FXUS62 KJAX 111940
AFDJAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
240 PM EST FRI DEC 11 2009
...INCREASING RAINS ACROSS THE AREA...
...FLOOD WATCH FOR N TIER OF COUNTIES...
.SYNOPSIS...UPPER HIGH CENTERED N OF CUBA WITH GENERALLY ZONAL
FLOW OVER THE AREA. STREAM OF MID AND UPPER LEVEL MOISTURE EVIDENT
ON H2O VAPOR SATELLITE IMAGERY FROM THE PACIFIC ACROSS THE GULF
COAST STATES. MID AND HIGH LEVEL CLOUDINESS COVER SE GA AND
EXTREME NE FL WITH LOWER CIGS OVER OUR S ZONES. AREA OF LIGHT RAIN...
THE RESULT OF ISENTROPIC LIFT...ALREADY PRESENT ACROSS OUR EXTREME
S ZONES. DUE TO THE THICK CLOUD COVER AND CONTINUED COLD AIR
ADVECTION...TEMPS UNIFORM IN THE MID 40S ACROSS THE AREA. IN FACT...
TEMPS HAVE DROPPED SEVERAL DEGREES OVER THE S DUE TO EVAPORATIVE
COOLING FROM RAIN FALLING THRU DRY AIR CLOSER TO THE SFC.
.SHORT TERM...FORECAST WILL BE DOMINATED BY ISENTROPIC LIFT AND
COASTAL CONVERGENCE ON THE W SIDE OF A DEVELOPING ATLC TROF. HAVE
GENERALLY USED A BLEND OF GFS AND NAM GUIDANCE AND TWEAKED POPS UP
OVER THE E COAST COUNTIES. HAVE STARTED OUT PRECIP AS STRATIFORM
RAIN BUT INCREASED SHOWER MENTION FROM THE S AND EVENTUALLY ISOLD
TSTMS AS LOW-LEVEL WINDS VEER TO MORE SLY BY SUN.
HEAVIEST PRECIP AMOUNTS WILL LIKELY OCCUR OVER OUR N AND COASTAL
ZONES DURING THIS PERIOD. DUE TO THE CHANCE OF SOME 2 INCH OR
GREATER RAINFALL AMOUNTS OVER OUR N TIER OF ZONES IN THE SAME
AREAS WHERE RADAR ESTIMATED 30-DAY PRECIP TOTALS HAVE APPROACHED 6
TO 8 INCHES AND WE ALREADY HAVE THE ALTAMAHA AT BAXLEY IN MINOR
FLOOD...HAVE OPTED TO ISSUE A FLOOD WATCH GENERALLY N OF WAYCROSS.
THANX FOR COORD FFC! PRECIP WILL LIFT N OF THE AREA DURING THE DAY
SUN WITH MORE SHOWERY PRECIP ON TAP FOR SUN AFTN.
FOG TOOLS AND MOS GUIDANCE HITTING FOG PRETTY HARD SAT NIGHT AND
SUN NIGHT...SO HAVE INCLUDED THIS IN THE FORECAST. NAM AND GFS MOS
TEMPS ARE IN FAIR AGREEMENT THRU THE PERIOD. HOWEVER...PRECIP...
CLOUD COVER...AND ADVECTION PATTERNS WILL PLAY HAVOC WITH THE TEMP
CURVE. HAVE USED A NON-DIURNAL TEMP FORECAST OVERNIGHT WITH TEMPS
FALLING AS DAYTIME HEATING GOES AWAY AND EVAPORATIVE COOLING
CONTINUES...THEN GRADUALLY WARMING AFTER MIDNIGHT AS LOW LEVELS
BECOME MORE SATURATED.
.LONG TERM...HAVE MADE FEW CHANGES TO THE EXTENDED PACKAGE. FRONT
STILL APPEARS TO MAKE CLEAN TRANSITION THRU THE AREA BY MID-WEEK
WITH COOLER TEMPS BY LATE IN THE WEEK. LATEST MEX MOS NUMBERS ARE
SLIGHTLY WARMER THAN PREVIOUS GUIDANCE DUE TO QUICKER TRANSITION
TO STRONGER ATLC FLOW BEHIND THE COLD FRONT.
&&
.AVIATION...VFR CONDS WILL CONTINUE AHEAD OF ISENTROPIC UPGLIDE
NORTH OF FRONTAL BOUNDARY THIS AFTERNOON AND EVENING. AFTER 06Z
LOWERING OF CLOUD DECK MAY START TO PRODUCE SOME MVFR CIGS WITH
CONTINUOUS LIGHT RAIN STARTING AT FL TAF SITES. CLOUDS WILL
CONTINUE TO LOWER SAT MORNING WITH CONTINUOUS LIGHT/MODERATE RAIN
AT ALL TAF SITES AND POSSIBLE IFR CIGS AT KGNV CLOSER TO THE WARM
FRONTAL BOUNDARY.
&&
.MARINE...SMALL CRAFT CONDS IN PLACE AS NORTHEAST WINDS CONTINUE
TO ESTABLISH ACRS THE COASTAL WATERS WITH SUSTAINED WINDS AT
15-20G25 KNOTS AND WILL CONTINUE TO INCREASE TO 20-25 KNOTS
TONIGHT. WINDS VEER TO THE EAST AT 25 KNOTS AHEAD OF WARM FRONT
WITH SEAS UP TO 10 FT. WINDS SHIFT TO THE SOUTH SAT NIGHT AS WARM
FRONT LIFTS NORTH THROUGH THE COASTAL WATERS. LOW PRESSURE
DEVELOPS ALONG THE CAROLINA COAST ON SUNDAY AND TRACKS QUICKLY
NORTHEAST AND LEAVES A LOOSE PRESSURE GRADIENT OVER THE COASTAL
WATERS ON MONDAY WITH NO HEADLINES IN PLACE. NEXT FRONT TO
APPROACH THE WATERS ON TUESDAY AND CROSS THE WATERS TUE NIGHT WITH
NEXT SURGE OF NORTH WINDS ON WEDNESDAY.
&&
.FIRE WEATHER...TOO MUCH CLOUD COVER AND SHALLOW COLD AIR DOOMED
RED FLAG WARNING AS RH VALUES FLIRTED WITH 35 PERCENT BUT
DURATIONS WERE NOT REACHED. NO FURTHER RED FLAG EVENTS EXPECTED IN
THE SHORT TERM.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 37 53 49 70 / 30 90 80 60
SSI 45 60 58 73 / 30 100 90 50
JAX 43 64 60 77 / 40 80 70 50
SGJ 52 68 65 78 / 50 80 60 40
GNV 44 69 60 79 / 50 60 50 30
OCF 48 72 63 81 / 40 60 40 30
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...FLOOD WATCH FROM LATE TONIGHT THROUGH SUNDAY AFTERNOON FOR
APPLING-BACON-COFFEE-JEFF DAVIS-WAYNE.
AM...SMALL CRAFT ADVISORY UNTIL 7 AM SUN FOR ALTAMAHA SOUND GA
TO FLAGLER BEACH FL 20 NM TO 60 NM OFFSHORE.
SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 10 PM
SAT FOR ALTAMAHA SOUND GA TO FLAGLER BEACH FL OUT 20 NM.
&&
$$
CARROLL/HESS/PRESNALL
