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000
FXUS62 KJAX 160846
AFDJAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
446 AM EDT SUN MAR 16 2014

...BREEZY AND WARM WITH SHOWERS AND THUNDERSTORMS OVERSPREADING
SOUTHEAST GEORGIA AND THE SUWANNEE VALLEY LATE THIS AFTERNOON...

...STRONG TO ISOLATED SEVERE THUNDERSTORMS POSSIBLE IN NORTHEAST
AND NORTH CENTRAL FLORIDA ON MONDAY AFTERNOON...

...WIDESPREAD RAINFALL TOTALS OF 1 TO 3 INCHES WITH LOCALLY HIGHER
AMOUNTS POSSIBLE REGION-WIDE THROUGH TUESDAY...

.CURRENTLY...
EARLY MORNING SURFACE ANALYSIS DEPICTS ATLANTIC RIDGING SHIFTING
EASTWARD AND AWAY FROM OUR REGION...WHILE LOW PRESSURE (1005
MILLIBARS) IS ORGANIZING OVER TEXAS. ALOFT...A SERIES OF
SHORTWAVES ARE ROTATING OVER THE PLAINS STATES AND THE DESERT
SOUTHWEST. STRENGTHENING SOUTHWEST TO WESTERLY FLOW ABOVE 700
MILLIBARS (10000 FEET) IS ADVECTING PATCHES OF MID AND HIGH
ALTITUDE CLOUD COVER ACROSS SOUTHEAST GEORGIA...WHILE FAIR SKIES
PREVAIL OVER MOST OF NORTHEAST FLORIDA. TEMPERATURES AT 08Z RANGED
FROM THE LOWER 50S NEAR THE ALTAMAHA RIVER...WHERE WINDS ARE
CALM...TO THE LOWER 60S IN COASTAL LOCATIONS...WHERE SOUTHERLY
WINDS ARE IN THE 5-10 MPH RANGE.

.NEAR TERM (TODAY AND TONIGHT)... SHORTWAVES OVER THE PLAINS STATES
AND THE DESERT SOUTHWEST WILL EVOLVE INTO A POSITIVELY TILTED
TROUGH THAT WILL EXTEND FROM THE OHIO VALLEY SOUTHWESTWARD TO DEEP
SOUTH TEXAS. THIS TROUGH WILL DRIVE A SURFACE LOW OVER TEXAS WILL
EAST-NORTHEASTWARD INTO THE TENNESSEE VALLEY TONIGHT...WITH THE
BASE OF THIS TROUGH DEVELOPING A SURFACE WAVE ALONG A FRONTAL
BOUNDARY IN THE EASTERN GULF OF MEXICO DURING THE OVERNIGHT HOURS.
AHEAD OF THE TROUGH...WARM FRONTOGENESIS TAKES PLACE OVER CENTRAL
GEORGIA ON SUN MORNING. OUR REGION WILL REMAIN WITHIN A DEVELOPING
WARM SECTOR...WITH MODEL SOUNDINGS INDICATING ROBUST SOUTHERLY
FLOW QUICKLY STRENGTHENING THIS MORNING. WE EXPECT SOUTHERLY WINDS
TO INCREASE TO NEAR 15 MPH BY THE LATE MORNING HOURS...WITH
OCCASIONAL GUSTS NEAR 25 MPH...OR JUST BELOW LAKE WIND ADV.
CRITERIA. STRENGTHENING WARM AIR ADVECTION WILL BRING HIGHS INTO
THE UPPER 70S IN SOUTHEAST GA...AND LOWER 80S FOR MOST OF
NORTHEAST FL. INCREASING SURFACE CONVERGENCE SOUTH OF THE WARM
FRONT WILL DEVELOP A FEW SHOWERS THIS MORNING OVER INTERIOR
SOUTHEAST GA. INCREASING MID-LEVEL LIFT (PER SREF 700 MILLIBAR
OMEGA PROGS) ARRIVES DURING THE AFTERNOON HOURS OVER INTERIOR
SOUTHEAST GA AS THE SURFACE LOW APPROACHES THE TENNESSEE VALLEY.
CHANCE POPS WERE USED BY EARLY AFTERNOON IN THESE LOCATIONS...WITH
LIKELY POPS (AND ISOLATED EMBEDDED THUNDER) PLACED IN THE FORECAST
GRIDS TOWARDS 21Z. POPS WILL RAMP UP MORE SLOWLY THIS AFTERNOON IN
NORTHEAST FL...WITH CHANCE POPS FROM GAINESVILLE TO JACKSONVILLE
AND POINTS WESTWARD BY SUNSET.

