387
FXUS62 KJAX 120813
AFDJAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
413 AM EDT SUN JUL 12 2026
KEY MESSAGES
FOR THE LATEST NE FL AND SE GA DAILY KEY MESSAGES PLEASE VISIT:
HTTPS:/WWW.WEATHER.GOV/MEDIA/JAX/BRIEFINGS/NWS-JAX-BRIEFING.PDF
- DANGEROUS HEAT CONTINUES TODAY, WITH HEAT ADVISORY CONDITIONS
ALONG THE I-95 AND MOST OF THE U.S. HIGHWAY 301 CORRIDORS.
- SCATTERED TO NUMEROUS AFTERNOON AND EARLY EVENING
THUNDERSTORMS TODAY, WITH STRONG TO ISOLATED SEVERE STORMS
POSSIBLE.
- INCREASING COVERAGE OF AFTERNOON & EVENING THUNDERSTORMS ON
MONDAY AND TUESDAY. HEAVY DOWNPOURS AND LOCALIZED FLOODING
WILL BE POSSIBLE.
- SUMMERTIME HEAT AND HUMIDITY POTENTIALLY RETURNS LATER THIS
WEEK AS THUNDERSTORM COVERAGE DECREASES.
NEAR TERM /THROUGH TONIGHT/
MAIN HIGHLIGHTS TODAY AND TONIGHT:
- DANGEROUS HEAT CONTINUES TODAY, WITH HEAT ADVISORY CONDITIONS
ALONG THE I-95 AND MOST OF THE U.S. HIGHWAY 301 CORRIDORS.
- SCATTERED TO NUMEROUS AFTERNOON AND EARLY EVENING
THUNDERSTORMS, WITH STRONG TO ISOLATED SEVERE STORMS
POSSIBLE. STRONGER STORMS WILL BE CAPABLE OF PRODUCING
DAMAGING WIND GUSTS, FREQUENT LIGHTNING STRIKES, AND HEAVIER
DOWNPOURS LATE THIS AFTERNOON AND EARLY THIS EVENING.
EARLY MORNING SURFACE ANALYSIS DEPICTS ATLANTIC HIGH PRESSURE
(1021 MILLIBARS) CENTERED TO THE SOUTH OF BERMUDA, WITH THIS
FEATURE EXTENDING ITS AXIS WESTWARD ACROSS SOUTH FL AND THE
SOUTHEASTERN GULF. MEANWHILE, A WAVY FRONTAL BOUNDARY EXTENDS
FROM NORTH CAROLINA'S OUTER BANKS WESTWARD ACROSS THE SOUTHERN
APPALACHIANS, THE TENNESSEE VALLEY, THE OZARKS AND THE SOUTHERN
PLAINS STATES. ANOTHER HIGH PRESSURE CENTER (1021 MILLIBARS) WAS
BUILDING OVER THE GREAT LAKES AND NEW ENGLAND IN THE WAKE OF
THIS FRONTAL BOUNDARY. ALOFT...A SHORTWAVE TROUGH WAS PUSHING
SLOWLY SOUTHWARD FROM THE OHIO VALLEY TOWARDS THE TENNESSEE
VALLEY, WITH THIS FEATURE SHIFTING DEEP-LAYERED RIDGING CENTERED
OVER THE BAHAMAS SLOWLY SOUTHWARD. OTHERWISE, "HEAT WAVE"
RIDGING WAS EXPANDING OVER THE ROCKIES AND THE PLAINS STATES.
LATEST GOES-EAST DERIVED TOTAL PRECIPITABLE WATER IMAGERY
INDICATES THAT PWAT VALUES CONTINUE TO SLOWLY INCREASE ACROSS
OUR REGION, WITH VALUES RANGING FROM 1.6 - 1.9 INCHES. MID AND
HIGH ALTITUDE CLOUDINESS WAS PERSISTING ACROSS PORTIONS OF
NORTHEAST AND NORTH CENTRAL FL, WITH FAIR SKIES OTHERWISE IN
PLACE. ISOLATED CONVECTION WAS ALREADY DEVELOPING ALONG THE FL
NATURE COAST NEAR CEDAR KEY AND CRYSTAL RIVER IN THE PREVAILING
WESTERLY FLOW PATTERN. TEMPERATURES AND DEWPOINTS AT 08Z WERE IN
THE 70S AREA-WIDE.
