Area Forecast Discussion
Issued by NWS Jacksonville, FL

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000
FXUS62 KJAX 290918
AFDJAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
500 AM EDT TUE JUL 29 2014

...NOT AS HOT TODAY...

.CURRENTLY(5 AM)...WEAK FRONT IS LOCATED OVER SE GA TO THE NE GULF
OF MEXICO WITH BROAD AREAS OF LOW LEVEL CONVERGENCE OVER THE NE GULF
AND OFFSHORE OF THE NE FL WATERS NEAR AND AHEAD OF FRONT. RADAR
TRENDS HAVE SHOWED INCREASED DEEP CONVECTION CELLS OVER THE NE GULF
AND PARTS OF NE FL AS THE FRONT AND A PREFRONTAL TROUGH PUSHES SEWD
BUT SO FAR NO THUNDER HAS OCCURRED IN NE FL. TEMPS ARE IN THE MID
70S TO NEAR 80.

.SHORT TERM...

TODAY...CERTAINLY A TRANSITION DAY AS WEAK COLD FRONT INITIALLY
LOCATED FROM EXTREME SE GA TO THE CENTRAL FL PANHANDLE WILL DRIFT
SEWD ALONG WITH A PRE-FRONTAL TROUGH. DEEP LAYER MOISTURE WILL BE
HIGH THE FIRST PART OF TODAY ACROSS OUR SE ZONES WHERE MODELS DEPICT
PWATS AROUND THE 1.6 TO 2 INCH RANGE BUT GOOD AGREEMENT IN GUIDANCE
IN A STEADY DECREASE IN MEAN 1000-500 MB RH VALUES (AND INSTABILITY)
THROUGH THE DAY AS DEEP W-NW FLOW USHERS IN MUCH DRIER AIR. THE
COMBINATION OF LOW LEVEL MOISTURE CONVERGENCE AHEAD OF THE FRONT AND
INSTABILITY WILL GENERATE ISOLATED TO SCT SHOWERS AND STORMS MAINLY
S OF A JAX-GNV LINE WITH BEST CHANCES OF PRECIP FROM NOW THROUGH
ABOUT 2 PM...AND THEN STEADILY DROPPING THEREAFTER AS AIRMASS DRIES
OUT. WHILE SOME INCREASED LOW LEVEL CONVERGENCE WILL BE REALIZED
FROM MID AFTERNOON ONWARD ACROSS OUR SE ZONES DUE TO DEVELOPMENT OF
ATLC SEA BREEZE...LOW LEVEL MOISTURE CONTENT WILL BE LACKING WITH
DEWPOINTS MIXING OUT TO POSSIBLY AROUND THE 64 TO 66 DEG RANGE NEAR
THE JAX METRO AREA AND PWATS OF ONLY 1.25 INCHES. WE HAVE NO POPS
TODAY FOR SE GA DUE TO MUCH DRIER AND MORE STABLE CONDITIONS
DEVELOPING THERE AS DEWPOINTS BOTTOM OUT TO UNSEASONABLE MID 50S
AROUND ALMA. HIGH TEMPERATURES NOT AS HOT AS PRIOR DAYS...BUT STILL
AROUND 91-95 WITH HEAT INDICES FOR THE MOST PART AT OR BELOW 100.

TONIGHT...ISOLD LINGERING CONVECTION MAY BE ONGOING FROM MARION TO
PUTNAM TO FLAGLER COUNTIES THEN QUICKLY FADE AFTER SUNSET. A MOSTLY
CLEAR TO BRIEFLY PARTLY CLOUDY SKY EXPECTED WITH MINS AT OR BELOW
NORMAL WITH MID/UPPER 60S IN SE GA INTO THE SUWANNEE VALLEY TO ABOUT
GNV AND NEAR 70-72 OVER REMINDER PARTS OF NE FL.

