Quantitative Precipitation Forecast
Issued by NWS

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750
FOUS30 KWBC 212116
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
415 PM EST SAT JAN 21 2017

...VALID 2115Z SAT JAN 21 2017 - 12Z SUN JAN 22 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
180 W ACV 130 W CEC 65 WNW CEC 10 WNW CEC 40 SE CEC 30 W O54
30 WSW O54 45 N UKI 25 ENE STS 10 ESE LVK 45 NNW PRB 20 SE PRB
40 SW BFL 10 WSW SDB NTD 40 NNW NSI 70 SSW LPC 110 SW VBG.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
50 NE KIPN 20 SSW HRT 15 SSW 11J 20 W TBR 35 NW NBC 20 S CHS
65 SE HXD 45 ENE SGJ 40 NW BKV 65 W BKV 130 ESE KIPN.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
90 SW O87 60 SW O87 30 S O87 25 NNW UKI 10 ESE UKI APC
10 ENE PAO 15 N WVI 20 SE SNS 25 NNE 87Q SBP 15 ESE SMX
10 SSE LPC 30 SW LPC 50 SW XVW 85 WSW VBG.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
70 ESE KVOA 20 S DTS 10 NNE BGE 20 SSE ABY 25 SSW VDI
15 WNW SAV 35 SE SVN 30 E SSI CRG 25 SSW CTY 100 S AAF.


2100 UTC UPDATE...

LOWER MS VALLEY/SE U.S..

WITH THE APCH OF STG SRN STREAM HEIGHT FALLS FROM THE SRN PLAINS
LATER THIS AFTN AND TONIGHT..TSTMS ARE EXPECTED TO DVLP AND
INTENSIFY INVOF WARM FRONTAL BNDRY LIFTING NWD IN ADVANCE OF APCHG
LOW PRES SYSTEM AND COLD FRONT.    WHILE MAIN THREAT WILL LIKELY
BE SEVERE WEATHER..WHERE SOME OF THE STGR SUPER CELLS OR MORE
INTENSE LINE SEGMENTS OVERLAP AREAS THAT RECEIVED HEAVY RAIN OVER
THE PAST 24 HRS...THERE COULD BE SOME CONCERN FOR FLASH FLOODING.
FOR THE MOST PART...CELLS SHOULD BE RATHER PROGRESSIVE SUGGESTING
ANY RUNOFF ISSUES WOULD BE RATHER ISOLD.  GIVEN THIS SMALL RISK OF
EXCESSIVE RAINS..HAVE EXPANDED MARGINAL RISK WWD FOR THE OVERNIGHT
ACRS PORTIONS OF THE LOWER MS VALLEY.  SULLIVAN

1900 UTC UPDATE

THE EXCESSIVE RAINFALL POTENTIAL OUTLOOK WAS UPDATED TO REFLECT
THE CURRENT RADAR TRENDS ACROSS THE SOUTHEASTERN U.S.   THE
NORTHERN PORTION OF THE MARGINAL AND SLIGHT AREAS WERE TAKEN OUT
ACROSS CENTRAL TO NORTHERN GEORGIA INTO CENTRAL TO UPSTATE SC.
THE CONVECTION ACROSS THESE AREAS IS VERY PROGRESSIVE WITH THE
RISK OF EXCESSIVE AMOUNTS AT THE MOMENT UNLIKELY. THE MARGINAL AND
SLIGHT RISKS WERE CONFINED TO EASTERN AREAS OF THE FL
PANHANDLE---INTO NORTHERN FL AND SOUTHERN GEORGIA WHERE THE
CONVECTION IS SLOWER MOVING AND MORE ALIGNED TO THE MOIST WEST
SOUTHWESTERLY LOW LEVEL FLOW OFF THE NORTHEAST GULF.  SLOWER
EASTWARD MOVEMENT OF THIS AXIS AND POTENTIAL FOR TRAINING IN THIS
AXIS WILL CONTINUE THROUGH THE REMAINDER OF THIS
AFTERNOON---POSSIBLE INTO THE EARLY EVENING.  IN AREAS OF
TRAINING---1.5-2"+ PRECIP TOTALS IN AN HOUR POSSIBLE.

NO CHANGES MADE ACROSS CALIFORNIA.

ORAVEC



...CALIFORNIA...

THE NEXT ATMOSPHERIC RIVER QUICKLY ORGANIZES BACK OFFSHORE AND
APPROACHES SATURDAY NIGHT...WITH THE INITIAL ONSLAUGHT OF HEAVIER
RAINFALL AIMED AGAIN AT NORTHERN CALIFORNIA. ONCE AGAIN A DEEP AND
AMPLIFYING TROUGH WILL BRING THE RIVER ONSHORE...ALTHOUGH WITH
STEADY PROGRESSION THERE WILL NOT BE TERRIBLY LONG RESIDENCE TIME
OF THE ENHANCED MOISTURE FLUX AT ANY ONE LOCATION. CERTAINLY THERE
WILL BE CAUSE FOR CONCERN IN FLOOD-PRONE
AREAS...HOWEVER...ESPECIALLY GIVEN THE RECENT EXTENDED STRETCH OF
WET WEATHER...AS ONCE AGAIN MODERATE PW AND MOISTURE FLUX
ANOMALIES WILL DEVELOP...SUPPORTING HEAVY 1-HOUR AND 3-HOUR RAIN
RATES. A CONSENSUS QPF APPROACH MATCHES REMARKABLY WELL TO THE
GEFS REFORECAST DATA BASED ON ANALOG CASES...INDICATING AREAL
AVERAGE AMOUNTS 1.5 TO 2.5 INCHES THROUGH SUNDAY MORNING IN THE
FAVORED COASTAL TERRAIN AND NORTHERN SIERRAS / SHASTA`S. THE EVENT
WILL WORK DOWN INTO SOUTHERN CALIFORNIA TOWARD DAY 2.

BURKE
$$





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