Heavy Rain in Florida, April 30, 2012

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
929 PM EDT SUN APR 29 2012

.UPDATE...WINDS ALONG THE ATLANTIC COAST ARE RUNNING A TAD
HIGHER THAN INHERITED FORECAST, SO INCREASED WINDS A BIT THERE.
VIRGINA KEY IS GUSTING TO 37 KT AND FOWEY ROCKS IS NOW SUSTAINED
AT 30 KT, BUT THESE SITES ARE A BIT ELEVATED. EVEN SO, HIGH-END
SMALL CRAFT ADVISORY CONDITIONS WILL BE OCCURRING OFF THE
BROWARD/MIAMI-DADE COAST OVERNIGHT.

THE SOLID RAIN SHIELD ACROSS SE FLORIDA AND THE ATLANTIC SURE
BROKE UP EARLIER THIS EVENING. WATER VAPOR IMAGERY SHOWS THAT
UPPER LEVEL DRY AIR HAS INFILTRATED INTO THE AREA FROM THE SOUTH
AS THE MID LEVEL LOW IS NOW BISECTING THE AREA WITH DRY AIR
WRAPPED INTO IT ON ITS WEST AND SOUTH SIDE. THE UPPER TROUGH AXIS
IS ALIGNED FROM NW TO SE ACROSS SOUTH FL. THIS HAS BROUGHT IN SOME
SUBSIDENCE ON ITS WEST SIDE. THE BIG QUESTION IS WHAT WILL BE THE
TREND OVERNIGHT. GIVEN RADAR TRENDS AND LACK OF APPRECIABLE
ENVIRONMENTAL CHANGES OVERNIGHT...THE CURRENT THINKING IS THAT
PERIODS OF SHOWERS WILL CONTINUE TO MOVE ONSHORE THE SE FL COAST
WITH JUST A SLIGHT CHANCE OF A THUNDERSTORM.

THE PWAT ON THE MIAMI EVENING SOUNDING IS AT 1.87 INCHES, OR 170%
ABOVE AVG AND IN THE 99TH PERCENTILE FOR THIS TIME OF THE YEAR.
SO WITH THAT SAID, SHOULD A BAND OF HEAVY SHOWERS
DEVELOP...LOCALIZED LOCALES COULD SEE HEAVY RAINFALL OVERNIGHT
WITH POTENTIAL FLOODING CONCERNS DEVELOPING. HOWEVER, THIS THREAT
DOES NOT LOOK AS HIGH AS EARLIER THOUGHT, THOUGH STILL POSSIBLE.
SO WILL KEEP THE FLOOD WATCH GOING. ALSO, THE HEAVY RAIN RISK MAY
INCREASE ON MONDAY. KEY WEST AND MIAMI RADAR IMAGERY SHOWS A
CLUSTER OF CONVECTION AND CYCLONIC FLOW SOME 70 NM SE OF MARATHON.
THIS IS AT 8-10K FT. RIGHT NOW NO SIGNS OF A SURFACE CIRCULATION.
THIS FEATURE ASSOCIATED WITH A TROUGH WILL MOVE WEST NORTHWEST
OVERNIGHT-MONDAY PLACING SOUTH FL IN A FAVORABLE ESE MOIST WIND
FLOW FOR POSSIBLE LOCALIZED HEAVY RAINS. /GREGORIA

&&

.PREV DISCUSSION... /ISSUED 720 PM EDT SUN APR 29 2012/

AVIATION...SFC TROF XTNDG FM UPR FLA STRAITS NE TO N BAHAMAS
SLOLY MOVG W AND JUST OFF OF THE SE FLA COAST AT 30/12Z. SYSTEM
CROSSES S FLA AND INTO GUF OF MEX BY 30/18Z. VRY MOIST EASTERLY
WND FLOW WL PERSIST ACRS THE AREA THRU PD. ATTM WDSPRD MVFR CIG
ACRS S FLA WITH AREAS OF -RA BUT VSBY VFR. AFT 06Z WDSPRD MVFR CIG
AND -RA CONTINUES BUT POCKETS OF EMBEDDED HVY SHWRS MAY PRODUCE
IFR CIG /VSBY AT TIMES. WILL PLACE TEMPO MVFR CIG/VSBY VALUES IN
TAFS AFT 06Z PENDING DEVELOPMENT. EASTERLY WINDS WL PERSIST ALL
TAF SITES AND ARE XPCTD TO INCRS.

