Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
756 PM EST Sat Jan 3 2026
Day 3
Valid 12Z Mon Jan 05 2026 - 12Z Tue Jan 06 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ALONG THE CENTRAL
TO NORTHERN CALIFORNIA COAST AND NORTHERN CALIFORNIA...

19z Update: Model QPF is trending up across portions of central
and/or northern CA this period as a closed low develops off the
coast. As these closed low develop you often see the
front/convergence axis briefly stall, which could allow for a
period of more persistent moderate to heavy rainfall. Still some
uncertainty on these details, and so we will stick with a Marginal
risk for now. But will need to continue to monitor trends, as
given saturated soil conditions over some of this region, a future
Slight risk upgrade can not be ruled out.

Chenard

...Previous Discussion...

The mean trof position is maintained day 3 off the West coast with
model consensus for amplification of a new closed low in the base
of the mean trof off the Central to Southern CA coast. The low
level southerly flow on the east side of this developing closed low
will not be as strong as the day 1 and 2 low level south
southwesterly flow, resulting in 850-700 mb moisture flux values
only 1 to 1.5 standard deviations above the mean. PW values also
expected to be lower than day 1 and 2, with anomalies only 1 to
1.5 standard deviations above the mean. Model consensus is for
additional .50-1"+ rainfall amounts along the Central to Northern
CA coast and into the upslope of the Northern Sierra. At the
moment, these amounts warrant keeping the Excessive Rainfall
Outlook threat level at marginal for the day 3 period, with no
significant changes made to the previous outlook.

Oravec

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