Special Marine Warning 113, NWS Key West, FL

AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
347 PM EDT TUE MAY 28 2013

.DISCUSSION...
TODAY HAS BEEN CLOUDY...RAINY...AND OCCASIONALLY STORMY ACROSS THE
FLORIDA KEYS AND ADJACENT COASTAL WATERS. CURRENTLY...AIR
TEMPERATURES IN MOST ISLAND COMMUNITIES ARE WITHIN A FEW DEGREES OF
80F...COOLER WHERE RECENT RAINS HAVE FALLEN...AND WARMER WHERE IT HAS
BEEN RAIN-FREE FOR A FEW HOURS. EASTERLY BREEZES PREVAIL ACROSS THE
SERVICE AREA.

THE SYNOPTIC SITUATION FEATURES A SOMEWHAT COMPLEX ARRANGEMENT OF
ATMOSPHERIC FORCES INVOLVING THE COUPLING OF FORCE FIELDS ASSOCIATED
WITH A SLOW-MOVING UPPER-TROPOSPHERIC SHORT-WAVE TROUGH OVER THE
EASTERN GULF OF MEXICO AND A LOWER-TROPOSPHERIC CYCLONIC VORTICITY
AND CONVERGENCE ZONE FROM WESTERN CUBA TO THE NORTHERN BAHAMAS.
FORCING FOR LARGE-SCALE ASCENT COINCIDES WITH THE NORTHERN PORTION OF
A LARGE PLUME OF RICH TROPICAL MOISTURE WHICH EXTENDS NORTH FROM THE
CARIBBEAN BASIN. AS A CONSEQUENCE...THE LOCAL ATMOSPHERE HAS BEEN
ABLE TO MAINTAIN AN UNSTABLY STRATIFIED VERTICAL PROFILE WITH LITTLE
OR NO CONVECTIVE INHIBITION. NUMEROUS AREAS OF MESOSCALE CONVERGENCE
HAVE SUPPORTED READY INITIATION OF SHOWERS AND THUNDERSTORMS...AND
THE DEEP MOIST LAYER HAS FACILITATED LONG-LIVED LAYERS OF
NIMBOSTRATUS CLOUDS AND RESULTANT LINGERING AREAS OF RAIN.

CLOUDY SKIES WITH HIGH RAIN CHANCES ARE FORECAST TONIGHT AND
WEDNESDAY WITH A CHANCE FOR THUNDERSTORMS AND LOCALLY HEAVY RAINFALL
AS WELL.

FOR WEDNESDAY NIGHT THROUGH SATURDAY...BOTH SKY COVER AND RAIN
CHANCES WILL REMAIN WELL ABOVE CLIMATOLOGICAL AVERAGES OWING TO THE
PRESENCE OF A DEEP...RICH...TROPICAL MOIST LAYER AND A SYNOPTIC-SCALE
VERTICAL MOTION PROFILE WHICH WILL AVERAGE NEUTRAL TO WEAK ASCENT.
THE MEAN SEA LEVEL PRESSURE PATTERN EVOLUTION IS SOMEWHAT UNCERTAIN
OWING TO THE FACT THAT THE RIDGE WILL REMAIN FAR AWAY TO THE NORTH
AND NUMERICAL WEATHER PREDICTION MODELS SHOW VARYING DEGREES OF
UNDULATION AND ASSOCIATED WIND SPEED MAXIMA AND MINIMA AROUND THE
FLORIDA KEYS. IN THE MEAN...A FRESH TO OCCASIONALLY STRONG EAST TO
SOUTHEAST FLOW IS EXPECTED. HOWEVER...NUMEROUS PEAKS AND LULLS ARE
LIKELY WITH HOUR-TO-HOUR WIND SPEEDS HIGHLY UNCERTAIN.
&&

.MARINE...
SMALL CRAFT SHOULD EXERCISE CAUTION TONIGHT...ESPECIALLY IN AND NEAR
SHOWERS AND SCATTERED THUNDERSTORMS WHERE LOCALLY GUSTY WINDS...
HEAVY DOWNPOURS...AND LIGHTNING STRIKES ARE POSSIBLE. A SMALL CRAFT
ADVISORY MAY BE REQUIRED LATER THIS EVENING AS EAST TO SOUTHEAST
BREEZES LIKELY SURGE AFTER DARK. WE LIKELY WILL CONTINUE FLIRTING
WITH SMALL CRAFT ADVISORY CRITERIA FOR THE NEXT FEW DAYS AS A WAVY
PRESSURE PATTERN PERSISTS AT THE SURFACE. SHOWER AND THUNDERSTORM
COVERAGE WILL REMAIN WELL ABOVE NORMAL TONIGHT AND WEDNESDAY... WITH
RAIN CHANCES FALLING OFF SLOWLY THEREAFTER.
&&

.AVIATION...
INTERMITTENT MVFR/IFR CONDITIONS ARE LIKELY AT EYW AND MTH THIS
AFTERNOON AND TONIGHT. SUSTAINED EAST TO SOUTHEAST WINDS NEAR 15
KNOTS FROM JUST OFF THE SURFACE TO ABOUT 3000 FEET WILL INCREASE TO
20 TO 25 KNOTS THIS EVENING.
&&