PREV DISCUSSION... /ISSUED 225 PM EDT SUN APR 29 2012/

DISCUSSION...WATER VAPOR CONTINUES TO SHOW WELL DEFINED MID LEVEL
TROUGH OVER THE WESTERN CARIBBEAN EXTENDING NORTHEAST INTO THE FL
STRAITS. AT THE SFC, A BROAD TROUGH ALSO STRETCHES ACROSS ROUGHLY
THE SAME AREA WITH VISIBLE SATELLITE INDICATING BROAD CIRCULATION
AROUND THESE TWO FEATURES WITH A RICH PLUME OF TROPICAL MOISTURE
FEED ACROSS CUBA, FL STRAITS AND S FL. THE 12Z MFL SOUNDING
ALTHOUGH CONTAMINATED BY CONVECTION AT LAUNCH TIME SHOWS THE DEEP
EASTERLY FLOW.

LOOKING AT THE VERY SHORT TERM, THE HRRR WHICH HAS BEEN DOING
REMARKABLY WELL THE PAST COUPLE OF DAYS SHOWS A DECREASING TREND
THROUGH THIS AFTERNOON BUT THEN A REGENERATION OFF THE SE CST AFT
03Z THIS EVENING WHICH IS AT THE END OF ITS CURRENT FCST CYCLE. BOTH
THE GFS AND NAM PERSIST IN SHOWING A DEEPENING SFC TROUGH OVER THE FL
KEYS FROM LATE THIS AFTERNOON INTO THIS EVENING AND MOVING IT WEST
INTO THE SE GULF BY LATE MONDAY. THEY HAVE HOWEVER BOTH SCALED BACK
THE STRENGTH AND NO LONGER SHOW A CLOSED CIRCULATION SO WILL STICK
CLOSER TO THE NAM SPEEDS WHICH IS THE WEAKER OF THE TWO MODELS. THE
LONGER RANGE MODELS STILL DIVERGE AS TO THE EVOLUTION OF THESE
SYSTEMS THROUGH THE NEXT 24 TO 36 HOURS BUT ALL AGREE TO A CERTAIN
DEGREE THAT THE BAND OF MOISTURE WILL MOVE VERY LITTLE THROUGH
THIS TIME FRAME. RAINFALL ACCUMULATION IS ALSO TROUBLESOME WITH
THE NAM NOT SHOWING MUCH AFT 00Z THIS EVENING AND ALTHOUGH THERE
HAS BEEN SOME DECREASE IN THE OVERALL REFLECTIVITY FROM THE
REGIONAL RADARS, THE TROPICAL FEED WILL CONTINUE AND THUS THAT
SOLUTION SEEMS UNREALISTIC. THE GFS SEEMS TO BE SUFFERING FROM
CONVECTIVE FEEDBACK AS IT IS SHOWING A BULLS EYE 12 HOUR TOTAL
ENDING AT 18Z MONDAY OF IN EXCESS OF 8 INCHES ACROSS NORTHERN
MIAMI-DADE COUNTY. OF COURSE, GIVEN THESE HISTORIC PWAT ANOMALIES
FOR LATE APRIL THIS SOLUTION CANNOT BE TOTALLY RULED OUT HOWEVER
AND SOMEWHERE FROM BROWARD TO MIAMI- DADE COUNTIES MAY INDEED APPROACH
8 INCHES OR EVEN SLIGHTLY HIGHER BY LATE MONDAY WITH THE GREATEST
COASTAL CONVERGENCE LIKELY OCCURRING AT LOW LEVELS ALONG AND NEAR
THE SOUTHEAST COAST LATE TONIGHT THROUGH EARLY MONDAY. THE ECMWF
IS A MIDDLE OF THE ROAD APPROACH. SO WITH ALL OF THIS BEING SAID,
THE FLOOD WATCH WILL CONTINUE THROUGH MONDAY EVENING FOR THE EAST
COASTAL REGION.

