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646
FXUS62 KKEY 251844
AFDKEY

AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
245 PM EDT FRI JUL 25 2014

.DISCUSSION...IN THE MID AND UPPER LEVELS...(700-200 MB)...LATEST IR
SATELLITE IMAGERY OVERLAID WITH STREAMLINE ANALYSIS AS OF 200 PM
THIS AFTERNOON DEPICT THE CENTER OF A REGIONAL SCALE MIDDLE AND
UPPER RIDGE...(500-200 MB) IS NOW LOCATED NEAR 28 NORTH 72 WEST. THE
CENTER OF A TUTT (TROPICAL UPPER TROPOSPHERIC TROUGH) LOW...AT ABOUT
250 MB...IS STILL LOCATED IN THE SOUTHEASTERN GULF OF MEXICO NEAR 25
NORTH 85 WEST. AS A RESULT...DEEP MID AND UPPER SOUTHERLY FLOW IS
INDICATED FROM 500 MB UP.

AT THE SURFACE AND IN THE LOWER LEVELS...(SURFACE TO 700
MB)...VISIBLE IMAGERY OVERLAID WITH LATEST AVAILABLE MARINE AND LAND
SURFACE OBSERVATIONS AND ANALYSIS AS OF 200 PM DETAILS THAT THE
FLORIDA KEYS REMAINS SOUTH OF THE 1020 MB SOUTHWESTERN PERIPHERY OF
A 1025 MB ANTICYCLONIC RIDGE CENTERED NEAR 30 NORTH 55 WEST. ACROSS
THE TROPICS...THE AXIS OF THE NEXT TROPICAL WAVE WAS ANALYZED
BISECTING THE MIDDLE OF HISPANIOLA.

.CURRENTLY...AS OF 200 PM...VISIBLE SATELLITE IMAGERY CONTINUES TO
SHOWS THAT SKIES ARE PARTLY CLOUDY TO MOSTLY SUNNY ACROSS THE ISLAND
CHAIN AND SURROUNDING WATERS. KEY WEST RADAR ONLY DETECTS A FEW
SHOWERS AND THUNDERSTORMS DOTTING MOSTLY THE ATLANTIC WATERS.
TEMPERATURES COMBINED WITH DEWPOINT (HIGH RELATIVE HUMIDITY) ACROSS
THE ISLANDS ARE CREATING TORRID CONDITIONS...AND HAVE REACHED AROUND
90 DEGREES OR ABOVE WITH 92 DEGREES REACHED AT THE KEY WEST AIRPORT
AND 94 DEGREES AT MARATHON AIRPORT BRIEFLY COMBINED WITH DEWPOINTS
IN THE MID TO UPPER 70S...CREATING HEAT INDICES BRIEFLY BETWEEN
105-110 DEGREES. C-MAN STATIONS ALONG THE REEF AND FLORIDA BAY ARE
SOUTHEAST NEAR 5 KNOTS.

.FORECAST...SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT. RAIN CHANCES
WILL BE LESS THAN NORMAL AS 500 MB RIDGING BUILDS ACROSS THE KEYS
WITH RISING HEIGHTS. THIS WILL OCCUR IN COMBINATION WITH THE
ENCROACHMENT OF THE 850-700 MB SAL (SAHARAN AIR LAYER) WHICH IS
PROGGED IN THE MODEL FORECAST SOUNDINGS TO MOVE ACROSS THE ISLANDS
FROM EAST TO WEST. A WEAK SURFACE RIDGE WILL REMAIN JUST TO THE
NORTH OF THE FLORIDA KEYS THROUGH THE WEEKEND. BUT AFTER
TONIGHT...FORECAST PWAT (PRECIPITABLE WATER) WILL FALL FROM NEAR
1.75 INCHES...DOWN TO NEAR OR BELOW 1.25 INCHES ON
SATURDAY...CONTINUING THROUGH SUNDAY NIGHT. THEREFORE WILL CONTINUE
TO ADVERTISE ONLY ISOLATED POPS TONIGHT...WITH UNFAVORABLE WIND
DIRECTION FOR CUMULUS CLOUDLINE THIS EVENING...AND DIME POPS FOR
SATURDAY THROUGH SUNDAY NIGHT.

THE OTHER STORY WILL BE WHAT IS NORMALLY UNSPOKEN AND A GIVEN HERE
IN THE KEYS AS WE APPROACH AUGUST AND THAT IS THE HEAT...BUT GIVEN
SLIGHTLY LESS THAN NORMAL CLOUD COVER WHICH WILL ACCOMPANY THE
AFOREMENTIONED SAL AND RIDGING...EXPECT HIGH AND LOW TEMPERATURES TO
BE SEVERAL DEGREES ABOVE CLIMATOLOGY. THESE TEMPERATURES IN THE
LOWER 90S THIS COMBINED WITH DEWPOINTS IN THE HIGH 70S TO AROUND 80
MAY INTRODUCE HEAT INDICES AROUND 110 DEGREES. NOTE WELL...A HEAT
ADVISORY MAY BE ISSUED FOR SATURDAY AND SUNDAY IF THE PROJECTED HEAT
INDEX REMAINS EQUAL TO OR GREATER THAN 108 DEGREE FAHRENHEIT FOR TWO
OR MORE CONSECUTIVE HOURS AT OBSERVING STATIONS.

.MONDAY THROUGH TUESDAY...MODEL INDICATIONS ARE STILL BRINGING A
WEAK TROPICAL WAVE ACROSS THE KEYS MONDAY AND MONDAY NIGHT...WITH
LINGERING MOISTURE AROUND DURING TUESDAY. SIGNALS ARE NOT THAT
STRONG BUT GIVEN DEPTH OF THE MOISTURE AND LIGHT NORTHEAST TO EAST
WINDS AHEAD OF THE AXIS WILL PROMPT GOOD MESOSCALE FORCING DURING
MONDAY AND MONDAY EVENING...SO WILL CONTINUE WITH MIDDLE OF THE ROAD
POPS IN THE GRIDS...WITH LOW CHANCE POPS FOR TUESDAY.

.EXTENDED...TUESDAY NIGHT THROUGH FRIDAY...WEAK SURFACE TO MIDDLE
LEVEL RIDGING RIGHT NEAR THE KEYS COMBINED WITH A MODERATELY MOIST
LOWER TO MID TROPOSPHERE WILL ALLOW FOR CLOUDLINES WITH SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS...AND CLIMATOLOGICAL LOW
CHANCE...30% POPS.

&&

.MARINE...LIGHT TO GENTLE EAST TO SOUTHEAST WINDS ARE EXPECTED NEAR
THE KEYS AND ADJOINING WATERS TONIGHT THROUGH SUNDAY NIGHT...WITH
THE EXCEPTION OF ACROSS THE FLORIDA STRAITS...WHERE GENTLE TO
MODERATE WINDS ARE EXPECTED AT TIMES DUE TO INCREASING DISTANCE FROM
THE SURFACE RIDGING. THEREAFTER THE AXIS OF A WEAK TROPICAL WAVE
WILL IMPACT THE KEYS...MORESO ON MONDAY AND MONDAY NIGHT...AND LESS
SO TUESDAY AND TUESDAY NIGHT...BUT WINDS WILL BE LIGHT TO
GENTLE...EXCEPT IN THE VICINITY OF HEAVIER SHOWERS AN STORMS. WINDS
WILL BECOME LIGHT AND VARIABLE TUESDAY THROUGH WEDNESDAY NIGHT AND A
WEAK PRESSURE PATTERN MOVES INTO THE KEYS TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT.

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL AT BOTH THE KEY WEST AND
MARATHON ISLAND TERMINALS THROUGH TONIGHT...WITH BRIEF MVFR/IFR CIGS
POSSIBLE WITHIN ISOLATED SHOWERS AND STORMS...ESPECIALLY THIS
EVENING.

&&
.PRELIMINARY POINT TEMPS/POPS...
KEY WEST  82  92  83  92  82  / 20  10  10  10  20
MARATHON  83  94  84  94  82  / 20  10  10  10  20

&&

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

$$

PUBLIC/MARINE/GRIDS.........DAF
AVIATION/NOWCASTS...........11/DAF
DATA COLLECTION.............BF/EV

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