges of Southern California day 2. The primary change
from the previous outlook was to add a small slight risk area in
the upslope area of the Northern Sierra. HREF neighborhood
probabilities for .50"+ hourly rainfall amounts are fairly
high...50%+ at the beginning of the day 2 period and again in the
2100 UTC Sat to 0000 UTC Sun period. This will result in day 2
rainfall totals of 2-4"+ in a region of fairly saturated soils from
recent heavy rains. No changes of note made to the previous slight
risk area over Southern CA in the vicinity of the Transverse
Range. The south southwesterly low level flow will have a
significant upslope component into the Transverse Ranges during
the first half of day 2. This is reflected in both the HREF and
RRFS .50"+ hourly probabilities which are high, 50-80%+ during this
period. Localized runoff issues are possible where soils remain
fairly saturated from recent heavy rains.

Oravec


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