Wind Chill Advisory 1, NWS Key West, FL

000 
WWUS42 KKEY 051408
WSWKEY

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE KEY WEST FL
910 AM EST THU FEB 5 2009

FLZ076-051525-
/O.EXP.KKEY.WC.Y.0001.000000T0000Z-090205T1400Z/
MONROE UPPER KEYS-
INCLUDING THE COMMUNITIES OF...OCEAN REEF...KEY LARGO...ISLAMORADA
910 AM EST THU FEB 5 2009

...THE WIND CHILL ADVISORY FOR THE UPPER KEYS HAS EXPIRED...

AS OF 900 AM...TEMPERATURES IN THE UPPER KEYS ARE IN THE LOWER 
40S...WITH A SUSTAINED WIND NEAR 15 MPH...PRODUCING WIND CHILLS IN 
THE LOWER 30S. AS TEMPERATURE CLIMB THROUGH THE 40S THIS MORNING...
WIND CHILL READINGS WILL RISE ABOVE 35 DEGREES. ALTHOUGH WIND CHILL 
READINGS IN THE NEXT HOUR WILL REMAIN BELOW 35 DEGREES...THE 
REQUIREMENT OF 4 HOURS OF LESS THAN 35 DEGREE WIND CHILL READINGS 
WILL NOT BE MET. THEREFORE...THE WIND CHILL ADVISORY THAT WAS IN 
EFFECT FOR THE UPPER KEYS HAS BEEN ALLOWED TO EXPIRE. 

$$
BS

AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
1105 PM EST WED FEB 4 2009

.DISCUSSION...
.CURRENTLY...
A WINDY AND COLD NIGHT IS IN PROGRESS ACROSS THE FLORIDA KEYS. STRONG
COLD ADVECTION IN THE WAKE A COLD FRONT THAT PLUNGED THROUGH THE KEYS
THIS AFTERNOON IS DRIVING TEMPERATURES ALONG THE ISLAND CHAIN
STEADILY DOWNWARD THROUGH THE 50S THIS EVENING. AS OF 10 PM...TEMPS
RANGED FROM THE LOWER 50S IN THE UPPER KEYS TO THE MID 50S IN THE
MIDDLE AND LOWER KEYS. NORTHERLY WINDS OF 20 TO 25 MPH WITH STRONGER
GUSTS ARE MAKING IT FEEL EVEN CHILLIER. CLEAR SKIES PREVAIL ACROSS
THE KEYS AT PRESENT.

SURFACE ANALYSIS DEPICTS A 1037 MB ARCTIC HIGH CENTERED OVER THE MID
MISSISSIPPI VALLEY...AND DOMINATING THE CENTRAL/EASTERN CONUS. AT MID
AND UPPER LEVELS...A DEEP TROUGH LIES ALONG THE EASTERN SEABOARD...
AND EXTENDS FAR TO THE SOUTH ACROSS FLORIDA AND THE BAHAMAS.

.SHORT TERM (OVERNIGHT)...
CLEAR...WINDY AND COLD CONDITIONS WILL CONTINUE THROUGH THE OVERNIGHT
HOURS. LOW LEVEL FLOW TRAJECTORIES WILL REMAIN LINED UP ALMOST
PERFECTLY DOWN THE LENGTH OF THE FLORIDA PENINSULA...ALLOWING STRONG
COLD ADVECTION TO CONTINUE. TEMPS HAVE BEEN FALLING 1-2 DEGREES AN
HOUR DURING THE EVENING...AND ARE STAYING CLOSE OR JUST SLIGHTLY
BELOW THE TREND SUGGESTED BY THE MOST RECENT MAV/LAV MOS. THIS SUGGESTS
THAT THE PREVIOUSLY FORECASTED LOWS ARE ON TRACK. DID ISSUE A ZONE
UPDATE TO INCREASE WINDS TO 20 TO 25 MPH AND GUSTY THROUGHOUT THE
ISLAND CHAIN FOR THE OVERNIGHT IN LINE WITH RECENT OBS...AND ALSO TO
SEPARATE THE MIDDLE AND UPPER KEYS FOR DIFFERING OVERNIGHT LOWS.
EXPECT THE MIDDLE KEYS TO REACH NO LOWER THAN THE MID 40S...WHILE MIN
TEMPS SHOULD RANGE FROM 40 TO 45 IN THE UPPER KEYS. ALSO OPENED UP
THE MIN TEMP RANGE SLIGHTLY FOR THE LOWER KEYS...GOING WITH UPPER 40S
TO NEAR 50.

