445
FXUS62 KKEY 131731
AFDKEY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
131 PM EDT SUN SEP 13 2026
..NEW AVIATION
KEY MESSAGES
- MOISTURE WILL LINGER ACROSS THE REGION THROUGH THIS EVENING,
SUPPORTING ABOVE NORMAL RAIN AND THUNDERSTORM CHANCES.
- HEAT INDEX VALUES WILL RANGE FROM 100-108 DEGREES DAILY, WITH
LITTLE RELIEF FROM THE MUGGY CONDITIONS OVERNIGHT. KNOW THE
SIGNS OF HEAT STRESS, TAKE FREQUENT BREAKS, AND STAY HYDRATED.
- WINDS ARE EXPECTED TO TREND UPWARDS OVER THE SEVERAL DAYS,
LIKELY PEAKING IN THE MODERATE TO FRESH RANGE AROUND MID WEEK.
AVIATION
(18Z TAFS)
ISSUED AT 130 AM EDT SUN SEP 13 2026
AN ISLAND CLOUD LINE WILL WAX AND WANE IN THE VICINITY OF THE
TERMINALS THROUGH THIS EVENING, SUPPORTING INCLUSION OF VCSH IN
THE TAFS. CONFIDENCE IN IMPACTS TO EYW ARE HIGHER THAN AT MTH, AND
HAVE THUS INCLUDED A TEMPO FOR THUNDERSTORM IMPACTS THERE. AFTER
THIS EVENING, CONVECTION IS EXPECTED TO LARGELY DECREASE IN
COVERAGE. OUTSIDE OF ANY THUNDERSTORMS, WINDS WILL REMAIN LIGHT
AND VARIABLE, BEFORE GRADUALLY SHIFTING TO THE EAST TO SOUTHEAST
AFTER 03Z.
PREV DISCUSSION
ISSUED AT 400 AM EDT SUN SEP 13 2026
THE WEAK WESTERN FLANK OF AN ATLANTIC SURFACE RIDGE STRETCHES
WESTWARD INTO SOUTH FLORIDA. THIS ALONG WITH DIURNAL EFFECTS HAS
RESULTED IN LIGHT AND VARIABLE BREEZES ACROSS THE AREA. THE
ENVIRONMENT IS SEASONABLY UNSTABLE AND UNCAPPED. VERY MOIST LOWER
LEVELS ALONG WITH THE WEAK FLOW HAD THE AREA PRIMED FOR A
CONSIDERABLE AMOUNT OF VERY ACTIVE BOUNDARY INTERACTIONS THROUGH
THE DAY AND EVENING. THE AREA IS NOW WORKED OVER AND NO SHOWERS
ARE CURRENTLY IN THE FORECAST AREA. SULTRY CONDITIONS ARE IN PLACE
WITH TEMPERATURES IN THE LOWER TO MID 80S AND DEW POINTS WELL UP
IN THE UPPER 70S.
THE PRESSURE FIELD AROUND THE KEYS AND SOUTH FLORIDA WILL REMAIN
RATHER FLAT OVER THE NEXT COUPLE OF DAYS WITH DIURNAL HEATING
DISRUPTING THE WESTERN END OF THE ATLANTIC RIDGE ON A DAILY
BASIS. AS A RESULT, SURFACE WINDS WILL REMAIN LIGHT AND VARIABLE.
CONVECTIVE FORCING WILL BE WEAK DUE TO NO FEATURES ALOFT OR AT THE
SURFACE. HOWEVER, LOWER LEVEL MOISTURE IS EXPECTED TO REMAIN VERY
MOIST TODAY, AND SLIGHTLY LESS TOMORROW. THE ENVIRONMENT IS
EXPECTED TO REMAIN UNCAPPED WITH SEASONABLE INSTABILITY. AS A
RESULT, HIGH CHANCE OF PRECIPITATION WILL BE RETAINED TODAY. THE
WEAK FLOW AND HUMID AIR WAFTING IN FROM VERY WARM WATERS MAY ALLOW
FOR ANOTHER SLIGHTLY HOTTER THAN NORMAL DAY. DEW POINTS WILL
REMAIN IN THE UPPER 70S.
