847
FXUS62 KTBW 210016
AFDTBW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
816 PM EDT THU AUG 20 2026
..NEW UPDATE, AVIATION
KEY MESSAGES
- HOT AND HUMID CONDITIONS CONTINUE, WITH HEAT INDICES JUST BELOW
TO NEAR ADVISORY CRITERIA ON FRIDAY.
- MOISTURE GRADUALLY CONTINUES TO INCREASE, LEADING TO GREATER
CHANCES FOR SHOWERS AND THUNDERSTORMS, ESPECIALLY AS THE WEEKEND
APPROACHES.
UPDATE
ISSUED AT 815 PM EDT THU AUG 20 2026
MINOR POP/WX ADJUSTMENTS MADE TO REFLECT LATEST RADAR TRENDS,
OTHERWISE NO CHANGES PLANNED FOR THE EVENING UPDATE. MOIST ONSHORE
FLOW PATTERN CONTINUES LOCALLY, WITH OVERNIGHT SHOWERS AND STORMS
FAVORING COASTAL WATERS AND ADJACENT COASTAL AREAS ASHORE.
GUIDANCE INDICATES LIKELIHOOD OF PREDAWN ACTIVITY ACROSS SWFL
EXTENDING THROUGH THE MORNING BEFORE GRADUALLY DIMINISHING EARLY
AFTERNOON AS FOCUS OF ACTIVITY SHIFTS INTO INTERIOR S FL. SLIGHTLY
LATER TIMING FOR AREAS FURTHER NORTH ACROSS WCFL INTO THE NATURE
COAST, WITH MID TO LATE MORNING THROUGH EARLY AFTERNOON FAVORED
ACROSS COASTAL LOCATIONS BEFORE SHIFTING INLAND OVER THE REMAINDER
OF THE AFTERNOON.
DISCUSSION
ISSUED AT 224 PM EDT THU AUG 20 2026
SCATTERED SHOWERS AND STORMS CONTINUE TO MAKE THEIR WAY EASTWARD
ACROSS THE REGION AND SHOULD BE MOSTLY OUT OF THE FORECAST AREA BY
THIS EVENING. FLOW BECOMES MORE WEST-SOUTHWEST TONIGHT INTO FRIDAY,
RESULTING IN EARLIER RAIN CHANCES OVER THE GULF AND COASTAL AREAS IN
THE MORNING.
PREVIOUS DISCUSSION MODIFIED...HIGH PRESSURE SURFACE AND ALOFT
PERSISTS OVER THE FLORIDA PENINSULA. ANOTHER HOT AND HUMID DAY
CONTINUES WITH HIGH TEMPERATURES IN THE LOWER TO MID 90S. A HEAT
ADVISORY IS IN EFFECT FOR ALL OF WEST CENTRAL AND SOUTHWEST FLORIDA
FOR HEAT INDICES OF UP TO 109. ONSHORE WEST TO NORTHWEST BOUNDARY
LAYER FLOW WILL HELP SHIFT CONVECTION INLAND AND INCREASE IN AREAL
COVERAGE THROUGH THE REMAINDER OF THE AFTERNOON. A FEW STRONG STORMS
WILL BE POSSIBLE WITH STRONG GUSTY WINDS, LOCALLY HEAVY RAIN AND
FREQUENT LIGHTNING.
HEIGHTS ALOFT WILL LOWER A BIT ON FRIDAY WHICH WILL SLIGHTLY
DECREASE LARGE SCALE SUBSIDENCE OVER THE FORECAST AREA. THIS SHOULD
KEEP AFTERNOON MAXIMUM HEAT INDICES JUST BELOW ADVISORY CRITERIA, IN
THE 104 TO 107 RANGE...ALTHOUGH IT WILL STILL BE RATHER HOT WITH
TEMPERATURES IN THE LOWER 90S. ONSHORE WEST BOUNDARY LAYER FLOW WILL
PERSIST, WITH STORMS DEVELOPING OVER THE COASTAL COUNTIES DURING THE
MORNING/EARLY AFTERNOON HOURS AND AGAIN SPREADING INLAND AND
INCREASING COVERAGE DURING THE MID/LATE AFTERNOON. A FEW STRONG
STORMS WILL AGAIN BE POSSIBLE WITH STRONG GUSTY WINDS, LOCALLY HEAVY
RAIN AND FREQUENT LIGHTNING.