STRONG LIFT OVER SOUTHEAST GA AND THE WESTERN SUWANNEE VALLEY WILL
GRADUALLY WEAKEN ON SUN EVENING AS THE BEST FORCING BECOMES
FOCUSED OVER THE EASTERN GULF OF MEXICO ASSOCIATED WITH A
DEVELOPING SURFACE WAVE ALONG A FRONTAL BOUNDARY. THIS WILL LIKELY
RESULT IN A SLOWING OF THE EASTWARD PROGRESSION OF A LARGE AREA OF
SHOWERS AND EMBEDDED ELEVATED THUNDERSTORMS...WITH LIKELY POPS NOT
ARRIVING IN AREAS SOUTH AND EAST OF A LINE FROM JACKSONVILLE TO
GAINESVILLE UNTIL THE LATE EVENING HOURS. FOLLOWED THE 00Z
OPERATIONAL ECWMF AND 00Z HI-RES ARW CLOSELY FOR POPS SUN NIGHT.
COLD POOL MOMENTUM FROM ONGOING ACTIVITY SHOULD PUSH SHOWERS AND
THUNDERSTORMS INTO COASTAL NORTHEAST AND NORTH CENTRAL FL AFTER
MIDNIGHT...ALTHOUGH LATEST TREND IN THE GUIDANCE SUGGESTS
WEAKENING INTENSITY OVERNIGHT AS 700 MILLIBAR LIFT GRADUALLY
DIMINISHES. RAINFALL AMOUNTS TOMORROW AFTERNOON AND NIGHT OVER
SOUTHEAST GA AND THE SUWANNEE VALLEY IN EXCESS OF 1 INCH ARE
FORECAST...WITH LOCALLY HIGHER TOTALS. CONTINUING WARM AIR
ADVECTION WILL KEEP LOWS AND DEWPOINTS IN THE 60S REGION-
WIDE...WHICH IS ABOUT 10-15 DEGREES ABOVE MID-MARCH CLIMO.

.SHORT TERM (MONDAY THROUGH TUESDAY)...
MODERATE TO LOCALLY HEAVY RAINFALL WITH EMBEDDED TSTORMS WILL BE
ONGOING EARLY MONDAY MORNING ACROSS INLAND SE GA AND THE SUWANEE
RIVER VALLEY AS THE PARENT UPPER LEVEL TROUGH CONTINUES TO DIG
ACROSS THE WESTERN GULF OF MEXICO AND A SFC TROUGH AND BROAD SFC
LOW DRIFT EASTWARD ACROSS THE EASTERN GULF COAST REGION. A NOSE OF
GULF MOISTURE WITH DEW PTS IN THE MID/UPPER 60S WILL EDGE INLAND
OVER NE FL JUST SOUTH OF THE TROUGH AXIS AS UPPER LEVEL DIVERGENCE
INCREASES. THIS SURGE OF LOW LEVEL INSTABILITY COUPLED WITH
INCREASED DYNAMICAL SUPPORT FAVOR WIDESPREAD RAINFALL SLOWLY
TREKKING SSE ACROSS THE FORECAST AREA MONDAY...WITH AN
INTENSIFICATION OF PRECIPITATION INCLUDING THUNDERSTORM ACTIVITY
EXPECTED ACROSS NE FL AS LOW LEVEL JET DYNAMICS INCREASE ON THE
SOUTH SIDE OF THE LOW LEVEL TROUGH AXIS. THE MAIN CONVECTIVE
CONCERN WILL BE STRONG GUSTY WINDS WITH 850 MB 40KTS...AND THE
STORM PREDICTION CENTER HAS PLACED NE FL WITHIN THE SLIGHT RISK OF
TSTORM ACTIVITY CONVECTIVE OUTLOOK. ROTATING STORM CELLS ARE ALSO
POSSIBLE GIVEN STRENGTH OF MID LEVEL SPEED SHEAR.

