Flash Flood Guidance
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000
AWUS01 KWNH 101824
FFGMPD
CAZ000-110030-

MESOSCALE PRECIPITATION DISCUSSION 0793
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
123 PM EST SAT DEC 10 2016

AREAS AFFECTED...N-CNTRL SIERRA NEVADA MOUNTAINSh

CONCERNING...HEAVY RAINFALL

VALID 101822Z - 110030Z

SUMMARY...A WEAKENING AXIS OF LOW LEVEL MOISTURE FLUX INTO THE
N-CNTRL SIERRA NEVADA WILL ALLOW RAINFALL RATES TO TAPER DOWN
BELOW 0.5 IN/HR AFTER 00Z.

DISCUSSION...AN ONGOING ATMOSPHERIC RIVER EVENT FOCUSED OVER CNTRL
CA SHOWED PRECIPITABLE WATER VALUES IN THE 1.2 TO 1.4 INCH RANGE
IN THE FAR SRN SACRAMENTO VALLEY AS OF 17Z...AHEAD OF A COLD FRONT
SLOWLY DROPPING SOUTH. VAD WIND PLOTS AND RAP ANALYSES SHOWED 850
MB WINDS WERE GENERALLY FROM THE WEST AT 25-30 KTS WITH 700 MB
WINDS OF 45-55 KTS ACROSS CNTRL CA. 24 HOUR RAINFALL TOTALS IN THE
3-6 INCH RANGE HAVE BEEN REPORTED FROM NWRN EL DORADO COUNTY TO
ERN BUTTE COUNTY ENDING 18Z.

MID-LEVEL HEIGHT FALLS TIED TO AN ELONGATED SHORTWAVE DROPPING
SEWD FROM JUST OFF OF THE OREGON COAST WILL CONTINUE TO SAG THE
COLD FRONT AND ROBUST MOISTURE PLUME STEADY TO THE SOUTH OVER THE
NEXT 6+ HOURS. LOW LEVEL WINDS ARE EXPECTED TO WEAKEN SLIGHTLY
INTO THE FOOT HILLS OF THE SIERRA NEVADA WITH SUBTLE VEERING
OCCURRING THROUGH OR JUST PAST 00Z. THE COMBINATION OF THESE
FACTORS SHOULD ALLOW ONGOING RAINFALL RATES OF 0.5 TO 0.6 IN/HR
ACROSS NWRN EL DORADO...NEVADA AND PLACER COUNTIES TO DROP SOUTH
AND WEAKEN TO LESS THAN 0.5 IN/HR AFTER 00Z. SNOW LEVELS ARE
EXPECTED TO RANGE FROM 8000-9000 FT ACROSS THE MPD THREAT AREA
WITH ADDITIONAL 6 HOUR RAINFALL AMOUNTS OF 1.5 TO LOCALLY 3+
INCHES THROUGH 00Z. THERE IS  UNANIMOUS MODEL AGREEMENT FROM THE
LATEST 12Z SUITE OF CAM GUIDANCE.

OTTO

...PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...HNX...REV...STO...

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

LAT...LON   39522081 39522049 39332021 38901995 38631979
            38291963 38001973 37952026 38432076 39122094
            39402091


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