515
FXUS62 KEYW 202007
AFDEYW
FLORIDA KEYS AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
405 PM EDT SAT MAY 20 2006
DISCUSSION
CURRENTLY
THE EARLIER PANCAKE TYPE CLOUD LINE WHICH FORMED NEAR THE LOWER KEYS
HAS EVAPORATED AS DRIER AIR MIXED DOWNWARD...LEAVING ONLY A FEW
SHREDS OF CUMULUS HUMILIS. LATEST SURFACE ANALYSIS DEPICTS A WEAK
RIDGE OF HIGH PRESSURE ACROSS SOUTH FLORIDA AND THE ADJACENT GULF
AND ATLANTIC WATERS. ACROSS THE MARINE DISTRICT...C-MAN STATION
PLATFORMS INDICATE VARIABLE WINDS OF 5 TO 10 KNOTS WHILE LOCAL
RADARS ARE NOT DETECTING ANY PRECIPITATION ECHOES.
SYNOPTIC DISCUSSION
AN UPPER LEVEL TROUGH OVER THE WESTERN GULF WILL TRACK SLOWLY
EASTWARD OVER THE SEVERAL DAYS...WHILE A WESTERN ATLANTIC RIDGE
HOLDS FIRM ACROSS THE ISLAND OF CUBA INTO THE EASTERN GULF OF
MEXICO. BOTH NAM AND ESPECIALLY GFS40 REVEAL AN INCREASING AREA OF
UPPER LEVEL DIVERGENCE BETWEEN THESE TWO SYSTEMS OVER OUR AREA
BEGINNING SUNDAY NIGHT...INTO EARLY NEXT WEEK. MEANWHILE...A BROAD
AND POORLY DEFINED LOW LEVEL CONFLUENCE ZONE ACCOMPANIED BY AN AXIS
OF HIGH MOISTURE WILL RETROGRADE WESTWARD AND GRADUALLY MOVE INTO
OUR REGION BY LATE SUNDAY...AND INTO THE EARLY PART OF NEXT WEEK.
FORECAST
TONIGHT THROUGH MONDAY NIGHT...
BOTH GFS AND NAM FORECAST SOUNDINGS SHOW A DEEPENING SOUTHEAST TO
SOUTH TRAJECTORY RESULTING IN A DRAMATIC INCREASE IN PWAT VALUES OF
AROUND 2 INCHES FROM LATE SUNDAY INTO TUESDAY...WITH GFS AROUND 2.30
INCHES MONDAY. ALTHOUGH GFS SEEMS WAY OVERDONE WITH UPPER LEVEL
DIVERGENCE...WILL INCREASE POPS INTO THE CHANCE CATEGORY BEGINNING
SUNDAY AFTERNOON...WITH A INCREASING POP TREND SUNDAY NIGHT THROUGH
MONDAY NIGHT.
TUESDAY THROUGH WEDNESDAY NIGHT...
GFS FORECAST SOUNDINGS MAINTAIN PWAT VALUES OF AROUND 2 INCHES WITH
BROAD AND ILL-DEFINED LOW LEVEL BOUNDARY NEARBY. HENCE...WILL
MAINTAIN SCATTERED POPS THROUGH THE PERIOD.
THURSDAY THROUGH SATURDAY...
WITH THE LOW LEVEL BOUNDARY WEAKENING AND GRADUAL DRYING DEPICTED BY
GFS...WILL MAINTAIN ISOLATED SHOWERS.
MARINE
WITH MEAN POSITION OF THE RIDGE AXIS REMAINING NEAR SOUTH FLORIDA
AND THE ADJACENT ATLANTIC AND GULF WATERS...LIGHT TO GENTLE WINDS
WILL PREVAIL INTO MOST OF NEXT WEEK. THE STRONGER WINDS WILL BE
FOUND OVER THE OUTER STRAITS BEYOND 20 NM FROM THE ISLAND KEYS FROM
TONIGHT THROUGH SUNDAY NIGHT. HENCE...NO CAUTIONARY HEADLINES OR
ADVISORIES WILL BE NECESSARY. HOWEVER...MARINERS SHOULD BE ALERT FOR
THE INCREASING THREAT OF THUNDERSTORM ACTIVITY ACCOMPANIED BY GUSTY
WINDS AND LOCALLY ROUGH SEAS BEGINNING SUNDAY NIGHT INTO AT LEAST
EARLY NEXT WEEK.
AVIATION
TONIGHT...MAINLY VFR CONDITIONS ARE EXPECTED ALONG THE KMIA-KEYW
TWEB ROUTE. ON THE MAINLAND...EXPECT JUST A FEW CLOUDS AND LIGHT
WINDS...BUT COULD SEE SOME BRIEF MVFR CEILINGS IN PATCHY FOG NEAR
THE EVERGLADES TOWARDS DAYBREAK. FOR THE REMAINDER OF THE
ROUTE...EXPECT LIGHT EAST WINDS COMBINED WITH LOW LEVEL INCREASING
MOISTURE MOVING OVER THE KEYS ISLAND TERMINALS. KEYW AND KMTH CAN
EXPECT SOME SCATTERED CLOUDS BETWEEN 2 AND 3 KFT...AND SOME STRATOCU
DEVELOPING AFTER MIDNIGHT BETWEEN 4 AND 6 KFT. LOCALIZED MVFR/VFR
CEILINGS AT 2500 AND 5000 FEET ARE POSSIBLE.
PRELIMINARY TEMPS AND POPS...
KEY WEST 75 85 77 86 / 00 30 40 50
MARATHON 76 87 77 89 / 00 30 40 50
KEY WATCHES/WARNINGS/ADVISORIES
NONE.
PUBLIC/MARINE..........APA...NWS KEY WEST
AVIATION/SHORT TERM....DAF...NWS KEY WEST
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