Area Forecast Discussion
Issued by NWS Jacksonville, FL

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FXUS62 KJAX 200818
AFDJAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
418 AM EDT WED AUG 20 2014

...VERY HOT TEMPERATURES EXPECTED FOR THE REST OF THE WEEK...

.NEAR TERM /TODAY-TONIGHT/...

EARLY THIS MORNING...JUST A FEW HIGH CLOUDS IN THE WESTERLY STEERING
FLOW WITH JUST ENOUGH OF A NOCTURNAL SWLY SURGE TO KEEP ANY FOG
FORMATION TO A MINIMUM. TEMPS IN THE 70S EXCEPT FOR SOME LOWER 80S
ALONG THE COAST AND ST JOHNS RIVER BASIN. ANY CONVECTIVE DEBRIS
CLOUDS TO THE WEST WILL CONTINUE TO DISSIPATE AND EXPECT A MOSTLY
SUNNY START TO THE DAY.

TODAY...HIGH PRESSURE RIDGE ALOFT AND AT THE SURFACE ACROSS THE
SOUTHERN FLORIDA PENINSULA WILL SLOWLY BUILD TO THE NORTHWEST INTO
THE EASTERN GOMEX AND THIS WILL TWEAK THE STEERING FLOW A BIT MORE
OUT OF THE WEST/NORTHWEST TODAY AND THIS WILL PUSH A SMALL RIBBON OF
MOISTURE/DISTURBANCE ALOFT OVER THE FLORIDA PANHANDLE INTO NORTH
FLORIDA ALONG THE I-10 CORRIDOR THIS AFTERNOON AND EVEN THOUGH THE
CURRENT PRECIP WATER AMOUNTS OF AROUND 1.50 INCHES WOULD NOT SUPPORT
MUCH IN THE WAY OF ANY CONVECTION...THE UPSTREAM PRECIP WATER
AMOUNTS OF 1.75 TO 2 INCHES OVER THE FLORIDA PANHANDLE COULD PUSH
INTO THE I-10 CORRIDOR OF NORTH FLORIDA AND NEAR THE FL/GA BORDER
THIS AFTERNOON AND MAY BE ENOUGH TO ALLOW THIS RIBBON OF MOISTURE TO
TRIGGER SCATTERED STORMS...BUT FOR NOW HAVE CAPPED POPS AT 30% AS
NOT AS CONFIDENT IN STORM ACTIVITY TODAY AS I WAS YESTERDAY DUE TO
THE BUILDING HIGH PRESSURE/RIDGING ALOFT. STORM MOTION SHOULD STILL
BE QUICK AS IT MOVES TOWARDS THE E/SE AT 15-20 MPH BUT WILL BE MORE
ISOLATED IN NATURE AND LIKE YESTERDAY WILL TEND TO FADE AS IT MOVES
E/SE AWAY FROM THE MORE MOIST AIRMASS OVER THE PANHANDLE. MAIN
THREAT WILL CONTINUE TO BE GUSTY WINDS FROM THE DECENT STORM MOTION
BUT WITH LOWER COVERAGE AND WITH HIGH PRESSURE RIDGE SUPPRESSION DO
NOT EXPECT MUCH IN THE WAY OF SEVERE STORMS BUT A FEW STRONG STORMS
WITH WIND GUSTS OF 40-50 MPH STILL POSSIBLE. WITH THE LOWER STORM
COVERAGE EXPECT MAX TEMPS TO PUSH INTO THE MID/UPPER 90S BUT STILL
EXPECT ENOUGH MIXING TO ALLOW DEWPOINTS TO FALL TO AROUND 70 DEGREES
DURING PEAK HEATING AND EXPECT HEAT INDICES TO TOP OUT AROUND 105
DEGREES...SLIGHTLY HIGHER THAN THE 100-105 DEGREE INDICES FELT
YESTERDAY. BUT STILL SHORT OF HEAT ADVISORY CRITERIA OF 108 DEGREES
ESPECIALLY SINCE THERE IS STILL SOME THREAT OF STORMS TO PROVIDE
SOME RELIEF DURING THE MID-LATE AFTERNOON HOURS.

TONIGHT...AS HIGH PRESSURE RIDGE BUILDS FROM THE EASTERN GOMEX
TOWARDS THE FLORIDA PANHANDLE AND NORTHERN GOMEX COAST THIS WILL
QUICKLY CUT OFF ANY CONNECTION TO MOISTURE W/NW OF THE REGION AND
EXPECT A QUICK END TO ANY STORMS AROUND SUNSET WITH WARM AND HUMID
OVERNIGHT LOWS IN THE 70S INLAND AND LOWER 80S RIVER/COAST.