CONSIDERATION WAS GIVEN TO ISSUANCE OF A WIND CHILL ADVISORY FOR THE
UPPER KEYS FOR VERY LATE TONIGHT INTO EARLY THURSDAY MORNING...AS
WIND CHILL VALUES MAY DROP INTO THE MID 30S FOR A FEW HOURS.
HOWEVER...THE BEST CHANCE FOR THIS TO OCCUR WILL BE ACROSS A
RELATIVELY SMALL PORTION OF THE UPPER KEYS...FROM OCEAN REEF TO NORTH
KEY LARGO...AND EVEN IF WIND CHILLS DO BRIEFLY DROP TO 35 DEGREES OR
SLIGHTLY LOWER...DO NOT HAVE MUCH CONFIDENCE THAT THE FOUR HOUR
DURATION REQUIREMENT FOR A WIND CHILL ADVISORY WILL BE MET. GIVEN THE
EXPECTED LIMITED GEOGRAPHICAL EXTENT AND LOW CONFIDENCE THAT CRITERIA
WILL BE MET...DECIDED NOT TO ISSUE AN ADVISORY AT THIS POINT.

&&

.MARINE...
STRONG NORTHWEST TO NORTH WINDS OF 20 TO 25 KNOTS WITH GUSTS AROUND
30 KNOTS PREVAIL AT THE C-MAN STATIONS THIS EVENING. THIS IS IN GOOD
AGREEMENT WITH THE EVENING QUIKSCAT PASS...WHICH SHOWS WIDESPREAD 20
TO 25 KNOT WIND BARBS OVER OUR MARINE AREA...AND WITH THE LOW LEVEL
WINDS FOUND IN THE EVENING KEY WEST SOUNDING. WITH NO RECENT SHIP
REPORTS OR JASON-1 SATELLITE ALTIMETRY PASS...AND NO BUOY DATA...
WE HAVE NO HARD DATA FOR OFFSHORE SEA HEIGHTS...BUT THE VALUES IN THE
EXISTING FORECAST ARE CLOSE TO THE LATEST WAVEWATCH AND SEEM REASONABLE
GIVEN THE OBSERVED WINDS. WILL MAINTAIN THE SMALL CRAFT ADVISORY ON ALL
KEYS WATERS DURING THE OVERNIGHT PERIOD. NO SIGNIFICANT CHANGES WERE
MADE FOR THE LATE EVENING CWF ISSUANCE.

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL OVERNIGHT AND THROUGH THURSDAY AT THE
ISLAND TERMINALS. STRONG AND GUSTY NORTH WINDS AT THE ISLAND
TERMINALS WILL DRIVE SIGNIFICANT CROSSWINDS AT OUR EAST WEST
RUNWAYS. WINDS WILL WEAKEN TO AROUND 15 KNOTS BY LATE THURSDAY
AFTERNOON.

&&

.FIRE WEATHER...
LATEST FORECAST GUIDANCE CONTINUES TO SUGGEST THAT DEWPOINTS WILL BE
IN THE MID 20S TO NEAR 30 DEGREES ON THURSDAY AFTERNOON...WHICH
COMBINED WITH TEMPERATURES IN THE MID 50S WILL PRODUCE RELATIVE
HUMIDITIES DROPPING TO NEAR OR BELOW 35 PERCENT FOR A FEW HOURS IN
THE AFTERNOON. COMBINED WITH NORTH WINDS AROUND 20 MPH...THERE IS
SUFFICIENT RISK OF RED FLAG CONDITIONS TO WARRANT MAINTAINING THE
FIRE WEATHER WATCH.

