350
AWUS01 KWNH 111452
FFGMPD
WAZ000-112048-
MESOSCALE PRECIPITATION DISCUSSION 1262
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
951 AM EST THU DEC 11 2025
AREAS AFFECTED...PORTIONS OF WESTERN WASHINGTON STATE
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 111448Z - 112048Z
SUMMARY...ONGOING MODERATE TO HEAVY RAINFALL WILL CONTINUE TO
FOSTER EXCESSIVE RUNOFF AND FLOOD/FLASH FLOOD ISSUES THROUGH AT
LEAST 20Z/NOON PACIFIC TIME.
DISCUSSION...A PERSISTENT ATMOSPHERIC RIVER CONTINUES TO SPREAD
AREAS OF MODERATE TO HEAVY RAINFALL ACROSS THE DISCUSSION AREA.
RECENT RAIN RATES RANGING FROM 0.15-0.5 INCH/HR HAVE BEEN NOTED -
ESPECIALLY IN TERRAIN-FAVORED UPSLOPE AREAS OF THE CASCADES. THE
RAINFALL WAS TIED TO STRONG 700MB FLOW PERPENDICULAR TO THE
CASCADES AND 1 INCH PW VALUES - SUPPORTING ABUNDANT OROGRAPHIC
ASCENT AND PRECIPITATION. UNFORTUNATELY, THESE RAIN RATES WERE
CONTINUING TO IMPACT INUNDATED AREAS THAT HAVE EXPERIENCED 6-10
INCHES OF RAIN OVER THE PAST 72 HOURS, WITH WIDESPREAD,
SIGNIFICANT RIVERINE FLOODING BEING REPORTED AS A RESULT.
RAINFALL COULD CONTINUE FOR ANOTHER 4-6 HOURS ACROSS THE REGION.
EVENTUALLY, MODELS DEPICT A WEAKENING OF 700MB FLOW OVER THE
CASCADES AS MID/UPPER RIDGING BUILDS NORTHWARD INTO THE REGION.
THIS MAY REDUCE ACUTE FLASH FLOOD POTENTIAL, THOUGH RIVERINE
ISSUES WILL LIKELY CONTINUE FOR SOME TIME.
COOK
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...OTX...PDT...PQR...SEW...
ATTN...RFC...PTR...NWC...
LAT...LON 48592119 48222044 47562035 46522081 46302172
46582328 47552397 48042403 48322289 48502243
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