971
FXUS62 KMFL 171757
AFDMFL
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
157 PM EDT THU SEP 17 2026
..NEW SHORT TERM
KEY MESSAGES
UPDATED AT 156 PM EDT THU SEP 17 2026
- SCATTERED THUNDERSTORMS EXPECTED TODAY. RAINFALL CHANCES REMAIN
ELEVATED THIS WEEKEND INTO EARLY NEXT WEEK AS AN UPPER LEVEL
LOW MOVES ACROSS THE REGION.
- HEAVY DOWNPOURS FROM THE STRONGER SHOWERS AND THUNDERSTORMS
COULD LEAD TO LOCALIZED FLOODING OVER THE URBAN AND LOW LYING
AREAS.
- HAZARDOUS MARINE CONDITIONS CONTINUE IN THE GULF WATERS THROUGH
THIS EVENING. A HIGH RISK OF RIP CURRENTS CONTINUES FOR THE
PALM BEACHES THROUGH EARLY FRIDAY, WITH AN ELEVATED RISK OF RIP
CURRENTS FOR THE REST OF THE ATLANTIC BEACHES.
SHORT TERM
(REST OF TODAY THROUGH FRIDAY)
ISSUED AT 156 PM EDT THU SEP 17 2026
HEAVY RAINFALL HAS BEEN PLAGUING THE EASTERN METROS OF SOUTH
FLORIDA THIS MORNING AS A TIGHT MOISTURE GRADIENT BETWEEN DRY AIR TO
OUR NORTH ASSOCIATED WITH ANOMALOUS RIDGING AND A PLUME OF MOISTURE
DRAPED ACROSS OUR REGION HAS SET UP OVER NORTHERN BROWARD AND PALM
BEACH COUNTIES. MESOANALYSIS DATA HAS ALSO CONFIRMED THAT WE HAD
COASTAL CONVERGENCE ALONG THE EAST COAST DUE TO BRISK NORTHEASTERLY
WINDS AT THE SURFACE AND A COUNTERACTING NORTHWESTERLY UPWIND
PROPAGATION VECTOR JUST ALOFT AT AROUND THE 850 MB LEVEL. MRMS AND
LOCAL RAIN GAUGES HAVE INDICATED POCKETS OF AS MUCH AS 4-6" THAT
HAVE FALLEN WITHIN A MATTER OF JUST AN HOUR OR TWO ACROSS PORTIONS
OF PALM BEACH COUNTY. FURTHER SOUTH, ISOLATED AREAS OF UP TO 3
INCHES HAVE BEEN OBSERVED OVER PORTIONS OF COASTAL/METRO BROWARD.
AS A RESULT OF ALL OF THIS MORNING ACTIVITY, IT HAS BEEN A RARELY
COOL AND COMFORTABLE START TO OUR DAY WITH MORE OF A FALL-LIKE
AMBIANCE ACROSS OUR EASTERN METROS. THESE GLOOMY CONDITIONS,
COMPOSED OF PLENTIFUL CLOUD COVER/ANVIL DEBRIS, SHOULD CONTINUE TO
KEEP MUCH OF SOUTH FLORIDA RATHER STABILIZED THROUGH THE MAJORITY OF
THE DAY AND LIMIT ANY WIDESPREAD CONVECTIVE COVERAGE ACROSS THE
MAINLAND. IN CORRESPONDENCE, HIGH-RES MODELS ARE NOT OVERLY
OPTIMISTIC WITH REGARDS TO SHOWER/THUNDERSTORM COVERAGE OVER
INTERIOR/SW FLORIDA AS THE REST OF THE AFTERNOON PROGRESSES AND IN
FACT, CONTINUE TO FOCUS CONVECTION ALONG OUR RECENTLY-DRENCHED
EASTERN METROS AS OUR LOCAL ATLANTIC WATERS STAY GENERALLY UNSTABLE
WITH AN ABUNDANCE OF MOISTURE AND FORCING ALOFT FROM AN ADJACENT
UPPER-LEVEL LOW. GIVEN THE SATURATION THAT HAS OCCURRED ACROSS THE
METROS THIS MORNING, ADDITIONAL INSTANCES OF URBAN FLOODING WILL BE
POSSIBLE THROUGH THE REST OF OUR THURSDAY WITH ANY SUPPLEMENTARY
PASSING SHOWERS AS THEY MOVE IN FROM THE ATLANTIC ALONG OUR SWIFT
ONSHORE FLOW. ALL THE CONVECTIVE INHIBITION, IN ADDITION TO POOR
OVERALL ATMOSPHERIC DYNAMICS THAT REMAIN IN PLACE TODAY, SHOULD
PREVENT SHOWERS AND THUNDERSTORMS MOVING ONSHORE DURING THE
REMAINDER OF THE DAY FROM BECOMING STRONG OR FROM EVEN PRODUCING AS
HEAVY OF RAINFALL RATES AS THIS MORNING.
