305
FXUS62 KKEY 170923
AFDKEY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
423 AM EST TUE DEC 17 2024
..NEW DISCUSSION, MARINE, AVIATION
DISCUSSION
ISSUED AT 423 AM EST TUE DEC 17 2024
A WET DECEMBER PATTERN CONTINUES ACROSS THE FLORIDA KEYS THIS
MORNING. A HIGH PRESSURE SYSTEM OVER THE NORTH ATLANTIC CONTINUES
TO SLOWLY MOVE EASTWARD WHILE AN INVERTED TROUGH SLIDES TO THE
WEST ALONG THE SOUTHERN PERIPHERY OF THIS HIGH. MIMIC TOTAL
PRECIPITABLE WATER SHOWS AN INCREASED PLUME OF MOISTURE (APPROX
1.65 INCHES TO 1.80 INCHES) THROUGHOUT THE FLORIDA KEYS WITH
SLIGHTLY LESS MOISTURE 1.45 TO 1.6 INCHES TO THE EAST OF THE
BAHAMAS ALONG WITH EVEN DEEPER MOISTURE APPROACHING 2 INCHES NORTH
OF HISPANIOLA. AS A RESULT, KBYX RADAR HAS REMAINED ACTIVE ALL
NIGHT WITH SHALLOW SHOWERS MOVING FROM EAST TO WEST. MRMS DATA
SHOWS ESTIMATED RAINFALL AMOUNTS OF 0.1 TO 0.25 INCHES WITH THE
HEAVIEST ACTIVITY OVER THE STRAITS OF FLORIDA PRODUCING ISOLATED
POCKETS OF A QUARTER INCH OR MORE. IN ADDITION, THE HIGH OVER THE
NORTH ATLANTIC AND THE INVERTED TROUGH OVER THE BAHAMAS IS
CREATING FOR A HEALTHY PRESSURE GRADIENT ACROSS THE KEYS. THIS IS
PROMOTING NORTHEAST TO EAST BREEZES OF 15 TO 20 KNOTS AT MARINE
PLATFORMS SOUTH OF THE CHAIN WITH 10 TO 15 KNOTS NORTH OF THE
CHAIN. ISLAND CHAIN COMMUNITIES ARE OBSERVING 10 TO 15 MPH OUT OF
THE NORTHEAST TO EAST. TEMPERATURES ALONG THE ISLAND CHAIN ARE IN
THE LOWER TO MID 70S WITH DEW POINTS NEAR 70 DEGREES.
FORECAST
THE FORECAST FOR THE NEXT SEVERAL PERIODS REMAINS UNSETTLED. THE
AFOREMENTIONED HIGH PRESSURE OVER THE NORTH ATLANTIC WILL SLOWLY
PROPAGATE FARTHER EASTWARD WHILE AN INVERTED TROUGH CONTINUES TO
SLOWLY SLIDE WESTWARD ALONG THE SOUTHERN PERIPHERY OF THIS HIGH.
AS A RESULT, BREEZES WILL REMAIN FAIRLY CONSISTENT OUT OF THE
NORTHEAST TO EAST ALONG THE ISLAND CHAIN THROUGH EARLY WEDNESDAY
BEFORE SHIFTING TO THE EAST. BREEZES WILL FURTHER SLACKEN
WEDNESDAY AS THE HIGH LOOSENS IT GRIP ACROSS THE KEYS. THE
INVERTED TROUGH WILL CONTINUE TO KEEP THE MOISTURE INCREASED
ACROSS THE KEYS RESULTING IN 40% BEING MAINTAINED THROUGH TONIGHT
WITH WEDNESDAY AND WEDNESDAY NIGHT BEING INCREASED FROM 30% TO
40%. SLIGHT CHANCE OF THUNDER WAS ALSO MAINTAINED THROUGH
WEDNESDAY NIGHT AS THE INVERTED TROUGH CONTINUES TO IMPACT THE
REGION. STATISTICAL GUIDANCE ALSO CONTINUES TO SHOW PROBABILITIES
OF 15 TO 40 PERCENT THROUGH WEDNESDAY NIGHT ALONG WITH NUMERICAL
WEATHER GUIDANCE DEPICTING AMPLE INSTABILITY THROUGH THIS TIME
FRAME WITH THE HIGHEST PROBABILITIES TODAY.
THE KEYS ARE EXPECTED TO REMAIN IN A COL REGION FOR MUCH OF
THURSDAY DUE TO NO LARGE SCALE WEATHER SYSTEMS NEARBY. HOWEVER,
MOISTURE IS EXPECTED TO STILL REMAIN FAIRLY ABUNDANT LEADING TO
30% CHANCES OF RAIN. THE ONLY CAVEAT TO THIS WILL BE THE LIGHT
FLOW, THEREFORE, RAIN CHANCES MAY BE LOWERED IN SUBSEQUENT
PACKAGES AS THE ONLY MECHANISM TO SPARK A SHOWER THURSDAY WOULD BE
MESOSCALE PROCESSES.
