502
FXUS62 KKEY 091418
AFDKEY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
1018 AM EDT THU JUL 9 2026
..NEW DISCUSSION, MARINE, AVIATION, PREV DISCUSSION
KEY MESSAGES
- A SAHARAN AIR LAYER IS EXITING THE FLORIDA KEYS THIS AFTERNOON
WITH SLIGHTLY BETTER MOISTURE MOVING BACK IN FOR THE AFTERNOON
AND EVENING.
- HEAT WILL BE THE PRIMARY WEATHER CONCERN THIS WEEK. HEAT INDICES
MAY CREEP TOWARDS 110 BEFORE THE WEEKEND.
- SHOWER COVERAGE IS EXPECTED TO INCREASE AT THE END OF THE WEEK
WHILE A LOW IN THE UPPER ATMOSPHERE TRACKS WESTWARD ACROSS THE
KEYS. THIS WILL BE FOLLOWED BY A STRONGER SAHARAN AIR LAYER FOR
THE WEEKEND.
DISCUSSION
ISSUED AT 1018 AM EDT THU JUL 9 2026
THE EFFECTS OF THE MOST RECENT SAHARAN AIR LAYER (SAL) PLUME WAS
EVIDENT THIS MORNING WITH THE MILKY SUNRISE ACROSS THE KEYS. THIS
PLUME IS ON ITS WAY OUT WITH SOMEWHAT BETTER MOISTURE MOVING IN
FROM THE BAHAMAS. THIS MOISTURE PLUME IS SADDLED BETWEEN THE
EXITING SAL PLUME AND A STRONGER SAL PLUME THAT WILL ARRIVE LATE
FRIDAY. IN ADDITION, A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT)
CELL WILL ACCOMPANY THIS MOISTURE SURGE AND SHOULD LEND A HAND IN
BRINGING RELATIVELY LARGE SCALE LIFT AS IT PASSES THROUGH. THIS
HOPEFULLY MEANS THAT OUR RAIN CHANCES WILL SPIKE TONIGHT THROUGH
FRIDAY. THIS WOULD BE VERY BENEFICIAL AS ALL OF THE FLORIDA KEYS
WERE PLACED BACK INTO THE D1 (MODERATE DROUGHT) CATEGORY THIS
WEEK.
OTHERWISE, WE ARE ENTERING A LULL IN THE WINDS FROM LAST NIGHT
WITH GENERALLY SPEEDS OF AROUND 10 MPH ACROSS THE ISLAND CHAIN AND
10 TO 15 KNOTS AT MOST OF OUR MARINE PLATFORMS. NO CHANGES MADE TO
THE GOING FORECAST FOR THE REMAINDER OF TODAY. AS HINTED AT ABOVE,
RAIN CHANCES WILL INCREASE TONIGHT ALONG WITH WINDS. EXPECT
ANOTHER PERIOD OF BREEZY CONDITIONS OVERNIGHT.
MARINE
ISSUED AT 1018 AM EDT THU JUL 9 2026
EAST TO SOUTHEAST BREEZES HAVE SLACKENED TO GENERALLY GENTLE TO
OCCASIONALLY MODERATE THIS MORNING AND WILL CONTINUE THROUGH THE
EARLY AFTERNOON. BY THE LATE AFTERNOON, EXPECT BREEZES TO
GRADUALLY FRESHEN, STARTING IN THE STRAITS OF FLORIDA WATERS FIRST
AND THEN SPREADING NORTHWEST THROUGH THE EVENING AND OVERNIGHT.
MODERATE TO FRESH BREEZES EXPECTED FOR MOST IF NOT ALL OF THE
COASTAL WATERS SURROUNDING THE FLORIDA KEYS TONIGHT. EXPECT
ANOTHER CYCLE OF LULLS AND PEAKS TO PERSIST THROUGH FRIDAY AND
FRIDAY NIGHT. IN ADDITION, INCREASING MOISTURE LATER THIS
AFTERNOON WILL LEAD TO A GREATER COVERAGE OF SHOWERS AND
THUNDERSTORMS THIS EVENING THROUGH FRIDAY AFTERNOON.