TROUGHING DIGGING SLOWLY SOUTHWARD ACROSS THE TENNESSEE VALLEY
AND THE SOUTHERN APPALACHIANS WILL PUSH A FRONTAL BOUNDARY
SOUTHWARD THROUGH THE CAROLINAS TODAY AND INTO NORTHERN GA
TOWARDS SUNRISE ON MONDAY. WESTERLY LOW LEVEL FLOW WILL
GRADUALLY DEEPEN DOWNSTREAM OF THIS BOUNDARY TODAY AND TONIGHT
ACROSS OUR AREA, ADVECTING A PLUME OF TROPICAL MOISTURE FROM
WEST TO EAST ACROSS OUR REGION THIS AFTERNOON AND EVENING,
RESULTING IN PWATS RISING ABOVE 2 INCHES LATER TODAY ACROSS
NORTHEAST AND NORTH CENTRAL FL, WITH TROPICAL MOISTURE THEN
OVERSPREADING SOUTHEAST GA THIS EVENING. ALTHOUGH MID- LEVEL DRY
AIR WILL BE DEPARTING OUR AREA THIS AFTERNOON, INTENSE HEATING
THIS MORNING AND EARLY AFTERNOON BENEATH MOSTLY SUNNY SKIES WILL
LIKELY KEEP RELATIVELY STEEP LAPSE RATES IN PLACE THIS
AFTERNOON, SETTING THE STAGE FOR ANOTHER ROUND OF STRONG TO
ISOLATED SEVERE STORMS ACROSS OUR AREA LATE THIS AFTERNOON AND
EARLY THIS EVENING.
WESTERLY FLOW WILL DELAY THE DEVELOPMENT OF THE ATLANTIC SEA
BREEZE BOUNDARY UNTIL THE EARLY AFTERNOON HOURS, DRIVING
DANGEROUS HEAT TO COASTAL LOCATIONS ONCE AGAIN TODAY. HIGHS WILL
AGAIN SOAR TO THE MID AND UPPER 90S AT MOST LOCATIONS BEFORE
THUNDERSTORM ACTIVITY INCREASES IN COVERAGE AND INTENSITY FROM
WEST TO EAST ACROSS NORTHEAST AND NORTH CENTRAL FL, WITH OUTFLOW
BOUNDARIES THEN ADVECTING NORTHWARD INTO SOUTHEAST GA EARLY
THIS EVENING, TRIGGERING SCATTERED CONVECTION. A HEAT ADVISORY
THAT WAS INITIALLY IN PLACE FOR THE I-95 AND U.S. HIGHWAY 17
CORRIDORS WAS EXPANDED INLAND TO INCLUDE THE U.S. HIGHWAY 301
CORRIDOR ACROSS NORTHEAST FL AND SOUTHEAST GA, WHERE HEAT INDEX
VALUES WILL PEAK AROUND THE 108 DEGREE THRESHOLD. COASTAL
LOCATIONS MAY EXPERIENCE PEAK HEAT INDICES AROUND 110 DURING THE
EARLY TO MID AFTERNOON HOURS AS THE ATLANTIC SEA BREEZE PUSHES
INLAND, RESULTING IN DEWPOINTS RISING TO THE MID AND UPPER 70S.
PEAK HEAT INDEX VALUES ELSEWHERE SHOULD REMAIN IN THE 100-107
DEGREE RANGE AS INTENSE HEATING ALLOWS DEWPOINTS TO MIX DOWN TO
AROUND 70 BY THE MID-AFTERNOON HOURS.
