MESOSCALE PRECIPITATION DISCUSSION 0775
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
431 PM EST THU NOV 24 2016
 
AREAS AFFECTED...SOUTHWEST WA...WESTERN OR 
 
CONCERNING...HEAVY RAINFALL 
 
VALID 242130Z - 250600Z
 
SUMMARY...CONTINUED MODERATE TO HVY RAINFALL ACROSS CENTRAL OR
COAST WITH APPROACH OF DEVELOPING SURFACE WAVE.  ADDITIONAL 3-4"
POSSIBLE THROUGH 06Z.

DISCUSSION...GOES-W WV LOOP INDICATES SHORTWAVE CROSSING VANCOUVER
ISLAND WITH STRONGER AMPLIFYING SHORTWAVE ENERGY/NOSE OF 110 KT
JET CORE NEARING 130W.  THIS HAS LED TO A WEAK BAROCLINIC LEAF
DEVELOPING WITH A VISIBLE IMAGERY INDICATING A SURFACE WAVE WITH
SOME SHALLOW CONVECTION NEAR 44N130W ATTM.  UPPER LEVEL BROADLY
DIFFLUENT FLOW ALOFT AND STRONG 85-7H SWLY FLOW ONSHORE CONTINUE
TO SUPPORT STRONG ASCENT WITH A WEDGE SHAPED COOLING AREA BEING
MAINTAINED A THE TRAILING EDGE OF THE HEAVY RAINBAND THAT HAS BEEN
AFFECTING CENTRAL OREGON INTO THE NORTHERN WILLAMETTE VALLEY OVER
THE PAST FEW HOURS WITH STEADY .3-.4"/HR TOTALS NOTED WITH ONE
HOUR 1.02" TOTAL NOTED AT ONP A FEW HOURS AGO.  LIGHTNING
CONTINUES TO BE DENOTED JUST OFFSHORE... THOUGH WITH STRONG
DIFFLUENCE AND STRENGTHENING FLOW APPROACHING
UPSTREAM/BACKBUILDING IS LIKELY SO THE LIKELIHOOD OF CORES
REACHING THE DOUGLAS/LANE/S LINCOLN COUNTY COAST SHOULD BE
DIMINISHING. STILL BROAD ASCENT SHOULD PROVIDE A CHANNEL FOR
BROKEN MODERATE .2-.3"/HR RATES OVER A BROADER AREA FROM THE MOUTH
OF THE COLUMBIA RIVER TOWARD N DOUGLAS COUNTY UNTIL ABOUT 00Z.

AS NOTED WITH 110KT RIGHT ENTRANCE AND BROAD CYCLONIC CURVATURE
AROUND 130W SUPPORTING STRONG DPVA AND SURFACE PRESSURE FALLS. 
THIS REGIME SHOULD SUPPORT SLIGHTLY BACKED FLOW IN THE SHORT TERM
LEADING TO WAA REGIME AND BACKING OF THE FRONTAL ZONE AS THE SFC
WAVE DEEPENS.  THIS ALSO HAS SUPPORTED BOUNDARY LAYER MST
CONVERGENCE WITH TPWS NOW TRICKLING UP TO .9-1.0" PER BLENDED
TPW...A BIT HIGHER THAN MOST GUIDANCE HAS BEEN SUGGESTING. BY
00Z...THE LEADING EDGE OF WAA WILL ONCE AGAIN ENHANCE RAIN RATES
FROM .2 TO EXTREME CASES UP TO .5"/HR ACROSS SW WA/NW OR...AND
INCREASED 850 FLOW FROM 50 KTS TO 70KTS VEERING TO SSW LIKELY TO
KEEP A FOCUS ON CENTRAL OR COASTLINE THROUGH 06Z. HI-RES GUIDANCE
SUCH AS RECENT ESRL EXP. HRRR...NSSL-WRF AND WRF-ARW ARE GENERALLY
AGREEABLE WITH MAGNITUDES OF AN ADDITIONAL 3-4" WITH 1-2" AS FAR
NORTH AS THE SW WA COMPOUNDING RISING RIVERS AND STEAM CONTINUING
FLOODING CONCERNS IN THE REGION THROUGH 06Z.  

GALLINA

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

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

LAT...LON   47472349 47142274 46222247 45292247 44362272 
            43612301 42662332 42292376 42332431 42552448 
            42822450 42872452 44422407 46022405 47072411