Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 240039
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
738 PM EST MON JAN 23 2017

...VALID 01Z TUE JAN 24 2017 - 12Z TUE JAN 24 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
50 SE WWD 15 ENE DOV ILG 15 NE ABE 10 S MGJ 30 NNW OXC FIT SFM
30 SE PWM 70 SE PWM 55 ENE CQX.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
NUC 15 WNW NFG 15 N RNM 15 NNW CZZ CZZ 50 SSW NRS 110 S NUC.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 NNE WRI TTN 10 SW SMQ 12N 20 S MGJ HPN JFK BLM 10 NNE WRI.


01Z UPDATE...

MID ATLANTIC AND NORTHEAST...

STG EASTERLY FETCH AND LOW LEVEL THETAE ADV NORTH OF DVLPG SFC LOW
OFF THE MID ATLC COAST IN ADVANCE OF NEG TILTED UPR LOW/TROF
LIFTING NWD ALONG THE EAST COAST TONIGHT WILL CONTINUE TO SUPPORT
A BAND OF VERY HEAVY COASTAL RAINS FROM NRN NJ INTO ERN MA
OVERNIGHT. THE HRRR CONTINUES TO TREND NWD WITH THE HEAVIER PCPN
AXIS BUT STILL SUGGESTS .75 TO 1"+ AMOUNTS IN 6 HRS ACRS PARTS OF
NRN NJ INTO LONG ISLAND WHERE SOME LOWER FFG VALUES EXIST AND
THEREFORE SUPPORTIVE OF MAINTAINING A SLIGHT RISK ACRS THAT AREA.
THE HEAVIEST RAINS MAY ACTUALLY OCCUR FARTHER NE TOWARD SE
MASSACHUSETTS/CAPE COD AREA CLOSER TO DEEPER MSTR AXIS AND PSBL
WEAK INSTABILITY NEAR THE TRIPLE POINT..THOUGH EXISTING FF
GUIDANCE HERE IS RATHER HIGH SUGGESTING MORE OF A MARGINAL RISK OF
RUNOFF ISSUES ACRS THIS AREA OVERNIGHT.

...SOUTHERN CALIFORNIA...

THREAT OF ADDITIONAL HEAVY RAIN CONTINUES TO DIMINISH ACRS
SOUTHERN CA THOUGH SUFFICIENT ONSHORE FLOW WILL CONTINUE TO
SUPPORT ADDITIONAL SHOWER ACTIVITY THROUGH THE OVERNIGHT.
HOWEVER...85H FLOW IS FCST TO CONTINUE TO VEER FROM WLY TO MORE
NWLY BY MORNING LEADING TO LESS FAVORABLE UPSLOPE COMPONENT INTO
THE MOUNTAINS EAST OF SAN DIEGO.  HAVE THUS LOWERED SLIGHT RISK TO
A SMALL MARGINAL RISK ACRS EXTREME SRN CA AND THAT IS MAINLY FOR
THE ADDITIONAL RAIN THREAT..ALBEIT MAINLY LIGHT..COULD ADD TO
RUNOFF ISSUES OVER AREAS WHERE ANTECEDENT CONDITIONS ARE SATURATED
OR NEARLY SATURATED FROM ONGOING RAINS THERE.

ADDITIONALLY REMOVED MARGINAL RISK AREA ACRS AZ WITH 85H/7H
VEERING FLOW WITH PASSAGE OF FRONTAL SYSTEM THIS EVENING LEADING
TO LESSENING HEAVIER RAIN THREAT.

SULLIVAN/BURKE
$$





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