.CLIMATE...
ON THIS DATE IN KEYS WEATHER HISTORY...IN 1916...THE LOW TEMPERATURE
IN KEY WEST WAS 68 DEGREES. THIS SET THE DAILY RECORD FOR MINIMUM
TEMPERATURE MEASURED IN KEY WEST ON MAY 28TH...A RECORD WHICH STILL
STANDS 97 YEARS LATER. TEMPERATURE RECORDS AT KEY WEST DATE BACK TO
1872.
&&

.PRELIMINARY POINT TEMPS/POPS...
KEY WEST  77  85  78  87 / 80 70 50 50
MARATHON  77  85  78  88 / 80 70 50 50
&&

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

PUBLIC/MARINE.........KASPER
AVIATION/NOWCASTS.....BS
DATA COLLECTION.......JACOBSON

VISIT US ON THE WEB AT WWW.WEATHER.GOV/KEYWEST

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE KEY WEST FL
1030 AM EDT TUE MAY 28 2013

FLZ076>078-GMZ031>035-042>044-052>055-072>075-291000-
MONROE UPPER KEYS-MONROE MIDDLE KEYS-MONROE LOWER KEYS-
FLORIDA BAY INCLUDING BARNES SOUND, BLACKWATER SOUND, AND BUTTONWOOD
SOUND-
BAYSIDE AND GULF SIDE FROM CRAIG KEY TO WEST END OF SEVEN MILE
BRIDGE-
GULF WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE 20 TO 60 NM OUT AND
BEYOND 5 FATHOMS-
GULF OF MEXICO INCLUDING DRY TORTUGAS AND REBECCA SHOAL CHANNEL-
GULF OF MEXICO FROM WEST END OF SEVEN MILE BRIDGE TO HALFMOON SHOAL
OUT TO 5 FATHOMS-
HAWK CHANNEL FROM OCEAN REEF TO CRAIG KEY OUT TO THE REEF-
HAWK CHANNEL FROM CRAIG KEY TO WEST END OF SEVEN MILE BRIDGE OUT TO
THE REEF-
HAWK CHANNEL FROM WEST END OF SEVEN MILE BRIDGE TO HALFMOON SHOAL
OUT TO THE REEF-
STRAITS OF FLORIDA FROM OCEAN REEF TO CRAIG KEY OUT 20 NM-
STRAITS OF FLORIDA FROM CRAIG KEY TO WEST END OF SEVEN MILE BRIDGE
OUT 20 NM-
STRAITS OF FLORIDA FROM WEST END OF SEVEN MILE BRIDGE TO SOUTH OF
HALFMOON SHOAL OUT 20 NM-
STRAITS OF FLORIDA FROM HALFMOON SHOAL TO 20 NM WEST OF DRY TORTUGAS
OUT 20 NM-
STRAITS OF FLORIDA FROM OCEAN REEF TO CRAIG KEY 20 TO 60 NM OUT-
STRAITS OF FLORIDA FROM CRAIG KEY TO WEST END OF SEVEN MILE BRIDGE
20 TO 60 NM OUT-
STRAITS OF FLORIDA FROM WEST END OF SEVEN MILE BRIDGE TO SOUTH OF
HALFMOON SHOAL 20 TO 60 NM OUT-
STRAITS OF FLORIDA FROM HALFMOON SHOAL TO 20 NM WEST OF DRY TORTUGAS
20 TO 60 NM OUT-
1030 AM EDT TUE MAY 28 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE FLORIDA KEYS AND ADJACENT
COASTAL WATERS.

.DAY ONE...THIS AFTERNOON AND TONIGHT

SCATTERED THUNDERSTORMS WILL IMPACT THE FLORIDA KEYS...AS WELL AS
NEARSHORE AND OFFSHORE WATERS SURROUNDING THE ISLAND CHAIN. THE
PRIMARY THUNDERSTORM HAZARDS WILL BE CLOUD TO SURFACE LIGHTNING
STRIKES AND WIND GUSTS NEAR 30 KNOTS.

A SMALL CRAFT ADVISORY WILL LIKELY BE REQUIRED FOR ALL KEYS COASTAL
WATERS TONIGHT.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE ALONG THE FLORIDA
KEYS...AS WELL AS OVER NEARSHORE AND OFFSHORE WATERS ADJACENT TO THE
ISLAND CHAIN. THE PRIMARY THUNDERSTORM HAZARDS WILL BE CLOUD TO
SURFACE LIGHTNING STRIKES AND LOCALLY GUSTY WINDS.

A SMALL CRAFT ADVISORY WILL LIKELY BE REQUIRED FOR ALL KEYS COASTAL
WATERS WEDNESDAY. A SMALL CRAFT ADVISORY MAY BE REQUIRED FOR ALL
KEYS COASTAL WATERS WEDNESDAY NIGHT THROUGH THURSDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.

BS