Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
319 AM EST Fri Feb 21 2025
Day 2
Valid 12Z Sat Feb 22 2025 - 12Z Sun Feb 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR MUCH OF
WESTERN WASHINGTON STATE AND COASTAL OREGON...

No significant changes made to the previous marginal risk across
coastal sections of Oregon, Washington and in the upslope of the
Washington Cascades and northern Oregon Cascades. The beginning of
a two day atmospheric river event on tap as broad west
southwesterly mid to upper level flow is established across the
northeast Pacific toward the Pacific Northwest. PW anomalies
expected to rise to 2 to 3+ standard deviations above the mean by
Saturday afternoon with the lead shortwave moving toward the Pac NW
coast and continue at that level into Sunday morning. Strong
850-700 mb moisture flux, anomalies 2 to 4+ standard deviations
above the mean expected in the anomalous PW axis, max IVT values
600-800 kg/m/s. This will support hourly rainfall rates of .50"+
and widespread totals of 1-2"+ and max totals of 3-5"+ in favored
terrain regions. Snow levels will be very high day 2 across the
Pac NW, with much of the precipitation falling as rain. This heavy
rain, combined with snow melt will support isolated runoff issues.
Precipitation has been below average over the past month over the
Pac NW, which should mitigate any widespread runoff issues day 1.


Oravec

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