Quantitative Precipitation Forecast
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000
FOUS30 KWBC 150830
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
329 AM EST WED NOV 15 2017

...VALID 12Z WED NOV 15 2017 - 12Z THU NOV 16 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
105 W ONP 35 W S47 25 SSE AST 25 WNW HIO 20 NW MMV 15 SW MMV
CVO 15 SW CVO 20 W RBG 30 SW SXT 45 NE ACV 15 NW O54 O54
15 ENE O54 30 ENE RDD 35 E RDD 45 NNE CIC 40 ENE CIC 50 ENE CIC
30 NNE BLU 10 SSW TRK 40 S TVL 40 NE MOD 15 ENE SCK 20 S MHR
10 SW OVE 10 SSE RBL 10 NNE RBL RDD 20 SSE O54 35 S O54
35 WSW RBL 45 NE UKI 30 WNW VCB 15 NW SUU CCR 10 SSW SJC
20 SW SJC 25 SW SFO 55 WSW SFO.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
45 W RBL 25 ENE UKI 30 E UKI 25 NNE STS APC 15 SW APC 15 S STS
20 SSW UKI 20 WNW UKI 20 SE O87 10 ENE O87 15 NNE O87 35 NE O87
40 NE O87 40 SW O54 45 W RBL.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
BAB OVE CIC 10 NNE CIC 20 NE CIC 25 NE CIC 40 NNW BLU
15 NNE BLU 15 WSW TVL 45 SSW TVL 45 ESE MHR 30 ESE MHR
10 SSW AUN BAB.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
35 SSW OTH 15 NW OTH 15 SW ONP ONP 20 NNE ONP 30 WNW EUG
35 WSW EUG 25 SSE OTH 35 NNE CEC 35 N CEC 35 SSW OTH.


UPSLOPE OF THE NORTHERN SIERRA---NORTHERN CALIFORNIA COAST RANGE
INTO COASTAL OREGON


THE STRONG CLOSED LOW OFF THE B.C./VANCOUVER ISLAND COAST WILL
PUSH VERY SLOWLY EASTWARD DAY 1 INTO COASTAL B.C.  THIS WILL
MAINTAIN DEEP LAYERED CYCLONIC FLOW TO ITS SOUTHEAST FROM THE
PACIFIC NORTHWEST SOUTH INTO NORTHERN CALIFORNIA.  THE STRONGEST
ONSHORE FLOW AND HEAVIEST PRECIPITATION FOCUSED INTO THE OLYMPIC
PENINSULA EARLY THIS MORNING WILL BE SHIFTING SOUTHWARD BY THE
BEGINNING OF THE UPCOMING DAY 1 PERIOD INTO COASTAL OREGON AND
FARTHER SOUTH BY EARLY AFTERNOON INTO NORTHERN CALIFORNIA AND THE
NORTHERN SIERRA.  RAINFALL RATES WEDNESDAY MORNING INTO EARLY
AFTERNOON WILL CONTINUE IN THE .25-50"+ RANGE INTO THE MID TO
LOWER COAST OF OREGON WITH A SLIGHT RISK AREA MAINTAINED.  PLEASE
SEE WPCS MESOSCALE PRECIPITATION DISCUSSION # 0931 VALID UNTIL
APPROXIMATELY 1800 UTC FOR ADDITIONAL INFORMATION ACROSS THIS
AREA.

PW VALUES THAT HAVE BEEN NEAR SEASONAL NORMS WITH THE HEAVY PRECIP
OVER THE PACIFIC NORTHWEST WILL BE INCREASING TO MUCH ABOVE
AVERAGE DURING THE DAY 1 PERIOD ACROSS NORTHERN CALIFORNIA INTO
THE NORTHERN SIERRA AS THIS TROF TAPS A POOL OF HIGH PW VALUES
EXTENDING INTO THE SUB TROPICS ALONG 130-140W.
SUBSEQUENTLY---THE MOISTURE FLUX VALUES THAT HAVE BEEN SLIGHTLY
ABOVE AVERAGE INTO THE COASTAL PAC NW WILL INCREASE TO MUCH ABOVE
AVERAGE---3 TO 4+ STANDARD DEVIATIONS ABOVE THE MEAN INTO NORTHERN
CALIFORNIA/NORTHERN SIERRA DURING WEDNESDAY.  THERE IS A STRONG
MODEL SIGNAL FOR VERY HEAVY PRECIPITATION AMOUNTS INTO THE
NORTHERN SIERRA GIVEN THE MUCH ABOVE AVERAGE PW VALUES/MOISTURE
FLUX WITH CONSENSUS FOR 5-8" AREAL AVERAGE AMOUNTS.  TOTALS ALONG
THE NORTHWEST CALIFORNIA COAST RANGE INTO FAR SOUTHWEST OREGON
WILL NOT BE AS HEAVY---BUT 2-4"+  AMOUNTS STILL POSSIBLE.    A
SLIGHT RISK AREA WAS ADDED FOR THE NORTHERN CALIFORNIA COAST RANGE
TO COVER MANY OF THE BURN AREAS TO THE NORTH OF SAN FRANCISCO.
RAINFALL RATES .25"+ PER HOUR POSSIBLE ACROSS THESE AREAS.
FARTHER INLAND---NO SIGNIFICANT CHANGES MADE TO THE PREVIOUS
EXCESSIVE RAINFALL POTENTIAL OUTLOOK.  HOURLY RATES LIKELY WILL BE
GREATER HERE...IN THE .25-50"+ RANGE INTO THE UPSLOPE OF THE
NORTHERN SIERRA.  SNOW LEVELS INTO THE NORTHERN SIERRA WILL REMAIN
HIGH FOR MOST OF THE DAY 1 PERIOD...6000-7000 FT---WITH MOST OF
THE PRECIP FALLING AS RAIN...ENHANCING THE RUNOFF POTENTIAL.
PLEASE SEE WPCS MESOSCALE PRECIPITATION DISCUSSION #0932 WHICH
WILL BE ISSUED SHORTLY AND VALID UNTIL APPROXIMATELY 2100 UTC.

ORAVEC

$$





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