WE CAN CONTINUE TO EXPECT PERIODIC ATLANTIC SHOWERS AND STORMS TO
KEEP PUSHING ONSHORE THROUGH THE OVERNIGHT HOURS AND INTO OUR
FRIDAY MORNING BEFORE ACTIVITY SUBSEQUENTLY BECOMES MORE SCATTERED
IN NATURE ACROSS SOUTH FLORIDA DURING THE AFTERNOON AND EARLY
EVENING HOURS. A WEAKENING NORTHEASTERLY FLOW ACROSS THE REGION, IN
ADDITION TO OUR UPPER-LEVEL STEERING FLOW BECOMING MORE WEST TO
SOUTHWESTERLY AND A DEVELOPING GULF SEA BREEZE AT THE SURFACE,
SHOULD ALLOW MOST OF FRIDAY'S CONVECTION TO FOCUS OVER THE INTERIOR
WITH THE POTENTIAL TO DRIFT TOWARDS EACH METRO. GIVEN THESE
COUNTERACTING WIND VECTORS AT DIFFERENT PRESSURE HEIGHTS, THE
POTENTIAL FOR SLOWER-MOVING CELLS WILL EXIST (WHICH COULD LEAD TO
MORE FLOOD CONCERNS WITH AN EMPHASIS ON THE EASTERN METROS WITH HOW
MUCH RAIN THEY ALREADY RECEIVED TODAY). THE PROLONGED ANTICIPATED
ARRIVAL OF AN UPPER-LEVEL LOW WILL FINALLY COME TO FRUITION, AS
ENSEMBLE GUIDANCE HAS OUR MID-LEVEL TEMPERATURES DROPPING TO AROUND -
8C AND THEREFORE STEEPENING OUR LAPSE RATES. THIS ALSO REFLECTED IN
OUR HIGH-RES MODELS WITH 700-500 MB LAPSE RATES COOLING TO 6.0-
6.5C/KM, WHICH COULD EVIDENTLY LEAD TO A FEW STRONGER CORES. IT IS
IMPORTANT TO NOTE, HOWEVER, THAT WITH THE ENCROACHMENT OF THIS UPPER-
LEVEL LOW THIS EVENING AND OUR WINDS ALOFT SHIFTING TO MORE OF A
NORTHERLY DIRECTION WILL COME SOME DRY INTRUSION FROM THE PARCHED
ANTECEDENT AIR MASS SITUATED OVER THE SOUTHEAST US IN ASSOCIATION
WITH OUR UPPER-LEVEL RIDGING. ALTHOUGH THIS IS YET TO BE DETERMINED,
IT WILL HAVE TO BE MONITORED AS TO HOW MUCH RESIDUAL DRY AIR
PERSISTS IN OUR ATMOSPHERIC COLUMN (MODELS HAVE PWATS DROPPING TO
1.7-2.0", WHICH IS BELOW TO AROUND AVERAGE FOR THIS TIME OF YEAR)
AND HOW IT COULD POTENTIALLY IMPACT THUNDERSTORM GROWTH IN THE
VERTICAL. NONETHELESS, THE ATMOSPHERE SHOULD BE FAIRLY PRIMED WITH
BAROTROPICALLY-DRIVEN INSTABILITY GRADIENTS FROM THE PRESENCE OF THE
UPPER-LEVEL LOW AND SUFFICIENT LOW-LEVEL MOISTURE TO PRODUCE
SCATTERED SHOWERS AND THUNDERSTORMS ACROSS SOUTH FLORIDA DURING PEAK
DAYTIME HEATING HOURS.
IT WILL BE DIFFICULT FOR TEMPERATURES ACROSS SOUTH FLORIDA'S EASTERN
METROS (CURRENTLY IN THE MID 70S) TO RECOVER FROM ALL THE ONGOING
CLOUD COVER FROM THIS MORNING'S ACTIVITY, AS THEY ARE FORECAST TO
GLACIALLY CLIMB TO AROUND THE MID 80S LATER THIS AFTERNOON WITH SOME
FORTHCOMING BREAKS IN THE CLOUD COVER. HIGHS ACROSS SOUTHWEST
FLORIDA SHOULD PEAK IN THE UPPER 80S. TOMORROW'S HIGH TEMPERATURES
SHOULD BE REACHING THE UPPER 80S TO LOW 90S ACROSS MUCH OF THE
REGION.
