Area Forecast Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KKEY 280845
AFDKEY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
445 AM EDT THU MAY 28 2015

.DISCUSSION...
A REVIEW OF UPPER-AIR DATA ACROSS THE REGION DURING THE LAST 24 HOURS
INDICATES THAT THE DEEP LAYER MEAN ANTICYCLONE WHICH HAS BEEN
GOVERNING THE LARGE-SCALE FORCING OVER THE SERVICE AREA HAS WEAKENED
FURTHER AND SHIFTED EASTWARD ALONG THE NORTHERN FLANK OF A RATHER
LARGE...DEEP...COLD-CORE CYCLONIC GYRE PRESENT OVER THE CENTRAL NORTH
ATLANTIC. RECENT SATELLITE-DERIVED SOUNDINGS AROUND THE KEYS AGAIN
SHOW VERY DRY AIR ALOFT...WITH DEWPOINT DEPRESSIONS OF 8C AND 27C AT
850MB AND 700MB...RESPECTIVELY. HOWEVER...THIS HOSTILE MOISTURE
ENVIRONMENT HAS NOT BEEN ABLE TO COMPLETELY SUPPRESS DEEP MOIST
CONVECTION OVER THE SERVICE AREA DURING THE LAST 24 HOURS...AND SOME
THUNDERSTORMS WERE EVEN ABLE TO DEVELOP OVER THE EXTREME SOUTHEASTERN
GULF OF MEXICO WEDNESDAY EVENING...AND MOVE OVER THE WATERS AROUND
DRY TORTUGAS NATIONAL PARK. AT PRESENT...ISOLATED SHOWERS AGAIN ARE
ROAMING THE WATERS IN THE VICINITY OF DRY TORTUGAS...WITH OTHER
ISOLATED SHOWERS AND SPRINKLES AROUND PORTIONS OF HAWK CHANNEL AND
THE STRAITS OF FLORIDA. THE DRY AIR WHICH HAS BEEN FILTERING INTO
THE KEYS FROM THE SUBTROPICAL ATLANTIC OVER THE LAST FEW DAYS HAS
EVEN REACHED THE SURFACE. CURRENTLY...DEWPOINT TEMPERATURES IN KEYS
ISLAND COMMUNITIES ARE IN THE UPPER 60S...WHILE AIR TEMPERATURES
RANGE FROM THE UPPER 70S TO NEAR 80. SKIES ARE MOSTLY CLEAR OVER THE
KEYS.

LARGE-SCALE FORCING DURING THE NEXT SEVERAL DAYS SHOULD BE VERY WEAK.
THIS COMBINED WITH GRADUALLY WEAKENING LOWER-TROPOSPHERIC MOMENTUM
WILL INCREASINGLY FAVOR DEVELOPMENT OF MORE INFLUENTIAL DAILY
MESOSCALE CIRCULATIONS...INCLUDING SEA/LAND BREEZES...OUTFLOW
BOUNDARIES...ETC. THE MOIST LAYER WILL BOTH DEEPEN AND ENRICH SLOWLY
OVER THE NEXT SEVERAL DAYS...AND THIS IN TURN WILL REDUCE STATIC
STABILITY...INCREASING THE PROBABILITY OF CUMULUS TOWERS GROWING
INTO THUNDERSTORMS. DRY AIR AT 850MB AND ABOVE STILL WILL REMAIN A
SIGNIFICANT LIMITING FACTOR. AN EVEN WETTER PERIOD MAY BE SETTING UP
FOR NEXT WEEK AS RICH TROPICAL MOISTURE APPROACHES FROM THE
CARIBBEAN. THIS WOULD BE RIGHT ON TIME AS THE FLORIDA KEYS RAINY
SEASON TYPICALLY RAMPS UP DURING THE FIRST WEEK OF JUNE. &&

.MARINE...
A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR HAWK CHANNEL AND THE
STRAITS OF FLORIDA THIS MORNING. SMALL CRAFT SHOULD EXERCISE CAUTION
IN FLORIDA BAY AND THE EXTREME SOUTHEASTERN GULF OF MEXICO. A HIGH
PRESSURE CELL FROM THE WESTERN NORTH ATLANTIC TO THE SOUTHEASTERN
UNITED STATES WILL WEAKEN GRADUALLY BETWEEN TODAY AND MONDAY. PERIODS
OF FRESH EAST BREEZES ARE LIKELY ACROSS FLORIDA KEYS COASTAL WATERS
TODAY THROUGH FRIDAY MORNING...WITH GRADUALLY SLACKENING BREEZES
THEREAFTER. WINDS WILL TEND TO FRESHEN AT NIGHT AND SLACKEN DURING
THE DAY...ESPECIALLY ACROSS HAWK CHANNEL AND THE STRAITS OF FLORIDA.
&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL AT THE KEY WEST AND MARATHON TERMINALS
TODAY. EAST WINDS WILL CONTINUE BETWEEN 10 AND 15 KNOTS WITH GUSTS UP
TO NEAR 20 KNOTS.
&&

.CLIMATE...
ON THIS DATE IN FLORIDA KEYS WEATHER HISTORY...IN 1953...THE DAILY
RECORD HIGH TEMPERATURE OF 92F WAS RECORDED. TEMPERATURE RECORDS AT
KEY WEST DATE BACK TO 1872.
&&

.PRELIMINARY POINT TEMPS/POPS...
KEY WEST  87  79  87  79 / 20 20 20 20
MARATHON  89  79  89  79 / 20 20 20 20
&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...SMALL CRAFT ADVISORY IN EFFECT FOR GMZ042-GMZ043-GMZ044-
     GMZ052-GMZ053-GMZ054-GMZ055-GMZ072-GMZ073-GMZ074-GMZ075.
&&

$$

PUBLIC/MARINE.........KASPER
AVIATION/NOWCASTS.....KN
DATA COLLECTION.......KN

VISIT US ON THE WEB AT WEATHER.GOV/KEY

FOLLOW US ON FACEBOOK AND TWITTER AT...

WWW.FACEBOOK.COM/NWSKEYWEST
WWW.TWITTER.COM/NWSKEYWEST


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.