Area Forecast Discussion
Issued by NWS Miami, FL

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000
FXUS62 KMFL 180118
AFDMFL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
918 PM EDT THU APR 17 2014

.UPDATE...
ALREADY AMENDED THE EVENING FORECAST TO REMOVE THUNDER OVER THE
INTERIOR AND WEST. THE 00Z MFL SOUNDING SHOWS HOW MOIST AND
UNSTABLE THE AIRMASS REMAINS SO KEPT SLIGHT CHANCE FOR THUNDER ALL
NIGHT ALONG THE EAST COAST AND THE ATLANTIC WATERS. AS THE EVENING
PROGRESSES AND IN A FLOW PATTERN LIKE THIS, THE ATMOSPHERE COULD
EASILY DESTABILIZE OVER THE GULF STREAM WITH A LITTLE BIT OF
COOLING JUST ABOVE THE SURFACE AND THE WARM WATER BELOW SO ANY
SHOWER MOVING INTO THIS ENVIRONMENT COULD EASILY GET THE UPLIFT TO
DEVELOP INTO A THUNDERSTORM. THE WESTERN PORTIONS HAVE STABILIZED
DUE TO THE AFTERNOON/EARLY EVENING CONVECTION AND THIS EVIDENT
WITH THE LOW STRATUS DECK THAT HAS DEVELOPED. NO OTHER CHANGES ARE
PLANNED.

KOB

&&

.PREV DISCUSSION... /ISSUED 804 PM EDT THU APR 17 2014/

AVIATION...

SHOWER ACTIVITY HAS LARGELY SUBSIDED EARLY THIS EVENING ALTHOUGH A
FEW SHOWERS ARE STREAMING WESTWARD ACROSS THE ATLANTIC WATERS. FOR
THIS EVENING...MAINLY VFR CONDITIONS EXPECTED ALTHOUGH A FEW
SHOWERS COULD AFFECT THE ATLANTIC COAST TERMINALS FROM TIME TO
TIME...WITH VCSH ASSIGNED...WITH VERY BRIEF SUB-VFR CONDITIONS
POSSIBLE. ADDITIONAL SHOWER ACTIVITY ACROSS THE ATLANTIC WATERS IS
POSSIBLE DURING THE EARLY MORNING HOURS ON FRIDAY AGAIN WITH BRIEF
SUB-VFR CONDITIONS POSSIBLE. THE LATEST GUIDANCE SUGGESTS THAT LOW
STRATUS AROUND 1500 FLEET IS POSSIBLE FOR TERMINAL KAPF DURING
THE EARLY HOURS FRIDAY WITH OCCASIONAL CEILINGS POSSIBLE.

60

PREV DISCUSSION... /ISSUED 303 PM EDT THU APR 17 2014/

NEAR TERM...(THIS EVENING)

THE INITIAL CONCERN WILL BE THROUGH LATE AFTERNOON AND EVENING
PERIODS ALONG THE GULF COAST AND FROM NAPLES TO THE LAKE REGION DUE
TO THE POTENTIAL FOR STRONG THUNDERSTORMS AND HEAVY RAINFALL
ASSOCIATED WITH A FRONTAL BOUNDARY LIFTING NORTH. THE LATEST RADAR
LOOP SHOWED SCATTERED TO NUMEROUS SHOWERS AND A FEW EMBEDDED
THUNDERSTORMS SHIFTING WESTWARD TOWARD THE GULF COAST ACROSS THE
INTERIOR AREAS. THE LATEST HRRR AND WRF MODELS REFLECT THIS AND
INDICATE THIS ACTIVITY BECOMING CONCENTRATED AROUND THE NAPLES AREA
THROUGH THIS TIME. IF THIS SCENARIO UNFOLDS...LOCALIZED FLOODING
COULD BECOME AN ISSUE DEPENDING ON WHERE THE HEAVY RAINFALL FOCUSES.
IN ADDITION TO THE RAINFALL...A FEW STRONG STORMS CAN`T BE RULED OUT
THROUGH THIS TIME OVER THESE AREAS WITH THE MAIN THREATS BEING
STRONG WIND GUSTS AND HAIL. THE MORNING SOUNDING INDICATED DECENT
MID-LEVEL LAPSE RATES WITH -12 C DEG 500 MB TEMPERATURES ALONG WITH
1.8" PWS. 85/AG

SHORT TERM...(TONIGHT THROUGH SATURDAY)...

