622 
FXUS62 KJAX 110813
AFDJAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
345 AM EDT THU APR 11 2013

...SLIGHT RISK OF SEVERE STORMS TONIGHT INTO FRIDAY MORNING ...

.SHORT TERM (TODAY-SATURDAY NIGHT)...

TODAY...WESTERN ATLANTIC RIDGE PULLING AWAY TODAY AS AN UPPER TROUGH 
AND  ASSOCIATED COLD FRONT BEGINS TO APPROACH THE AREA. THIS WILL 
ALLOW CAP AT 800 MB TO QUICKLY ERODE BY LATE THIS AFTERNOON WHICH 
WILL MAKE THE ENVIRONMENT MORE FAVORABLE  FOR STORMS TO FORM AS 
INSTABILITY INCREASES WITH AFTERNOON HEATING. GRADIENT TIGHTENS 
TODAY WITH APPROACH OF FRONT AND HAVE GONE BREEZY WITH WIND GUSTS TO 
25 MPH MOST LOCALES. AFTER STRATUS DECK LIFTS THIS MORNING...WILL 
BECOME MOSTLY SUNNY FROM LATE MORNING INTO THE EARLY AFTERNOON. 
EXPECTING SCATTERED TO NUMEROUS SHOWERS TO FORM MAINLY LATE THIS 
AFTERNOON INTO THE EARLY EVENING AS INCREASINGLY MOIST AND UNSTABLE 
SOUTHERLY FLOW COMBINES WITH A SHORT WAVE THAT WILL BE RAPIDLY 
MOVING THROUGH THE AREA LATE THIS AFTERNOON. STEEP LOW LEVEL LAPSE 
RATES AND ADDITIONAL LIFT FROM THE SHORT WAVE MAY RESULT IN A FEW OF 
THE STORMS BECOMING STRONG WITH STRONG AND GUSTY WINDS AND FREQUENT 
LIGHTNING THE MAIN CONCERNS.  

TONIGHT...THE FRONT AND TROUGH WILL APPROACH OUR REGION FROM THE 
WEST. FOLLOWING A LATE EVENING LULL...HAVE INDICATED LIKELY POPS FOR 
AREAS ALONG AND NORTH OF THE I-10 CORRIDOR AFTER MIDNIGHT THROUGH 
EARLY FRIDAY MORNING. WHILE MOST OF THE STRONGER DYNAMICS BEGINS TO 
LIFT NORTH OF THE AREA...SOME MODELS (ESPECIALLY ECMWF) CONTINUE TO 
BRING IN A STRONG LOW LEVEL JET PRECEDING THE FRONT AND MAY POSSIBLY 
SEE A FEW SEVERE STORMS WITH DAMAGING WIND POTENTIAL FROM SOUTHEAST 
GEORGIA TO THE UPPER SUWANNEE VALLEY INTO EARLY FRIDAY. MORNING. 
LOWS WILL BE WELL ABOVE NORMAL DUE TO CLOUD COVER WITH READINGS IN
THE MID TO UPPER 60S. 

FRIDAY...MODELS CONTINUE TO TREND TOWARDS A SLOWER FRONTAL PASSAGE 
ACROSS NORTHEAST FLORIDA ON FRIDAY. HAVE KEPT LIKELY POPS IN PLACE 
FOR MUCH OF NE FL...LOWER POPS ACROSS INLAND SE GA DURING THE LATE 
AFTERNOON AND KEPT HIGH-END CHANCE OVER NORTH CENTRAL FL. THE LOW 
LEVEL JET WILL BE LIFTING NORTH OUT OF THE AREA BUT MAY STILL SEE
A FEW ISOLATED SEVERE STORMS ACROSS NE FL IN THE MORNING. HAVE 
TRENDED TEMPS A FEW DEGREES LOWER DUE TO CLOUDINESS WITH HIGHS 
FROM NEAR 80 TO LOWER 80S. 

FRIDAY NIGHT...THE COLD FRONT WILL SLOWLY EXIT NE FL AND WILL SEE A 
DECREASE IN POPS/CLOUDINESS FROM NW TO SE. COOLER AND DRIER AIR 
BEGINS TO MOVE INTO SE GA LATE AT NIGHT. LOWS WILL RANGE FROM THE 
MID 50S NORTH TO THE MID 60S IN NORTH CENTRAL FL. 

