MESOSCALE PRECIPITATION DISCUSSION 0032
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
100 AM EST FRI FEB 19 2016
 
AREAS AFFECTED...SOUTHWEST OR...NORTHWEST CA 
 
CONCERNING...HEAVY RAINFALL 
 
VALID 190600Z - 191700Z
 
SUMMARY...A SHORT WAVE PUSHES A COLD FRONT ACROSS PORTIONS OF
SOUTHWEST OR/NORTHERN CA TOWARD 17Z. AHEAD OF THE FRONT...A
MOISTURE PLUME ON A STRENGTHENING LOW LEVEL SOUTHWEST FLOW COULD
RESULT IN HOURLY RAINFALL RATES NEAR 1/2 INCH BETWEEN 14Z AND
17Z...WITH TOTAL RAINFALL AMOUNTS BETWEEN 1.00 AND 2.00 INCHES
POSSIBLE.

DISCUSSION...THE LATEST WV LOOP SHOWED A STRONG SHORT WAVE NEAR
38N 136W...TRACKING TOWARD THE SOUTHWEST OR/NORTHWEST CA COAST.
THE MID LAYERED PRECIPITABLE WATER PRODUCT SHOWED AN ATMOSPHERIC
RIVER ASSOCIATED WITH THE SHORT WAVE...AND THE BLENDED TOTAL
PRECIPITABLE WATER IMAGES SHOWED VALUES NEAR 1.00 INCHES IN THE
MOISTURE PLUME. A 0240Z AMSU PASS SHOWED HOURLY RAINFALL RATES
NEAR 0.25 INCHES IN ASSOCIATION WITH THE MOISTURE PLUME.

THE SHORT WAVE IS PUSHING ALONG A COLD FRONT...AND BOTH FEATURES
ARE EXPECTED TO IMPACT THE COAST BETWEEN 14Z AND 17Z. THE LATEST
RAP SHOWED A 45 TO 55 KNOT LOW LEVEL SOUTHWEST FLOW TRANSPORTING
PRECIPITABLE WATER VALUES BETWEEN 0.75 AND 1.00 INCHES TO THE
SOUTHWEST OR/NORTHWEST CA COAST IN THAT TIME WINDOW. THE LOW LEVEL
FLOW SUPPORTS HEAVIER QPF AMOUNTS OVER THE SOUTHWEST FACING SLOPES
IN THIS AREA.

THE LATEST HRRR/RAP...AS WELL AS THE 00Z WRF ARW...SHOWED HOURLY
RAINFALL RATES NEAR 0.50 INCHES ACROSS THE SISKIYOUS AND
SHASTA/TRINITY MOUNTAINS AHEAD OF THE COLD FRONT IN THE 14Z TO 17Z
TIME FRAME. TOTAL RAINFALL AMOUNTS BETWEEN 1.00 AND 2.00 INCHES
ARE POSSIBLE...WITH THE HIGHEST AMOUNTS ACROSS THE SOUTHWEST
FACING SLOPES. 

HAYES

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

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

LAT...LON   43062391 42962372 42712366 42402354 41732335 
            40612345 39972347 39742387 40012401 40432426 
            41212412 41692418 42152449 42422455 42732449 
            42872443 43022422