499
FXUS62 KKEY 281610
AFDKEY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
1210 PM EDT TUE JUL 28 2026
..NEW DISCUSSION, MARINE, AVIATION, PREV DISCUSSION
KEY MESSAGES
- LIGHT FLOW IN THE LOWER LEVELS WILL BECOME SOUTHWESTERLY TODAY,
AND WILL FAVOR WATERSPOUT DEVELOPMENT. BOATERS ARE ENCOURAGED
TO KEEP AN EYE ON THE SKY IF VENTURING OUT THIS AFTERNOON.
- HOWEVER, SMALL CRAFT SHOULD EXERCISE CAUTION OFFSHORE OF THE
UPPER KEYS DUE TO A BRIEF FRESHENING OF WINDS THIS AFTERNOON.
BREEZES WILL SLACKEN SLIGHTLY OVERNIGHT.
- HEAT INDICES MAY APPROACH 105 TO 110 DEGREES EACH AFTERNOON FOR
SOME FLORIDA KEYS ISLAND COMMUNITIES, ESPECIALLY IN THE UPPER
KEYS.
DISCUSSION
ISSUED AT 1102 AM EDT TUE JUL 28 2026
UNSETTLED WEATHER CONDITIONS ARE STILL IN PLACE ACROSS THE
FORECAST AREA THIS AFTERNOON WITH SLOPPILY SCATTERED SHOWERS AND
THUNDERSTORMS STILL MOVING THROUGH. THE HANDFUL OF OBSERVATIONS
AVAILABLE TO US SHOW 12-HOUR RAINFALL TOTALS IN THE MIDDLE KEYS
NEAR A TENTH OF AN INCH, BUT MRMS RADAR-DERIVED ACCUMULATION
VALUES SHOW POCKETS OF HIGHER AMOUNTS NEAR ONE INCH, PARTICULARLY
ALONG THE UPPER KEYS. MRMS ALSO SHOWS SOME POCKETS OF HIGHER
VALUES OVER THE WATER, SO SOME OF THESE HEFTIER SHOWERS AND
THUNDERSTORMS HAVE MADE USE OF THE PRECIPITABLE WATER IN THE
VERTICAL. THE 12Z SOUNDING DIDN'T SHOW AN OVERLY EXCITING PROFILE,
OTHER THAN A LOT OF MOISTURE WITH JUST OVER TWO INCHES OF PWAT.
SOMETHING OF NOTE FROM THE MORNING SOUNDING IS THE LIGHT AND
ALMOST VARIABLE FLOW IN THE LOWER LEVELS.
WITH SOUTHWESTERLY SURFACE WINDS EXPECTED TO HOLD UP THROUGH THIS
AFTERNOON AS THE ISLAND CHAIN HEATS UP, THE LIGHT FLOW MAY FAVOR
WATERSPOUT DEVELOPMENT, PARTICULARLY ALONG THE LOWER AND MIDDLE
KEYS. THE LOCALLY-CALCULATED WATERSPOUT INDEX ASSOCIATED WITH THE
MORNING SOUNDING WAS 30%, WHICH IS NO SURPRISE CONSIDERING THE LOW
LEVEL MOISTURE AND LIGHT FLOW. WATERSPOUTS ARE NOT ALWAYS VISIBLE
IN THEIR ENTIRETY, AND MAY ONLY APPEAR AS A FUNNEL CLOUD
EXTENDING DOWN FROM THE PARENT STORM. ANYONE WHO OBSERVES A
WATERSPOUT IS ENCOURAGED TO REPORT IT TO OUR OFFICE EITHER BY
PHONE OR SOCIAL MEDIA.
TEMPERATURES ALONG THE ISLAND CHAIN ARE CURRENTLY IN THE MID TO
UPPER 80S WITH HEAT INDEX VALUES NEAR 100F. VISIBLE SATELLITE
SHOWS A MIX OF PARTLY CLOUDY TO MOSTLY CLEAR SKIES, ESPECIALLY AS
SOME RESIDUAL CLOUD DEBRIS FROM NEARBY SHOWERS DIMINISH. THESE
TEMPERATURE NUMBERS WILL LIKELY COME UP A FEW MORE DEGREES, AND
EVERYONE OUT AND ABOUT, ESPECIALLY THOSE OUT TO SPOT SOME
WATERSPOUTS, ARE ENCOURAGED TO STAY HYDRATED AND TO TAKE BREAKS IN
AIR CONDITIONING IF POSSIBLE.
