MESOSCALE PRECIPITATION DISCUSSION 0051
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
421 AM EST WED FEB 15 2017

AREAS AFFECTED...OLYMPIC PENINSULA OF WASHINGTON

CONCERNING...HEAVY RAINFALL

VALID 150920Z - 151602Z

SUMMARY...INCREASING RAINFALL RATES ARE EXPECTED ACROSS THE
OLYMPICS OVER THE NEXT FEW HOURS...APPROACHING AND EXCEEDING 0.5
IN/HR THROUGH 15Z. THIS IS EXPECTED TO BE THE START OF A LONGER
DURATION HEAVY RAINFALL EVENT FOR THE REGION...EXPECTED TO LAST
INTO LATE WED NIGHT.

DISCUSSION...AT 09Z...SURFACE COLD FRONT WAS ANALYZED JUST
OFFSHORE OF THE WA COAST...ORIENTED NNE TO SSW. BLENDED TPW
IMAGERY SHOWED AN ATMOSPHERIC RIVER CONTAINING A NEARLY CONTINUOUS
AXIS OF 1.5+ INCH PRECIPITABLE WATER VALUES EXTENDING FROM NEAR
130W TO THE TROPICAL WEST PACIFIC. ADDITIONALLY...THE AR DETECTION
TOOL IS INDICATING INTEGRATED WATER TRANSPORT VALUES EXCEEDING
1250 KG/M/S SHIFTING NORTHEAST OVER THE NEXT 6 HOURS. THE MOISTURE
IS BEING STREAMED NORTHEAST ALONG AND AHEAD OF THE SURFACE
FRONT...WHICH WAS LOCATED AHEAD OF A BROAD MID-UPPER LEVEL TROUGH
AXIS COVERING THE EASTERN PACIFIC...WITH A POWERFUL CORE OF THE
160-180 KT JET LOCATED IN THE BASE OF THE TROUGH NEAR 35N 145W.

GIVEN THE IMPRESSIVE LOW LEVEL FLOW OF 60+KT...EXPECT RAIN RATES
TO INCREASE OVER 0.5"/HR THROUGH 15Z OVER THIS AREA AS THE
ATTENDANT SHORTWAVE APPROACHES.  RAINFALL AMOUNTS OF 2-3" CAN BE
EXPECTED...AIDED BY OROGRAPHIC ENHANCEMENT ALONG THE SOUTHWEST
FACING OLYMPICS.

MONTEFUSCO

ATTN...WFO...PQR...SEW...

ATTN...RFC...NWRFC...

LAT...LON   48652374 48412299 47952274 47462281 46992324
            46662394 46762453 46912470 47472482 48072472
            48572439