WEDNESDAY AND WEDNESDAY NIGHT...
AN UNSEASONABLY DRY AIR MASS WILL CONTINUE TO SETTLE OVER OUR
REGION...WITH MODEL SOUNDINGS DEPICTING PRECIPITABLE WATER
VAPOR (PWAT) VALUES FALLING TO BETWEEN 1-1.25 INCHES...OR NEARLY
2 STANDARD DEVIATIONS BELOW LATE JULY CLIMATOLOGY. AFTERNOON
DEWPOINTS WILL FALL INTO THE UPPER 50S IN INTERIOR SOUTHEAST GA
AND THE NORTHERN SUWANNEE VALLEY...WHILE A WEAK SEA BREEZE PUSHES
INLAND TO NEAR THE ST. JOHNS RIVER AND INCREASES AFTERNOON
HUMIDITY VALUES. MOSTLY SUNNY SKIES WILL BOOST TEMPS TO CLIMB INTO
THE LOW/MID 90S INLAND AND NEAR 90 AT THE COAST...BUT LOW HUMIDITY
WILL PRECLUDE ANY HEAT INDEX CONCERNS. FAIR SKIES AND LIGHT WINDS
WILL ALLOW LOWS TO FALL INTO THE UPPER 60S TO NEAR 70 INLAND...WITH
A WEAK ONSHORE WIND KEEPING LOWS IN THE 70S FOR THE COASTAL COUNTIES.

THURSDAY AND THURSDAY NIGHT...
WEAK SURFACE RIDGING WILL REMAIN SITUATED TO OUR NORTH...WITH
DEEP-LAYERED TROUGHING PREVAILING OVER THE CENTRAL AND EASTERN
UNITED STATES. A WEAK ONSHORE WIND REGIME WILL BEGIN A GRADUAL
MOISTENING TREND...BUT WE ARE EXPECTING ONLY ISOLATED AFTERNOON
CONVECTION TO DEVELOP ALONG THE ATLANTIC SEA BREEZE THAT WILL
PROGRESS INLAND TOWARDS THE ST. JOHNS RIVER BY LATE AFTERNOON. HIGHS
WILL RANGE FROM THE LOWER 90S INLAND TO THE UPPER 80S AT THE COAST.
DIURNAL CONVECTION MAY BLOSSOM OVER THE COASTAL WATERS ON THURS NIGHT
AS ACTIVITY QUICKLY FADES TOWARDS SUNSET OVER LAND. LOWS WILL RANGE
FROM NEAR 70 INLAND TO THE MID/UPPER 70S AT THE COAST.

.LONG TERM (FRIDAY THROUGH MONDAY)...
DEEP-LAYERED TROUGHING WILL SHARPEN OVER THE EASTERN U.S. ON FRI AND
SAT...WITH THE AXIS OF THIS FEATURE LOCATED JUST WEST OF OUR REGION.
THIS PATTERN WILL PROMOTE A DEEPENING SOUTHWESTERLY FLOW ALOFT...WITH
A CONTINUED WEAK SURFACE PRESSURE GRADIENT LOCALLY PROMOTING ACTIVE
SEA BREEZES DURING THIS TIME FRAME. EXPECT A RETURN TO A SEASONABLY WET
WEATHER PATTERN...WITH HIGH-END CHANCE DIURNAL POPS USED IN THE EXTENDED
FORECAST GRIDS. THIS PATTERN NORMALLY PROMOTES A MORE CONVECTIVELY ACTIVE
GULF COAST SEA BREEZE DURING THE LATE MORNING AND EARLY AFTERNOON
HOURS...WITH COVERAGE INCREASING AS THIS ACTIVITY MEETS THE ATLANTIC SEA
BREEZE NEAR THE ST. JOHNS BASIN/I-95 CORRIDOR DURING THE MID TO LATE
AFTERNOON HOURS. THE EASTERN U.S. TROUGH WILL BEGIN TO FILL LATE IN THE
WEEKEND AS ATLANTIC RIDGING BUILDS WESTWARD INTO THE FL PENINSULA TOWARDS
EARLY NEXT WEEK. NEAR CLIMO TEMPERATURES ARE EXPECTED AS RAIN CHANCES AND
AFTERNOON CLOUD COVER INCREASES.