HIGH PRESSURE WILL REMAIN TO THE NORTHEAST OVER THE WESTERN ATLANTIC
WITH THE PRESSURE GRADIENT REMAINING TIGHT SO STRONG COASTAL
CONVERGENCE MAY AGAIN SET UP MONDAY NIGHT INTO EARLY TUESDAY AS THE
HIGH MOISTURE REMAINS ACROSS THE AREA. THE ECMWF HAS COME MORE IN
LINE WITH THE GFS AND SHOWING THE DEEP MOISTURE REMAINING IN PLACE
THROUGH THE END OF THIS WEEK SO RAIN CHANCES WILL CONTINUE WITH THE
HIGHEST CHANCES FOR THE EAST COAST.

MARINE...DETERIORATING MARINE CONDITIONS WILL CONTINUE THROUGH
EARLY IN THE WEEK WITH SCA FOR ATLANTIC AND GULF WATERS. SEAS IN
THE GULF STREAM WILL LIKELY BE UP TO 8 FEET THROUGH LATE TUESDAY
BEFORE SUBSIDING BY THE MIDDLE OF THE WEEK AS THE GRADIENT WEAKENS.

FIRE WEATHER...NO PROBLEMS OR CONCERNS WITH AMPLE TROPICAL
MOISTURE IN PLACE.

&&

.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH  73  80  73  82 / 70 60 40 50
FORT LAUDERDALE  72  79  74  83 / 80 70 50 50
MIAMI            70  80  72  83 / 80 70 50 50
NAPLES           68  82  70  86 / 40 50 30 50

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...FLOOD WATCH THROUGH MONDAY EVENING FOR COASTAL BROWARD-COASTAL
     MIAMI DADE-COASTAL PALM BEACH-FAR SOUTH MIAMI DADE-INLAND
     MIAMI DADE-METRO BROWARD-METRO MIAMI DADE-METRO PALM BEACH.

     HIGH RIP CURRENT RISK THROUGH MONDAY AFTERNOON FOR COASTAL
     BROWARD-COASTAL MIAMI DADE-COASTAL PALM BEACH.

AM...SMALL CRAFT ADVISORY UNTIL 8 AM EDT TUESDAY FOR COASTAL WATERS
     FROM DEERFIELD BEACH TO OCEAN REEF, FL OUT 20 NM-COASTAL
     WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL OUT 20 NM-
     WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL EXTENDING
     FROM 20 NM TO THE TERRITORIAL WATERS OF THE BAHAMAS-WATERS
     FROM JUPITER INLET TO DEERFIELD BEACH, FL EXTENDING FROM 20
     NM TO 60 NM.

     SMALL CRAFT ADVISORY UNTIL 8 PM EDT MONDAY FOR BISCAYNE BAY.

GM...SMALL CRAFT ADVISORY UNTIL 8 AM EDT TUESDAY FOR COASTAL WATERS
     FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM-COASTAL
     WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT 20 NM-
     GULF WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL EXTENDING
     FROM 20 TO 60 NM.

&&

DISCUSSION/MARINE/FIRE...30/KOB
AVIATION/RADAR...10/CD

HAZARDOUS WEATHER OUTLOOK FOR SOUTH FLORIDA
NATIONAL WEATHER SERVICE MIAMI FL
412 PM EDT SUN APR 29 2012

AMZ610-630-FLZ063-066>075-168-172>174-301030-
LAKE OKEECHOBEE-BISCAYNE BAY-GLADES-HENDRY-INLAND PALM BEACH-
METRO PALM BEACH-COASTAL COLLIER-INLAND COLLIER-INLAND BROWARD-
METRO BROWARD-INLAND MIAMI DADE-METRO MIAMI DADE-MAINLAND MONROE-
COASTAL PALM BEACH-COASTAL BROWARD-COASTAL MIAMI DADE-
FAR SOUTH MIAMI DADE-
412 PM EDT SUN APR 29 2012

...FLOOD WATCH EAST COAST METRO AREAS THROUGH MONDAY EVENING...
...HAZARDOUS MARINE AND COASTAL CONDITIONS THROUGH TUESDAY...
...STRONG WIND GUSTS POSSIBLE IN THE SHOWERS/THUNDERSTORMS...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH FLORIDA.

