470 
FOUS30 KWBC 050745
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
245 AM EST Mon Jan 5 2026

Day 1
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...

Upper disturbance off the California coast will meander to the 
southeast closer to the coastal plain, eventually pinching off the
mean trough centered to the north and closing off into an ULL as it
migrates down near the latitude of the Bay area. Proximity of the
disturbance and prevailing flow will send a modest IVT pulse
(300-400 kg/ms) crashing into the northern CA coastal plain with 
some minor protrusion of the IVT signature inland with a secondary
QPF maxima forecast around the Trinity Mountains over into Shasta
National Forest domain. Hi-res deterministic output is pretty
consistent with the axis of heaviest precip focused from the King
Range down towards Santa Rosa, north of the Bay area with the
latest HREF EAS probs for 1" running between 60-90% for much of
that location with another prob max focused near Mount Shasta. 

The main threat for this setup is easily over any urbanized zones
and remnant burn scars across northern CA leading to mainly a
lower-end flash flood concern in the grand scheme of the setup. IVT
signature is one that historically yields more isolated flash flood
threats with the primary focus typically aimed at that coastal
urban centered from the Bay area up towards Eureka, and over the
northern valley locations like Redding. This is where the MRGL 
risk was maintained during the forecast as the trend for the 
southern edge of any heavy rain prospects south of San Jose has all
but disappeared on guidance. It's still something we'll monitor 
for any last minute trends back, but guidance favors mainly the 
area north of the Bay at this time. Total QPF for the impacted
areas will be between 1.5-3" with a max between 4-5" for the
coastal ranges north of the Bay area, and over the Shasta National
Forest. 

Kleebauer


Day 2
Valid 12Z Tue Jan 06 2026 - 12Z Wed Jan 07 2026

...The probability of rainfall exceeding flash flood guidance is
less than 5 percent.

Kleebauer


Day 3
Valid 12Z Wed Jan 07 2026 - 12Z Thu Jan 08 2026

...The probability of rainfall exceeding flash flood guidance is
less than 5 percent.

Kleebauer


Day 1 threat area: https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Day 2 threat area: https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Day 3 threat area: https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt