Area Forecast Discussion
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000
FXUS62 KKEY 020909
AFDKEY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
509 AM EDT SUN AUG 2 2015

.DISCUSSION...THE FLORIDA KEYS ARE IN NO MAN`S LAND. IN THE LOWER
TROPOSPHERE...THE WESTERN ATLANTIC RIDGE AXIS STRETCHES ACROSS THE
SOUTHERN FLORIDA PENINSULA...GIVING WAY TO A RESILIENT TROUGH IN THE
NORTHEASTERN GULF OF MEXICO. MEANWHILE...THE UPPER LEVELS ARE HASHING
OUR THEIR OWN CHESS MATCH. A MEAN ANTICYCLONIC GYRE REMAINS CENTERED
ACROSS THE SOUTHERN ROCKIES...GIVING UP ITS EASTERN FLANK TO AN
ENCROACHING TUTT CELL. BASED ON THE LATEST VORTICITY ANALYSES FROM
CIMSS...THE TUTT HAS CARVED OUT CYCLONIC CURVATURE INTO THE LOWER
TROPOSPHERE. AS SUCH...SCATTERED CONVECTION HAS PERSISTED ACROSS THE
BAHAMAS. THE MIMIC TPW PRODUCT HIGHLIGHTS SIGNIFICANT DRY AIR PLUMES
ACROSS HISPANIOLA AND NEAR THE LESSER ANTILLES.

.CURRENTLY...MODERATE SOUTHEAST TO SOUTH BREEZES PREVAIL AT THE
AVAILABLE OBSERVING STATIONS...IDENTIFYING THE PROXIMITY OF THE
RIDGE AXIS. ISOLATED SHOWERS HAVE PERSISTED NORTH OF THE MIDDLE KEYS.
ALSO...A LONE THUNDERSTORM HAS DRIFTED NORTH THROUGH THE
SADDLEBUNCHES. TEMPERATURES ARE IN THE MID 80S...AND SKIES ARE PARTLY
TO MOSTLY CLOUDY.

.SHORT TERM (TODAY THROUGH TUESDAY)...THE GOVERNING WEATHER PATTERN
WILL CHANGE VERY LITTLE TODAY AND TONIGHT. DRY AND RELATIVELY WARM
AIR AROUND 700 MB WILL LIMIT CONVECTIVE VIGOR. GENTLE TO MODERATE
SOUTHEAST BREEZES AND AMPLE CLOUD COVER WILL PERSIST.
HOWEVER...THINGS SHOULD CHANGE MONDAY AND MONDAY NIGHT AS THE TUTT
APPROACHES. THE SURFACE TROUGH COMBINED WITH THE LONG WAVE TROUGH
REACHING INTO THE SOUTHEASTERN UNITED STATES SHOULD AT LEAST PROTECT
THE VERTICAL DEPTH OF THE TUTT. THUS...RAIN CHANCES INCREASE TO 20
PERCENT MONDAY AND MONDAY NIGHT...FOLLOWED BY 30 PERCENT ON TUESDAY
AS THE TUTT AXIS REACHES THE KEYS.

&&

.LONG TERM (TUESDAY NIGHT THROUGH SATURDAY)...THE DEGREE OF LOW LEVEL
MOISTURE IS UNCERTAIN ON THE BACK SIDE OF THE TUTT AXIS. WE HAVE
RETAINED A 20 PERCENT CHANCE OF RAIN TUESDAY NIGHT THROUGH WEDNESDAY
NIGHT. THERE ARE TWO THINGS WHICH ARE MORE CERTAIN BEHIND THE TUTT.
FIRST...THE WESTERN ATLANTIC RIDGE WILL FINALLY FILL-IN THE RESILIENT
TROUGH IN THE GULF OF MEXICO...TIGHTENING THE GRADIENT ACROSS THE
FLORIDA KEYS. SECONDLY...THE GLOBAL MODELS HAVE INITIALIZED THE SAL
PLUME APPROACHING THE LESSER ANTILLES RATHER WELL. THEIR TIMING FOR
THIS DEEP LAYER OF DRY AIR IS REMARKABLY CONSISTENT. WE HAVE LOWERED
RAIN CHANCES AND REDUCED CLOUD COVER THURSDAY THROUGH FRIDAY TO
ACCOUNT FOR THIS FEATURE. A RETURN TO CLIMO HAS BEEN RETAINED FOR THE
LATTER PARTS OF THE LONG TERM.

&&

.MARINE...A RIDGE OF HIGH PRESSURE OVER SOUTH FLORIDA WILL SLOWLY
LIFT NORTHWARD TODAY THROUGH MONDAY NIGHT. THIS RIDGE OF HIGH
PRESSURE WILL EXTEND ACROSS FLORIDA TUESDAY THROUGH AT LEAST
THURSDAY NIGHT. GENTLE TO MODERATE SOUTHEASTERLY BREEZES WILL
PERSIST. A NOTE ON THE GULF STREAM CURRENT ANALYSIS...THE CURRENT
PRODUCT IS FIVE DAYS OLD. THE PERSISTENT CLOUD COVER AND LACK OF
SIGNIFICANT TEMPERATURE GRADIENT HAS DELAYED THE PRODUCTION OF A MORE
CURRENT ANALYSIS.

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL AT THE ISLAND TERMINALS
TODAY. SURFACE WINDS WILL BE 10 KNOTS OUT OF THE SOUTHEAST
EARLY...BECOMING LIGHT OUT OF THE EAST TO VARIABLE LATER THIS
AFTERNOON.

&&

.PRELIMINARY POINT TEMPS/POPS...
KEY WEST  90  83  90  82 / 10 10 20 20
MARATHON  93  83  92  82 / 10 10 20 20

&&

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

$$

PUBLIC/MARINE.........CLR
AVIATION/NOWCASTS.....11
DATA COLLECTION.......CHESSER

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