Area Forecast Discussion
Issued by NWS Miami, FL

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FXUS62 KMFL 222355
AFDMFL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
755 PM EDT WED OCT 22 2014

.UPDATE...LIGHT RAIN SHIELD HAS INVADED AREAS SOUTH OF ALLIGATOR
ALLEY WITH ONLY A FEW SHOWERS TO THE NORTH. THE FORECAST WAS
UPDATED TO REFLECT AN EVEN TIGHTER POP GRADIENT FROM NORTH TO
SOUTH. HOWEVER, NO SIGNIFICANT CHANGES WERE MADE. LOW PRESSURE IS
DEVELOPING OVER THE SOUTHEASTERN GULF OF MEXICO AHEAD OF AN UPPER
LEVEL TROUGH DIGGING INTO THE GULF. THIS NON-TROPICAL LOW WILL
MOVE ENE TOWARDS THE FL STRAITS AND POTENTIALLY BRING HEAVY
RAINFALL TO SOUTH FL...ESPECIALLY SOUTHERN AREAS SOUTH OF
ALLIGATOR ALLEY NEAR THE DEEPEST MOISTURE/CONVERGENCE...AND WE
CONTINUE TO MONITOR THIS FOR THE POTENTIAL FOR FLOODING THROUGH
FRIDAY. /GREGORIA

&&

.AVIATION...LIGHT RAIN WILL CONTINUE ACROSS THE BROWARD AND
MIAMI-DADE TERMINALS TONIGHT BUT PREVAIL IN THE VFR CATEGORY.
VISIBILITY AND CIGS ARE FORECAST TO LOWER A BIT ON THU...BUT
EXPECTED TO PREVAIL ABOVE IFR. SO ADDED PREVAILING MVFR VIS/CIGS
FOR THE BROWARD AND MIAMI-DADE TERMINALS FOR THU ALONG WITH VCTS.
BRIEF IFR IS POSSIBLE IN THE HEAVIER TSRA, BUT TOO DIFFICULT TO
TIME SO WAS NOT ADDED. FOR KPBI AND KAPF, DRIER AIR IS FORECAST
TO MOVE IN SO MAINTAINED ONLY VCSH THERE. WINDS WILL BE LIGHT
OVERNIGHT THEN PREVAIL NORTHEAST AT NEAR 10 KT ON THU. THX CWSU
MIAMI FOR COLLABORATION. /GREGORIA

&&

.PREV DISCUSSION... /ISSUED 344 PM EDT WED OCT 22 2014/

SYNOPSIS...
A NEARLY STATIONARY FRONT OVERHEAD COMBINED WITH DEEP TROPICAL
MOISTURE WILL LEAD TO SIGNIFICANT RAIN CHANCES THROUGH FRIDAY
NIGHT. DRIER AIR WILL FILTER IN TO SOUTH FLORIDA THIS WEEKEND.

SHORT TERM /TONIGHT-FRIDAY NIGHT/...
SHOWERS/THUNDERSTORMS OVER SOUTH FLORIDA HAVE BEEN SLOW TO
DEVELOP...PARTIALLY DUE TO EXTENSIVE HIGH CLOUDINESS/DEBRIS FROM
CONVECTION IN SE GULF. SHOWERS NOW FIRING OVER PORTIONS OF MIAMI-
DADE COUNTY...AND EXPECT THIS ACTIVITY TO SPREAD NORTHWARD WITH
TIME...AS LIGHT STRATIFORM RAIN SPREADS EASTWARD FROM THE GULF.
MUCH DRIER AIR...NORTH OF NEARLY-STATIONARY FRONT LOCATED ALONG
I-4 CORRIDOR...WILL GRADUALLY FILTER SOUTHWARD THROUGH
TONIGHT...THUS CONFIDENCE IS LOW THAT PRECIPITATION WILL REACH
NORTHERN CWA OVERNIGHT. TIGHT N-S POP GRADIENT EXHIBITS NEAR-
CERTAIN RAIN OVER THE EVERGLADES/SOUTHERN MIAMI-DADE...TO ONLY
SLIGHT CHANCES ACROSS GLADES COUNTY.

WITH BOUNDARY NEARLY OVERHEAD THURSDAY...TIGHT MOISTURE/POP
GRADIENTS WILL CONTINUE. TROPICAL DEPRESSION 9 IS FORECAST TO
HAVE NO DIRECT IMPACT ON SOUTH FLORIDA...BUT MOISTURE ASSOCIATED
WITH WILL POUR NORTHEASTWARD ACROSS THE SOUTHERNMOST PENINSULA
THURDAY AND THURDAY NIGHT. MODELS HINTING THIS AFTERNOON THAT
DRIER AIR MAY MAKE SIGNIFICANT PROGRESS INTO SOUTH
FLORIDA...MEANING THE AREAS NORTH OF A NAPLES TO WEST PALM BEACH
LINE WILL HAVE A FAIRLY DRY DAY...WITH EVEN METRO BROWARD SEEING
LESS SHOWER COVERAGE THAN POINTS FURTHER SOUTH DURING THIS PERIOD.