ISOLATED CONVECTION DEVELOPING ALONG THE FL NATURE COAST DURING
THE PREDAWN HOURS COULD SEND A FEW SHOWERS TOWARDS WESTERN
PORTIONS OF MARION COUNTY THROUGH AROUND SUNRISE. OTHERWISE,
CONVECTION WILL INITIALLY DEVELOP ALONG THE GULF COAST SEA
BREEZE EARLY THIS AFTERNOON ALONG THE FL BIG BEND AND NATURE
COASTS, WITH ACTIVITY THEN INCREASING IN COVERAGE AND INTENSITY
AS THE GULF SEA BREEZE BOUNDARY PROGRESSES EASTWARD. STRONG TO
ISOLATED SEVERE STORMS WILL BE POSSIBLE BY THE MID TO LATE
AFTERNOON HOURS, WITH ACTIVITY POTENTIALLY INTERACTING WITH A
MUCH SLOWER MOVING ATLANTIC SEA BREEZE BOUNDARY LATE THIS
AFTERNOON ALONG THE I-95 CORRIDOR. MESOSCALE BOUNDARY COLLISIONS
WILL AGAIN DRIVE STORM INTENSITY, WITH "PULSING" STORMS
POTENTIALLY CREATING DOWNBURST WINDS OF 40-60 MPH, ALONG WITH
FREQUENT LIGHTNING STRIKES AND LOCALLY HEAVY DOWNPOURS. ACTIVITY
WILL THEN SPREAD INTO SOUTHEAST GA TOWARDS SUNSET, WHERE
ACTIVITY COULD LINGER INTO THE EVENING HOURS, WHILE CONVECTION
OVER NORTHEAST AND NORTH CENTRAL FL PUSHES EASTWARD OVER THE
ATLANTIC WATERS. ACTIVITY COULD LINGER THROUGH AROUND MIDNIGHT
FOR THE I-95 CORRIDOR AND COASTAL SOUTHEAST GA BEFORE
DISSIPATING OVERNIGHT. NOCTURNAL CONVECTION MAY BE A LITTLE MORE
NUMEROUS OVER APALACHEE BAY AND THE FL BIG BEND AND NATURE
COASTS DURING THE PREDAWN HOURS ON MONDAY, WITH ISOLATED
CONVECTION POTENTIALLY PUSHING INTO SOUTHERN PORTIONS OF THE
SUWANNEE VALLEY AND PORTIONS OF NORTH CENTRAL FL TOWARDS
SUNRISE. LOW LEVEL WESTERLY FLOW WILL KEEP LOWS IN THE LOW TO
MID 70S INLAND AND THE MID TO UPPER 70S AT COASTAL LOCATIONS
TONIGHT.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/
MAIN HIGHLIGHTS DURING THIS PERIOD:
- INCREASED STORM CHANCES MONDAY AND TUESDAY.
- POTENTIAL FOR EXCESSIVE RAINFALL AND STRONG STORMS NORTH OF
I-10.
MORE WIDESPREAD DIURNAL BOUTS OF SHOWERS AND STORMS ARE
ANTICIPATED FOR MONDAY AND TUESDAY AS HIGH PRESSURE RIDGING
EXTENDING IN OVER THE SOUTHERN FLORIDA PENINSULA AND AS LOW
PRESSURE TO THE NORTH INTERACT TO CREATE A SOUTHWESTERLY-
WESTERLY FLOW THROUGH THE START OF THE WEEK BRINGING INCREASED
MOISTURE LEVELS AND INSTABILITY LEADING TO A POTENTIAL FOR
EXCESSIVE RAINFALL AND STRONG TO SEVERE STORMS, ESPECIALLY FOR
AREAS NORTH OF THE I-10 CORRIDOR. HIGH TEMPERATURES FOR THE
BEGINNING OF THE WEEK WILL RISE INTO THE LOWER TO MID 90S WITH
OVERNIGHT LOW TEMPERATURES DROPPING DOWN INTO THE LOWER TO MID
70S. HEAT INDEX VALUES WILL ARE EXPECTED TO RANGE UPWARDS OF
ABOVE 100, BUT IS LIKELY TO REMAIN BELOW HEAT ADVISORY CRITERIA.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
MAIN HIGHLIGHTS DURING THIS PERIOD:
- REDUCED CHANCES FOR STORMS STARTING MIDWEEK
- HEAT RE-BUILDS INTO THE REGION THROUGH FRIDAY
CONVECTION IS EXPECTED TO BE LESS WIDESPREAD BY MIDWEEK AS THE
INFLUENCE OF HIGH PRESSURE RIDGING EXTENDING IN FROM OUT OF THE
EAST CROSSES FURTHER OVER THE FLORIDA PENINSULA AND LOW PRESSURE
TO THE NORTH SHIFTS FURTHER TO THE WEST, RESULTING IN
RELATIVELY MORE STABLE CONDITIONS AND DRIER AIR OVERHEAD. STORM
DEVELOPMENTS ARE EXPECTED TO BECOME MORE WIDESPREAD BY THE END
OF THE WEEK AND INTO THE WEEKEND AS HIGH PRESSURE MOVES WESTWARD
INTO THE GULF AND FLOW SHIFTS TO BE MORE OUT OF THE NORTHWEST
WITH UPPER LEVEL SHORT WAVES POTENTIALLY DIPPING IN OVER THE
REGION BY THE WEEKEND. ABOVE AVERAGE TEMPERATURES, WITH MAX
TEMPS RISING INTO THE MID 90S, WILL CONTINUE THROUGH THE END OF
THE WEEK WITH HEAT INDEX VALUES POTENTIALLY RISING TO HEAT
ADVISORY LEVELS THROUGH THE PERIOD.
