Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1157 AM EDT Mon Mar 24 2025

Day 1
Valid 16Z Mon Mar 24 2025 - 12Z Tue Mar 25 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
NORTHWEST WASHINGTON STATE AND ALONG THE CENTRAL GULF COAST...

16Z Update...
Based on current radar trends and the 12Z HREF, made only minor
adjustments, including to the recently introduced Marginal Risk
area along the Gulf Coast.

13Z Update...
...Central Gulf Coast...
Merging and training cells associated with a pair of linear
complexes moving east across southern Louisiana into southern
Mississippi and Alabama are supporting short-term heavy rainfall
rates and a flash flooding threat. A Marginal Risk was added for
areas where these storms may pose an isolated flash flooding threat
into the late morning. Refer to WPC MPD #082 for additional
information regarding the near-term heavy rainfall and flooding
threat.

Pereira

Previous Discussion...
...Olympic Peninsula and Northern Cascades in Northwest
Washington... A Marginal Risk of excessive rainfall will continue
during Day 1 over the Olympic Ranges and across the foothills and
western slopes of the northern Cascades, as the modest Atmospheric
River slowly diminishes today and Monday night. Given continuation
of the AR event, this too is a continuation of the previous
(yesterday's) ERO, albeit with a drop in the category across the
board. In other words, a Marginal Risk is in effect across areas
where there was a Slight in yesterday's D1 ERO, while areas in
yesterday's Marginal are now within the <5% probability of
exceeding flash flood guidance.

Latest guidance shows an atmospheric river continuing to impact
the region, but also gradually waning through the period. The 00Z
GEFS shows IVTs decreasing from ~500 kg/m/sec early in the period
to 300-350 kg/m/sec, as a ridge continues to build and onshore
flow into the region diminishes. As the AR diminishes, so will the
potential for additional heavy precipitation. However, the continued
moisture flux into the region early in the period may be sufficient
for additional amounts of 2-3 inches, as indicated by the 00Z
HREF. These amounts along with additional snowmelt may prolong
runoff concerns.

Hurley


Day 2
Valid 12Z Tue Mar 25 2025 - 12Z Wed Mar 26 2025

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

Hurley


Day 3
Valid 12Z Wed Mar 26 2025 - 12Z Thu Mar 27 2025

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

Hurley


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