THE 00Z NAM12 WAS TRENDING SLOWER WITH THE PRECIP CLEARING THE
FORECAST AREA WHEN COMPARED TO THE GFS40...ECMWF AND SREF MON
NIGHT...AND THIS SCENARIO LOOKS POSSIBLE...ALL DEPENDS ON WHEN THE
UPPER TROUGH BEGINS TO LIFT NE OVER THE GULF. FOR THIS FORECAST
PACKAGE...DID EXTEND THE DURATION OF 80-90% RAINFALL CHANCES
THROUGH MONDAY EVENING...WITH THE DEEPER CONVECTION PROGRESSING
OFFSHORE OF THE ATLANTIC BY MIDNIGHT AS SURFACE LOW PRESSURE
DEEPENS OFFSHORE OF THE SE ATLANTIC COAST. GIVEN THE SLOWER AND
WETTER RUN-TO-RUN MODEL TRENDS...ADVERTISED HIGH 60-70% RAIN
CHANCES AFTER MIDNIGHT WITH DRIER AIR NOSING IN FROM THE WEST TUE
MORNING PUTTING AND END TO THE PRECIP FROM WEST TO EAST TUE AFTN.
IF THE NAM12 PANS OUT...THEN RAIN CHANCES WILL NEED TO BE
INCREASED MON NIGHT INTO EARLY TUESDAY.

THE WEATHER PREDICTION CENTER CONTINUES TO ADVERTISE WIDESPREAD
1-3 INCHES OF PRECIP WITH THIS SYSTEM...WITH HIGHER AMOUNTS OF 2-4
INCHES POSSIBLE. BASED ON SLOWER MODEL SOLUTIONS...WILL REFRAIN
FROM A FLOOD WATCH AT THIS TIME.

BASED ON ANTICIPATED PRECIP THROUGH MUCH OF THE PERIOD...LEANED
TOWARD THE WARMER MOS TEMPS FOR NIGHTTIME TEMPS AND COOLER MAX
TEMPS WITH HIGHS MON IN THE LOW/MID 60S OVER SE GA...WITH A
CORRIDOR OF MID/UPPER 70S POSSIBLE ACROSS OUR EXTREME SOUTHERN FL
COUNTIES DUE TO WARM AIR ADVECTION ON THE SOUTH SIDE OF THE SFC
FRONT. MON NIGHT TEMPS IN THE LOW 50S NORTH TO THE UPPER 50S SOUTH
DUE TO SLOWER PASSAGE OF PRECIP. LITTLE CONFIDENCE FOR HIGH TEMPS
TUESDAY WITH MOS TEMPS RANGING AT JAX GREATLY WITH THE MAV
ADVERTISING 71 WITH THE MET MOS AT 57. LEANED TOWARD THE
GFS40/ECMWF FOR TEMPS WITH A COOLER NORTHERLY FLOW AS A WEDGE OF
HIGH PRESSURE BEGINS TO NOSE DOWN FROM THE NE OVER CENTRAL GA WITH
HIGHS RANGING FROM THE LOW/MID 60S SE GA TO THE UPPER 60S/LOW 70S
OVER NE FL.

.LONG TERM (WEDNESDAY THROUGH SUNDAY)...
MOSTLY DRY CONDITIONS ARE EXPECTED WITH NEAR ZONAL ALOFT WHICH
WILL KEEP COLDER AIR WELL NORTH OF THE AREA. A DRY FRONT WILL PUSH
SOUTH OF THE AREA WED NIGHT TRAILED BY SHALLOW NORTHERLY FLOW THU
AS SURFACE HIGH PRESSURE BUILDS OVER LOWER MS RIVER. THE RIDGE
WILL BUILD EASTWARD AND OFFSHORE OF THE SE ATLANTIC COAST THROUGH
FRI. NEAR TO SLIGHTLY BELOW CLIMO TEMPS WED-FRI WILL MODERATE TO
ABOVE CLIMO VALUES BY THE WEEKEND AS ONSHORE FLOW DEVELOPS. HIGHS
WILL RANGE IN THE 70S WITH LOWS IN THE 40S TO 50S. INTRODUCED A
LOW 20% CHANCE OF COASTAL SHOWERS LATE FRI WITH THE SYNOPTIC
PATTERN FAVORABLE FOR COASTAL TROUGHING OFFSHORE...AND THEN
ADVERTISED A 20% CHANCE OF SHOWERS  NEXT WEEKEND AHEAD OF THE
NEXT SHEARED OUT FRONTAL SYSTEM.