AVIATION /06Z SUNDAY THROUGH 06Z MONDAY/
VFR CONDITIONS WILL PREVAIL AT THE REGIONAL TERMINALS THROUGH AT
LEAST 18Z. SHOWERS AND THUNDERSTORMS WILL BEGIN DEVELOPING ALONG
SEA BREEZE BOUNDARIES TOWARDS 19Z, WITH POTENTIAL IMPACTS
BEGINNING AT GNV BEFORE 20Z, FOLLOWED BY ACTIVITY PROGRESSING
EASTWARD TOWARDS THE REST OF THE NORTHEAST FL TERMINALS AND SSI,
WHERE POTENTIAL IMPACTS COULD CONTINUE THROUGH AROUND 01Z
MONDAY. ENOUGH UNCERTAINTY IN TIMING AND COVERAGE REMAINS IN
PLACE FOR US TO MAINTAIN PROB30 GROUPS AT EACH TERMINAL DURING
THE AFTERNOON AND EARLY EVENING HOURS, WITH BRIEF WIND GUSTS UP
TO 35 KNOTS POSSIBLE, ALONG WITH IFR VISIBILITIES DURING HEAVIER
DOWNPOURS AND BRIEF PERIODS OF MVFR CEILINGS AROUND 3,000 FEET.
LINGERING SHOWERS COULD CONTINUE AT THE SGJ AND SSI COASTAL
TERMINALS THROUGH AROUND 03Z, BUT VFR CONDITIONS WILL OTHERWISE
PREVAIL AFTER 01Z MONDAY. SOUTHWESTERLY SURFACE WINDS WILL
REMAIN SUSTAINED AT 5-10 KNOTS THROUGH AROUND 14Z AT THE COASTAL
TERMINALS, WITH SPEEDS OF 5 KNOTS OR LESS AT THE INLAND
TERMINALS. SURFACE WINDS WILL THEN SHIFT TO WEST-NORTHWESTERLY
AFTER 14Z, WITH SPEEDS GRADUALLY INCREASING TO AROUND 10 KNOTS
AT THE REGIONAL TERMINALS. THE ATLANTIC SEA BREEZE WILL DEVELOP
EARLY ON SUNDAY AFTERNOON AND WILL MOVE INLAND, SHIFTING SURFACE
WINDS AT SGJ TO SOUTHEASTERLY TOWARDS 19Z, WITH SPEEDS
INCREASING TO 10-15 KNOTS. SURFACE WINDS AT SSI WILL SHIFT TO
SOUTHERLY BY 20Z, WHERE SPEEDS WILL ALSO INCREASE TO 10-15
KNOTS. SOUTHWESTERLY SURFACE WINDS WILL THEN REMAIN SUSTAINED AT
5-10 KNOTS AT THE REGIONAL TERMINALS ONCE CONVECTION WINDS DOWN
AFTER 02Z MONDAY.
MARINE
ATLANTIC HIGH PRESSURE WILL CONTINUE TO EXTEND ITS AXIS WESTWARD
ACROSS THE FLORIDA PENINSULA TODAY. WESTERLY WINDS WILL CONTINUE
THIS MORNING, FOLLOWED BY SOUTHEASTERLY AND THEN SOUTHERLY
WINDS DEVELOPING AND SURGING TO CAUTION LEVELS DURING THE LATE
AFTERNOON AND EVENING HOURS AS THE ATLANTIC SEA BREEZE SHIFTS
INLAND. A FEW STRONG OR EVEN SEVERE THUNDERSTORMS PUSHING
EASTWARD MAY IMPACT OUR LOCAL WATERS LATE THIS AFTERNOON AND
EARLY THIS EVENING, POSSIBLY CONTAINING STRONG WIND GUSTS AND
FREQUENT LIGHTNING STRIKES.