LATE THURSDAY NIGHT INTO FRIDAY...DEEP ULVL TROF OVER EASTERN
CONUS WILL PROGRESS EASTWARD INTO THE ATLANTIC. AS IT DOES...AN H5
SHRTWV TROF IN THE GULF WILL DRAG ENEWARD ACROSS SOUTH FLORIDA.
RICH TROPICAL MOISTURE SHOULD STREAM NORTHWARD IN ADVANCE OF THIS
SHRTV TROF AND ASSOCIATED SURFACE LOW PRESSURE...WHICH WILL RIDE
ACROSS THE REMNANT FRONTAL BOUNDARY SITUATED NEAR/JUST SOUTH OF
CWA. THIS HAS THE POTENTIAL TO BRING VERY HEAVY RAIN TO ESPECIALLY SOUTHERN
SECTIONS OF SOUTH FLORIDA...AS PWAT VALUES ARE FORECAST TO BE NEAR
2.5 INCHES. THE LOCATION OF THE HEAVIEST RAIN IS QUITE UNCERTAIN
AT THIS TIME...AS A SMALL DEVIATION IN THE TRACK OF THE LOW
PRESSURE OR LOCATION OF SURFACE BOUNDARY WOULD CAUSE SIGNIFICANT
FORECAST ADJUSTMENTS.

LONG TERM /SATURDAY THROUGH WEDNESDAY/...

THE TROUGH WILL PUSH THROUGH THE REGION FRIDAY NIGHT AND
SATURDAY...WITH MUCH DRIER AIR MOVING INTO THE REGION BY SATURDAY
EVENING. DEWPOINTS ARE FORECAST TO DROP INTO THE 50S TO LOW 60S
ACROSS THE REGION SATURDAY NIGHT AND SUNDAY UNDER NORTHEASTERLY
FLOW. HIGH PRESSURE WILL THEN BUILD INTO THE SOUTHEAST AND WESTERN
ATLANTIC EARLY NEXT WEEK...WITH EASTERLY FLOW RETURNING.

MODELS ARE SUGGESTING THAT THE REMNANTS OF TD 9 AND THE TAIL END
OF THE TROUGH MAY COMBINE AND TRY TO REDEVELOP ACROSS THE
NORTHWEST CARIBBEAN SEA EARLY NEXT WEEK. THE GFS IS MUCH MORE
AGGRESSIVE WITH DEVELOPMENT...WHICH HAS BEEN THE CASE ALL SEASON
IN THIS REGION...AND MOVES A CYCLONE INTO THE SOUTHERN GULF BY THE
MIDDLE OF NEXT WEEK. THE ECMWF IS MUCH WEAKER...BUT SPREADS
MOISTURE BACK ACROSS SOUTH FLORIDA BEGINNING TUESDAY AFTERNOON. SO
SOUTH FLORIDA MAY NEED TO KEEP AN EYE ON THE TROPICS...AND MORE
WET WEATHER COULD BE ON THE WAY ONCE AGAIN EARLY NEXT WEEK.

AVIATION...
RAIN SHIELD CURRENTLY LOCATED ACROSS FLORIDA KEYS WILL CONTINUE TO
SLOWLY WORK ITS WAY TO THE NORTHEAST THROUGH THE EVENING AND INTO
TONIGHT. AS IT DOES...LIGHT TO MODERATE SHOWERS OUT AHEAD OF THE
MAIN SHIELD SHOULD AFFECT THE EAST COAST SITES. ISOLATED
THUNDERSTORMS ARE POSSIBLE BUT DECIDED TO REMOVE VCTS MENTION FOR
NOW AS IT APPEARS SHOWERS WILL BE PREDOMINANT. MODELS ALSO DEPICT
A FAIRLY SHARP PRECIPITATION GRADIENT FROM SOUTH TO NORTH ACROSS
THE AREA THROUGH THE NIGHT. THEREFORE KEPT VCSH MENTION OUT FOR
KPBI DURING THE OVERNIGHT PERIOD.

MARINE...
EASTERLY WINDS OVER THE WATERS TODAY AND TONIGHT WILL INCREASE
THRUSDAY AND FRIDAY...ENOUGH SO THAT SMALL CRAFT ADVISORIES MAY BE
WARRANTED. NUMEROUS SHOWERS AND A FEW THUNDERSTORMS CAN BE
EXPECTED THROUGH FRIDAY NIGHT...BEFORE SOME DRIER AIR MOVES IN FOR
THE WEEKEND.

&&

.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH  72  82  73  82 /  40  30  30  50
FORT LAUDERDALE  73  82  76  82 /  60  70  60  70
MIAMI            72  83  74  82 /  70  80  70  80
NAPLES           70  86  70  84 /  50  30  20  30

&&

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

$$



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