320
FXUS62 KKEY 201543
AFDKEY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
1143 AM EDT THU AUG 20 2026
..NEW DISCUSSION, MARINE, AVIATION
KEY MESSAGES
- CONDITIONS WILL BE FAVORABLE FOR ISLAND CLOUD LINE AND
ASSOCIATED WATERSPOUTS THROUGH THE EARLY AFTERNOON.
- RAIN CHANCES WILL SLOWLY INCREASE INTO THE WEEKEND AS DUST
CONCENTRATIONS DECREASE.
- WARM AND MUGGY CONDITIONS WILL CONTINUE THROUGHOUT THE WORK
WEEK, WITH LIGHT AND OFTEN VARIABLE BREEZES.
DISCUSSION
ISSUED AT 1136 AM EDT THU AUG 20 2026
WHAT A DIFFERENCE TWENTY-FOUR HOURS CAN MAKE. THE 12Z MORNING
SOUNDING AT KEY, RELATIVE TO THE 12Z SOUNDING WEDNESDAY MORNING,
SAMPLED A NEARLY SATURATED LAYER FROM THE SURFACE UP TO AROUND THE
840 MB ISOBARIC SURFACE. THE CAPPING INVERSION ABOVE WEAKENED
SUBSTANTIALLY, WITH NEARLY NIL INHIBITION AND PLENTY OF POTENTIAL
CONVECTIVE INSTABILITY TO BE REALIZED. GIVEN THE SAMPLED LIGHT
AND GENERALLY VARIABLE WINDS ACROSS THE FLORIDA KEYS AND THE
ADJACENT MARINE ZONES, AND THE BOUNDARY LAYER MOISTENING, WE
HYPOTHESIZED THAT IT WOULD NOT TAKE MUCH TO IGNITE AN ISLAND CLOUD
LINE TODAY. INDEED, SHORTLY AFTER 11 AM, THIS INDEED OCCURRED.
FOR THE REST OF THE FIRST PERIOD, EXPECT THE CLOUD LINE TO WAX AND
WANE OVER THE NEXT SEVERAL HOURS, WITH DIMINISHING SHOWER AND
THUNDERSTORM ACTIVITY THEREAFTER. AFTER THE CLOUD LINE DIMINISHES,
PLENTY OF TIME TO REALIZE ADVERTISED AFTERNOON HIGHS NEAR 90F.
BESIDES THE UPTICK IN RAIN CHANCES, NO CHANGES PROPOSED FOR THIS
SHORT TERM FORECAST UPDATE ITERATION.
MARINE
ISSUED AT 1136 AM EDT THU AUG 20 2026
CONDITIONS WILL BE FAVORABLE FOR WATERSPOUT FORMATION THROUGH THE
EARLY AFTERNOON HOURS. MARINERS ARE REMINDED A WATERSPOUT WOULD
MOST LIKELY APPEAR BENEATH A DARK, FLAT BOTTOM OF A BUILDING
CUMULUS LINE, JUST AT THE HINT OF RAIN. FROM SYNOPSIS, A SPLIT
RIDGE ACROSS OUR WATERS WITH A NEARBY COL WILL RESULT IN LIGHT AND
VARIABLE WINDS THIS AFTERNOON. THE SPLIT RIDGE PATTERN WILL
REMAIN IN PLACE THROUGH THE END OF THE WEEK AND EARLY IN THE
WEEKEND WITH A MOSTLY LIGHT TO GENTLE VARIABLE WIND PATTERN. WINDS
WILL THEN INCREASE AND BECOME MORE SOUTHEASTERLY FOR LATE WEEKEND
AND INTO THE NEW WORK WEEK, WITH DAILY GENTLE TO MODERATE BREEZES
EXPECTED.
AVIATION
(15Z TAFS)
ISSUED AT 1136 AM EDT THU AUG 20 2026
AN ISLAND CLOUD LINE WILL REMAIN IN THE VICINITY OF THE TERMINALS
THROUGH AT LEAST 18Z THIS AFTERNOON. HAVE INCLUDED MENTION OF VCSH
AT MTH, AND VCTS AT EYW, TO ACCOUNT FOR THIS, WITH SPECIFIC
IMPACTS LEFT TO ANY POSSIBLE NEEDED TEMPO GROUPS. RAIN AND
THUNDER CHANCES SHOULD GRADUALLY DIMINISH LATER IN THE TAF PERIOD.
VARIABLE NEAR SURFACE WINDS WILL GRADUALLY CLOCK AROUND TO THE
EAST TO SOUTHEAST OVERNIGHT.
PRELIMINARY POINT TEMPS/POPS
KEY WEST 92 82 91 83 / 20 10 0 0
MARATHON 90 83 90 83 / 30 10 0 0
KEY WATCHES/WARNINGS/ADVISORIES
FL...NONE.
GM...NONE.
PUBLIC/MARINE/FIRE...BT
AVIATION/NOWCASTS....BT
DATA ACQUISITION.....BT
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