Quantitative Precipitation Forecast
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FOUS30 KWBC 140033
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
832 PM EDT WED SEP 13 2017

...VALID 01Z THU SEP 14 2017 - 12Z THU SEP 14 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
50 NE MCE 10 SSE BLU 55 ENE CIC 45 NNW RNO 30 WSW NFL
25 SSE LOL 50 W AWH 25 SW TWF 10 NW 77M 20 SSE IDA 20 NNW RXE
30 ENE SMN 30 WSW 3HT 25 ENE BIL 15 SW SHR 30 NW LND 40 S BIT
40 ENE PUC 25 NNE U24 55 W CDC 60 SE TPH 30 N TPH 55 W TPH
45 S BIH 15 WNW WJF 30 NNW OXR 40 WSW BFL 10 N PTV 50 NE MCE.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 S MRY 30 WSW MRY 40 W WVI 30 SW SFO 25 W SFO 40 SSW STS
30 SW STS 30 WNW STS 10 SSE UKI 35 E UKI 30 NW VCB 10 WNW VCB
10 NW SUU CCR 15 SE LVK 20 E RHV 25 ENE SNS 25 S MRY.


14/01 UTC UPDATE...
CHANGES TO 15Z UPDATE WERE TO REMOVE MARGINAL RISK ALONG THE CNTL
CA COAST AND TO SHRINK MARGINAL RISK TO A SMALLER AREA OF CNTL NV
WWD INTO THE NRN SIERRA AND EXTENDING SOUTHWEST FROM THERE INTO
PARTS OF THE SAN JOAQUIN VALLEY AND ADJACENT COASTAL MTNS.  LATTER
AREA STILL SHOWS ML CAPES OF BETWEEN 500 TO 1000 J/KG JUST AHEAD
OF UPPER LOW FCST TO MOVE EWD ACROSS THE SRN PORTION OF CA
OVERNIGHT..SUGGESTING POTNL FOR SCTD TSTMS WITH LOCALLY HEAVY
RAINS COULD LINGER THROUGH THE OVERNIGHT PD..BUT ESPECIALLY OVER
THE HIGHER TERRAIN.
SULLIVAN


13/15 UTC UPDATE

CHANGES TO THE PREVIOUS EXCESSIVE RAINFALL POTENTIAL OUTLOOK WERE
TO ADD A MARGINAL RISK AREA ALONG THE NORTH-CENTRAL CALIFORNIA
COAST FROM IN THE VICINITY OF MONTEREY NORTHWARD TO NORTH OF SAN
FRANCISCO.  THIS WAS TO COVER POTENTIAL FOR BRIEF HEAVY RAINFALL
RATES ACROSS THE BURN SCAR AREAS OF THE
SOBERANES...VALLEY...ROCKY...JERUSALEM AND SAWMILL BURN AREAS.
ISOLATED .50"+ RAINFALL AMOUNTS IN AN HOUR POSSIBLE.

ORAVEC

INITIAL DISCUSSION

CALIFORNIA INTO THE CENTRAL GREAT BASIN AND NORTHERN ROCKIES

SLOW EASTWARD MOVEMENT FORECAST FOR THE CLOSED LOW OFF THE CENTRAL
CALIFORNIA COAST INTO SOUTHERN CALIFORNIA DURING THE DAY 1 PERIOD
(THROUGH 12Z THU).H NO SIGNIFICANT CHANGES EXPECTED TO THE RECENT
SHOWERY PATTERN---TO THE EAST OF THIS CLOSED LOW AND TO THE
SOUTHEAST OF A NORTHERN STREAM TROF PUSHING INTO THE PACIFIC
NORTHWEST---IN AN AREA OF BROAD UPPER DIFFLUENCE AND ABOVE AVERAGE
PW VALUES STRETCHING ACROSS NORTHERN TO CENTRAL CALIFORNIA---THE
GREAT BASIN---THE SOUTHWEST AND THROUGH THE CENTRAL TO NORTHERN
ROCKIES. THE DAY 1 QPF DID NOT DEVIATE FROM THE MODEL CONSENSUS OF
LIGHT TO LOCALLY MODERATE PRECIP TOTALS ACROSS THESE AREAS. GIVEN
THE ANOMALOUS MOISTURE AND MODEST (AT BEST) DIURNAL
INSTABILITY...A LOCALIZED/MARGINAL FLASH FLOOD THREAT WILL
CONTINUE ACROSS THIS REGION...AS DEPICTED BY THE HIGH-RES CAMS AND
NAM/GFS CONVECTIVE PCPN OUTPUT.

HURLEY
$$





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