&&

.AVIATION...
TEMPO MVFR CONDITIONS ARE POSSIBLE AT GNV AND VQQ THIS MORNING AS
MID AND HIGH CLOUDS INCREASE FROM THE WEST. PREVAILING VFR
CONDITIONS ARE EXPECTED THROUGH MID AFTERNOON WITH BREEZY SW WINDS
15G25KTS...THEN MVFR CONDITIONS WILL BECOME PROBABLE AS PRE-
FRONTAL PRECIP EDGES EASTWARD THROUGH THE EVENING HOURS.
ADVERTISED VCSH AT ALL SITES AROUND 21-23Z...WITH PREVAILING MVFR
CIGS AND RAIN AROUND 01-03Z. HIGHEST CONFIDENCE FOR TS THIS
EVENING IS AT GNV...AND INTRODUCED VCTS.

&&

.MARINE...
SOUTHERLY WINDS ARE EXPECTED TO INCREASE QUICKLY AFTER
SUNRISE...WITH SUSTAINED WINDS OFFSHORE REACHING 20 KTS AND
15-20 KTS IN THE NEAR SHORE WATERS AROUND NOON. WILL KEEP THE
INHERITED START TIME OF ADVISORY IN THE OFFSHORE WATERS BEGINNING
AT 2 PM. A LONG SOUTHERLY FETCH WILL BUILD SEAS OFFSHORE TO 5-7 FT
OFFSHORE BY LATE AFTERNOON...WITH 3 TO 5 FT SEAS NEARSHORE BY THIS
EVENING. SHOWERS AND EMBEDDED STORMS WILL PROGRESS INTO THE GA
WATERS BY LATE AFTERNOON AND EARLY EVENING...AND INTO THE FL
WATERS DURING THE OVERNIGHT HOURS. WINDS OVER THE GA WATERS WILL
DECREASE AND BECOME NORTHEASTERLY ON MON MORNING AS A SURFACE WAVE
DEVELOPS ALONG AN APPROACHING FRONTAL BOUNDARY......WHILE WINDS
OVER THE FL WATERS BECOME SOUTHWESTERLY AND WILL SLOWLY DIMINISH.
WILL KEEP THE EXPIRATION TIME OF THE ADVISORY OFFSHORE AT NOON ON
MON. STRONG THUNDERSTORMS CONTAINING GUSTY WINDS ARE EXPECTED TO
MOVE ACROSS THE FLORIDA WATERS ON MONDAY AFTERNOON AND EVENING. LOW
PRESSURE WILL MOVE NORTHEASTWARD AND WILL CROSS THE COASTAL WATERS
ON MON EVENING...AND THEN WILL STRENGTHEN WELL OFF THE CAROLINA
COAST OVERNIGHT...DRIVING A COLD FRONT THROUGH THE WATERS. WINDS
WILL BECOME NORTHWESTERLY ON TUES MORNING...WITH SPEEDS BRIEFLY
SURGING TO ADVISORY LEVELS OFFSHORE.

RIP CURRENTS: DEVELOPING LONGSHORE CURRENT WILL MAKE FOR
INCREASINGLY ROUGH SURF CONDITIONS...BUT THE OVERALL RISK SHOULD
REMAIN LOW AS EASTERLY SWELLS HAVE DIMINISHED.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  77  61  65  52 /  70  90  90  80
SSI  77  63  63  53 /  40  90  90  90
JAX  81  64  69  58 /  30  90  90  90
SGJ  78  68  68  59 /  20  80  90  90
GNV  81  64  71  57 /  30  90  90  90
OCF  83  66  75  59 /  20  80  90  80

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...NONE.
AM...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO NOON EDT MONDAY
     FOR ALTAMAHA SOUND GA TO FERNANDINA BEACH FL 20 NM TO 60 NM
     OFFSHORE-FERNANDINA BEACH TO ST AUGUSTINE FL 20 NM TO 60 NM
     OFFSHORE-ST AUGUSTINE TO FLAGLER BEACH FL 20 NM TO 60 NM
     OFFSHORE.

&&

$$

NELSON/ENYEDI