A FRONTAL BOUNDARY WILL THEN SINK SOUTHWARD TOWARDS THE GEORGIA
WATERS ON MONDAY, WITH THIS FEATURE STALLING OVER THE GEORGIA
WATERS ON TUESDAY BEFORE WEAKENING LATER THIS WEEK. SHOWERS
AND THUNDERSTORMS MAY IMPACT OUR LOCAL WATERS EARLIER DURING THE
AFTERNOON HOURS ON MONDAY AND TUESDAY, WITH A FEW STRONG STORMS
POSSIBLE, ESPECIALLY FOR THE WATERS NORTH OF ST. AUGUSTINE.
COVERAGE OF SHOWERS AND THUNDERSTORMS WILL THEN DECREASE BY
WEDNESDAY AND ESPECIALLY ON THURSDAY AND FRIDAY AS THE FRONTAL
BOUNDARY DISSIPATES, WITH ONLY ISOLATED TO WIDELY SCATTERED LATE
AFTERNOON AND EARLY EVENING ACTIVITY POSSIBLE FOR THE NEAR
SHORE WATERS AS A PREVAILING WESTERLY FLOW CONTINUES DURING THE
OVERNIGHT AND MORNING HOURS EACH DAY.
RIP CURRENTS:
SOUTHEASTERLY WINDS STRENGTHENING LATE THIS AFTERNOON WILL AGAIN
CREATE A LOWER END MODERATE RISK AT THE NORTHEAST FL BEACHES,
WITH SURF INCREASING TO AROUND 2 FEET TOWARDS SUNSET. LOWER SURF
OF ONLY 1-2 FEET AT THE SOUTHEAST GA BEACHES SHOULD YIELD A LOW
RISK THROUGHOUT THE UPCOMING WEEK. SURF HEIGHTS OF LESS THAN 2
FEET AT THE NORTHEAST FL BEACHES SHOULD ALSO YIELD A LOW RISK
DURING THE UPCOMING WORK WEEK.
FIRE WEATHER
- AREAS OF HIGH DISPERSIONS THROUGH WEDNESDAY NORTH OF I-10.
HIGH CHANCES FOR SHOWERS AND STORMS TODAY AND MONDAY AS
INSTABILITY SITUATED AHEAD OF A FRONTAL BOUNDARY APPROACHES
FROM THE NORTH. SOUTHWESTERLY SURFACE WINDS CONTINUE THROUGH
EARLY NEXT WEEK, WITH AREAS OF HIGH AFTERNOON DISPERSION ALONG
AND NORTH OF I-10. HEAVY RAIN POTENTIAL TODAY THROUGH TUESDAY
DUE TO EXPECTED NUMEROUS SHOWERS AND STORMS EACH AFTERNOON AND
EVENING WITH WINDS CONSISTENTLY BUILDING IN THE AFTERNOON FROM
OUT OF THE WEST AND SOUTHWEST THROUGH THE END OF THE WEEK.
FOG POTENTIAL AND OTHER REMARKS: SIGNIFICANT FOG POTENTIAL IS
NOT EXPECTED. ERRATIC WIND GUSTS POSSIBLE IN AND NEAR
THUNDERSTORMS, AND AT TIMES, AT A DISTANCE DUE TO OUTFLOWS.
PRELIMINARY POINT TEMPS/POPS
AMG 98 73 90 72 / 40 40 60 50
SSI 95 76 93 76 / 30 20 70 60
JAX 97 75 94 74 / 70 30 70 40
SGJ 94 76 94 76 / 60 30 60 10
GNV 94 74 93 74 / 70 30 50 20
OCF 93 74 93 76 / 70 10 40 10
JAX WATCHES/WARNINGS/ADVISORIES
FL...HEAT ADVISORY FROM 11 AM THIS MORNING TO 7 PM EDT THIS EVENING
FOR FLZ023-024-030-031-038-124-125-132-137-138-225-232-
233-237-325-333-425-433-533-633.
GA...HEAT ADVISORY FROM 11 AM THIS MORNING TO 7 PM EDT THIS EVENING
FOR GAZ136-151>154-165-166-264-350-364.
MARINE...NONE.
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