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< Day 2 Outlook
WPC Day 3 Excessive Rainfall Outlook Risk of 1 to 6 hour rainfall exceeding flash flood guidance at a point
Updated: 1922 UTC Sun Nov 10, 2024
Valid: 12 UTC Nov 12, 2024 - 12 UTC Nov 13, 2024
Forecast Discussion
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
219 PM EST Sun Nov 10 2024
Day 3
Valid 12Z Tue Nov 12 2024 - 12Z Wed Nov 13 2024
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS WESTERN
WASHINGTON AND NORTHWEST OREGON...
20z Update: No changes to the inherited Marginal risk area over
western WA/OR. Still on track for a slightly stronger atmospheric
river to begin impacting these areas between 00z-12z Wednesday.
Combining this system and the previous one today into
Tuesday...and rainfall totals from Sunday through 12z Wed should
average 3-5" across terrain areas, with as much as 5-7" over the
Olympic Peninsula. Thus the uptick in rainfall rates with this AR
Tuesday night should be enough to result in at least minor flood
impacts given gradually saturating soil conditions and rising
streamflows with time.
Chenard
...Previous Discussion...
Precipitable water values of 0.75-1" advect in as a cold front
approaches, perhaps moves ashore, the Washington and northern
Oregon coast Wednesday morning. Inflow from the Pacific rises to 60
kts at 850 hPa out of the south-southwest with limited instability
available near and behind the front. The ingredients appear to be
there for hourly rain totals of 0.5"+, which would be most
problematic in burn scars. Over the full day, local amounts of 3-4"
are advertised for much of the guidance, which would be most
problematic along the Skokomish river in the Olympic Peninsula.
Enough was there in the guidance for the inherited Marginal Risk
area to remain from continuity; simplified its shape.
Roth
Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt
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