A FRONTAL BOUNDARY WILL APPROACH NORTH FLORIDA FRIDAY NIGHT AND
SATURDAY WITH WINDS VEERING TO THE SOUTHWEST. SLIGHTLY DRIER AIR
ALOFT WILL ADVECT OVER THE AREA MAINLY SOUTH OF I-4 AND WILL HOLD
OVER THE REGION INTO SUNDAY. THIS WILL DECREASE AREAL COVERAGE OF
SHOWERS/STORMS WITH HIGHEST POPS EACH DAY ACROSS THE NATURE COAST IN
VCNTY OF THE FRONTAL BOUNDARY.
EARLY NEXT WEEK, DEEP LAYER MOISTURE WILL RECOVER OVER THE CENTRAL
AND SOUTHERN FORECAST AREA. THE SURFACE RIDGE AXIS WILL LIFT NORTH
ACROSS THE CENTRAL PENINSULA WITH THE GRADIENT WEAKENING. THE WEST
COAST SEA BREEZE BOUNDARY WILL PUSH INLAND DURING THE AFTERNOON
HOURS AND WILL LIKELY COLLIDE WITH THE EAST COAST SEA BREEZE
BOUNDARY LATE IN THE DAY OVER THE INTERIOR, WHICH WILL BE THE ZONE
FOR THE BEST CHANCE OF RAIN.
BY MID WEEK, DEEP LAYER MOISTURE WILL BE ENHANCED ACROSS THE
SOUTHERN FORECAST AREA WHICH WILL BECOME THE BEST REGION FOR
AFTERNOON SHOWERS AND STORMS.
AVIATION
(00Z TAFS)
ISSUED AT 730 PM EDT THU AUG 20 2026
VFR EXPECTED OVERNIGHT INTO FRIDAY. EARLY MORNING VCTS POTENTIAL
FOR SWFL TERMINALS, FOLLOWED BY LATE MORNING VCTS FOR WCFL
TERMINALS. GENERALLY BRIEF MVFR/LCL IFR IMPACTS WITH CONVECTION
THROUGH EARLY TO MID AFTERNOON BEFORE ACTIVITY PUSHES INLAND,
WITH OVERALL TIMING A BIT LATER FOR INLAND KLAL TERMINAL. ONSHORE
FLOW PATTERN PERSISTS, WITH LIGHTER FLOW OVERNIGHT THEN INCREASING
MORNING THROUGH AFTERNOON.
MARINE
ISSUED AT 224 PM EDT THU AUG 20 2026
HIGH PRESSURE WILL HOLD OVER THE WATERS THROUGH THE PERIOD WITH
RELATIVELY LIGHT WINDS AND SEAS. THE MAIN HAZARD WILL BE SCATTERED
SHOWERS AND THUNDERSTORMS WHICH MAY PRODUCE LOCALLY GUSTY WINDS AND
ROUGH SEAS, MAINLY DURING THE OVERNIGHT AND EARLY MORNING HOURS.
FIRE WEATHER
ISSUED AT 224 PM EDT THU AUG 20 2026
NO FIRE WEATHER HAZARDS ARE EXPECTED AS SUFFICIENT MOISTURE WILL
KEEP MINIMUM AFTERNOON RELATIVE HUMIDITY VALUES WELL ABOVE CRITICAL
LEVELS FOR THE NEXT SEVERAL DAYS.
PRELIMINARY POINT TEMPS/POPS
TPA 79 91 80 90 / 10 40 30 40
FMY 78 94 78 93 / 10 30 10 20
GIF 76 94 76 93 / 30 30 10 20
SRQ 78 91 78 91 / 10 20 20 20
BKV 74 92 74 90 / 10 40 40 50
SPG 80 90 80 89 / 10 30 20 30
SEA BREEZE THUNDERSTORM REGIME FOR FRIDAY: 4
SEA BREEZE THUNDERSTORM REGIME FOR SATURDAY: 5
FOR ADDITIONAL INFORMATION ON SEA BREEZE REGIMES, GO TO:
HTTPS://WWW.WEATHER.GOV/TBW/THUNDERSTORMCLIMATOLOGY
TBW WATCHES/WARNINGS/ADVISORIES
FL...NONE.
GULF WATERS...NONE.
UPDATE/AVIATION...HURT
DISCUSSION/MARINE/FIRE WEATHER...CARLISLE
DECISION SUPPORT/UPPER AIR/CLIMATE...FLANNERY
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