877
FXUS62 KMFL 170734
AFDMFL
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
334 AM EDT THU JUL 17 2025
..NEW SHORT TERM, LONG TERM, AVIATION, MARINE
KEY MESSAGES
UPDATED AT 335 AM EDT THU JUL 17 2025
- ONE MORE DAY OF SCATTERED TO NUMEROUS SHOWERS AND STORMS.
- DANGEROUS HEAT INDICES BEGIN FRIDAY AND LAST THROUGH THE
WEEKEND.
- LOWER RAIN CHANCES FRIDAY THROUGH THE WEEKEND.
SHORT TERM
(TODAY THROUGH FRIDAY)
ISSUED AT 335 AM EDT THU JUL 17 2025
AN UPPER LOW WILL MOVE FROM THE WESTERN ATLANTIC OVER THE
PENINSULA BY TONIGHT. UNDER THE DIFFLUENT UPPER FLOW AND WITH
DEEP LAYER MOISTURE AHEAD OF IT, EXPECT SCATTERED TO NUMEROUS
SHOWERS AND STORMS TO DEVELOP. FORCING FROM THE SURFACE LEVEL WILL
LIKELY BE A COMBINATION OF COASTAL CONVERGENCE FROM THE
BACKGROUND WINDS ON THE WESTERN PERIPHERY OF THE BUILDING
SUBTROPICAL RIDGE, OUTFLOW FROM CONVECTION OVER THE BAHAMAS THIS
MORNING, AND A LITTLE BIT OF SEABREEZE INFLUENCE. WHILE MAYBE A
LITTLE MORE ACTIVE THAN A TYPICAL SEABREEZE TYPE DAY, THE
EVOLUTION WILL BE SIMILAR. EXPECT EAST COAST SHOWERS THIS MORNING
TO SPREAD INLAND THROUGH MID-MORNING, WITH MORE ROBUST STORM
DEVELOPMENT BY THE EARLY AFTERNOON. STORMS WILL SPREAD WEST AND
BECOME MORE NUMEROUS THROUGH THE AFTERNOON.
ON FRIDAY, THE STRONG MID-LEVEL RIDGE THAT DEVELOPED UNDER THE
UPPER-LEVEL +PV ANOMALY WILL SHIFT OVERHEAD. ENSEMBLES CONTINUE TO
SHOW THE STRENGTH OF THE RIDGE AT THE TOP END OF CLIMATOLOGY FOR
THIS TIME OF YEAR, WITH ACCOMPANYING MID-LEVEL DRY AIR. THE LOW-
LEVEL RIDGING IS ALSO QUITE IMPRESSIVE, WITH HEIGHTS IN THE 90TH
PERCENTILE VS CLIMO. THIS ALSO MEANS THAT LOWER TROPOSPHERIC
TEMPERATURES WILL BE WELL ABOVE AVERAGE AND IN SIMILAR PERCENTILE
RANGES VS CLIMO. AND WHILE THE MID-LEVEL DRY AIR WILL KEEP
THUNDERSTORM DEVELOPMENT SEVERELY LIMITED, THE PLENTIFUL LOW-LEVEL
MOISTURE FROM THE NEAR SURFACE SE FLOW WILL KEEP DEWPOINTS, RH,
AND SUBSEQUENTLY HEAT INDICES QUITE HIGH. UNDER THE EASTERLY FLOW
REGIME, THE WESTERN HALF OF SOUTH FLORIDA WINDS UP BEING THE
WARMEST, WITH HIGHS IN THE MID 90S AND THE POTENTIAL FOR ISOLATED
LOCATIONS TO EXPERIENCE HEAT INDICES IN EXCESS OF 110. ALONG THE
EAST COAST, LOW-TO MID 90S WILL BE MORE LIKELY WITH SCATTERED
LOCATIONS HEAT INDICES EXCEEDING 105.
