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000
FXUS62 KKEY 190804
AFDKEY

AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
404 AM EDT FRI SEP 19 2014

.DISCUSSION...BROAD CYCLONIC FLOW PREVAILS IN THE MID TO UPPER LEVELS
ACROSS THE EASTERN THIRD OF THE UNITED STATES. THE BASE OF THIS LONG
WAVE TROUGH SLANTS FROM THE NORTHERN GULF COAST TO SOUTHERN FLORIDA
AND THE BAHAMAS. DEWPOINTS RANGE FROM THE MID 60S IN THE SOUTHEASTERN
UNITED STATES TO THE MID 70S ACROSS THE FLORIDA KEYS...BROADLY
DEFINING AN AIRMASS BOUNDARY. PRESSURE FIELDS PLACE A WEAK...EAST-
WEST TROUGH AXIS ACROSS CENTRAL AND SOUTHERN FLORIDA AND THE EASTERN
GULF. THIS SURFACE TROUGH IS NESTLED UNDERNEATH CIMSS IDENTIFIED LOW
LEVEL VORTICITY...AND THE AFOREMENTIONED BASE OF THE UPPER LEVEL
TROUGH. SHOWER COVERAGE HAS INCREASED ACROSS THE SOUTHEASTERN GULF
WATERS...WHILE ISOLATED SHOWERS WAX AND WANE OVER THE REMAINING
COASTAL WATERS OF THE FLORIDA KEYS. TEMPERATURES RANGE FROM THE
UPPER 70S TO LOWER 80S.

.SHORT TERM (TODAY THROUGH SUNDAY)...THE FORECAST THROUGH THE SHORT
TERM WILL HINGE UPON UPPER LEVEL ENERGY MOVING THROUGH THE
MISSISSIPPI RIVER VALLEY. NORMALLY...SYNOPTIC FEATURES OF THIS
VARIETY BECOME WELL ANALYZED BY THE AVAILABLE MODEL CAMPS...BUT THIS
IS NOT THE CASE. MODEL INITIALIZATIONS...OVERLAID WITH SATELLITE
IMAGERY AND THE MOST RECENT CIMSS ANALYSES DO NOT CONFORM WITH ONE
ANOTHER. NEVERTHELESS...THIS ENERGY WILL ACT UPON AND SHARPEN THE LOW
LEVEL TROUGH TO OUR NORTH...TODAY THROUGH SATURDAY...EVENTUALLY
LEADING TO CYCLOGENESIS EAST OF CENTRAL FLORIDA SATURDAY EVENING OR
SATURDAY NIGHT. FOR TODAY...EXPECT MOST OF THE SYNOPTIC CONFLUENCE TO
REMAIN NORTH OF THE FLORIDA KEYS...LEAVING THE ISLAND CHAIN SETUP FOR
A REVERSE CU-LINE SCENARIO. THEREAFTER...WE WILL REMAIN WITHIN THE
ZONE OF TRAILING CONFLUENCE BEHIND THE DEVELOPING SURFACE LOW AND THE
PRESSING SURFACE RIDGE TO OUR EAST. RAIN CHANCES ARE ADVERTISED TO
DROP ON SUNDAY...BUT WITH LITTLE CONFIDENCE. HIGH TEMPERATURES WILL
BE BELOW NORMAL DUE TO THE ENHANCED CLOUD COVER...WHILE LOW
TEMPERATURES WILL BE DETERMINED BY THOSE AREAS COOLED BY RAIN.

&&

.LONG TERM (SUNDAY NIGHT THROUGH THURSDAY)...THE LONG WAVE TROUGH
ACROSS THE EASTERN UNITED STATES FINALLY BREAKS AS UPPER LEVEL
RIDGING PROGRESSES EAST INTO THE CENTRAL UNITED STATES...SHUNTING
THE WAVE TRAIN EAST OF NEW ENGLAND. DESPITE THIS LONG WAVE
SOLUTION...DETERMINISTIC RUNS HAVE HAD EXTREME DIFFICULTY ADJUSTING
TO THIS PATTERN CHANGE AND IRONING OUT THE DETAILS. OUR FORECAST FOR
THE LONG TERM TRENDS TOWARDS CLIMO. A COUPLE UNDULATIONS IN THE
EASTERLIES PASS THROUGH MID WEEK...BUT THE AVAILABLE MODEL OPINIONS
ARE OUT OF PHASE BY MORE THAN 24 HOURS. WE HAVE RETAINED THE
PREVIOUS FORECAST THOUGHTS...BUT WILL PASS ALONG THE TIMING
DIFFERENCES WHICH ARE BOUND TO CHANGE.

&&

.MARINE...NO ADVISORIES AND NO HEADLINES. A WEAK PRESSURE PATTERN
ACROSS THE FLORIDA KEYS AND ADJACENT COASTAL WATERS WILL SUPPORT
LIGHT SOUTHWEST TO WEST (OCCASIONALLY VARIABLE) BREEZES THROUGH
SATURDAY NIGHT. A RIDGE MAY BEGIN TO BUILD BACK OVER THE FLORIDA
PENINSULA THEREAFTER. WINDS AND SEAS WILL BE HIGHER IN-AND-NEAR
SCATTERED SHOWERS AND THUNDERSTORMS.

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL. WITH THAT SAID...THERE WILL
BE A CHANCE FOR A SPELL OR TWO OF MVFR CONDITIONS AT THE ISLAND
TERMINALS...ESPECIALLY AT MTH. SURFACE WINDS WILL BE LIGHT AND
VARIABLE...TENDING OUT OF THE SOUTHWEST.


&&

.PRELIMINARY POINT TEMPS/POPS...
KEY WEST  87  78  87  79 / 40 50 50 50
MARATHON  88  78  88  79 / 40 50 50 50

&&

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

$$

PUBLIC/MARINE.........CLR
AVIATION/NOWCASTS.....11
DATA COLLECTION.......CHESSER

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