THEN AN UPPER LEVEL TROUGH CURRENTLY MOVING INTO THE PACIFIC
NORTHWEST WILL MOVE OVER THE INTERMOUNTAIN WEST TODAY THROUGH THIS
EVENING BEFORE DIVING SOUTHEASTWARD TO THE NORTH GULF COAST LATE
IN THE DAY ON WEDNESDAY. THIS TROUGH IS EXPECTED TO SWING FROM
POSITIVELY TILTED TO NEGATIVELY TILTED AS IT TRAVERSES THE
SOUTHEASTERN U.S. AND DEVELOPS INTO A FAIRLY SIGNIFICANT STORM AS
IT HEADS TO ATLANTIC CANADA. AT THE SURFACE, THIS TROUGH WILL ACT
TO HELP PUSH A COLD FRONT THROUGH THE KEYS AS THE SURFACE LOW
DEVELOPS EAST OF FLORIDA THURSDAY NIGHT. THIS WILL BRING
FRESHENING NORTHERLY BREEZES TO THE CHAIN ALONG WITH MUCH DRIER
AIR AND NEAR NIL RAIN CHANCES FOR THURSDAY NIGHT THROUGH SUNDAY.
A SECONDARY FRONT IS ANTICIPATED TO PRESS THROUGH THE KEYS
SOMETIME ON FRIDAY WHICH WILL FRESHEN BREEZES FURTHER YET AGAIN.
ALSO, A MORE SIGNIFICANT DROP IN DEW POINTS AND TEMPERATURES IS
EXPECTED HEADING INTO THE WEEKEND WITH HIGHS SATURDAY ONLY NEAR 70
DEGREES.
IN THE WAKE OF THE SECONDARY FRONT, A LARGE AND STRONG HIGH
PRESSURE BUILDS ACROSS THE EASTERN UNITED STATES OVER THE WEEKEND
INTO EARLY NEXT WEEK WITH MOST ENSEMBLE AND DETERMINISTIC GUIDANCE
ON BOARD WITH THIS SOLUTION. THIS WILL PROMOTE FRESHENING
NORTHEAST TO EAST BREEZES WITH ANOTHER POTENTIALLY LENGTHY BLOW
EXPECTED AS A HEALTHY PRESSURE GRADIENT DEVELOPS. INITIALLY,
MOISTURE IS EXPECTED TO REMAIN SCARCE, BUT THIS IS EXPECTED TO
RAPIDLY CHANGE AS MOISTURE QUICKLY INCREASES AT 850 MB. ANY
SHOWERS WILL YET AGAIN REMAIN SHALLOW AND QUICK MOVING IN THE
EASTERLIES PRODUCING MINOR RAINFALL AMOUNTS GENERALLY UNDER A
TENTH OF AN INCH. THIS MAY BE JUST ENOUGH TO CREATE A WET LEAD-UP
TO CHRISTMAS WITH THE WET REGIME AND WINDY CONDITIONS POTENTIALLY
CONTINUING INTO THE CHRISTMAS HOLIDAY.
MARINE
ISSUED AT 423 AM EST TUE DEC 17 2024
SMALL CRAFT SHOULD EXERCISE CAUTION (SCEC) IS HEADLINED FOR TODAY
ACROSS THE STRAITS OF FLORIDA WITH SMALL CRAFT SHOULD EXERCISE
CAUTION UNTIL WINDS DECREASE FOR HAWK CHANNEL. FROM SYNOPSIS, AN
INVERTED TROUGH OVER THE BAHAMAS IN COMBINATION WITH A HIGH
PRESSURE SYSTEM OVER THE NORTH ATLANTIC WILL PROMOTE MODERATE TO
FRESH NORTHEAST TO EAST BREEZES TODAY. AS THE HIGH SLIDES FURTHER
INTO THE NORTH ATLANTIC AND THE INVERTED TROUGH SLIDES FURTHER
WEST TOWARDS THE KEYS, BREEZES WILL CONTINUE TO GRADUALLY SLACKEN
THROUGH MID WEEK. SHALLOW TROPICAL MOISTURE ASSOCIATED WITH THE
TROUGH WILL SUPPORT ROUNDS OF ISOLATED TO SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS THROUGH MID WEEK. LATE IN THE WEEK, A WEAK
COLD FRONT IS FORECAST TO MOVE SOUTH FROM THE GULF OF MEXICO AND
REGENERATE MODERATE TO FRESH NORTHERLY BREEZES FOR THE WEEKEND.
AVIATION
(06Z TAFS)
ISSUED AT 423 AM EST TUE DEC 17 2024
WHILE VFR CONDITIONS WILL PREVAIL AT THE ISLAND TERMINALS THROUGH
THE TAF PERIOD, BOUTS OF SCATTERED SHOWERS WITH POSSIBLE EMBEDDED
BRIEF THUNDERSTORMS MAY OCCASIONALLY RESULT IN SUB-VFR CIGS AND
VISIBILITIES. AFTER A LULL IN ACTIVITY EXPECTED THROUGH SUNRISE,
ADDITIONAL SCATTERED DEVELOPMENT IS EXPECTED, CONTINUING THROUGH
THE END OF THE TAF PERIOD. TIMING OF ANY IMPACTFUL ACTIVITY IS
HIGHLY UNCERTAIN, WARRANTING EXCLUSION FROM THE TAFS AT THIS TIME.
CLIMATE
ON THIS DAY IN 2006, A DAILY RECORD RAINFALL OF 2.24" WAS
MEASURED IN MARATHON. RAINFALL RECORDS FOR MARATHON DATE BACK TO
1950.
PRELIMINARY POINT TEMPS/POPS
KEY WEST 79 72 80 72 / 30 30 30 20
MARATHON 79 72 81 71 / 40 40 40 40
KEY WATCHES/WARNINGS/ADVISORIES
FL...NONE.
GM...NONE.
PUBLIC/MARINE/FIRE...MJV
AVIATION/NOWCASTS....BT
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