Area Forecast Discussion
Issued by NWS Miami, FL

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FXUS62 KMFL 301245
AFDMFL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
845 AM EDT TUE SEP 30 2014

.UPDATE...
THE LATEST GRIDDED FORECAST PACKAGE HAS BEEN UPDATED BASED ON THE
LATEST OBSERVATIONS AND TRENDS AROUND THE LOCAL AREA. THE RAINFALL
CHANCES WERE INCREASED THROUGH THE AFTERNOON HOURS BASED ON THE
LATEST SHORT-RANGE MODEL GUIDANCE AND ANALYSIS...WHICH INDICATES
THE BULK OF THE COVERAGE WILL FOCUS OVER THE EASTERN HALF OF THE
SOUTH FLORIDA PENINSULA. /85

&&

.PREV DISCUSSION... /ISSUED 748 AM EDT TUE SEP 30 2014/

AVIATION...
WESTERLY WINDS WILL CONTINUE OVER ALL OF SOUTH FLORIDA TAF SITES
TODAY WITH WIND SPEEDS LESS THAN 5 KNOTS EARLY THIS MORNING
INCREASING TO 5 TO 10 KNOTS BY THIS AFTERNOON. THE WEATHER WILL
REMAIN DRY THIS MORNING OVER THE EAST COAST TAF SITES...BUT THEN
COULD SEE SOME THUNDERSTORMS THIS AFTERNOON MAINLY AFTER 17Z. FOR
KAPF TAF SITE...VCSH IS IN THE FORECAST BETWEEN 14Z AND 23Z.
MAINLY VFR CONDITIONS ARE EXPECTED...BUT MVFR/IFR CONDITIONS ARE
POSSIBLE IN SHOWERS AND STORMS.

PREV DISCUSSION... /ISSUED 338 AM EDT TUE SEP 30 2014/

DISCUSSION...LOW PRESSURE OFF THE NORTH FLORIDA COAST WILL MOVE
EASTWARD WITH A TRAILING FRONTAL BOUNDARY MOVING INTO CENTRAL
FLORIDA. W-SW WINDS WILL PICK UP ACROSS SOUTH FL TODAY. AMDAR
DATA SHOWS THIS HAPPENING WITH PALM BEACH WINDS NEAR 15 KT A FEW
THOUSAND FEET UP. THIS INCREASED FLOW LIKELY WILL PREVENT AN EAST
COAST SEA BREEZE FROM DEVELOPING...AND WITH THE SYNOPTIC SCALE
CONVERGENCE OVER CENTRAL FLORIDA, HAVE UNCERTAINTY IN THE LIKELY
POPS PROVIDED BY THE MODEL BLENDS, SO HAVE ADJUSTED POPS DOWN
SLIGHTLY BUT STILL AT OR ABOVE GFS MOS POPS. TSTORM COVERAGE IS
EXPECTED TO BE HIGHEST ACROSS THE LAKE OKEECHOBEE REGION THIS
AFTERNOON TO THE PALM BEACHES...IN THE HIGHER MOISTURE AND CLOSER
TO POSSIBLE TSTORM OUTFLOW BOUNDARIES ORIGINATING FROM CENTRAL
FLORIDA TSTORMS. LIGHTNING LOOKS TO BE THE PRIMARY HAZARD. TSTORMS
WILL BE ON THE MOVE WITH THE FASTER STEERING FLOW, LIMITING
RAINFALL AMOUNTS.

THE SHORTWAVE TROUGH ASSOCIATED WITH THE AFOREMENTIONED LOW
WILL LIFT AWAY AS RIDGING BUILDS FROM THE CARIB INTO SOUTH FL
WED-FRI. AS WIND FLOW LIGHTENS, WE RETURN TO A DIURNAL CONVECTIVE
REGIME ON SEA BREEZE CONVERGENCE. TSTORMS LOOK TO DEVELOP AND
FOCUS OVER THE INTERIOR AND EAST COAST METRO DUE TO A CONTINUED
WESTERLY STEERING FLOW, ALBEIT LIGHTER. SO WITH LIGHTER STEERING
WINDS, LIGHTNING AND LOCALLY HEAVY RAINFALL COULD OCCUR IN TYPICAL
SOUTH FL FASHION.

A SIGNIFICANT SHORTWAVE IS SHOWN BY BOTH THE GFS AND ECMWF DIGGING
INTO THE UPPER MIDWEST FRIDAY AND AMPLIFYING WITH A LONGWAVE
TROUGH ENCOMPASSING THE EASTERN SEABOARD BY SUNDAY. A STRONG COLD
FRONT WILL PLOW SOUTHEASTWARD WITH THIS HIGHLY AMPLIFIED TROUGH
WITH THE POSSIBILITY (LOW CONFIDENCE RIGHT NOW) OF AN EARLY
SEASON COLD FRONT MOVING ALL THE WAY ACROSS SOUTH FL ON SUNDAY!
ECMWF IS MORE AGGRESSIVE COMPARED TO THE PAST COUPLE GFS RUNS,
SHOWING DEWPOINTS INTO THE 60S SUN-MON (AND TEMPS A FEW DEGREES
LOWER) WHICH WOULD BE A VERY NOTICEABLE AIRMASS CHANGE SINCE
SPRING HERE. GFS THOUGH HANGS THIS FRONT NEAR THE LAKE OKEECHOBEE
REGION WITH DEWPOINTS HANGING AT OR ABOVE 70F ACROSS SOUTH FL.
SCATTERED THUNDERSTORMS ARE EXPECTED THIS WEEKEND, BUT POSSIBLY
ENDING FOR A COUPLE DAYS SHOULD THE FRONT CLEAR OUR AREA, THE
EXTENDED FORECAST SHOWS A TREND OF LOWERING POPS TO ACCOUNT FOR
THIS POSSIBILITY. /GREGORIA

MARINE...SW WINDS AROUND 10 KT TODAY WILL LIGHTEN OVER THE NEXT
COUPLE OF DAYS TO ONLY AROUND 5 KT. A STRONG COLD FRONT IS
FORECAST TO MOVE ACROSS NORTH FL ON SATURDAY...WITH SW WINDS
INCREASING A TAD OVER THE LOCAL WATERS IN RESPONSE. THIS FRONT
COULD MOVE ACROSS SOUTH FL ON SUNDAY...OR BECOME HUNG UP OVER THE
AREA. CONFIDENCE IS LOW ON WHICH SCENARIO WILL PLAY OUT, BUT SINCE
IT WILL BE LOOSING ITS PUNCH, NO HAZARDOUS WINDS/SEAS ARE
EXPECTED EITHER WAY, THOUGH HIGHER SURF WOULD BRIEFLY IMPACT THE
PALM BEACHES SUN-MON. /GREGORIA

&&

.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH  88  74  88  75 /  80  20  60  30
FORT LAUDERDALE  89  77  89  77 /  70  20  60  30
MIAMI            89  77  89  77 /  60  10  60  20
NAPLES           87  77  87  77 /  40  20  40  10

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&

$$

SHORT TERM...54/BNB
LONG TERM....57/DG



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