&&

.AVIATION...OCNL MVFR CIGS ANTICIPATED AROUND GNV AND VQQ WITH VCSH
NEAR GNV AS WELL THROUGH MID MORNING. CONVECTION RAIN CHANCES LOOK
TOO MINIMAL TO HAVE ANYTHING MORE THAN VCSH/VCTS TODAY...WITH BEST
CHANCE OF TSTMS NEAR GNV. VFR EXPECTED TO PREVAIL AFTER 12Z AND
WINDS WILL BE WLY AROUND 10 KT WITH LOWERING SPEEDS IN THE MID TO
LATE AFTERNOON AS ATLC SEA BREEZE HELPS SHIFT WINDS TO SELY ALONG
THE COAST FOR CRG AND SSI. FOR TONIGHT...VFR WITH LIGHT/CALM WINDS.

&&

.MARINE...WLY FLOW AROUND 15-20 KT EARLY TODAY AHEAD OF A COLD
FRONT. WINDS WILL DECREASE THROUGH THE DAY AND BECOME ONSHORE NEAR
THE COAST. THE FRONT WILL PUSH SLOWLY SEWD THROUGH WEDNESDAY AND
THEN BECOME DIFFUSE. WEAK SFC HIGH PRES DEVELOP N OF THE AREA WED
AND THU WHILE WEAK LOW PRES FORMS OVER INLAND NRN FL. WINDS BECOME
VARIABLE LESS THAN 10 KT TONIGHT AND THEN TURNING ONSHORE ON WED AND
THU WHILE SLOWLY INCREASING. ON FRI AND SAT...BROAD LOW PRES IN THE
NRN GULF AND WEAK HIGH PRES TO THE N AND NE WILL PRODUCE GENERAL
S-SE FLOW. THIS LATTER TRANSITION COULD POTENTIALLY ALLOW FOR
EVENTUAL INCREASE IN MEAN SEA HEIGHTS AND ESE-SE SWELLS LATE IN THE
WEEKEND AND EARLY NEXT WEEK.

RIP CURRENTS: PREVAILING OFFSHORE FLOW AND SMALL ESE SWELL OF ABOUT
1 FOOT WILL KEEP RIP CURRENT ACTIVITY LOW TODAY. WEDNESDAY...A
SIMILAR RISK...IF NOT SLIGHTLY ENHANCED POTENTIAL OF RIPS AS WINDS
TURN ENE DURING THE DAY.

&&

.FIRE WEATHER...
AN UNSEASONABLY DRY AIR MASS WILL FILTER INTO SOUTHEAST GA
IN THE WAKE OF THE COLD FRONT TODAY...WITH MINIMUM RH VALUES
FALLING TO NEAR 30 PERCENT AT INLAND LOCATIONS. AFTERNOON RH
VALUES WILL FALL TO 35-40 PERCENT ALONG THE INTERSTATE 10
CORRIDOR IN NORTHEAST FLORIDA THIS AFTERNOON. HIGH TEMPS RISING
INTO THE LOW AND MID 90S WILL CREATE ELEVATED DISPERSION INDICES
FOR LOCATIONS ALONG AND NORTH OF I-10. THIS UNSEASONABLY DRY AIR
MASS WILL PLUNGE ALL THE WAY INTO NORTH CENTRAL FL ON WED...WITH
MINIMUM RH VALUES FALLING TO 25-30 PERCENT IN INTERIOR SOUTHEAST
GA...AND 30-35 PERCENT IN INTERIOR NORTHEAST AND NORTH CENTRAL FL.
WIND SPEEDS WILL REMAIN NEAR OR BELOW 10 MPH AND FUEL MOISTURE/ERC
VALUES ARE NOT EXPECTED TO REACH CRITICAL THRESHOLDS. RED FLAG
CONDITIONS ARE THUS NOT EXPECTED TO MATERIALIZE. CONDITIONS WILL
SLOWLY MOISTEN ON THURS...WITH INCREASING RAIN CHANCES BY FRI
AFTERNOON.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  93  65  94  70 /   0  10  10  10
SSI  92  75  88  76 /  10  10  10  10
JAX  93  70  91  73 /  20  10  10  10
SGJ  91  74  89  76 /  30  20  10  10
GNV  94  68  93  70 /  30  10  10  10
OCF  94  70  94  71 /  50  20  10  10

&&

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

$$

SHASHY/NELSON





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