Quantitative Precipitation Forecast
Issued by NWS

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052
FOUS30 KWBC 040048
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
847 PM EDT TUE MAY 03 2016

...VALID 01Z WED MAY 04 2016 - 12Z WED MAY 04 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...



01Z UPDATE...

...ACRS THE CAROLINAS...
EARLY EVENING RADAR IMAGERY ACRS NC CONTINUE TO SHOW SOME STG
TSTMS BUT THESE REMAIN RATHER SCTED WITH LITTLE ORGANIZATION TO
SUPPORT AN ORGANIZED THREAT OF EXCESSIVE RAINS.  SFC DATA
INDICATED RATHER WEAK FLOW ACRS THE REGION..GENLY OUTH OF THE
SOUTH WHERE NOT AFFECTED BY OUTFLOW FROM LOCAL STORMS.  SHORT TERM
MESOANALYSIS TRENDS SHOW A GRADUAL WEAKENING OF MLCAPES FROM
EARLIER DAYTIME HEATING..SO EXPECT A GENL DOWNTREND OF TSTM
ACTIVITY WHICH IS SUPPORTED BY RECENT HRRR SIMULATED REFLECTIVITY.
 MODELS DO INDICATE A STGR AREA OF HEIGHT FALLS MOVING TOWARD WRN
NC/SW VA BY 12Z..BUT AT THE SAME TIME THE AXIS OF HIER PWS IS
EXPECTED TO HAVE SHIFTED NEAR OR JUST OFF THE SC/NC COASTS..SO
THAT ANY REDEVELOPMENT OF SHWRS/TSTMS SHOULD BE OF LESSER
INTENSITY RAINRATE-WISE.

...ACRS SOUTHERN GEORGIA/ALABAMA...
ACTIVITY THERE HAS REMAINED A LITTLE MORE ORGANIZED WITH SLOWER
MOVING SMALL CLUSTERS OF STORMS AHEAD OF SLOW MOVING COLD FRONT.
MEAN LAYER FLOW REMAINS A BIT MORE FAVORABLE FOR SOME SMALL
TRAINING BANDS OR SLOWER MOVING CONVECTION IN GENERAL WITH SOME
ISOLD RUNOFF ISSUES PSBL THROUGH ABOUT MIDNIGHT BEFORE MAIN
CONVERGENCE AXIS WITH COLD FRONT SHIFTS SWD INTO FL.  SULLIVAN
PREVIOUS DISCUSSION FOLLOWS.


...CAROLINAS...

ANTECEDENT CONDITIONS HAVE BEEN WETTENED BY AN AVERAGE OF 1 TO 2
INCHES OF RAIN SINCE MONDAY MORNING IN A FAIRLY BROAD SWATH FORM
NORTHERN SOUTH CAROLINA INTO EASTERN NORTH CAROLINA. ESTIMATED
TOTALS FROM RADAR HAVE EXCEEDED 3...4...OR EVEN 5 INCHES IN SOME
SPOTS...INCLUDING NEAR THE RADAR / BENEATH THE MELTING LEVEL WHERE
DUAL-POL ESTIMATES ARE MORE TRUSTWORTHY. FLASH FLOOD
GUIDANCE...WHICH IS TYPICALLY HIGH AND DIFFICULT TO REACH IN THIS
REGION...HAD DECREASED OVER THE PAST DAY...AND SHOULD DECREASE
FURTHER AFTER THE EARLY MORNING RAINFALL IS INCLUDED. THIS RAISES
SOME CONCERN FOR THE AFTERNOON/EVENING PERIOD...WHEN THE LATEST
MODEL CONSENSUS IS FOR MODERATE TO LOCALLY HEAVY PRECIP TOTALS
ASSOCIATED WITH SWATHS OF LOOSELY ORGANIZED CONVECTION BENEATH
CYCLONIC FLOW ALOFT. PW VALUES WILL REMAIN ABOVE AVERAGE AND UVVS
WILL BE ENHANCED IN A BROADLY DIFLUENT HEIGHT PATTERN BETWEEN THE
SUB-TROPICAL JET ALONG THE GULF COAST AND A NORTHERN STREAM JET
STRETCHING FROM THE SOUTHERN APPALACHIANS INTO THE NORTHEAST.
THERE IS A SIGNAL FOR LOCALLY HEAVY RAINFALL AMOUNTS OF ADDITIONAL
1 TO 2 INCHES...WHICH COULD LEAD TO RUNOFF ISSUES / FLASH FLOODING
IN MORE SUSCEPTIBLE LOCATIONS.


...SOUTHERN GEORGIA AND ALABAMA...

DEEP LAYER LIFT IS FORECAST TO INCREASE AT A FAVORABLE TIME OF
DAY...MID/LATE AFTERNOON...AS COMBINED NORTHERN/SOUTHERN STREAM
HEIGHT FALLS PUSH INTO THE DEEP SOUTH...AND A SUB-TROPICAL JET
CIRCULATION NOSES IN FROM THE GULF. BROAD CONFLUENCE OF 850 MB
WINDS IS FORECAST...ESPECIALLY ACROSS SOUTHERN AL/GA...WHERE THE
MODELS FOCUS AN ORGANIZED PRECIPITATION EVENT. WITH MODERATE
INSTABILITY AND PRECIPITABLE WATER 1.25 TO 1.50 INCHES...CELLS
WILL LIKELY BE EFFICIENT RAIN PRODUCERS. CELL MOTIONS SUGGEST A
FAVORABLE SETUP FOR TRAINING...WITH 0-6 KM MEAN WINDS NEARLY
PARALLEL TO CORFIDI VECTORS FOR FORWARD PROPAGATION. THIS COULD
YIELD SPOT TOTALS OVER 2.5 OR EVEN 3 INCHES PER THE HI-RES
GUIDANCE. THERE IS...HOWEVER...NO INDICATION OF EXTREME TOTALS IN
THE MODELS...AND WITH FLASH FLOOD GUIDANCE BEING ON THE HIGH
SIDE...WE STOPPED SHORT OF OUTLINING A RISK AREA AT THIS TIME.

BURKE/ORAVEC
$$





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