LONG TERM
(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 335 AM EDT THU JUL 17 2025
THE STRONG LOW/MID-LEVEL RIDGING AND DRIER MID-LEVEL AIR WILL
PERSIST THROUGH THE WEEKEND AND SO WILL THE LOWER RAIN CHANCES AND
HIGH TEMPS/HEAT INDICES. WPC GUIDANCE BASED ON FORECAST HIGHS AND
ENSEMBLE SPREAD INDICATES A GREATER THAN 50% CHANCE THAT MAX HEAT
INDICES WILL EXCEED 110 ACROSS THE WESTERN HALF OF SOUTH FLORIDA
AND EXCEED 105 ACROSS THE EASTERN HALF EACH DAY. BY NEXT WEEK, THE
DRY MID-LEVEL AIR WILL SHIFT WEST OF SOUTH FLORIDA AND RAIN
CHANCES WILL START TO INCREASE ONCE AGAIN TO SEASONABLE LEVELS.
WITH DEEP LAYER RIDGING PREVAILING, EXPECT THE PRIMARY FORCING
MECHANISM FOR CONVECTION TO BE THE SEABREEZE. THERE ARE SOME
INDICATIONS THAT A SURFACE LOW RESULTANT FROM LEE CYCLOGENESIS
NEAR THE MID-ATLANTIC WILL ADVECT SW ACROSS THE NORTHERN PART OF
FLORIDA EARLY TO MID-WEEK. WHILE THIS MOST LIKELY WON'T DIRECTLY
IMPACT SOUTH FLORIDA, IT COULD DISRUPT THE EASTERLY FLOW REGIME
AND RESULT IN CONVECTION ACROSS A LARGER PORTION OF THE REGION
RATHER THAN MOSTLY ACROSS THE WESTERN HALF.
AVIATION
(06Z TAFS)
ISSUED AT 335 AM EDT THU JUL 17 2025
ANOTHER LOW-CONFIDENCE FORECAST AS FAR AS WHEN A SHOWER OR STORM
COULD IMPACT OUR EAST COAST TERMINALS. THE GREATEST CHANCE WILL BE
FROM SUNRISE THROUGH MID-AFTERNOON, WITH THE THREAT SHIFTING
INLAND AFTER THAT. THE PROBABILITY OF STORMS IMPACTING APF IS
HIGHER THAN ALONG THE EAST COAST AND THIS IS MOST LIKELY LATER
THIS AFTERNOON. OCCASIONAL GUSTS AS HIGH AS 20KTS WILL BE
POSSIBLE AGAIN THIS AFTERNOON.
MARINE
ISSUED AT 335 AM EDT THU JUL 17 2025
CAUTIONARY LEVEL WINDS WILL BE POSSIBLE OVER ATLANTIC WATERS
THROUGH THE FIRST HALF OF THE DAY TODAY. AS THE CALMER CENTER OF THE
SUBTROPICAL RIDGE DRAWS NEARER WINDS WILL SUBSIDE BELOW HEADLINE
LEVELS ONCE AGAIN. SHOWERS AND THUNDERSTORMS REMAIN LIKELY AGAIN
TODAY BUT A PERIOD OF DRIER CONDITIONS IS EXPECTED BEGINNING
TOMORROW AND LASTING INTO THE WEEKEND.
PRELIMINARY POINT TEMPS/POPS
MIAMI 90 81 91 80 / 70 10 10 10
WEST KENDALL 90 78 91 77 / 70 10 20 10
OPA-LOCKA 92 81 93 80 / 70 10 10 10
HOMESTEAD 90 81 90 80 / 60 10 20 10
FORT LAUDERDALE 90 81 90 80 / 70 10 10 10
N FT LAUDERDALE 90 81 90 80 / 70 10 10 10
PEMBROKE PINES 93 83 94 82 / 70 10 10 10
WEST PALM BEACH 90 80 90 79 / 60 10 10 0
BOCA RATON 92 80 91 79 / 60 20 10 0
NAPLES 93 77 94 77 / 80 30 30 10
MFL WATCHES/WARNINGS/ADVISORIES
FL...NONE.
AM...NONE.
GM...NONE.
SHORT TERM...HARRIGAN
LONG TERM....HARRIGAN
AVIATION...HARRIGAN
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