Area Forecast Discussion
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000
FXUS62 KKEY 041845
AFDKEY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
300 PM EDT SAT JUL 4 2015

.DISCUSSION...IN THE MID AND UPPER LEVELS...(700-200 MB)...LATEST
AVAILABLE IR IMAGERY OVERLAID WITH MODEL STREAMLINE ANALYSIS AS OF
200 PM CONTINUES TO DEPICT LARGE SCALE MIDDLE AND UPPER TROUGHING
ACROSS THE EASTERN TWO THIRDS OF THE CONUS...EXCEPT ACROSS
FLORIDA. ACROSS THE TROPICS...MID AND UPPER RIDGING IS
CONSOLIDATING FROM 28 NORTH 70 WEST TO ACROSS THE NORTHERN BAHAMAS.
THE CENTER OF AN UPPER LEVEL LOW PRESSURE SYSTEM IS JUST NORTH OF
THE YUCATAN PENINSULA.

AT THE SURFACE AND IN THE LOWER TO MID LEVELS...SURFACE TO 700 MB...
A NEAR 1020 MB SURFACE RIDGE REMAINS POSITIONED FROM NEAR 30 NORTH
60 WEST WESTWARD TO ACROSS THE FLORIDA PENINSULA. LATEST
UNIVERSITY OF WISCONSIN CIMMS SAL (SAHARAN AIR LAYER DUST)
ANALYSIS ILLUSTRATES VERY DRY AIR IS IN PLACE ACROSS FROM THE GULF
OF MEXICO UPSTREAM AND EASTWARD ACROSS THE KEYS TO THE BAHAMAS THEN
EAST TO NEAR THE AFRICAN CONTINENT.

.CURRENTLY...AS OF 200 PM...SKIES ARE MOSTLY SUNNY ACROSS THE
ISLANDS AND SURROUNDING WATERS...WITH A FEW LOW TOPPED SHOWERS
ACROSS THE FLORIDA STRAITS. A CLUSTERS OF HEAVIER SHOWERS IS IN
GMZ033 DOWNWIND OF SOUTHWEST FLORIDA. TEMPERATURES HAVE REACHED NEAR
90 DEGREES ACROSS THE ISLANDS WITH UNCOMFORTABLE DEWPOINTS IN THE
UPPER 70S. C-MAN STATIONS ARE NEAR 15 KNOTS ALONG THE FLORIDA REEF
AND IN FLORIDA BAY...BUT ONLY 10 TO 15 KNOTS SMITH SHOAL LIGHT.

.FORECAST...AN ABNORMALLY DRY PATTERN WILL ENSUE ON ACCOUNT OF A
VERY DEEP CONCENTRATION AND FETCH DURATION SAL (SAHARAN AIR LAYER)
EVENT WHICH WILL CONTINUE THROUGH THE REST OF THE HOLIDAY WEEKEND
AND INTO NEXT WEEK. MID AND UPPER RIDGING WILL BECOME MORE
ESTABLISHED AND PUMP DRIER AIR DOWN INTO THE LOWER LEVELS. THIS WILL
RESULT IN THE PRESENTATION OF ONLY A FEW CLOUDS EACH DAY AND NIGHT.
HAVE ONLY 10 PERCENT CHANCE OF VERY LIGHT LOW TOPPED SHOWER IS IN
THE GRIDS TONIGHT AND SUNDAY AND THUNDER WAS REMOVED GIVEN THE DEPTH
OF THE DRY AIR VS ANY PARCEL RISING HIGH ENOUGH. THE EXCEPTION IS
DOWNWIND OF SOUTHWEST FLORIDA WHERE A FEW SEABREEZE THUNDERSTORMS
WILL MOVE OFFSHORE. ALTHOUGH DEEPER DRY AIR REMAINS UPSTREAM OF THE
KEYS...MAINTAIN 20 PERCENT WITH THUNDER...BUT MAY NEED TO TAKE OUT
THE THUNDER AND LOWER OR REMOVE POPS FOR MONDAY AND BEYOND IF THE
MODELS STILL ARE CONSISTENT. STILL NEED TO SEE FORECAST SOUNDINGS
ILLUSTRATE GREATER STABILITY AS WELL. THE OTHER THING TO MENTION
ARE THE CONTINUED POSSIBLE HIGH AND LOW RECORDS GIVEN THE AMOUNT OF
INSOLATION AVAILABLE EACH DAY...AND WARMING SEA TEMPERATURES NEAR
THE TOP OF THE OCEANIC BOUNDARY LAYER.

&&

.MARINE...SMALL CRAFT WILL NEED TO EXERCISE CAUTION ACROSS THE
FLORIDA STRAITS TONIGHT...AND WINDS NEAR 15 KNOTS IN HAWK CHANNEL
ARE LIKELY...WITH LESSER WINDS ELSEWHERE. THE SAME MAY BE THE CASE
FOR THE NEXT FEW PERIODS THAT FOLLOW...BUT SINCE ONLY LAST FEW MODEL
RUNS HAVE BEEN A BIT LOW...WILL WAIT MORE FOR CONSISTENCY. FOR NOW
WILL BE ADVERTISING NEAR 15 KNOTS AND GUSTY IN THE STRAITS FOR
SUNDAY ONWARD...BUT THE POSSIBILITY EXISTS ACROSS
THESE WATERS FOR A CAUTIONARY HEADLINE.

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL TONIGHT AT THE ISLAND
TERMINALS. WINDS WILL BE LIGHT OUT OF THE EAST SOUTHEAST...WITH SOME
GUSTINESS EARLY.


&&

.PRELIMINARY POINT TEMPS/POPS...
KEY WEST  84  90  83  90 / 10 10 10 20
MARATHON  84  93  84  92 / 10 10 10 20

&&

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

$$

PUBLIC/MARINE.........FUTTERMAN
AVIATION/NOWCASTS.....11
DATA COLLECTION.......VICKERY

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