Area Forecast Discussion
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FXUS62 KKEY 111952
AFDKEY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
252 PM EST THU FEB 11 2016

.DISCUSSION...A BROAD MID-UPPER LEVEL TROUGH PERSISTS ACROSS THE
EASTERN HALF OF THE UNITED STATES...ANCHORED BY UPSTREAM RIDGING WEST
OF THE ROCKIES. A DRY AND STABLE CP AIRMASS REMAINS ENTRENCHED AT THE
SURFACE EAST OF THE ROCKIES. HIGH TEMPERATURES THIS AFTERNOON HAVE
REACHED INTO THE MID 60S. MODERATE NORTH TO NORTHEAST BREEZES
HAVE MAINTAINED THEIR STRENGTH...AND AVERAGE NEAR 15 KNOTS ALONG THE
REEF TRACT...WITH GUSTS APPROACHING 20 KNOTS. THE RADAR REMAINS FREE
OF METEOROLOGICAL ECHOES.

.SHORT TERM (TONIGHT THROUGH SATURDAY NIGHT)...A EASTWARD MOVING SHORT
WAVE TROUGH AXIS IN THE SOUTHERN GULF OF MEXICO WILL REACH SOUTH
FLORIDA AFTER MIDNIGHT. SUBSIDING AIR ON THE BACK SIDE OF THIS AXIS
WILL AIDE IN THE EROSION OF PERSISTENT CIRRUS CURRENTLY STREAKING
ACROSS THE AREA. MODEL GUIDANCE INDICATES WINDS WILL VEER TO THE
EAST- NORTHEAST...HOWEVER...THESE PREDICTIONS APPEAR DUBIOUS GIVEN
THE DRASTIC GRADIENT IN WATER TEMPERATURES BETWEEN THE GULF SIDE AND
THE ATLANTIC SIDE. A REINFORCING SHOT OF CP AIR WILL PUSH THROUGH THE
KEYS LATE SATURDAY AND SATURDAY NIGHT. RAIN CHANCES THROUGH THE
SHORT TERM WILL BE NEARLY NIL. TEMPERATURES WILL SLOWLY MODERATE
THROUGH SATURDAY...THEN DROP A FEW DEGREES WITH A BRIEF EPISODE OF
COLD AIR ADVECTION SATURDAY NIGHT.

&&

.LONG TERM (SUNDAY THROUGH THURSDAY)...A DIXIE BOUND SHORT WAVE
TROUGH WILL DIVE SOUTHEAST THROUGH THE ROCKIES AND PLAINS SUNDAY
THROUGH MONDAY NIGHT. AT THE SAME TIME...THE WESTERN ATLANTIC
SUBTROPICAL RIDGE WILL CONCEDE TO THE LOWER HEIGHTS ACROSS THE
EASTERN UNITED STATES. THUS...THE PRESSURE GRADIENT WILL STRENGTHEN
AS WIND TRAJECTORIES VEER TO THE EAST SOUTHEAST. WE REDUCED DIGITAL
AND DERIVED WIND SPEEDS FOR THE COOLER WATERS BAYSIDE AND GULF SIDE
OF THE ISLAND CHAIN...A PROBABLE OCCURRENCE WHEN WINDS TURN TO THE
EAST-SOUTHEAST IN THE WINTER. WARM AIR ADVECTION AND ISENTROPIC
UPGLIDE WILL RESULT IN INCREASING RAIN CHANCES MONDAY
NIGHT...FOLLOWED TUESDAY BY RAIN CHANCES ASSOCIATED WITH THE
CONFLUENT FLOW AHEAD OF A COLD FRONT. WE INCREASED RAIN CHANCES TO 30
PERCENT FOR BOTH THESE PERIODS. COLD AIR ADVECTION IS EXPECTED
TUESDAY NIGHT INTO WEDNESDAY AFTERNOON...HOWEVER...THE STRENGTH OF
THE NOR`EASTER ALONG THE ATLANTIC COAST WILL GOVERN HOW LOW
TEMPERATURES WILL FALL. THEREFORE...WE BLENDED GUIDANCE FOR TUESDAY
NIGHT THROUGH THURSDAY TO ACCOUNT FOR THIS UNCERTAINTY.

&&

.MARINE...SMALL CRAFT SHOULD EXERCISE CAUTION ACROSS THE FLORIDA
STRAITS DUE TO NORTHEAST WINDS AVERAGING 15 TO 20 KNOTS. FROM
SYNOPSIS...AN AREA OF HIGH PRESSURE WILL MOVE EASTWARD ACROSS THE
GULF OF MEXICO TONIGHT AND FRIDAY. A REINFORCING HIGH PRESSURE AREA
THEN WILL BUILD SOUTHEASTWARD...ACROSS THE GULF OF MEXICO AND FLORIDA
PENINSULA ON SATURDAY AND SUNDAY.

&&

.AVIATION...PREDOMINATE VFR CONDITIONS WILL PREVAIL AT BOTH THE KEY
WEST AND MARATHON ISLAND TERMINALS THROUGH THE END OF THE FORECAST
PERIOD. GENTLE BREEZES WILL HAIL FROM THE NORTH NORTHEAST...AVERAGING
BETWEEN 5 TO 10 KNOTS OVERNIGHT...AND NEAR 10 KNOTS FROM MID MORNING
FRIDAY ONWARD. SCT CIRRUS AOA 250 WILL ERODE THIS EVENING...RESULTING
IN CLEAR SKIES...AS LOW LEVEL MOISTURE WILL REMAIN LIMITED...AND RAIN
CHANCES NEAR NIL.

&&

.CLIMATE...ON THIS DATE IN KEY WEST WEATHER HISTORY...BACK IN THE
YEAR 2000...THE DAILY RECORD LOW TEMPERATURE OF 50F WAS RECORDED.
THE LAST TIME TEMPERATURES IN KEY WEST DIPPED TO 50F OR COLDER WAS
BACK ON FEBRUARY 21ST 2015...SOME 355 DAYS AGO. TEMPERATURE RECORDS
IN KEY WEST DATE BACK TO THE YEAR 1872.

&&

.PRELIMINARY POINT TEMPS/POPS...
KEY WEST  60  73  63  72 / 0 0 0 0
MARATHON  59  73  61  72 / 0 0 0 0

&&

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

$$

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

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