.DAY ONE...TONIGHT

FLOODING: A FLOOD WATCH IS IN EFFECT FOR THE EAST COAST
METROPOLITAN AREAS OF WEST PALM BEACH, FORT LAUDERDALE, AND
MIAMI THROUGH MONDAY EVENING. HEAVY RAINS COULD CAUSE STREET
FLOODING AND FLOODING OF LOW LYING AREAS. THERE IS EVEN THE
POTENTIAL FOR STRUCTURAL FLOODING SHOULD A PERSISTENT BAND OF
TORRENTIAL RAINS SET UP OVER A GIVEN AREA. ADDITIONAL RAINFALL
AMOUNTS OF 1 TO 3 INCHES ARE EXPECTED ACROSS SOUTHEAST FLORIDA
TONIGHT, WITH ISOLATED HEAVIER AMOUNTS.

RIP CURRENTS: THERE IS A HIGH RISK OF RIP CURRENTS AT ALL
LOCAL ATLANTIC BEACHES.

THUNDERSTORMS: A FEW THUNDERSTORMS ARE POSSIBLE. THE MAIN
IMPACTS WOULD BE TORRENTIAL RAINS, STRONG WIND GUSTS, AND
LIGHTNING STRIKES.

WATERSPOUTS: THERE IS A SLIGHT RISK OF WATERSPOUTS OVER THE
ATLANTIC WATERS, INCLUDING BISCAYNE BAY.

WIND: EAST WINDS WILL AVERAGE 20 TO 25 KNOTS OVER THE LOCAL
ATLANTIC AND GULF WATERS, WITH OCCASIONAL GUSTS TO 35 KNOTS
POSSIBLE. SOME HEAVIER SHOWERS AND THUNDERSTORMS MAY ALSO
PRODUCE STRONG WIND GUSTS UP TO 50 MPH.

WAVES: SEAS WILL BUILD TO 6 TO 8 FEET OVER THE ATLANTIC WATERS,
AND TO 5 TO 7 FEET OVER THE OFFSHORE GULF WATERS. CHOPPY
CONDITIONS ARE ALSO EXPECTED ON BISCAYNE BAY. A SMALL CRAFT
ADVISORY HAS BEEN ISSUED FOR ALL LOCAL WATERS EXCEPT LAKE
OKEECHOBEE.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL CONTINUE MONDAY
THROUGH AT LEAST THURSDAY AS A LOW LEVEL TROUGH REMAINS NEAR THE
LOCAL AREA. THE POTENTIAL FOR LOCALLY HEAVY RAINFALL WILL PERSIST
THROUGH AT LEAST TUESDAY, ESPECIALLY ACROSS THE EAST COAST METRO
AREAS.

SOME OF THE MORE INTENSE SHOWERS AND THUNDERSTORMS MAY PRODUCE
STRONG WIND GUSTS AROUND 50 MPH MONDAY INTO TUESDAY.

THERE WILL LIKELY BE A CONTINUED HIGH RISK OF RIP CURRENTS AT THE
ATLANTIC BEACHES MONDAY THROUGH AT LEAST TUESDAY.

STRONG WINDS AND SEAS WILL RESULT IN HAZARDOUS MARINE CONDITIONS
OVER PORTIONS OF THE LOCAL WATERS MONDAY THROUGH AT LEAST EARLY
TUESDAY.

.SPOTTER INFORMATION STATEMENT...

WIDESPREAD SPOTTER ACTIVATION IS NOT ANTICIPATED, HOWEVER
INDIVIDUAL SPOTTERS ARE ENCOURAGED TO REPORT HIGH WIND AND
FLOODING TO THE NATIONAL WEATHER SERVICE FORECAST OFFICE IN
MIAMI.

FOR MORE INFORMATION...VISIT THE NATIONAL WEATHER SERVICE IN
MIAMI WEBSITE AT WWW.WEATHER.GOV/MIAMI.

GREGORIA