000
FXUS62 KKEY 010215
AFDKEY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
1015 PM EDT WED SEP 30 2026
..NEW DISCUSSION, MARINE, AVIATION
KEY MESSAGES
- A COASTAL FLOOD ADVISORY IS IN EFFECT FOR ALL OF THE FLORIDA
KEYS. MINOR TO MODERATE SALTWATER FLOODING OF LOW ELEVATION
STREETS. DON'T DRIVE THROUGH FLOODED ROADWAYS. BOATERS CAN
EXPECT LESS CLEARANCE UNDER FIXED BRIDGES.
- A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE WATERS OF THE
FLORIDA STRAITS.
- A WET PATTERN AND THUNDERY PATTERN WILL CONTINUE THROUGH FRIDAY.
RAIN AND THUNDER CHANCES WILL DECREASE OVER THE WEEKEND THROUGH
EARLY NEXT WEEK.
DISCUSSION
ISSUED AT 1015 PM EDT WED SEP 30 2026
THE LAST EVENING OF SEPTEMBER PROVED TO BE RATHER QUIET IN TERMS
OF SHOWER ACTIVITY ACROSS THE FLORIDA KEYS. LINES OF SHOWERS AND
THUNDERSTORMS BROUGHT BURSTS OF HEAVY RAINFALL AND GUSTS TO THE
REGION EARLY THIS MORNING, AND A SQUALL LINE MOVED ONSHORE AT KEY
LARGO. CURRENT CONDITIONS SUGGEST THE LULL IN SHOWER ACTIVITY WILL
LAST A FEW MORE HOURS, AND THUNDERSTORMS MAY NOT FORM UNTIL AFTER
MIDNIGHT. BREEZES ALONG THE REEF ARE MODERATE TO FRESH
EASTERLIES, BUT THE ATLANTIC RIDGE IS EXPECTED TO BUILD IN OVER
THE SOUTHEASTERN UNITED STATES. BREEZY CONDITIONS ARE EXPECTED TO
LAST THROUGH THE NIGHT.
THE MAIN QUESTION IS WHEN AND WHERE SHOWERS WILL REDEVELOP ACROSS
THE KEYS WATERS. THE 00Z KKEY SOUNDING SAMPLED A PWAT VALUE OVER
THE 90TH PERCENTILE FOR THE DAY. THIS WAS NOT VERY SURPRISING, AS
THE LOW LEVEL ENVIRONMENTAL FLOW CONTINUES TO DIRECT DEEP TROPICAL
MOISTURE FROM THE SOUTH TO SOUTHEAST ACROSS THE KEYS. THE SOUNDING
ALSO IDENTIFIED A SUFFICIENT AMOUNT OF UNCERTAINTY TO WARRANT
KEEPING HIGH POPS IN THE FORECAST, DESPITE THE ABSENCE OF SHOWERS
NEARBY AT TIME OF WRITING. A LAYER OF INHIBITION WAS IDENTIFIED
JUST ABOVE THE SURFACE. THAT LAYER WILL BE ABLE TO MITIGATE THE
FIRST WAVE OF SHOWERS FOR THE OVERNIGHT HOURS. HOWEVER, CONVECTIVE
MODELS SUGGEST THE ENVIRONMENT WILL DESTABILIZE BEFORE SUNRISE.
THE PATTERN THAT USHERED IN THE HEAVY RAINFALL OVER THE PAST FEW
DAYS, AN UPPER LEVEL TROUGH TO OUR NORTHWEST AND SOUTHEASTERLY
STEERING FLOWS, IS STILL IN PLACE. THUS, WE ARE OPTING TO KEEP
SHOWER CHANCES HIGH TONIGHT INTO TOMORROW.
MARINE
ISSUED AT 1015 PM EDT WED SEP 30 2026
A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE STRAITS OF FLORIDA.
SMALL CRAFT SHOULD EXERCISE CAUTION CONDITIONS APPLY FOR ALL OTHER
WATERS SURROUNDING THE FLORIDA KEYS.
FROM SYNOPSIS: HIGH PRESSURE OFFSHORE THE EASTERN SEABOARD WILL
MERGE WITH AN EXISTING HIGH PRESSURE ACROSS THE SUBTROPICAL
ATLANTIC, AND SUBSEQUENTLY BUILD THROUGH THE REMAINDER OF THE
WEEK. MODERATE TO FRESH BREEZES ARE EXPECTED TO DEVELOP ACROSS THE
FLORIDA KEYS WATERS BEFORE SUNRISE. WIDESPREAD SMALL CRAFT SHOULD
EXERCISE CAUTION HEADLINES WILL BE NECESSARY THROUGH AT LEAST
FRIDAY AFTERNOON WHILE A SMALL CRAFT ADVISORY IS NOT IN EFFECT. IN
ADDITION, A VERY WET PATTERN WILL REMAIN ACROSS THE KEYS OVER THE
NEXT COUPLE DAYS, RESULTING IN PERIODS OF SCATTERED TO NUMEROUS
SHOWERS AND THUNDERSTORMS.
AVIATION
(00Z TAFS)
ISSUED AT 1015 PM EDT WED SEP 30 2026
PREVAILING VFR CONDITIONS AT EYW AND MTH WILL BE INTERRUPTED BY
ROUNDS OF SHRA AND POSSIBLE TSRA THROUGH THE UPCOMING TAF PERIOD.
SUB-VFR CONDITIONS ARE POSSIBLE NEAR ANY STRONGER TSRA. CONFIDENCE
IS LOW ON WHEN AND WHERE TSRA WILL DEVELOP. VCSH WAS INITIALLY
LEFT OUT OF THE TAFS, BUT SHOWERS WERE ABLE TO REDEVELOP SOUTH OF
THE TERMINALS BEFORE MIDNIGHT. A PROB30 GROUP WAS INCLUDED FOR
TOMORROW MORNING, BUT SHRA MAY FORM BEFORE SUNRISE. EXPECT
AMENDMENTS AS SHOWERS BEGIN TO FORM NEAR THE ISLAND CHAIN.
PRELIMINARY POINT TEMPS/POPS
KEY WEST 78 89 79 90 / 80 80 60 50
MARATHON 79 88 80 88 / 80 70 50 50
KEY WATCHES/WARNINGS/ADVISORIES
FL...COASTAL FLOOD ADVISORY UNTIL 5 AM EDT THURSDAY FOR FLZ076>078.
GM...SMALL CRAFT ADVISORY UNTIL 11 AM EDT THURSDAY FOR GMZ052>055-
072>075.
PUBLIC/MARINE/FIRE...AJP
AVIATION/NOWCASTS....AJP
DATA ACQUISITION.....MJV
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