THE LATEST SHORT-RANGE MODEL GUIDANCE REMAINS IN DECENT AGREEMENT
AND GENERALLY INDICATES THE WARM FRONT LIFTING NORTH OUT OF OUR
LOCAL AREA TONIGHT AS A COLD FRONT ASSOCIATED WITH A GULF LOW
APPROACHES THE AREA FROM THE WEST FRIDAY AND FRIDAY NIGHT. THE
FRONTAL BOUNDARY IS PROGGED TO MOVE THROUGH THE AREA WITH DRIER AIR
AND NW FLOW SATURDAY AFTERNOON THROUGH SATURDAY NIGHT. MODEL
SOUNDINGS INDICATE THE LOW-LEVEL FLOW SHIFTING TO THE SOUTH THROUGH
THE DAY FRIDAY WITH DECENT DRY MID-LEVEL AIR FILLING IN FROM THE
SOUTHEAST. ALTHOUGH SOME SHOWER/TSTM ACTIVITY WILL REMAIN POSSIBLE
THROUGH THE DAY FRIDAY...ESPECIALLY AROUND THE LAKE THROUGH THE
AFTERNOON PERIOD...PLENTY OF UPPER CLOUDS MAY ACT TO LIMIT
INSTABILITY DURING THE PEAK HEATING HOURS OF THE DAY...WHICH IS
INDICATED FROM THE MODEL SOUNDINGS. THE LATEST WRF MODEL
REFLECTIVITIES MAINLY SHOW SCATTERED ACTIVITY DEVELOPING ALONG AND
JUST AHEAD OF THE FRONTAL BOUNDARY LATE FRIDAY NIGHT THROUGH EARLY
SATURDAY MORNING AS THE FRONT APPROACHES AND BEGINS TO MOVE INTO
THE AREA. TEMPERATURES WILL REMAIN AT AND JUST ABOVE NORMAL
THROUGH THIS TIME...THEN TREND BACK TO NORMAL IN THE WAKE OF THE
FRONTAL BOUNDARY SATURDAY NIGHT INTO SUNDAY MORNING. 85/AG

LONG TERM...(SUNDAY-EARLY NEXT WEEK)

THE DRY WEATHER WILL REMAIN IN PLACE OVER SOUTH FLORIDA FOR EARLY
NEXT WEEK...AS HIGH PRESSURE BUILDS INTO THE SOUTHEASTERN UNITED
STATES FROM THE CENTRAL UNITED STATES. THE HIGH WILL THEN MOVE EAST
INTO THE WESTERN ATLANTIC WATERS FOR THE MIDDLE TO END OF NEXT WEEK
ALLOWING FOR A COLD FRONT TO MOVE THROUGH SOUTH FLORIDA. THIS FRONT
WILL BE A DRY COLD FRONT WHICH WILL JUST REINFORCE THE DRY WEATHER
OVER SOUTH FLORIDA FOR THE MIDDLE TO END OF NEXT WEEK.

BNB



MARINE...

LIGHT TO MODERATE NORTHEAST WINDS WILL SHIFT TO THE SOUTHEAST BY
FRIDAY AS A WARM FRONT LIFTS NORTH AND A COLD FRONT APPROACHES AND
MOVES THROUGH THE AREA FRIDAY NIGHT INTO SATURDAY MORNING. A MIX OF
NORTHEAST SWELL AND WIND WAVES WILL REMAIN AT ADVISORY LEVELS
THROUGH TONIGHT...THEN ONCE AGAIN OVER THE WEEKEND IN THE WAKE OF
THE COLD FRONT...MAINLY ACROSS THE PALM BEACH WATERS. IN ADDITION TO
THE WINDS AND SEAS...SCATTERED TO NUMEROUS SHOWERS AND ISOLATED
STORMS OVER THE LOCAL WATERS WILL BE CAPABLE OF GENERATING FREQUENT
LIGHTNING...HEAVY RAINFALL AND LOCALLY CHOPPIER CONDITIONS IN AND
AROUND THE HEAVIER SHOWERS.

&&

.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH  73  84  72  86 /  30  50  50  40
FORT LAUDERDALE  74  85  75  87 /  30  40  50  40
MIAMI            73  85  74  86 /  30  40  50  40
NAPLES           70  87  69  79 /  20  50  50  30

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 2 AM EDT FRIDAY
     FOR AMZ650-670.

GM...NONE.
&&

$$


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