FXUS62 KJAX 251851
AFDJAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
151 PM EST FRI DEC 25 2009
...WHAT IS LEFT OF PRE-FRONTAL SQUALL LINE WILL EXIT AREA LATER
THIS AFTERNOON...
...MUCH COOLER TEMPS ON THE WAY WITH A BRIEF DRYING PERIOD...
.SHORT TERM...CURRENT MSAS ANALYSIS SHOWS A WEAK WAVE OF LOW
PRESSURE DID INDEED FORM ALONG THE INITIAL FRONT OVER SOUTH
CAROLINA INTO SOUTHEAST GEORGIA. THIS DID PROVIDE FOR INCREASED
CONVERGENCE ALONG THE LINE WITH HIGHER DBZ LOW TOPPED CORES...BUT
LAPSE RATES IN THE MID LEVELS JUST REMAINED TOO WEAK TO SUPPORT
THE UPDRAFTS NEEDED TO SUSTAIN CIRCULATION CENTERS. BEST LOW LEVEL
WIND CORE AND SHEAR IS NOW LIFTING WELL NORTH OF THE AREA SO EVEN
IF ACTIVITY BECOMES ENHANCED OVER THE WATERS THIS
AFTERNOON...OVERALL STRENGTH OF ACTIVITY WILL BE VERY LIMITED WITH
MAINLY JUST SHOWERS EXPECTED.
FOR THE EVENING HOURS AND INTO THE OVERNIGHT PERIOD...EXPECT A
CONTINUED CLEARING OF THE PRECIP FIELDS BUT CLOUD COVER LOOKS TO
BE MUCH SLOWER. IN FACT...BASED ON CURRENT SAT PICS WITH EXPANSIVE
DECK WELL BACK INTO THE PANHANDLE...WILL KEEP CLOUDS IN LONGER
THAN GUIDANCE DEPICTS...ESPECIALLY OVER THE SOUTHEAST ZONES.
EXPECT PARTLY CLOUDY CONDITIONS BY 06Z WHICH SHOULD ALLOW FOR
ENOUGH COOLING FOR MOST SITES TO REACH THE UPPER 30S TO LOWER 40S
FOR MINIMUMS.
HIGH PRESSURE WILL BRIDGE ACROSS THE I10 CORRIDOR THROUGH SAT
NIGHT WITH CONTINUED LIGHT DRAINAGE FLOW KEEPING TEMPS SEASONABLY
COOL WITH UPPER 50S TO AROUND 60 VALUES. NOTICED THE ENSEMBLE IS
CONSIDERABLY HIGHER THAN THE MOSGUIDE AND HAVE GENERALLY USED A
BLEND FOR THE SHORT TERM.
AS HAS BEEN THE CASE THE LAST FEW WEEKS...FLOW ALOFT WILL REMAIN
ZONAL AND HIGH CLOUDS MAY NEVER REALLY LEAVE THE AREA BEFORE NEXT
IMPULSE ARRIVES FOR THE LATTER HALF OF THE WEEKEND. MODELS DIFFER
ON THE NORTH/SOUTH PLACEMENT OF THIS FEATURE AS WELL THE INTENSITY
AND TIMING WITH THE GFS THE MOST AGGRESSIVE AND THE ECMWF SHOWING
VERY LOW PRECIP CHANCES. CONTINUING A BLENDED APPROACH TO THE
FORECAST...WILL FEATURE LOWERING CLOUD DECKS THROUGH SUNDAY WITH
JUST A BRIEF SHOT AT LIGHT RAIN ACROSS THE AREA CAPPING POPS AT
30% FOR NOW.
.LONG TERM...ANOTHER WEAK IMPULSE WITH RAIN CHANCES IS ON TAP FOR
THE MIDDLE OF THE WEEK BEFORE A MORE SIGNIFICANT SYSTEM ARRIVES ON
FRIDAY. STILL TOO EARLY TO MAKE ANY SIGNIFICANT CHANGES TO THE
EXTENDED AND WILL LIKELY LEAVE THAT FOR THE MID SHIFT.
&&
.AVIATION...WIND SHIFT TO WSW HAS OCCURRED ALREADY AND CIGS
SHOULD BE LIFTING FROM MVFR TO VFR NLT 21Z AS DRIER AIR PUSHES IN.
VFR CONDS WILL CONTINUE THRU SATURDAY. THERE IS A POTENTIAL FOR
LOW CIGS OR MIFG MAINLY AT GNV LATE TONIGHT...BUT HAVE NOT
MENTIONED IN TAF FOR NOW.
&&
.MARINE...BUOYS CONTINUE TO REPORT PEAK WINDS NEAR 30 KT. WINDS
WILL DIMINISH AFTER THE FRONT PASSES AND LINES OF SHOWERS HAVE
CLEARED THE WATERS. LOOKS LIKE 20Z WILL BE APPROPRIATE TIME FOR
SCA TO BE LOWERED TO A CAUTION STATEMENT FOR NEAR SHORE WATERS.
WILL MAKE NO CHANGES TO SCA OVER THE OFFSHORE WATERS. HIGH
PRESSURE WILL BUILD INTO THE REGION SAT NIGHT AND SUN WITH
LIGHTER WINDS. HOWEVER...A REINFORCEMENT OF COLD AIR EXPECTED
LATE SUNDAY NIGHT WILL RAMP UP NWLY WINDS AND SEAS AGAIN...LIKELY
INTO SCA CRITERIA THROUGH EARLY TUE.
&&
.FIRE WEATHER...DRIER AIR WILL BE IN PLACE SATURDAY AND RH VALUES
WILL FALL BELOW 35 PCT FOR AROUND 4 HOURS WEST OF THE TRAIL RIDGE
IN NE FL. THE AREA FROM LIVE OAK TO LAKE CITY AND S TO TRENTON
WILL HAVE THE LOWEST RH WHILE MACCLENNY TO GNV TO OCALA MAY NOT
QUITE MAKE 4 HRS. WILL GO AHEAD AND ISSUE A FIRE WX WATCH FOR
THESE 9 COUNTIES. FINAL DETERMINATION FOR A RED FLAG WILL BE MADE
ON MID SHIFT. RH'S SHOULD REBOUND ON SUNDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 36 58 34 54 / 0 0 10 30
SSI 41 57 40 56 / 0 0 10 20
JAX 41 59 38 60 / 0 0 10 20
SGJ 46 60 44 61 / 0 0 10 20
GNV 39 60 38 61 / 0 0 10 20
OCF 42 62 40 64 / 0 0 10 20
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...NONE.
AM...SMALL CRAFT ADVISORY UNTIL 10 AM EST SATURDAY 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.
SMALL CRAFT ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR ALTAMAHA
SOUND GA TO FERNANDINA BEACH FL OUT 20 NM-FERNANDINA BEACH
TO ST AUGUSTINE FL OUT 20 NM-ST AUGUSTINE TO FLAGLER BEACH
FL OUT 20 NM.
&&
$$
DEESE/TRABERT/WALKER
