FXUS62 KJAX 100935
AFDJAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
435 AM EST THU DEC 10 2009
SURFACE COLD FRONT IS CURRENTLY POSITIONED NEAR A
KJAX TO KLCQ LINE AT 08Z...AND THIS FEATURE WILL CONTINUE A SLOW
SOUTHWARD PROGRESSION ACROSS NORTHEAST FLORIDA THROUGH THIS
MORNING. DOPPLER RADAR SHOWS A DEFINE LINE OF SHOWERS ASSOCIATED
WITH THE FRONTAL BOUNDARY...WITH CLUSTERS OF SHOWERS SOUTH OF THE
FRONT. BANDS OF LIGHT SHOWERS WERE NOTED NORTH OF THE FRONT AND
THESE BANDS ARE IN RESPONSE TO ISENTROPIC LIFT COUPLED WITH MID
LEVEL ENERGY TRAVERSING THE REGION.
ALTHOUGH FRONT SHOULD CLEAR MARION COUNTY BY 15Z...BANDS OF SHOWERS
WILL CONTINUE TO TRAVERSE THE REGION TODAY UNDER FAVORABLE ISENTROPIC
LIFT. THESE BANDS WILL BE MOST NUMEROUS ACROSS NORTHEAST FLORIDA
THIS MORNING WHERE I HAVE INCLUDED LIKELY POPS. ADDITIONALLY...CANNOT
RULE OUT A STRAY THUNDERSTORM ALONG AND SOUTH OF A KGNV-KSGJ LINE
THROUGH AROUND DAYBREAK AS TEMP/DEWPT VALUES ARE CURRENTLY IN THE
70S...YIELDING SURFACE-BASED CAPE OF AROUND 1000 J/KG. RAIN WILL
END FROM THE NORTHWEST TODAY...WITH RAIN GENERALLY ENDING ACROSS
SOUTHEAST GEORGIA BY MIDDAY.
A LARGE NW-SE TEMPERATURE GRADIENT CURRENTLY EXISTS...WITH
READINGS RANGING FROM LOWER 50S ACROSS INTERIOR SOUTHEAST GEORGIA
TO LOWER 70S ALONG AND SOUTH OF A KGNV-KSGJ LINE. TEMPERATURES
ARE FORECAST TO HOLD IN THE 50S OVER THE NORTHERN SUWANNEE RIVER
VALLEY OF NORTH FLORIDA AND SOUTHEAST GEORGIA. MEANWHILE...
TEMPERATURES ARE FORECAST TO FALL INTO THE 50S ACROSS THE BALANCE
OF THE JACKSONVILLE COUNTY WARNING AREA TODAY.
CLOUDS WILL CONTINUE TO BLANKET MUCH OF THE JACKSONVILLE COUNTY
WARNING AREA THIS MORNING...WITH BREAKS IN THE CLOUDS FORECAST
ACROSS SOUTHEAST GEORGIA THIS AFTERNOON WHERE WINDS ABOVE THE
SURFACE WILL BEGIN TO VEER FROM THE SOUTHWEST TO NORTHWEST...SHUTTING
OFF MOISTURE SOURCE.
STRONG SURFACE HIGH IS FORECAST TO REACH THE LOWER MISSISSIPPI
VALLEY THIS AFTERNOON...THEN IS FORECAST TO DOMINATE MUCH OF THE
SOUTHEAST UNITED STATES TONIGHT. THE PLACEMENT OF THIS HIGH TO OUR
NORTH TONIGHT WILL LIKELY BRING LIGHT NORTHERLY WINDS FOR AREAS
ALONG AND WEST OF THE U.S. HIGHWAY 301 CORRIDOR. THIS FLOW REGIME
COUPLED WITH SMATTERING OF OF MID TO HIGH CLOUDS WILL ALLOW
TEMPERATURES TO PLUMMET INTO THE 30S ACROSS THIS AREA. THERE IS THE
POTENTIAL FOR A LIGHT FREEZE ALONG AND NORTH OF A HOMERVILLE-
ALMA-JESUP LINE TOWARDS DAYBREAK FRIDAY. WILL HOIST FREEZE WATCH
FOR THIS AREA. TEMPERATURES ARE GENERALLY FORECAST TO DIP INTO THE
40S EAST OF U.S HIGHWAY 301 CORRIDOR. ADDITIONALLY...PATCHES TO
AREAS OF FROST ARE EXPECTED FOR MUCH OF THE INTERIOR.
FRIDAY/FRIDAY NIGHT...SURFACE HIGH WILL REMAIN ANCHORED ACROSS THE MID-
ATLANTIC REGION...WITH AN INVERTED TROUGH LIKELY ESTABLISHING
ACROSS THE LOCAL WATERS. CLOUDS ARE FORECAST TO INCREASE FROM THE
SOUTH AS NORTHERLY WINDS AT THE SURFACE ARE FORECAST TO VEER TO
THE SOUTHWEST ALOFT...WITH GULF MOISTURE DRAWN INTO THE AREA. THERE
APPEARS TO BE SUFFICIENT MOISTURE TO INTERACT WITH AFOREMENTIONED
COASTAL TROUGH AND DEEPENING ISENTROPIC LIFT TO WARRANT POPS
ACROSS NORTHEAST FLORIDA.
