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Excessive Rainfall Discussion
 
(Latest Discussion - Issued 1516Z Jan 26, 2020)
 
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Abbreviations and acronyms used in this product
 
Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1016 AM EST Sun Jan 26 2020

Day 1
Valid 16Z Sun Jan 26 2020 - 12Z Mon Jan 27 2020

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

Chenard


Day 2
Valid 12Z Mon Jan 27 2020 - 12Z Tue Jan 28 2020

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR COASTAL
AREAS OF THE PACIFIC NORTHWEST...

...Southwest Washington to northwest California...

Strong energy and moisture will be directed into the Pacific
Northwest resulting a vast area of precipitation. A broad area
with enhanced vertical motion will develop over the coast and
inland over the Cascades as the trough nears the coast and
eventually moves inland. During this time low-level, W/SW flow of
35 to 50 knots will be transporting PW values of 0.50 to 1 inch
nearly orthogonal to the terrain; which will help sustain several
hours of moderate to the heavy rainfall. Model guidance continues
to focus 1 to 3 inches all along the Washington to northern
California coast with local maxes of 4 to 6 inches. Rainfall rates
0.50 inch per hour or greater could quickly lead to an increased
risk for flash flooding, or debris flows in sensitive areas such
as steep terrain or burn scars. As previously noted, portions of
this region have had >150% percent of normal precipitation
resulting in saturated soils with additional rainfall quickly
becoming runoff. The Marginal Risk for excessive rainfall that was
in effect for southwest Washington to northwest California remains
valid for this issuance.

Campbell


Day 3
Valid 12Z Tue Jan 28 2020 - 12Z Wed Jan 29 2020

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

Campbell



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