SATURDAY...THE FRONT STALLS SOUTH OF THE AREA AS HIGH PRESSURE 
BEGINS TO BUILD ACROSS THE MID ATLANTIC. KEPT LOW POPS ACROSS THE 
EXTREME SOUTH NEAR THE FRONTAL BOUNDARY. OTHERWISE SHOULD BE PARTLY 
CLOUDY AND DRY WITH ONSHORE FLOW.  

.LONG TERM (SUNDAY-WEDNESDAY)...

SUNDAY/MONDAY...GOOD AGREEMENT AMONG GFS AND ECMWF ON THE STALLED 
FRONT MOVING BACK NORTH AS A WARM FRONT AS THE HIGH TO THE NORTH 
MOVES OFFSHORE. WILL SHOW A NORTH-SOUTH POP DISTRIBUTION SUNDAY WITH 
BEST RAIN CHANCES ACROSS THE SOUTH. HAVE INCREASED POPS ALL AREAS 
SUNDAY NIGHT INTO MONDAY AS THE WARM FRONT LIFTS NORTH INTO THE AREA 
AND COMBINES WITH MOISTURE/INSTABILITY AS WELL AS SHORT WAVE ENERGY. 
WENT A FEW DEGREES BELOW GUIDANCE ON TEMPS DUE TO CLOUD COVER. 

TUESDAY/WEDNESDAY...WARM FRONT LIFTS NORTH OF THE AREA WHILE WESTERN 
ATLANTIC RIDGE SHIFTS SOUTH ACROSS N CNTL FL. HAVE GONE WITH PARTLY 
CLOUDY AND WARM CONDITIONS WITH LOW POPS.

&&

.AVIATION...
A MIXTURE OF IFR/MVFR STRATUS CIGS AROUND 1000 FEET HAVE DEVELOPED 
AT ALL OF THE TAF SITES AND WILL CONTINUE INTO THE MID-MORNING HOURS 
BEFORE SLOWLY LIFTING TO BROKEN VFR CIGS AROUND 3000-4000 FEET BY 
THE AFTERNOON HOURS. WITH POTENTIAL SCTD SBRZ SHOWER/TSTM ACTIVITY 
AFTER 18Z...HAVE ADDED A VCSH TO ALL TAF SITES WHICH WILL NEED 
FURTHER REFINEMENT IN LATER TAF FORECASTS TO INCLUDE ANY POTENTIAL 
TSTM ACTIVITY BY THE EVENING HOURS.

&&

.MARINE...
INCREASING SOUTH FLOW AHEAD OF COLD FRONT TODAY WILL PUSH WINDS 
CLOSE TO 20 KNOTS AND HAVE HEADLINED THE OFFSHORE WATERS WITH SMALL 
CRAFT ADVISORY STARTING LATE THIS AFTERNOON. EVENT WILL PEAK TONIGHT 
WITH WINDS CLOSE TO 20-25 KNOTS AND SEAS UP TO 6-8 FT WELL OFFSHORE. 
FRONT WILL PUSH INTO WATERS ON FRIDAY WITH CONTINUED SHOWERS/STORMS 
AND WINDS/SEAS WILL SLOWLY DECREASE LATE IN THE DAY INTO FRIDAY 
NIGHT. WEAK HIGH PRESSURE WILL BUILD OVER THE REGION THIS WEEKEND 
WITH NO HEADLINES EXPECTED. WARM FRONT WILL LIFT NORTH THROUGH THE 
WATERS ON MONDAY...BUT WINDS/SEAS SHOULD REMAIN BELOW HEADLINE 
LEVELS.

RIP CURRENTS: EASTERLY SWELLS AT 2-3 FT ALONG WITH SE/S WINDS AT 
15-20 MPH ALONG THE COAST WILL CONTINUE A MODERATE RISK OF RIPS THEN 
A SHIFT TO OFFSHORE FLOW ON FRIDAY SHOULD BRING THEM BACK TO LOW.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  83  68  81  54 /  50  60  60  20 
SSI  77  67  79  60 /  50  50  60  40 
JAX  83  67  81  59 /  50  60  60  50 
SGJ  80  68  81  63 /  50  50  50  50 
GNV  84  67  82  61 /  50  50  60  50 
OCF  86  68  84  63 /  50  50  50  50 

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...NONE.
AM...SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 3 PM EDT FRIDAY 
     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.

&&

$$

PP/JH