Area Forecast Discussion
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000
FXUS62 KKEY 010858
AFDKEY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
458 AM EDT SAT AUG 1 2015

.DISCUSSION...THE CENTER OF A LARGE UPPER-LEVEL ANTICYCLONIC GYRE
HAS SHIFTED WEST INTO THE SOUTHERN ROCKIES...SUPPORTED BY THE FALLING
MEAN LAYER HEIGHTS ACROSS TEXAS (SEE 00Z RAOB ANALYSIS). THE MOST
RECENT WATER VAPOR IMAGERY REVEALS A WESTWARD MOVING TROPICAL UPPER
TROPOSPHERIC TROUGH (TUTT) ACROSS THE BAHAMAS. IN BETWEEN THESE TWO
FEATURES...A NEARLY PERMANENT SURFACE TROUGH STRETCHES FROM THE
NORTHWESTERN GULF TO THE CAROLINA COASTS. LOCALLY...THE WESTERN
ATLANTIC RIDGE HAS BUILT INTO THE FLORIDA KEYS AND THE SOUTHERN
FLORIDA PENINSULA...MIRRORING THE RETROGRADE OF THE LARGE
ANTICYCLONE. WINDS ARE SOUTHEASTERLY AT THE AVAILABLE OBSERVING
STATIONS AND AVERAGE 10 TO 15 KNOTS. TEMPERATURES ALONG THE ISLAND
CHAIN ARE IN THE MID 80S...A FEW DEGREES BELOW HAWK CHANNEL`S WATER
TEMPERATURE. THE KBYX RADAR DETECTS A FEW SHOWERS ACROSS THE STRAITS
OF FLORIDA. A LARGE AREA OF DIFFLUENCE...BETWEEN THE TUTT AND THE
SOUTHEASTERN FRINGES OF THE ANTICYCLONE...CONTINUES TO STREAM MID-
UPPER LEVEL CLOUDS ACROSS OUR AREA.

.SHORT TERM (TODAY THROUGH MONDAY)...VERY LITTLE CHANGE TO THE
FORECAST REASONING. THE SURFACE RIDGE AXIS WILL REMAIN NORTH OF THE
KEYS LENDING TO GENTLE-MODERATE SOUTHEASTERLY BREEZES. THE LOWER
TROPOSPHERE (850-600MB) WILL BE WARM AND DRY...THEREFORE...EXPECT A
HOSTILE ENVIRONMENT FOR CONVECTIVE UPDRAFTS. RAIN CHANCES WILL BE
SLIGHT (10%) THROUGH SUNDAY NIGHT...WITH LOWS IN THE LOWER TO MID 80S
AND AFTERNOON HIGHS IN THE LOWER 90S. BASED ON THE AVAILABLE
NUMERICAL GUIDANCE RAIN CHANCES WILL INCREASE ON MONDAY...LIKELY DUE
TO AN IDEAL SETUP FOR ISLAND CLOUD-LINE GENESIS. ADDITIONALLY...THE
WESTWARD MOVING TUTT`S INFLUENCE WILL BE MAXIMIZED ON MONDAY...IF IT
CAN LINK-UP WITH THE LOWER TROPOSPHERE.

&&

.LONG TERM (MONDAY NIGHT THROUGH FRIDAY)...STEERING FLOW WILL REMAIN
WEAK THROUGH THE LONG TERM. THE RIDGE AXIS WILL LINGER ACROSS...OR
JUST NORTH OF THE KEYS. THUS...NEAR NORMAL TEMPERATURES AND RAIN
CHANCES...WITH LIGHT TO GENTLE BREEZES. NO CHANGES NEEDED FROM THE
INHERITED FORECAST.

&&

.MARINE...A RIDGE OF HIGH PRESSURE WILL LIFT NORTH OF THE FLORIDA
KEYS COASTAL WATERS TODAY AND TONIGHT. THIS RIDGE WILL LIE NEAR OR
JUST NORTH OF THE KEYS SUNDAY THROUGH WEDNESDAY NIGHT.

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL AT THE ISLAND TERMINALS
TODAY. WINDS WILL BE GENTLE RANGING OUT OF A MAINLY SOUTHEASTERLY
DIRECTION.

&&

.PRELIMINARY POINT TEMPS/POPS...
KEY WEST  90  83  90  82 / 10 10 10 10
MARATHON  93  83  93  82 / 10 10 10 10

&&

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

$$

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

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