&&

.SHORT TERM /THU-FRI/...
HIGHLY AMPLIFIED UPPER RIDGE OVER THE LOWER MISSISSIPPI RIVER
VALLEY WILL MAINTAIN A HOT AND MOSTLY DRY PATTERN INTO THE
UPCOMING WEEKEND. TEMPS WILL BE THE MAIN STORY WITH HIGHS IN THE
UPPER 90S TO 100 DEGREES WITH THE HOTTEST TEMPS ALONG AND NORTH OF
THE I-10 CORRIDOR. BASED ON CURRENT PROJECTIONS OF RELATIVELY HIGH
MIXING LEVELS...IT IS ANTICIPATED THAT DEWPOINTS WILL GET MIXED
DOWN INTO THE 60S TO AROUND 70...ESPECIALLY IN GA WHERE THE
HOTTEST TEMPS ARE EXPECTED. FOR THURSDAY THIS WILL YIELD HEAT
INDICES JUST BELOW ADVISORY CRITERIA OF 108 DEGREES WITH HEAT
INDICES EXPECTED TO TOP OUT IN THE 105 TO 107 DEGREE RANGE.
DEWPOINTS MAY END UP JUST SLIGHTLY HIGHER ON FRIDAY WHICH MEANS
HEAT INDICES OF 108 DEGREES WILL BE POSSIBLE ALONG AND NORTH OF
THE I-10 CORRIDOR. IF THIS PANS OUT...A HEAT ADVISORY WILL BE
NEEDED FOR FRIDAY.

SUBSIDENCE/DRY AIR ALOFT WILL AID TO SUPPRESS CONVECTION DESPITE
MODERATELY HIGH INSTABILITY. RAIN CHANCES WILL THUS REMAIN LOW
WITH MAINLY JUST ISOLATED STORMS...PERHAPS WIDELY SCATTERED ALONG
SEABREEZE BOUNDARIES IN NE FL LATE IN THE AFTERNOON INTO THE EARLY
EVENING HOURS. NIGHTS WILL REMAIN WARM AND MUGGY WITH LOWS IN THE
MID TO UPPER 70S.

&&

.LONG TERM /SAT-TUE/...
HOT TEMPS IN THE MID TO UPPER 90S WILL CONTINUE ON SATURDAY
BEFORE SETTLING BACK DOWN INTO THE LOW TO MID 90S ON SUNDAY. HEAT
INDICES ON SATURDAY WILL AGAIN NEAR ADVISORY LEVEL CRITERIA OVER
PORTIONS OF THE AREA. CONVECTIVE CHANCES WILL INCREASE ON SUNDAY
INTO EARLY NEXT WEEK AS A BACKDOOR FRONT SLIPS INTO THE
FORECAST AREA. TEMPS WILL SETTLE BACK DOWN TO AROUND NORMAL ON
MONDAY AND TUESDAY WITH HIGHS IN THE LOWER 90S INLAND AND HIGHS
ONLY IN THE 80S AT THE COAST AS ONSHORE FLOW BECOMES ESTABLISHED.

&&

.AVIATION...
VFR WITH JUST A FEW HIGH CLOUDS EARLY THIS MORNING. SW FLOW STILL
MAINLY STRONG ENOUGH TO PREVENT MUCH FOG ALONG THE COAST BUT SOME
BRIEF MVFR VSBYS AT KGNV NOT OUT OF THE QUESTION AROUND SUNRISE.
WITH SMALL RIBBON OF MOISTURE STILL PUSHING INTO THE I-10 CORRIDOR
OF NORTH FLORIDA HAVE KEPT MENTION OF VCTS AT ALL NORTH FL TAF SITES
AFTER 18Z AND THROUGH ABOUT 00Z AT SUNSET WHEN JUST LINGERING HIGH
CLOUDS EXPECTED AFTERWARDS.

&&

.MARINE...
NOCTURNAL SWLY SURGE AROUND 15 KNOTS STILL ONGOING AT THIS TIME AND
WILL WEAKEN SLIGHTLY THIS MORNING BEFORE S/SW WINDS EXPECTED THIS
AFTERNOON AND EVENING WITH LOCAL SEA BREEZES ALONG THE COAST. A
GENERAL WEST-SOUTHWEST FLOW AROUND 10 KNOTS WILL CONTINUE THROUGH
SATURDAY WITH DAILY SEA BREEZES ALONG THE COAST...THEN A SHIFT TO
ONSHORE FLOW STILL EXPECTED SUNDAY INTO EARLY NEXT WEEK AT SPEEDS OF
10-15 KNOTS AND POSSIBLY HIGHER IN NORTHEAST SURGE MONDAY AND
TUESDAY. SEAS WILL REMAIN GENERALLY IN THE 2-4 FT RANGE POSSIBLY
AS HIGH AS 5 FT WELL OFFSHORE DURING NOCTURNAL SURGES.

RIP CURRENTS: LOW RISK WITH PRE-DOMINANT OFFSHORE FLOW.

&&

.CLIMATE...
FYI...UPPER 90S (>= 97 F) HAVE NOT BEEN REACHED AT THE JACKSONVILLE
OR GAINESVILLE CLIMATE STATIONS SINCE AUGUST OF 2011.

&&


.PRELIMINARY POINT TEMPS/POPS...
AMG  97  75 100  75 /  20  20  20  20
SSI  94  79  95  79 /  30  20  10  10
JAX  95  75  98  76 /  30  20  20  20
SGJ  93  76  93  76 /  20  20  20  20
GNV  95  73  97  75 /  30  20  30  30
OCF  95  72  96  74 /  20  20  30  30

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...NONE.
AM...NONE.
&&

$$

HESS/SHULER/








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