Quantitative Precipitation Forecast
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FOUS30 KWBC 041410
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1009 AM EDT WED MAY 04 2016

...VALID 15Z WED MAY 04 2016 - 12Z THU MAY 05 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...



...CENTRAL TO SOUTH FLORIDA...

AS OF MID MORNING...STRONG CONVECTION HAD ESTABLISHED A COLD
POOL...WITH WEST TO EAST OR WNW-ESE ORIENTATION OF TRAINING ECHOES
JUST SOUTH OF TAMPA...FROM SARASOTA TO VENUS. THE CENTRAL AND
SOUTHEAST PENINSULA WILL SEE SEVERAL HOURS OF ENHANCED MID LEVEL
DIFLUENCE AND LOWER LEVEL INFLOW LEADING INTO THE EARLY
AFTERNOON...SUGGESTING A CONTINUATION OF ORGANIZED CONVECTION.
ACTIVITY MAY BE PARTICULARLY WELL FOCUSED NEAR THE WEST TO EAST
OUTFLOW BOUNDARY...AND EVENTUALLY ALONG THE EAST COAST SEA BREEZE
FARTHER SOUTH INTO THE JUPITER TO FORT LAUDERDALE CORRIDOR.
SEVERAL HI-RES MODELS SUCH AS THE HRRR...ESRL EXPERIMENTAL
HRRR...AND NSSL WRF...SUGGEST THIS LATTER EAST COAST FOCUS...WHICH
WAS ALSO HIGHLIGHTED IN STORM PREDICTION CENTER OUTLOOKS. MOISTURE
AND INFLOW INTO THE REGION WILL BE ANOMALOUS...WITH STRENGTHENING
WEST SOUTHWESTERLY LOW LEVEL FLOW OFF OF THE GULF RAISING PW
VALUES TO 2 TO 3 STANDARD DEVIATIONS ABOVE THE MEAN. THIS WILL
SUPPORT EFFICIENT RAINFALL PRODUCTION...WITH INSTANTANEOUS RATES
PEAKING WELL ABOVE 3 INCHES/HOUR...BUT ACTUAL ACCUMULATIONS
PEAKING MORE LIKELY IN THE 2.0 TO 2.5 INCH/HOUR RANGE. WHILE FLASH
FLOOD GUIDANCE VALUES ARE VERY HIGH...AND DIFFICULT EXCEED ACROSS
CENTRAL TO SOUTH FLORIDA...ISOLATED FLASH FLOODING IS POSSIBLE IN
URBAN AREAS ALONG THE WEST CENTRAL TO SOUTHWEST COAST AND THE EAST
CENTRAL TO SOUTHEAST COAST. PLEASE SEE WPC MESOSCALE PRECIPITATION
DISCUSSION #0176...VALID UNTIL 1720Z FOR ADDITIONAL INFORMATION.


...CENTRAL APPALACHIANS INTO THE EASTERN UPSLOPE AREAS OF THE
CENTRAL APPALACHIANS...

THE PATTERN HAS FAVORED REPEATED RAIN EVENTS WITH DIURNAL
AFTERNOON/EVENING ENHANCEMENT TO RAIN RATES IN THIS REGION OVER
THE PAST SEVERAL DAYS. FLASH FLOOD GUIDANCE VALUES ARE ACCORDINGLY
LOW...BUT AT THE SAME TIME...INSTABILITY HAS BEEN DECREASING EACH
DAY AS THE POLAR FRONTAL BOUNDARY AND PRIMARY LARGE SCALE WARM
CONVEYOR BELT SLIPS FARTHER OFF THE COAST OF THE MID ATLANTIC.
CONVECTION THIS AFTERNOON SHOULD BE MORE SHALLOW AND WEAKER THAN
IN PREVIOUS DAYS...WITH THE MODELS DEPICTING 500 J/KG OR LESS OF
CAPE. STILL...SLOW CELL MOVEMENT AND SOME PIVOTING OF THE
PRECIPITATION MAY OCCUR WITHIN THE DIFLUENT MID LEVEL FLOW AREA
OPENING UP AHEAD OF A DIGGING 500 MB LOW. THIS MAY LEAD TO
ISOLATED HEAVY RAINFALL...AT LEAST RELATIVE TO THE LOW FFG. WITH
SUCH WEAK INSTABILITY AND AN ABSENCE OF INFLOW...HOWEVER...IT IS
DOUBTFUL HOW EFFICIENT THE CELLS CAN BE. MOST OF THE HIGH
RESOLUTION MODELS PRODUCE SPOTTY 1.0 TO 1.5 INCH TOTALS.

BURKE/ORAVEC
$$





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