DISCUSSION
ISSUED AT 437 AM EDT TUE JUL 28 2026
SURFACE TROUGHING WILL REMAIN EXTENDED INTO THE KEYS FOR ONE MORE
DAY KEEPING RAIN CHANCES ABOVE NORMAL AT 40%. LOOKING AT THE
GLOBAL NUMERICAL MODEL GUIDANCE TOTAL PRECIPITABLE WATER
NORMALIZED ANOMALY, THIS MAKES SENSE SINCE WE STILL HAVE ABUNDANT
MOISTURE ACROSS THE REGION. A DEVELOPING LOW PRESSURE SYSTEM
ACROSS THE MID-ATLANTIC AND NORTHEAST COMBINED WITH HIGH PRESSURE
ACROSS THE NORTH ATLANTIC WILL ACT IN TANDEM WITH ONE ANOTHER
CREATING FOR A SQUEEZE PLAY ACROSS MUCH OF FLORIDA. THIS LOOKS TO
PLAY OUT WITH MUCH OF THE MOISTURE FOCUSED ACROSS THE CENTRAL AND
NORTHERN PART OF THE STATE WHILE THE SOUTHERN PART AND THE KEYS
GET TREATED TO INCREASINGLY DRIER AIR AS IT GETS FUNNELED IN BY
THE HIGH OVER THE ATLANTIC. THIS DRY AIR WILL ALSO GET STUCK WITH
NO WHERE TO GO AND WILL REMAIN OVER THE KEYS FOR SEVERAL DAYS.
THEREFORE, STARTING TONIGHT, RAIN CHANCES FALL TO SLIGHT CHANCES
WITH SOME PERIODS LATE WEEK INTO THE WEEKEND BEING DRIED OUT
COMPLETELY. SINCE WE WILL HAVE MUCH DRIER AIR OVER US IN THE
COMING DAYS, THE HEAT WILL BECOME THE CENTER OF THE STORY AGAIN.
DAYTIME HIGHS NEAR 90 DEGREES AND IN THE LOWER 90S AT TIMES AND
DEW POINTS IN THE MID TO UPPER 70S WILL CREATE FOR HEAT INDEX
VALUES OF 105 TO 110 DEGREES. AS OF NOW, WE DON'T ANTICIPATE HEAT
ADVISORY CONDITIONS AS IT SHOULD REMAIN JUST BELOW IT. OVERNIGHT
LOWS WILL ALSO NOT PROVIDE FOR MUCH RELIEF FROM THE DAYTIME HEAT
REMAINING IN THE LOWER TO MID 80S IN SOME CASES.
DEVELOPING LOW PRESSURE OFF THE NORTHEAST AND MID-ATLANTIC
COMBINED WITH HIGH PRESSURE OVER THE ATLANTIC WILL ALSO CREATE FOR
AN INCREASED PRESSURE GRADIENT ACROSS THE AREA. THIS WILL LEND TO
MAINLY LIGHT TO GENTLE SOUTHWEST TO WEST BREEZES, OCCASIONALLY
GENTLE TO MODERATE ALONG THE ISLAND CHAIN, ESPECIALLY THE UPPER
KEYS OVER THE NEXT FEW DAYS. THE GRADIENT RELAXES FOR LATE WEEK
INTO THE WEEKEND RESULTING IN A PERIOD OF LIGHT BREEZES OF EVEN
VARIABLE AT TIMES.
MARINE
ISSUED AT 1102 AM EDT TUE JUL 28 2026
TROUGHING JUST OFF THE EASTERN SEABOARD WILL CONTINUE
TO REACH SOUTHWESTWARD ACROSS THE FAR SOUTHEAST FOR THE NEXT DAY
AND BE REINFORCED BY ANOTHER SHORTWAVE. THIS WILL RESULT IN A
BROAD CONFLUENCE ZONE REMAINING DRAPED ACROSS NORTHERN
FLORIDA/GEORGIA FOR MUCH OF THIS WEEK. GENERALLY LIGHT TO GENTLE
BREEZES WILL CONTINUE OUT OF THE SOUTHWEST TO WEST, BUT MAY
VARIABLE AT TIMES. BREEZES WILL BECOME GENTLE TO MODERATE TOWARDS
MID WEEK BEFORE SLACKENING BACK TO LIGHT TO GENTLE BY LATE WEEK.
AVIATION
(15Z TAFS)
ISSUED AT 1102 AM EDT TUE JUL 28 2026
VFR CONDITIONS WILL PREVAIL AT BOTH ISLAND TERMINALS, BUT
LINGERING LOWER LEVEL CLOUDS FROM OFFSHORE SHOWERS AND
THUNDERSTORMS MAY LEAD TO OCCASIONAL MVFR OBSERVATIONS. IF THERE
ARE LOWERED CATEGORIES AT EITHER TERMINAL, CONDITIONS SHOULD
IMPROVE SWIFTLY. LIGHT AND VARIABLE WINDS AT THE SURFACE WILL
EVENTUALLY ASSUME A SOUTHWESTERLY DIRECTION AT 5 TO 10 KNOTS.
OPTING TO MAINTAIN VCSH DUE TO EXPECTED SHOWER DEVELOPMENT IN THE
MIDDLE OF THE TAF PERIOD.
PRELIMINARY POINT TEMPS/POPS
KEY WEST 89 83 90 83 / 40 10 10 0
MARATHON 90 82 90 82 / 40 10 10 0
KEY WATCHES/WARNINGS/ADVISORIES
FL...NONE.
GM...NONE.
PUBLIC/MARINE/FIRE...DP
AVIATION/NOWCASTS....DP
DATA ACQUISITION.....DP
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