AVIATION
(12Z TAFS)
ISSUED AT 1018 AM EDT THU JUL 9 2026
VFR CONDITIONS EXPECTED WITH GENTLE EAST TO SOUTHEAST BREEZES.
WILL SEE OCCASIONAL GUSTS AROUND 20 KNOTS FOR THE AFTERNOON. THIS
WILL BE FOLLOWED BY A MINOR SURGE THIS EVENING AND OVERNIGHT WITH
GUSTS NEAR 25 KNOTS. LASTLY, MOISTURE WILL GRADUALLY INCREASE
THROUGH THE FORECAST PERIOD AND COULD SEE SHOWERS AND OR
THUNDERSTORMS POP UP NEAR THE ISLAND TERMINALS THIS AFTERNOON
WITH BETTER COVERAGE OVERNIGHT.
PREV DISCUSSION
ISSUED AT 1215 AM EDT THU JUL 9 2026
QUIET WEATHER CONTINUES ACROSS THE KEYS THIS MORNING. A NARROW BUT
HEALTHY SURFACE THROUGH LOWER LEVEL ATLANTIC RIDGE STRETCHES
WESTWARD ACROSS CENTRAL FLORIDA AND IS DRIVING BREEZY EAST TO
SOUTHEASTERLY FLOW ACROSS THE KEYS. THIS FLOW IS HOLDING UP
TEMPERATURES AND CURRENT READINGS ARE IN THE MID TO UPPER 80S WITH
DEW POINTS IN THE MID TO UPPER 70S. WHILE THIS EVENINGS SOUNDING
INDICATED A PRECIPITABLE WATER NOT TO FAR FROM NORMAL AT 1.67
INCHES, THERE WAS A ROBUST SUBSIDENCE INVERSION BASED JUST ABOVE
900 MB WITH A GOOD SLUG OF DRY AIR. THIS HAS KEPT SHOWER ACTIVITY
DOWN TO ESSENTIALLY NON EXISTENT ACROSS OUR FORECAST AREA.
A CUT OFF UPPER LOW IS CURRENTLY CREEPING ITS WAY WESTWARD THROUGH
THE CENTRAL BAHAMAS AND HAS PRODUCED A WEAK LOWER LEVEL REFLECTION
THAT IS BEGINNING TO MOVE ACROSS CUBA. WHILE TODAY WILL REMAIN
DRY, THE WEAK TROUGH WILL PUSH THROUGH OUR AREA BEGINNING TONIGHT.
THIS WILL WIPE OUT THE STABLE AND DRY LAYER HOLDING SHOWERS AT
BAY. EXPECT A SLIGHT TO LOW CHANCE FOR SHOWERS AND THUNDERSTORMS
BEGINNING TONIGHT. EAST TO SOUTHEASTERLY BREEZES WILL REMAIN
MODERATE TO FRESH, PEAKING IN THE EVENING AND EARLY NIGHT HOURS
AND LULLING SLIGHTLY DURING THE DAY. THIS WILL CONTINUE TO DRIVE
SLIGHTLY ABOVE NORMAL TEMPERATURES WITH HIGHS NEAR 90, LOWS IN THE
MID 80S, AND DEW POINTS HOLDING IN THE MID TO UPPER 70S.
THE PREVIOUSLY MENTIONED UPPER LOW WILL CONTRIBUTE TO YET ANOTHER
LOWER LEVEL TROUGH HEADING INTO THE WEEKEND. THIS WILL KEEP AT
LEAST A LOW CHANCE FOR SHOWERS AND THUNDERSTORMS. THEREAFTER, MUCH
DRIER AND MORE STABLE LOWER LEVELS IS EXPECTED TO SWEEP IN. AS A
RESULT, RAIN CHANCES WILL BE SLIGHT OR LESS FROM LATER IN THE
WEEKEND AND WELL INTO NEXT WEEK.
PRELIMINARY POINT TEMPS/POPS
KEY WEST 92 83 92 83 / 10 30 40 30
MARATHON 90 83 90 83 / 10 30 40 30
KEY WATCHES/WARNINGS/ADVISORIES
FL...NONE.
GM...NONE.
PUBLIC/MARINE/FIRE...LIW
AVIATION/NOWCASTS....LIW
DATA ACQUISITION.....LIW/SD/RG
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