317
FOUS30 KWBC 201549
QPFERD
EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1149 AM EDT FRI MAR 20 2026
DAY 1
VALID 16Z FRI MAR 20 2026 - 12Z SAT MAR 21 2026
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
WESTERN WASHINGTON STATE...
..16Z UPDATE
MODERATE TO LOCALLY HEAVY RAIN CONTINUED OVER WESTERN WASHINGTON
THIS MORNING OUT AHEAD OF A COLD FRONT LOCATED ~100 MILES WEST
OF THE COAST AS OF 15Z. AN ADDITIONAL 1 TO 2 INCHES OF RAIN (PEAK
AMOUNTS) ARE EXPECTED THROUGH THE LATE EVENING WITHIN THE CASCADES
AND UP TO A HALF INCH OR SO FOR THE COASTAL RANGES/OLYMPICS.
ONGOING RIVER FLOODING AND WET ANTECEDENT CONDITIONS CONTINUE TO BE
THE MAIN DRIVER FOR THE MARGINAL RISK, BUT THE RISK AREA CAN
LIKELY BE REMOVED WITH THE NEXT UPDATE AT 01Z AS IVT VALUES LOWER
WITH THE COLD FRONTAL PASSAGE.
OTTO
..PREVIOUS DISCUSSION FOLLOWS
AT THE BEGINNING OF THE FORECAST PERIOD, A STUBBORN ATMOSPHERIC
RIVER IS FORECAST TO WEAKEN AS A SURFACE LOW AND ATTENDANT COLD
FRONT PROGRESS EASTWARD INTO THE PACIFIC NORTHWEST. EVEN SO,
MODERATE IVT VALUES ON THE ORDER OF 500-700 KG/M * S DIRECTED INTO
THE WA COASTLINE FROM 12-18Z SHOULD MAINTAIN THE THREAT OF LOCALLY
HEAVY RAINFALL AHEAD OF THE FRONT. WHILE HOURLY RAINFALL RATES WILL
LIKELY REMAIN BELOW 0.5 INCHES PER HOUR, ISOLATED INSTANCES OF
EXCESSIVE RAINFALL REMAIN POSSIBLE IN UPSLOPE REGIONS OF THE
OLYMPICS AND CASCADES OWING TO ANTECEDENT RAINFALL OVER THE LAST
FEW DAYS.
ASHERMAN
DAY 2
VALID 12Z SAT MAR 21 2026 - 12Z SUN MAR 22 2026
THE PROBABILITY OF RAINFALL EXCEEDING FLASH FLOOD GUIDANCE IS LESS
THAN 5 PERCENT.
ASHERMAN
DAY 3
VALID 12Z SUN MAR 22 2026 - 12Z MON MAR 23 2026
THE PROBABILITY OF RAINFALL EXCEEDING FLASH FLOOD GUIDANCE IS LESS
THAN 5 PERCENT.
ASHERMAN
DAY 1 THREAT AREA: HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/94EPOINTS.TXT
DAY 2 THREAT AREA: HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/98EPOINTS.TXT
DAY 3 THREAT AREA: HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/99EPOINTS.TXT
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