Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
742 PM EST Sat Dec 13 2025
Day 3
Valid 12Z Mon Dec 15 2025 - 12Z Tue Dec 16 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
WASHINGTON AND OREGON...

2100 UTC Update -- Only minor (cosmetic) changes made to the
previous D3 outlook, some of which was to pull the eastern edges of
the Slight ever so slightly westward in WA based on the latest
snowfall forecast (lowering snow levels).

Hurley

Previous discussion...

Areal coverage of rainfall expands and rain rates increase on
Monday as a well defined atmospheric river continues to direct
abundant moisture into the Washington coastal ranges and Cascades
that gradually makes its way southward into Oregon. Given
antecedent conditions from the excessive rainfall event from
earlier in the week plus whatever falls on Day 2...the concern is
for renewed flooding potential in addition to worsening on-going
flooding especially in the terrain with potential for additional
landslides or mudslides. Saw little reason to modify the Slight
risk area that propagated into the Day 3 period from yesterdays Day
4 outlook especially given the magnitude of the IVT and
precipitable water values forecast by the global models. The focus
of the heavy rainfall should gradually shift southward into an area
that did not receive as much rainfall from the previous
atmospheric river. Opted to extend a Marginal risk area along the
coast as far south as northwestern California more in deference to
uncertainty of timing as to the rainfall amounts.

Bann

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