Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
856 PM EDT Thu Oct 30 2025

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

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

Hurley


Day 2
Valid 12Z Fri Oct 31 2025 - 12Z Sat Nov 01 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR WESTERN
WASHINGTON...

2030Z Update...

Generally no changes to the previous thinking. The latest guidance
continues to support atmospheric river conditions arriving across
western WA this period which will drive heavy rainfall into the
coastal ranges and the windward slopes of the Cascades. Snow levels
will be rather high, some there will be heavier rainfall amounts
materializing at some of the higher elevations which as previously
mentioned may reach as high as 3 to 5 inches for the period. Made
only cosmetic changes to the Marginal Risk area for this update.

Orrison

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 beginning Friday afternoon, carrying through the late
evening Friday into Saturday. 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. MU CAPE is forecast to
remain weak, under 250 J/kg. Precip rates should rise to between
0.5-0.75"/hr during the peak of the heavy rainfall, producing local
amounts of 3-5" in the higher terrain of western WA, which would
be particularly challenging for the Skokomish river. Considering
the consistency within guidance on totals and expectation for some
enhanced rates to generate river rises and minor flooding, a
Marginal Risk was maintained, with some expansion to the south to
account for the wetter 00z UKMET solution.

Roth


Day 3
Valid 12Z Sat Nov 01 2025 - 12Z Sun Nov 02 2025

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

Roth/Orrison


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