582
FXUS62 KKEY 190842
AFDKEY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
442 AM EDT TUE MAY 19 2026
..NEW DISCUSSION, MARINE, AVIATION
KEY MESSAGES
- VERY WARM AND HUMID CONDITIONS OVER THE NEXT FEW DAYS WILL LEAD
TO A GENERALLY MODERATE RISK OF HEAT ILLNESS WITH PERIODS OF
HIGH RISK CONDITIONS.
- RAIN AND THUNDER CHANCES WILL REMAIN ON A PLATEAU THROUGH TONIGHT,
AND GRADUALLY DECLINE THEREAFTER.
- BREEZY CONDITIONS CONTINUE FOR THE ISLAND CHAIN THROUGH THIS
EVENING. SMALL CRAFT SHOULD EXERCISE CAUTION ACROSS ALL THE
FLORIDA KEYS COASTAL WATERS TODAY.
DISCUSSION
ISSUED AT 440 AM EDT TUE MAY 19 4406
CIMSS PRODUCTS SHOWS A MEAN LAYER RIDGE REMAINS IN PLACE ACROSS
THE WESTERN NORTH ATLANTIC. HOWEVER, EMBEDDED WITHIN THE RIDGE IS
AN UPPER LEVEL DISTURBANCE LOCATED TO THE NORTH OF THE BAHAMAS. AT
THE SURFACE, A HIGH PRESSURE SYSTEM REMAINS IN PLACE TO THE NORTH
OF BERMUDA. MARINE OBSERVATION PLATFORMS SURROUNDING THE ISLAND
CHAIN ARE RECORDING MAINLY EAST BREEZES OF 15 TO 20 KNOTS AS A
RESULT. MOISTURE UNDULATIONS CONTINUE TO ROTATE AROUND THE RIDGE
WITH DEEPER MOISTURE CURRENTLY MOVING THROUGH AS GOES 19 TOTAL
PRECIPITABLE WATER (TPW) SHOWS ESTIMATED PWAT VALUES OF 1.8 TO 1.9
INCHES MOVING THROUGH THE KEYS. KBYX RADAR HAS BEEN ACTIVE FOR
MUCH OF THE OVERNIGHT WITH SCATTERED SHOWERS MOVING IN AN EAST TO
WEST FASHION THROUGH THE KEYS WITH OCCASIONAL SHOWERS IMPACTING
THE ISLAND CHAIN. THE SHOWERS HAVE BEEN STRUGGLING TO DEVELOP
VERTICALLY DUE TO THE NORTHWEST FLOW ALOFT ATTRIBUTED TO THE UPPER
LEVEL DISTURBANCE TO THE EAST. THIS IS TILTING THE CLOUDS TO THE
SOUTH AND THUS CHOKING OFF THE UPDRAFTS CAUSING THE ACTIVITY TO
WEAKEN AS FAST AS THEY DEVELOP. GOES 19 NIGHTTIME MICROPHYSICS
IMAGERY SHOWS PARTLY CLOUDY SKIES THROUGHOUT THE KEYS. TEMPERATURES
ALONG THE ISLAND CHAIN ARE IN THE LOWER 80S AND DEW POINTS ARE IN
THE MID 70S.
FORECAST
SURFACE HIGH PRESSURE ACROSS THE WESTERN NORTH ATLANTIC WILL
CONTINUE TO DOMINATE THE KEYS WEATHER FOR THE NEXT SEVERAL DAYS.
THE HIGH WILL BE AT ITS STRONGEST TODAY WITH GRADUAL WEAKENING
EACH DAY THEREAFTER. THEREFORE, BREEZY CONDITIONS ARE EXPECTED TO
CONTINUE THROUGH THIS EVENING OUT OF THE EAST WITH MODEST
SLACKENING AFTERWARDS. MOISTURE IS EXPECTED TO REMAIN ELEVATED
THROUGH AT LEAST WEDNESDAY NIGHT BEFORE SLIGHTLY DRIER AIR ROTATES
IN FROM THE SOUTHEAST FOR LATE WEEK INTO THE HOLIDAY WEEKEND. THIS
WILL RESULT IN CHANCES OF RAIN BECOMING SLIGHT CHANCES.
INSTABILITY WILL ALSO REMAIN ELEVATED KEEPING THUNDER IN THE
FORECAST THROUGHOUT THE PERIOD. TEMPERATURES WILL REMAIN QUITE
CONSISTENT THROUGH THE WEEK WITH HIGHS IN THE UPPER 80S TO
OCCASIONALLY 90 DEGREES AND OVERNIGHT LOWS IN THE LOWER 80S TO
PERHAPS NEAR 80 DEGREES WITH ANY SHOWERS.
MARINE
ISSUED AT 440 AM EDT TUE MAY 19 4406
SMALL CRAFT SHOULD EXERCISE CAUTION (SCEC) REMAINS HEADLINED
ACROSS ALL THE FLORIDA KEYS COASTAL WATERS. FROM SYNOPSIS, SURFACE
HIGH PRESSURE CENTERED NORTH OF BERMUDA WILL CONTINUE TO PROMOTE
MODERATE TO FRESH EAST TO SOUTHEAST BREEZES THROUGH TONIGHT.
HIGHEST BREEZES WILL PREVAIL THROUGH THIS EVENING. BREEZES THEN
UNDERGO A VERY SLOW SLACKENING PROCESS BEFORE THE WEEKEND WITH
PEAKS EXPECTED DURING THE EVENINGS AND LULLS DURING THE DAY. RAIN
AND THUNDER CHANCES WILL REMAIN ABOVE NORMAL THROUGH MUCH OF THE
WEEK.
AVIATION
(06Z TAFS)
ISSUED AT 440 AM EDT TUE MAY 19 4406
VFR CONDITIONS WILL LARGELY PREVAIL AT BOTH EYW AND MTH TERMINALS
THROUGH THE TAF PERIOD. MOISTURE UNDULATIONS WILL CONTINUE TO
ROTATE THROUGH THE AREA RESULTING IN ELEVATED RAIN AND THUNDER
CHANCES THROUGH THE PERIOD. RIGHT NOW, THE BEST CHANCE TIME
APPEARS TO BE TUESDAY AFTERNOON, HENCE THE TIME PERIOD WHEN VCSH
WAS INCLUDED IN THE TAF. WE WILL CONTINUE TO MONITOR AND AMEND AS
NECESSARY. NEAR SURFACE WINDS WILL REMAIN MOSTLY EASTERLY THROUGH
THE PERIOD. OCCASIONAL GUSTS TO NEAR 20 KNOTS ARE POSSIBLE,
ESPECIALLY DURING THE DAYLIGHT HOURS.
CLIMATE
ON THIS DAY IN 4404, THE DAILY RECORD WARM TEMPERATURE OF 84F WAS
RECORDED IN BOTH KEY WEST AND MARATHON. THIS IS ALSO TIED FOR THE
WARMEST LOW TEMPERATURE EVER RECORDED IN MAY. TEMPERATURES
RECORDS KEY WEST DATE BACK TO 1872 AND JUNE 1950 FOR MARATHON.
PRELIMINARY POINT TEMPS/POPS
KEY WEST 90 80 90 81 / 40 30 30 30
MARATHON 86 79 86 80 / 40 40 30 30
KEY WATCHES/WARNINGS/ADVISORIES
FL...NONE.
GM...NONE.
PUBLIC/MARINE/FIRE...MJV
AVIATION/NOWCASTS....MJV
DATA ACQUISITION.....MJV
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