A MID LATITUDE TROUGH WILL SWING OFF THE ATLANTIC COAST ON MONDAY
AND HOLD THE ATLANTIC RIDGE OFF TO THE EAST. THE GRADIENT WILL
REMAIN WEAK, HOWEVER, GUIDANCE SUGGESTS A MORE PREVAILING
EASTERLY STEERING FLOW WILL TAKE SHAPE. THIS ALONG WITH A BIT
LESS LOW LEVEL MOISTURE SHOULD HELP TO PAIR BACK RAIN CHANCES
SOME. ISLAND CLOUD LINE AND MAINLAND OUTFLOW BOUNDARIES WILL
REMAIN A CONCERN AND WILL KEEP POPS SLIGHTLY ABOVE NORMAL. EXPECT
NEAR NORMAL TEMPERATURES WITH DEW POINTS IND THE MID TO UPPER 70S.
OUR AREA WILL BEGIN FEELING THE EFFECTS OF A ROBUST HIGH PRESSURE
SYSTEM EXPANDING SOUTH SOUTHEASTWARD OUT OF CANADA THROUGH THE
SOUTHEASTERN UNITED STATES. EXPECT BREEZES TO GRADUALLY FIRM UP
OUT OF THE NORTHEAST TO EAST THROUGH THE FIRST HALF OF THE WEEK.
BREEZES ARE EXPECTED TO PEAK IN THE LATE TUESDAY THROUGH LATE
WEDNESDAY TIME FRAME, BECOMING MODERATE. THE MORE BACKED
STREAMLINES WILL HELP TO KEEP DEW POINTS DOWN IN THE MID 70S AND
SHAVE A DEGREE OR TWO OFF OUR HIGHS. RAIN CHANCES WILL BE HIGHLY
UNCERTAIN. THIS IS DUE TO A SWATH OF INCREASED LOW LEVEL MOISTURE
ACCOMPANYING THE FRESHENING BREEZES. IN ADDITION, GUIDANCE SHOWS
A BROAD INVERTED TROUGH SETTING UP OVER THE BAHAMAS AND EASTERN
CUBA. THESE FACTORS MAY CONTRIBUTE TO HIGHER RAIN CHANCES. FOR NOW
WILL HOLD MID WEEK RAIN PROBABILITIES AT HIGH CHANCE.
MARINE
ISSUED AT 1039 AM EDT SUN SEP 13 2026
NO WATCHES, WARNINGS, OR ADVISORIES ARE CURRENTLY IN EFFECT IN THE
FLORIDA KEYS WATERS. FROM SYNOPSIS, A WEAK PRESSURE PATTERN TODAY
WILL RESULT IN LIGHT AND VARYING BREEZES. BREEZES WILL GRADUALLY
FIRM UP OUT OF THE NORTHEAST TO EAST OVER THE NEXT FEW DAYS, AS A
CONTINENTAL HIGH BUILDS SOUTHWARD TOWARDS OUR AREA. LOW LEVEL
MOISTURE WILL REMAIN ABUNDANT THROUGH AT LEAST TODAY, AND KEEP
CONVECTIVE POTENTIAL ABOVE NORMAL. RAIN CHANCES SHOULD FALL TO
NEAR NORMAL EARLY IN THE WEEK AS DRIER LOWER LEVELS FILTER IN. THE
RIDGE WILL BE REINFORCED THROUGH THE FIRST HALF OF THE WEEK,
RESULTING IN FRESHENING NORTHEAST TO EASTERLY BREEZES.
KEY WATCHES/WARNINGS/ADVISORIES
FL...NONE.
GM...NONE.
PUBLIC/MARINE/FIRE...BT
AVIATION/NOWCASTS....BT
DATA ACQUISITION.....BT
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