Scientific Forecaster Discussion

NWS Discussion
			
				
AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
955 PM EDT SAT MAY 25 2013

.DISCUSSION...
DURING THE LATE AFTERNOON AND EARLY EVENING HOURS...SCATTERED 
SHOWERS AND ISOLATED THUNDERSTORMS MIGRATED SOUTHWEST AND WEST AND 
IMPACTED THE NORTHERN HALF OF THE GULF WATERS NORTH OF THE MIDDLE 
KEYS...MOST OF THE GULF WATERS NORTH OF THE LOWER KEYS...AS WELL AS 
A PORTION OF THE LOWER KEYS FROM BOCA CHICA TO THE NORTHERN EXTENT 
OF BIG PINE KEY. CURRENTLY...SKIES ARE MOSTLY CLEAR WITH 
TEMPERATURES HOVERING AROUND 80 DEGREES. MEANWHILE...LOCAL RADARS 
ARE DETECTING AN AREA OF SHOWERS MOVING WEST SOUTHWEST THROUGH THE 
NORTHERN EXTENT OF THE OUTER WATERS OF MAINLAND MONROE. SURFACE 
WISE...AN AREA OF HIGH PRESSURE IS CENTERED (1024 MB) JUST OFFSHORE 
OF THE EXTREME SOUTHEAST UNITED STATES WITH A RIDGE POKING ACROSS 
THE GULF COAST REGION. OF NOTE...THIS ANTICYCLONE HAS WEAKENED ABOUT 
3 MB OVER THE LAST 12 HOURS. ACROSS OUR MARINE DISTRICT...NORTHEAST 
TO EAST WINDS ARE BLOWING NEAR 20 KNOTS. BECAUSE OF A POCKET OF MUCH 
HIGHER MOISTURE IN AND AROUND OUR AREA ASSOCIATED WITH A WIND 
SURGE AND ACTIVITY PUSHING OFF THE SOUTHWEST FLORIDA MAINLAND...THE 
KAMX SOUNDING IS MORE REPRESENTATIVE OF THE AIRMASS CURRENTLY 
OVERHEAD. WITH THAT SAID...SCANT MOISTURE (PWAT 1.01 INCHES) ALONG 
WITH A WEAK 1 DEGREE C INVERSION BASED AT 750 MB IS EVIDENT. FRESH 
TO STRONG NORTH TO NORTHEAST WINDS REACH UP TO 850 MB....BEFORE 
BACKING TO NORTH AND SLACKENING APPRECIABLY TO 500 MB.   

.SHORT TERM (REST OF TONIGHT)...
A DEEP TROPOSPHERIC ANTICYCLONE CENTERED OVER THE SOUTHEAST UNITED 
STATES WITH A RIDGE REACHING ACROSS THE ENTIRE SUNSHINE STATE AND 
OUR REGION...WILL RESULT AN INTENSIFICATION OF LARGE SCALE 
SUBSIDENCE. BECAUSE OF THIS...MOISTURE WILL BE LIMITED TO BELOW 
925 MB OVERNIGHT AND ON SUNDAY. MOSTLY CLEAR SKIES ALONG WITH 
NORTHEAST TO EAST WINDS OF 15 TO 20 MPH WILL KEEP LOW TEMPERATURES 
PREDOMINATELY IN THE UPPER 70S. HENCE...HAVE UPDATED THE PUBLIC ZONE 
FORECAST A SECOND TIME TO RECOMBINE THE ZONES AND INSERT NICKLE POPS 
FOR THE ENTIRE ISLAND CHAIN. 

&&

.MARINE...
FRESH TO STRONG NORTHEAST TO EAST WINDS WILL PREDOMINATE ON ALL KEYS 
COASTAL WATERS WITH TYPICAL LATE AFTERNOON AND EVENING SURGES...AND 
DAYTIME LULLS WITH THE HIGHEST AND STEADIEST WINDS ON THE FLORIDA 
STRAITS AWAY FROM DAYTIME HEATING ON THE MAINLAND. WITH THAT 
SAID...A SMALL CRAFT ADVISORY WILL REMAIN IN EFFECT FOR OUR ENTIRE 
MARINE DISTRICT UNTIL 5 AM SUNDAY. OTHERWISE...ONLY A FEW SHOWERS 
WILL BE INSERTED ON ALL KEYS COASTAL WATERS.    

&&

.AVIATION...
OVERNIGHT...VFR CONDITIONS WILL PREVAIL AT BOTH THE KEY WEST AND 
MARATHON ISLAND TERMINALS. VERY BRIEF MVFR/IFR CIGS AND/OR VIS ARE 
POSSIBLE IN ANY ISOLATED SHOWERS BUT THIS POSSIBILITY IS TOO REMOTE 
TO INCLUDE IN THE TAFS ATTM. WINDS WILL AVERAGE FROM 080 DEGREES AOA 
12 TO 15 KNOTS WITH GUSTS BETWEEN 18 AND 23 KNOTS. SCATTERED CLOUDS 
WITH BASES AOA FL020-030 AND FL060-070 ARE EXPECTED.

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...SMALL CRAFT ADVISORY IN EFFECT FOR GMZ032-GMZ033-GMZ034-  
GMZ042-GMZ043-GMZ044-GMZ052-GMZ053-GMZ054-GMZ055-GMZ072-GMZ073-     
GMZ074-GMZ075.

&&

$$

PUBLIC/MARINE/FIRE/DIGITAL...APA 
AVIATION/NOWCASTS............DAF
DATA ACQUISITION.............BWC

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