&&

.CLIMATE...
THE RECORD LOW TEMPERATURE FOR KEY WEST ON FEBRUARY 5TH IS 45
DEGREES...LAST SET IN 1996. THIS RECORD APPEARS SAFE...BUT THERE IS
A CHANCE WE MAY TIE THE RECORD LOW MAXIMUM TEMPERATURE FOR FEBRUARY
5TH...WHICH IS 55 DEGREES...SET IN 1966.

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...FIRE WEATHER WATCH THURSDAY AFTERNOON FOR FLZ076>078.
GM...SMALL CRAFT ADVISORY IN EFFECT FOR GMZ031>033-052>054-072>075.

&&

PUBLIC/MARINE/FIRE WX...JACOBSON
AVIATION................11

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE KEY WEST FL
630 AM EST WED FEB 4 2009

FLZ076>078-GMZ031>033-052>054-072>075-051000-
MONROE UPPER KEYS-MONROE MIDDLE KEYS-MONROE LOWER KEYS-
FLORIDA BAY-GULF SIDE OF THE LOWER KEYS OUT 20 NM-
GULF WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE 20 TO 60 NM OUT-
OCEAN REEF TO CRAIG KEY OUT 20 NM-
CRAIG KEY TO THE WEST END OF THE 7 MILE BRIDGE OUT 20 NM-
WEST END OF THE 7 MILE BRIDGE TO KEY WEST OUT 20 NM-
OCEAN REEF TO CRAIG KEY 20 TO 60 NM OUT-
CRAIG KEY TO THE WEST END OF THE 7 MILE BRIDGE 20 TO 60 NM OUT-
WEST END OF THE 7 MILE BRIDGE TO KEY WEST 20 TO 60 NM OUT-
KEY WEST TO 20 NM WEST OF DRY TORTUGAS OUT 60 NM-
630 AM EST WED FEB 4 2009

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

.DAY ONE...TODAY AND TONIGHT

A SMALL CRAFT ADVISORY WILL IS POSTED ACROSS ALL KEYS COASTAL WATERS
FOR TODAY AND TONIGHT. A COLD FRONT WILL MOVE ACROSS THE KEYS WATERS
BY AFTERNOON. EXPECT NORTHWEST TO NORTH WINDS AROUND 20 KNOTS TO
SHIFT TO MAINLY NORTH THIS EVENING AND INCREASE TO BETWEEN 20 AND 25
KNOTS DURING THE OVERNIGHT HOURS.

OTHERWISE...NO HAZARDOUS WEATHER IS EXPECTED.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

ARCTIC HIGH PRESSURE MOVING SOUTHEASTWARD OVER THE SOUTHEASTERN
UNITED STATES WILL MAINTAIN FRESH TO STRONG NORTH WINDS ACROSS ALL
WATERS IN THE KEYS MARINE DISTRICT THROUGH THURSDAY AFTERNOON.
THEREAFTER...SMALL CRAFT ADVISORIES FOR HAZARDOUS SEAS WILL REMAIN
IN PLACE ACROSS THE ATLANTIC WATERS THURSDAY NIGHT THROUGH FRIDAY
NIGHT...WHILE EXERCISE CAUTIONARY HEADLINES REMAIN IN PLACE ACROSS
THE GULF WATERS AND FLORIDA BAY THURSDAY NIGHT THROUGH FRIDAY NIGHT.

A STRONG RIDGE IS FORECASTED TO EXTEND ACROSS THE WESTERN ATLANTIC
TO NORTH FLORIDA DURING THE UPCOMING WEEKEND. AS A RESULT...WINDS
WILL INCREASE TO NEAR 20 KNOTS ON SATURDAY AND SUNDAY ACROSS THE
ATLANTIC WATERS...LIKELY PROMPTING THE REISSUANCE OF A SMALL CRAFT
ADVISORIES FOR THESE WATERS SATURDAY AND SUNDAY. SMALL CRAFT
EXERCISE CAUTIONARY HEADLINES WILL LIKELY REMAIN POSTED SATURDAY AND
SUNDAY AS WELL FOR THE FLORIDA BAY AND THE NEARSHORE GULF WATERS
ADJOINING THE FLORIDA KEYS AS WELL AS THE OFFSHORE GULF WATERS 20 TO
60 NM WEST OF MAINLAND MONROE COUNTY.

NO OTHER HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.

DAF