Area Forecast Discussion
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FXUS62 KKEY 181048
AFDKEY

AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
645 AM EDT FRI APR 18 2014

.DISCUSSION...
DURING THE OVERNIGHT PERIOD...ITS BEEN A VERY QUIET NIGHT WITH ONLY
A FEW LIGHT SHOWERS MIGRATING NORTHWEST IN OUR REGION. DUE TO A
MODERATE TO FRESH EAST TO SOUTHEAST WIND...TEMPERATURES HAVE BEEN
STEADY IN THE MID TO UPPER 70S ALONG THE ISLAND CHAIN. SURFACE
WISE...A TROUGH OF LOW PRESSURE IS DRAPED FROM THE BAY OF CAMPECHE
INTO THE NORTHEAST GULF OF MEXICO...WITH AN EXTENSIVE AREA OF HIGH
PRESSURE ALONG THE ENTIRE EASTERN UNITED STATES. ACROSS OUR MARINE
DISTRICT...EAST TO SOUTHEAST WINDS AVERAGE BETWEEN 15 AND 20 KNOTS
WHILE A COUPLE OF SHIP REPORTS ON THE FLORIDA STRAITS INDICATE WIND
GUSTS OF NEAR 25 KNOTS.

.SHORT TERM (TODAY THROUGH SUNDAY NIGHT)...
A MID AND UPPER LEVEL TROUGH OVER EXTREME EASTERN TEXAS WILL MOVE
EAST SOUTHEASTWARD AND INTENSIFY AS IT TRACKS THROUGH THE GULF COAST
REGION TODAY AND TONIGHT...BEFORE TRACKING ACROSS NORTHERN FLORIDA
SATURDAY. BECAUSE OF THIS SYSTEM ALOFT...SURFACE CYCLOGENESIS WILL
OCCUR IN THE NORTHEAST GULF OF MEXICO THIS AFTERNOON...BEFORE
SLIDING ACROSS NORTHERN FLORIDA AND PULLING A WEAK COLD FRONT
THROUGH OUR AREA EARLY SATURDAY MORNING. THE MAIN UNCERTAINTY LIES
WITH THE EXTENT OF MID AND UPPER LEVEL ASCENT IMPACTING OUR REGION.
THE ECMWF SHOWS THE LEFT EXIT REGION OF A JET MAX AND MODEST MID AND
UPPER LEVEL DIFFERENTIAL VORTICITY NEARBY...WHILE THE GFS KEEPS THE
MAJORITY OF THE LIFT NORTH OF OUR AREA WRAPPED WITHIN THE SYSTEM.
WITH THAT SAID...HAVE DECIDED TO INSERT HIGH CHANCE POPS LATE
TONIGHT AND EARLY SATURDAY MORNING WHICH IS A BLEND OF THE MAV AND
ECMWF MOS GUIDANCE. OTHERWISE...ONLY ISOLATED SHOWERS WILL BE
CARRIED FOR TODAY BUT WITH INCREASING HIGH CLOUDINESS SPEWING
EASTWARD FROM A LARGE MESOSCALE CONVECTIVE COMPLEX IN THE GULF OF
MEXICO. IN WAKE OF THE WEAK COLD FRONT...MUCH DRIER AIR WILL
PRECLUDE SHOWER ACTIVITY SO ONLY NICKLE POPS WILL BE KEPT IN THE
GRIDS BEGINNING SATURDAY AFTERNOON. TEMPERATURES WILL RETURN TO NEAR
NORMAL WITH AVERAGE HIGHS IN THE LOWER 80S AND OVERNIGHT LOWS IN THE
LOWER 70S.

&&

.LONG TERM (MONDAY THROUGH THURSDAY)...
ALTHOUGH ECMWF REVEALS A SLIGHTLY MORE AMPLIFIED MID AND UPPER LEVEL
FLOW THAN GFS...BOTH MODELS INDICATE A FAIRLY BENIGN AND DRY PATTERN
WILL GOVERN OUR SENSIBLE WEATHER THROUGH THE PERIOD. HENCE...WILL
MAINTAIN ONLY DIME POPS BEGINNING MONDAY NIGHT WITH AVERAGE HIGH
TEMPERATURES IN THE LOWER 80S AND OVERNIGHT LOWS IN THE LOWER 70S.
&&

.MARINE...
FRESH TO STRONG EAST TO SOUTHEAST WINDS WILL PROMPT A SMALL CRAFT
ADVISORY TO REMAIN IN EFFECT FOR THE FLORIDA STRAITS AND AN EXERCISE
CAUTION HEADLINE ELSEWHERE THIS MORNING...BEFORE WINDS ABATE DURING
THIS AFTERNOON. LIGHT TO GENTLE SOUTHEAST TO SOUTH WINDS THIS
EVENING WILL BECOME SOUTHWEST LATE. AFTER MIDNIGHT...MARINERS SHOULD
BE ALERT FOR INCREASING COVERAGE OF SHOWERS AND THUNDERSTORMS...A
FEW OF WHICH COULD BE STRONG. FOR THIS WEEKEND...A TROUGH OF LOW
PRESSURE WILL PASS THROUGH OUR ENTIRE MARINE DISTRICT SATURDAY
MORNING...FOLLOWED BY FRESH NORTHWEST WINDS WHEN AN EXERCISE CAUTION
HEADLINE OR SMALL CRAFT ADVISORY MAY BE REQUIRED.

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL AT BOTH THE KEY WEST AND MARATHON
TERMINALS. THROUGH THE MORNING AND EARLY AFTERNOON WINDS WILL BE
FROM THE SOUTHEAST AT 10 TO 15 KNOTS...DECREASING BELOW 10 KNOTS
LATER IN THE AFTERNOON.

&&

.PRELIMINARY POINT TEMPS/POPS...
KEY WEST  84  73  82  72 / 10 50 30 -
MARATHON  87  73  83  72 / 10 50 30 -

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...SMALL CRAFT ADVISORY FOR GMZ052>055-072>075.

&&

$$

PUBLIC/MARINE.........APA
AVIATION/NOWCASTS.....AD

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