000
FXUS62 KKEY 160914
AFDKEY

AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
514 AM EDT THU MAY 16 2013

.DISCUSSION...
AN UPPER LEVEL RIDGE AXIS EXTENDS NORTHEASTWARD FROM OLD
MEXICO THROUGH THE GULF OF MEXICO AND INTO THE SOUTHEASTERN UNITED
STATES. UPSTREAM FROM THIS AXIS...A SOUTHERN STREAM SHORT WAVE
CONTINUES TO WEAKEN...CUTOFF FROM COLD FUEL FOR ITS BAROCLINIC
FIRE...AS IT PROGRESSES EASTWARD INTO THE RIDGE AXIS. IN THE LOW
LEVELS...A LARGE HIGH PRESSURE CELL SPINS EAST OF THE FLORIDA
PENINSULA....ROOTED AT THE SURFACE IN THE WESTERN ATLANTIC...JUST
SOUTHWEST OF BERMUDA. EASTERLY WINDS ON THE SOUTHWESTERN PERIPHERY OF
THE HIGH PRESSURE CELL HAVE BEEN SUSTAINED IN THE 15 TO 20 KNOTS
RANGE FOR MOST OF THE MORNING...WITH THE LATEST OBSERVATIONS
REVEALING A SHIFT TO THE EAST SOUTHEAST AND SUBTLE SLACKENING TO NEAR
15 KNOTS. TEMPERATURES ALONG THE ISLAND CHAIN ARE IN THE MID
70S...WITH DEWPOINTS CREEPING INTO THE MID 60S.

.SHORT TERM (TODAY THROUGH SATURDAY)...THE WESTERN EXTENSION OF THE
ATLANTIC SURFACE RIDGE WILL REMAIN MORE OR LESS IN PLACE THROUGH THE
SHORT AND LONG TERM...ALBEIT WEAKER THAN IT HAS BEEN THE PAST FEW
DAYS. EAST SOUTHEASTERLY SURFACE WINDS WILL SLOWLY INCREASE BOUNDARY
LAYER MOISTURE AND THE LOW LEVEL INVERSION WILL WEAKEN. BY FRIDAY
AFTERNOON...MESOSCALE PROCESSES SHOULD COMPLEMENT THE SYNOPTIC WIND
GRADIENT. DIFFERENTIAL HEATING OF THE LAND MASSES SHOULD PROVIDE
ENOUGH MOISTURE CONVERGENCE TO DEVELOP A CLOUD LINE. MID LEVEL
THERMODYNAMICS PORTRAY AN ATMOSPHERE RIPE WITH INSTABILITY...AND ANY
PARCEL REACHING THE LFC WILL LIKELY BE WILLED INTO DEEP CONVECTION.
THUS...WE HAVE ADDED A SLIGHT CHANCE OF THUNDERSTORMS FOR FRIDAY. THE
SAME CAN BE SAID OF FRIDAY NIGHT AND SATURDAY...ANY SHOWER THAT DOES
DEVELOP WILL NOT BE LIMITED VERTICALLY BY DRY AIR OR INCREASING
TEMPERATURES. ALSO...A FORMIDABLE SLUG OF LOW LEVEL MOISTURE NEAR
HISPANIOLA APPEARS TO BE PROGGED TO PILE UP NEAR THE FLORIDA KEYS
FRIDAY NIGHT AND INTO THE WEEKEND. IT IS DIFFICULT TO ASSESS WHETHER
THE INCREASED MOISTURE WITHIN FORECAST SOUNDINGS WILL BE FROM THE
SOUTHEASTERLY WINDS...DEEP RESIDUAL CUBAN BOUNDARIES...OR THIS
PREVIOUSLY MENTIONED SLUG OF MOISTURE. NEVERTHELESS...RAIN CHANCES
WILL BE ON THE INCREASE ON FRIDAY AND WILL CONTINUE INTO THE WEEKEND.
HI AND LOW TEMPERATURES WILL CONTINUE THEIR RECOVERY TODAY AND INTO
SATURDAY...AS SOUTH OF EAST WINDS ACCLIMATE TO THE WARM ATLANTIC
WATERS.

&&

.LONG TERM (SATURDAY NIGHT THROUGH WEDNESDAY)...THERE IS LOW
CONFIDENCE IN THE DETAILS OF THE UPPER LEVEL PATTERN THROUGH THE LONG
TERM...AS THE SUBTROPICAL JET WEAKENS AND SLIDES SOUTH OF OUR
LATITUDE. WITHOUT DESCRIPTIONS OF THE MEAN ATMOSPHERE...PREDICTIONS
OF SENSIBLE WEATHER ARE ROOTED IN DIFFICULTY. HAVE OPTED TO MAINTAIN
PERSISTENCE IN THE FORECAST...WHICH IS IN LINE WITH CLIMATOLOGY AND A
BLEND OF GUIDANCE.

&&

.MARINE...A HIGH PRESSURE RIDGE WILL PERSIST FROM THE WESTERN
NORTH ATLANTIC TO THE NORTHERN GULF OF MEXICO FOR THE NEXT SEVERAL
DAYS. THE SMALL CRAFT ADVISORY FOR THE FLORIDA STRAITS HAS BEEN
CANCELLED. SUSTAINED EAST WINDS NEAR 20 KNOTS ARE NO LONGER EXPECTED
IN THE FLORIDA STRAITS.

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL THROUGH THIS EVENING AT THE
KEY WEST AND MARATHON TERMINALS...WITH SCT-BKN STRATOCU AROUND 3500
FEET. ISOLATED SHOWERS MAY BE PRESENT OVER THE FLORIDA STRAITS AT
TIMES... BUT THE CHANCES OF THESE SHOWERS DIRECTLY IMPACTING EITHER
TERMINAL ARE EXTREMELY LOW. SURFACE WINDS WILL REMAIN FROM THE EAST
AT 8 TO 12 KNOTS WITH GUSTS OF 15 TO 18 KNOTS.


&&

.PRELIMINARY POINT TEMPS/POPS...
KEY WEST  85  78  86  79 / -  10 30 30
MARATHON  88  79  89  80 / -  10 30 30

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...NONE.
&&

$$

PUBLIC/MARINE.........CLR
AVIATION/NOWCASTS.....JACOBSON
DATA COLLECTION.......VICKERY

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