LONG TERM
(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 100 AM EDT THU SEP 17 2026
AS WE HEAD INTO THE WEEKEND AND EARLY INTO NEXT WEEK, THE MID/UPPER
LEVEL LOW WILL MOVE INTO THE GULF, AND HIGHER MOISTURE LEVELS MOVE
INTO THE REGION. LIGHT ESE FLOW THIS WEEKEND WILL EVENTUALLY BECOME
SOUTHERLY BY EARLY NEXT WEEK. WITH DEEP TROPICAL MOISTURE MOVING
INTO SOUTH FL, HIGHER THAN NORMAL POPS (80-90%) ARE EXPECTED EACH
DAY. WITH GENERALLY WEAK STEERING FLOWS EXPECTED ALONG WITH
EFFICIENT RAINFALL RATES, URBAN AND POOR DRAINAGE FLOODING WILL
LIKELY BE THE MAIN THREAT EACH DAY. ALL OF THIS WILL CONTINUE TO BE
GOOD NEWS FOR THE ONGOING IMPROVING DROUGHT CONDITIONS.
TEMPERATURES DURING THE EXTENDED PERIOD WILL BE RIGHT AROUND NORMAL
WITH HIGHS GENERALLY IN THE UPPER 80S TO LOWER 90S, AND LOW TEMPS IN
THE MID TO UPPER 70S.
AVIATION
(18Z TAFS)
ISSUED AT 1253 PM EDT THU SEP 17 2026
NORTHEASTERLY WINDS WILL CONTINUE ACROSS ALL TERMINALS AND COULD
BE GUSTY AT TIMES THROUGH THE AFTERNOON HOURS. COVERAGE OF SHOWERS
AND STORMS IS DECREASING, ALTHOUGH KEEPING VCTS IN THE FORECAST
FOR ANOTHER COUPLE OF HOURS. PERIODS OF MVFR OR IFR WILL BE
POSSIBLE IN AND AROUND ANY STORM ALONG WITH GUSTY AND ERRATIC
WINDS. LULL IN SHOWERS AND THUNDERSTORMS EXPECTED OVERNIGHT WITH
LIGHT AND VARIABLE WINDS, WITH POTENTIAL THUNDERSTORM DEVELOPMENT
BY LATE MORNING FRIDAY.
MARINE
ISSUED AT 100 AM EDT THU SEP 17 2026
HAZARDOUS NORTHEAST WINDS TODAY IN THE GULF WATERS, WITH CAUTIONARY
WINDS IN THE ATLANTIC. SEAS 3-6 FT IN THE ATLANTIC WATERS AND 2-3 FT
IN THE GULF WATERS. CONDITIONS CONTINUE TO IMPROVE ON FRIDAY AS
MODERATE EASTERLY WINDS ARE EXPECTED AND SEAS CONTINUE TO SUBSIDE.
BEACHES
ISSUED AT 100 AM EDT THU SEP 17 2026
A MODERATE ENE FLOW AND ELEVATED SWELL WILL RESULT IN A HIGH RISK OF
RIP CURRENTS FOR THE PALM BEACHES THROUGH EARLY FRIDAY, AND AN
ELEVATED RISK FOR THE REST OF THE ATLANTIC BEACHES.
PRELIMINARY POINT TEMPS/POPS
MIAMI 78 89 76 89 / 30 70 50 80
WEST KENDALL 76 89 75 88 / 30 70 40 80
OPA-LOCKA 77 89 76 89 / 30 70 40 80
HOMESTEAD 76 90 76 89 / 40 70 50 80
FORT LAUDERDALE 77 88 77 88 / 40 70 50 80
N FT LAUDERDALE 78 89 77 89 / 40 70 40 80
PEMBROKE PINES 78 89 76 89 / 30 70 40 80
WEST PALM BEACH 77 89 76 90 / 40 60 40 80
BOCA RATON 77 88 77 88 / 40 60 40 80
NAPLES 74 91 74 89 / 10 70 40 80
MFL WATCHES/WARNINGS/ADVISORIES
FL...HIGH RIP CURRENT RISK THROUGH FRIDAY MORNING FOR FLZ168.
AM...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR GMZ656-657-
676.
SHORT TERM...AD
LONG TERM....CMF
AVIATION...RIZZUTO
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