MESOSCALE PRECIPITATION DISCUSSION 0680
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
837 PM EST WED DEC 16 2015
 
AREAS AFFECTED...OR 
 
CONCERNING...HEAVY RAINFALL 
 
VALID 170135Z - 171400Z
 
SUMMARY...A MOISTURE PLUME AHEAD OF A STRONG SHORT WAVE OFF THE
PACIFIC NORTHWEST COAST WILL BRING HEAVY RAINFALL TO THE OR COAST
TOWARD 17/12Z.

DISCUSSION...A DEEP MOISTURE PLUME (WITH PRECIPITABLE WATER VALUES
NEAR 2.00 INCHES PER THE LATEST BLENDED TPW IMAGERY) AHEAD OF A
STRONG SHORT WAVE NEAR 40N/145W IS EXPECTED TO REACH THE OR COAST
TOWARD 17/12Z. A 0050Z AMSU PASS SHOWED HOURLY RAINFALL RATES
BETWEEN 0.25 AND 0.50 INCHES. 

AS THE SHORT WAVE TRACKS EAST...A 30 TO 35 KNOT LOW LEVEL WESTERLY
FLOW WILL FOCUS THE DEEPENING MOISTURE ON THE OR COASTAL RANGES
TOWARD 17/12Z. THERE IS A HIGH RESOLUTION MODEL CONSENSUS
(INCLUDING THE LATEST HRRR/RAP/18Z NAM CONEST AND 12Z WRF ARW))
THAT 0.50+ INCH RAINFALL RATES ARRIVE ALONG THE OR COAST BETWEEN
17/09Z AND 17/12Z. BASED ON THE MOST RECENT AMSU RAINFALL
RATES...THIS LOOKS CONSISTENT WITH THE HIGH RESOLUTION GUIDANCE
TIMING. RAINFALL RATES ARE THEN EXPECTED TO INCREASE AFTER
17/15Z...AS THE CORE OF THE DEEP MOISTURE PLUME REACHES THE COAST.

RAINFALL TOTALS THROUGH 17/14Z SHOULD RANGE BETWEEN 1.50 AND 2.50
INCHES...WITH THE HIGHEST AMOUNTS ACROSS THE OR COASTAL RANGE.
LESSER QPF AMOUNTS (CLOSER TO 1.50 INCHES) ARE EXPECTED OVER THE
OR CASCADE RANGE.

HAYES

ATTN...WFO...EKA...MFR...PQR...

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

LAT...LON   46112392 45652268 42062303 41402423 42562457 
            44572438