Area Forecast Discussion
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000
FXUS62 KKEY 270720
AFDKEY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
320 AM EDT FRI MAR 27 2015

.DISCUSSION...
.CURRENTLY...
STARTING CLOSE TO HOME WE FIND A CLUSTER OF SHOWERS WITH A FEW
THUNDERSTORMS ARE ALONG THE EASTERN EDGE OF THE KEYS MARINE AREA.
ANOTHER LINE OF SHOWERS IS JUST MAKING IT INTO THE 250 NM RANGE OF
THE KBYX RADAR...AND MOVING ACROSS THE EASTERN GULF OF MEXICO. WINDS
ARE OUT OF THE SOUTH NEAR 15 KNOTS...WITH SOME HIGHER GUSTS AT THIS
HOUR. A BROADER VIEW FROM SATELLITE WE CAN SEE THE REASON FOR THE
GUSTINESS. FROM WATER VAPOR IMAGES WE FIND A DISTINCT AND DEEP
FEATURE THAT WAS LIKELY A COLD POOL DROPPING OUT OF EARLIER
CONVECTION WEST OF TAMPA. THERE IS PLENTY OF LOW LEVEL MOISTURE AS
INDICATED IN THE EVENING SOUNDING WITH 1.45 INCHES OF PWAT. ALSO
SHOWN IN THE SOUNDING IS SOME WEAK LIFT.

.FORECAST...
KEEPING AN EYE ON THE WATER VAPOR IMAGES...AND EXTRAPOLATING THE
ARRIVAL OF THE PRE-FRONTAL LINE...HAVE ADJUSTED WINDS ONLY IN THIS
VERSION OF THE FORECAST. WITH THE POTENTIAL FOR ADDITIONAL CONVECTIVE
ENHANCEMENT OVER THE SOUTHEAST GULF OF MEXICO...WHICH IS BEGINNING TO
DEVELOP WEST OF NAPLES...HAVE INCREASED WINDS EARLIER...BETWEEN 15Z
AND 18Z TODAY. GUIDANCE...BOTH MESO AND SYNOPTIC SCALE...HAVE
SUGGESTED A BURST OF WINDS AHEAD OF THE ACTUAL FRONT...AND SUSPECT
THAT THE GUIDANCE WAS SUGGESTING A PRE-FRONTAL SQUALL LINE...BUT
THINK THAT THIS MAY BE OUTFLOW FROM SHOWERS AND THUNDERSTORMS ALONG
THE FRONT. WILL KEEP THE INCREASING TREND FOR LIKELY SHOWERS WITH THE
SLIGHT CHANCE OF THUNDERSTORMS. THE THETA PROFILE IS WEAK TO MODERATE
WITH A LIMIT FOR MOISTURE IN THE MODEL SOUNDINGS...WHICH WOULD NOT
LEAD TO ADEQUATE LIFTING TO INCREASE THE SLIGHT CHANCE FOR THUNDER.
THE FRONT WILL PASS THROUGH THE AREA BETWEEN 60Z AND 12Z
SATURDAY...WITH A LARGE ANTICYCLONE MOVING ACROSS THE EASTERN UNITED
STATES IN ITS WAKE. AS THE FRONT MOVES CLOSER THIS EVENING...THE
THREAT OF THUNDERSTORMS WILL DIMINISH. DECENT HEIGHT FALLS WILL
FOLLOW THE FRONT WITH COOLER AND DRIER CONTINENTAL AIR MOVING OVER
THE WARMER WATERS AROUND THE KEYS THE AREA...EXPECT WINDS TO SURGE TO
15 TO 20 MPH AND GUSTY.

MOST OF THE DISCUSSION IS FOCUSED ON THE FRONT MOVING TOWARD THE
KEYS. THE REST OF THE FORECAST WILL INCLUDE MUCH LESS MISHEGAS AS THE
RIDGE MOVING ACROSS THE EASTERN UNITED STATES WILL SLIDE SOUTHWARD
THROUGH THE WEEKEND WITH THE RIDGE AXIS CROSSING THE FLORIDA
PENINSULA MONDAY AFTERNOON...THEN THE NEXT AREA OF HIGH PRESSURE
MOVES OVER THE CAROLINA COAST...REINFORCING THE RIDGING FOR THE
KEYS. THIS TURNS WINDS MORE EASTERLY WHILE INCREASING WINDS A BIT
TUESDAY NIGHT AND WEDNESDAY. WITH THE INCREASE IN EASTERLIES...HAVE
ADDED SLIGHT CHANCE OF SHOWERS THURSDAY THROUGH FRIDAY NIGHT.


&&

.MARINE...
A COLD FRONT IS MOVING SOUTHWARD ACROSS THE EASTERN GULF OF MEXICO
AND WILL PASS THROUGH THE KEYS AREA EARLY SATURDAY MORNING.
CONVECTION OVER THE GULF WILL SEND OUTFLOWS TOWARD THE AREA THROUGH
THE DAY WITH A GRADUALLY INCREASING CHANCE FOR SHOWERS THIS
MORNING...AND SOME ISOLATED THUNDERSTORMS MAY CROSS THE AREA LATE
THIS AFTERNOON. A ROBUST AREA OF HIGH PRESSURE WILL FOLLOW THE
FRONT...FRESHENING WINDS WHILE TURNING THEM AROUND THE COMPASS ROSE
FROM SOUTH THROUGH NORTH BY SATURDAY MORNING. A SMALL CRAFT ADVISORY
WILL ALMOST CERTAINLY BE REQUIRED FOR THE AFTERNOON FORECAST. AS THE
FRONT MOVES PAST...EXPECT FRESH TO STRONG SUSTAINED WINDS WITH HIGHER
GUSTS THROUGH SATURDAY NIGHT ON ALL KEYS WATERS...AND POSSIBLY
THROUGH SUNDAY OVER THE STRAITS OF FLORIDA. BY SUNDAY NIGHT ALL
ADVISORY AND CAUTIONARY STATEMENTS SHOULD BE RESCINDED...AND NONE
WILL BE REQUIRED THROUGH WEDNESDAY.

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL AT EYW AND MTH THIS MORNING INTO EARLY
THIS AFTERNOON. IFR OR LOWER CONDITIONS ARE CONCEIVABLE AT EYW AND
MTH AHEAD OF AN APPROACHING COLD FRONT LATE THIS AFTERNOON INTO
EARLY TONIGHT. SUSTAINED SOUTH TO SOUTHWEST WINDS NEAR 15 KNOTS FROM
JUST OFF THE SURFACE TO ABOUT 3000 FEET WILL SHIFT TO NORTHWEST AND
INCREASE TO 20 TO 25 KNOTS THIS EVENING.

&&

.CLIMATE...
ON THIS DATE IN FLORIDA KEYS WEATHER HISTORY...IN 1940...2.07 INCHES
OF RAIN FELL IN KEY WEST. THIS SET THE DAILY RECORD FOR MAXIMUM
RAINFALL MEASURED IN KEY WEST ON MARCH 27TH...A RECORD WHICH STILL
STANDS 75 YEARS LATER. RAINFALL RECORDS AT KEY WEST DATE BACK TO
1871.

&&

.PRELIMINARY POINT TEMPS/POPS...
KEY WEST  84  70  73  63 / 60 50 -  -
MARATHON  88  69  74  62 / 60 50 -  -

&&

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

$$

PUBLIC/MARINE.................BWC
AVIATION/NOWCASTS/CLIMATE.....BS

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