Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1052 AM EDT Fri Oct 31 2025

Day 1
Valid 12Z Fri Oct 31 2025 - 12Z Sat Nov 01 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR WESTERN
WASHINGTON AND FAR NORTHWESTERN OREGON...

...16Z Outlook Update...
The ongoing forecast is on track, with only minimal spatial
extensions to the Marginal Risk area to account for areas of
greatest heavy rain likelihood tonight through 12Z Sat.

See the previous discussion below for additional details.

Cook

...Previous Discussion...

A modestly strong atmospheric river will setup across the Pacific
Northwest with an advection of high IVT (>750 Kg/ms) into the
region from afternoon through late evening. Inflow at 850 hPa 
approaches 50 kts out of the southwest while precipitable water 
values in the coastal ranges rise into the 1.25-1.5" range, though
little to no instability is forecast. Precip rates will generally
remain below 0.5"/hr, but may locally peak between 0.5-0.75"/hr.
This may result in localized amounts of 2-5" in the higher terrain
of western WA and far northwestern OR, which would be particularly
challenging for the Skokomish river. Given the consistency of the
forecast and the expectation for some enhanced rates to generate 
river rises and minor flooding, a Marginal Risk was maintained and
expanded a bit south into far northwestern OR. 

Churchill/Roth


Day 2
Valid 12Z Sat Nov 01 2025 - 12Z Sun Nov 02 2025

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

Churchill


Day 3
Valid 12Z Sun Nov 02 2025 - 12Z Mon Nov 03 2025

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

Churchill


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