UNSETTLED WEATHER PATTERN WILL ENSUE FRIDAY NIGHT AND CONTINUING
THROUGH AT LEAST SATURDAY AS NUMERICAL MODELS CONTINUE TO INDICATE
SOUTHERN JET-STREAM WILL ALIGN ACROSS THE GULF COAST REGION.
EMBEDDED DISTURBANCES WILL LIKELY SPAWN THE DEVELOPMENT OF SEVERAL
LOW PRESSURE CENTERS OVER THE NORTHERN GULF OF MEXICO. THESE FEATURES
WILL LIKELY DRAW OLD FRONTAL BOUNDARY NORTHWARD INTO THE JACKSONVILLE
COUNTY WARNING AREA BEFORE STALLING. THE COMBINATION OF DEEP
ATMOSPHERIC MOISTURE AND LARGE SCALE ASCENT WILL LEAD TO NUMEROUS
SHOWERS AND POSSIBLE STORMS.
.LONG TERM...UNSETTLED WEATHER PATTERN WILL EXTEND THROUGH
SATURDAY NIGHT AND POSSIBLY INTO SUNDAY MORNING. LAST IN SERIES OF
LOW PRESSURE CENTERS IS FORECAST TO DEPART EAST ON SUNDAY...WITH
RAIN MAINLY ENDING FROM THE WEST SUNDAY AFTERNOON.
DRY CONDITIONS ARE FORECAST MONDAY WITH RAIN RETURNING MONDAY
NIGHT AND TUESDAY AS YET ANOTHER FRONTAL SYSTEM IS FORECAST TO
IMPACT THE AREA. THIS FRONT AND ATTENDANT DYNAMICS ARE FORECAST
TO EXIT OFFSHORE LATE TUESDAY...FOLLOWED BY DRY AND MUCH COOLER
CONDITIONS.
&&
.AVIATION...
COLD FRONT JUST PASSED KJAX AND WILL PASS THROUGH THE REMAINING
FLORIDA TERMINALS PRIOR TO SUNRISE. MVFR CEILINGS WILL LINGER
INTO THE MORNING HOURS BEFORE MUCH DRIER AND COLDER AIR FILTERS IN
AND LOW CLOUDS BEGIN TO DISSIPATE. SCATTERED RAIN SHOWERS WILL
ACCOMPANY THE FRONT WITH BRIEF MVFR VISIBILITIES. VFR CONDITIONS
WILL THEN PREVAIL THROUGH THE REST OF THIS TAF CYCLE.
&&
.MARINE...
A BRIEF SURGE OF WINDS FOLLOWING THE COLD FRONTAL PASSAGE THIS
MORNING WILL RESULT IN A FEW HOURS OF WIND SPEEDS AROUND 20 KNOTS
ACROSS THE NORTHERN 2 OFFSHORE LEGS. A SMALL CRAFT ADVISORY IS NOW
IN EFFECT TO COVER THIS BRIEF INCREASE IN NORTHWEST WINDS. SEAS
WILL ALSO RESPOND BRIEFLY WITH INCREASES TO 6 FEET POSSIBLE
OFFSHORE.
NORTHERLY WINDS IN THE 15 TO 20 KNOT RANGE WILL CONTINUE THROUGH
FRIDAY. A TURN TO THE NORTHEAST AND AN INCREASE TO 25 KNOTS WITH
HIGHER GUSTS IS EXPECTED LATE FRIDAY NIGHT AND SATURDAY AS A LOW
PRESSURE SYSTEM DEVELOPS OVER THE COASTAL WATERS. AS A RESULT...AT
LEAST SMALL CRAFT ADVISORY CONDITIONS ARE ANTICIPATED OVER THE
WEEKEND ACROSS BOTH THE NEARSHORE AND OFFSHORE LEGS NORTH OF ST
AUGUSTINE. SEAS ARE EXPECTED TO CLIMB AS HIGH AS 10 FEET.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 55 32 52 38 / 30 10 10 60
SSI 57 38 55 47 / 50 0 10 60
JAX 59 36 56 48 / 60 10 20 60
SGJ 69 42 60 55 / 70 10 20 60
GNV 64 38 57 49 / 60 10 30 50
OCF 71 42 59 52 / 60 10 30 50
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...FREEZE WATCH FROM LATE TONIGHT THROUGH FRIDAY MORNING FOR
APPLING-BACON-COFFEE-JEFF DAVIS-WAYNE.
AM...SMALL CRAFT ADVISORY UNTIL 2 PM EST THIS AFTERNOON 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.
&&
$$
ZAPPE/SHULER/
