Quantitative Precipitation Forecast
Issued by NWS

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987
FOUS30 KWBC 060101
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
800 PM EST MON DEC 05 2016

...VALID 01Z TUE DEC 06 2016 - 12Z TUE DEC 06 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 NNE KMDJ 15 NNE 1B7 10 SSW PQL 10 NE BFM 25 N GZH 20 ENE ALX
LZU 20 NNE GRD 25 W UDG 15 W EYF 15 ESE ILM 65 SSE SUT 85 SE HXD
10 E GNV 70 SSW CTY 120 S AAF.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
40 NE KVOA 15 N CEW 30 E TOI 30 SSW OPN 10 ENE MLJ 10 SSW AGS
10 S OGB 30 SW MYR 50 SSE MYR 65 SE CHS 45 E SSI 15 NNW VQQ
10 WSW CTY 60 SE AAF 60 S AAF.


0100Z UPDATE

HEAVY RAINS CONTINUE ACROSS ESPECIALLY AREAS OF SOUTHEAST AL AND
ACROSS MUCH OF SOUTHERN GA IN RESPONSE TO ROBUST SOUTHERLY
MOISTURE TRANSPORT IN OFF THE EASTERN GULF OF MEXICO AND WITH A
SIGNIFICANT POOL OF INSTABILITY NOTED ALONG AND SOUTH OF A FRONTAL
ZONE IN VICINITY OF THE FL PANHANDLE. RECENT HRRR RUNS ARE LIKELY
TOO HEAVY TOO FAR NORTH GIVEN THE LATEST RADAR TRENDS AND LOCATION
OF THE FRONT...BUT A LARGE AREA OF HEAVY RAIN IS STILL EXPECTED
FOR AREAS EVEN A LITTLE FARTHER NORTH UP ACROSS CENTRAL GA. THE
HEAVY CONVECTIVE RAINS OVER SOUTHERN GA SHOULD TEND TO EVENTUALLY
HAVE AN IMPACT ON SOUTHERN SC LATER IN THE NIGHT. ADDITIONAL
RAINFALL AMOUNTS OF AS MUCH AS 2 TO 4 INCHES CAN BE EXPECTED
THROUGH 12Z ALONG AND NORTH OF THE FRONTAL ZONE WHICH WILL
GRADUALLY LIFT NORTH AS A WARM FRONT AHEAD OF THE APPROACHING
UPSTREAM TROUGH AND WAVE OF LOW PRESSURE. THE MARGINAL AND SLIGHT
RISK AREAS WERE ADJUSTED TO ACCOUNT FOR THE LATEST RADAR TRENDS
AND OVERALL HIRES MODEL OUTPUT. GIVEN THAT HEAVY RAINS HAVE
GENERALLY MOVED OUT OF THE CENTRAL GULF COAST AREA AND OFF TO THE
EAST...THE THREAT FOR EXCESSIVE RAINS HERE HAVE DIMINISHED.

ORRISON


PREVIOUS DISCUSSION...

1900 UTC UPDATE

CENTRAL GULF COAST INTO THE COASTAL SOUTHEAST

THE PREVIOUS EXCESSIVE RAINFALL POTENTIAL OUTLOOK WAS MODIFIED TO
REFLECT THE MODEL TRENDS OF EMPHASIZING HEAVIEST PRECIPITATION
PUSHING DOWNSTREAM FROM THE CENTRAL GULF COAST INTO THE COASTAL
SOUTHEAST FROM THIS AFTERNOON INTO TONIGHT/EARLY TUESDAY.  THE
PREVIOUS MODERATE RISK AREA WAS DROPPED AS THE HEAVIEST PRECIP IS
NOW MOVING INTO AREAS THAT HAVE NOT SEEN AS HEAVY PRECIPITATION AS
WHERE THE PREVIOUS MODERATE RISK WAS OVER.    WHILE THERE IS
FAIRLY GOOD MASS FIELD EVOLUTION AGREEMENT---FROM THE SURFACE TOP
MID LEVELS WITH THE EJECTING MID TO UPPER LEVEL LOW PUSHING FROM
THE SOUTHERN PLAINS INTO LOWER MS VALLEY DURING THE REMAINDER OF
THIS PERIOD---THERE ARE A LOT OF QPF DETAIL DIFFERENCES.  WPC QPF
LEANED TOWARD THE IDEA OF SEVERAL OF THE HI RES RUNS IN SHOWING A
CONVECTIVE PRECIP MAX FROM THE CENTRAL GULF COAST INTO COASTAL SC
WHERE INSTABILITY IS EXPECTED TO BE GREATEST---WHILE A SECONDARY
MAX FOCUSES FARTHER INLAND WITH THE COMMA HEAD/DEFORMATION PRECIP
AREA ALONG AND NORTH OF THE MID LEVEL CENTER MOVING FROM THE LOWER
MS VALLEY INTO THE TN VALLEY.  AREAL AVERAGE 1.5-3" TOTALS
EXPECTED WITH THE COASTAL CONVECTIVE MAX WHERE PW ANOMALIES 2-3+
STANDARD DEVIATIONS ABOVE THE MEAN ARE EXPECTED---WITH ISOLATED
TOTALS OVER 5" WHERE CONVECTION TRAINS/MAXIMIZES.

ORAVEC

$$





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