FXUS62 KCHS 260824
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
324 AM EST SAT DEC 26 2009
.SYNOPSIS...
HIGH PRES WILL BUILD INTO GEORGIA AND THE CAROLINAS TODAY AND
PERSIST FOR THE REMAINDER OF THE WEEKEND. BY EARLY MON...A DRY
COLD FRONT WILL PUSH THROUGH THE REGION...FOLLOWED BY STRONGER
HIGH PRES WHICH WILL BUILD OVER THE REGION THROUGH TUE. LOW
PRES WILL IMPACT THE REGION FOR THE LATTER HALF OF THE WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
SURFACE HIGH PRES WILL BUILD E FROM THE LOWER MISSISSIPPI VALLEY
REGION TODAY IN THE WAKE OF THE RAINY AND WINDY STORM SYSTEM WE SAW
ON CHRISTMAS DAY. LOWER CLOUDS WERE DISSIPATING PRE-DAWN AS MUCH
DRIER AIR THROUGH A DEEP LAYER BUILDS IN FROM THE WNW. A GENERAL
COLD AIR ADVECTION PATTERN IS ON TAP TODAY BUT A BIT OF DOWNSLOPE
COMPONENT IS NOTED ALONG COASTAL AREAS. WE MADE A FEW DOWNWARD
ADJUSTMENTS TO HIGH TEMPERATURES TO THE W OF I-95 IN GEORGIA TODAY
WITH PLACES SUCH AS METTER AND COBBTOWN HAVING A HARD TIME SURPASSING
THE MID 50S. OTHERWISE...MOST AREAS WILL SPEND THE WARMEST PART OF
THE AFTERNOON IN THE UPPER 50S.
AN ACTIVE SUBTROPICAL JET STREAM FROM THE EAST PACIFIC TO THE GULF
COAST REGION WILL SPREAD A ROUND OF HIGH CLOUDS OUR WAY TODAY AND
A GENERAL INCREASE IN COVERAGE IS LIKELY AND WE HAVE MAINTAINED
A PARTLY CLOUDY SKY COVER FORECAST TODAY. WINDS WILL BE NW TO W
BY LATE DAY...A FEW GUSTS TO 15 MPH A GOOD BET FROM TIME TO TIME
LATE MORNING AND EARLY AFTERNOON...BUT SPEEDS MAINLY 10 MPH OR
LESS.
THE HIGH SURF ADVISORY ALONG THE COLLETON/CHARLESTON COUNTY COAST
HAS BEEN CANCELLED THIS MORNING AS WAVES HAVE DIMINISHED BELOW 4 FT
ON RECENT FOLLY BEACH PIER OBSERVATIONS.
&&
.SHORT TERM /TONIGHT THROUGH 6 PM SUNDAY/...
THE FAST JET ALOFT WILL STEER AN ELONGATED SHORT WAVE THROUGH
THE NE GULF AND SE STATES TONIGHT BRINGING FURTHER INCREASES IN
MID AND UPPER LEVEL MOISTURE AND CLOUDINESS. OUR LOWER LEVELS
REMAIN DRY AND DESPITE THE HIGH CLOUDS COMBATING RADIATIONAL
COOLING...LOW TEMPERATURES ARE STILL GOING TO BE SUB-FREEZING
OVER OUR COLDER NW INLAND TIER AREAS. WE NUDGED LOW TEMPERATURES
UP A DEGREE OR TWO ALONG AND E OF THE U.S. 17 CORRIDOR WHERE
THICKER MID CLOUDS ARE EXPECTED TO ALIGNED OVERNIGHT.
00Z GUIDANCE CONTINUES TO DEPICT A SHORTWAVE EJECTING NE ACROSS THE
REGION SUNDAY INTO SUNDAY NIGHT...WITH ASSOCIATED ENHANCED MID LEVEL
MOISTURE SURGING NE AHEAD OF AN APPROACHING COLD FRONT. MODEL
SOUNDINGS DEPICT A VERY DRY LOW LEVEL AIRMASS ACROSS THE
REGION...THE TYPE OF AIRMASS THAT WOULD SUPPORT NOTHING MORE THAN
A FEW SPRINKLES/ICE PELLETS EARLY SUNDAY MORNING THEN ISOLATED
SPRINKLES FOR THE BALANCE OF THE DAY INTO SUNDAY EVENING. PER
COLLABORATION WITH JAX OPTED TO LOWER POPS BELOW 15 PERCENT/REMOVE
ALL MENTION OF PRECIPITATION FROM SUNDAY/SUNDAY EVENING FORECASTS.
OTHERWISE...MID/HIGH LEVEL CLOUDS SHOULD PRODUCE MOSTLY CLOUDY
SKIES. DESPITE THE CLOUD COVER...AHEAD OF THE APPROACHING COLD FRONT
TEMPERATURES SHOULD RECOVER TO AROUND 60F MOST LOCATIONS SUNDAY
AFTERNOON...CLOSE TO NORMAL FOR LATE DECEMBER.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
LATE SUNDAY NIGHT...A DRY COLD FRONT WILL PUSH THROUGH THE
REGION...FOLLOWED BY BUILDING HIGH PRESSURE/A SURGE OF COLD
ADVECTION AND BEGINNING A PERIOD OF BELOW NORMAL TEMPERATURES THAT
WILL MOST LIKELY PERSIST THROUGH LATE WEEK AND BEYOND. THE HIGH
PRESSURE WILL ALSO ENSURE RAIN-FREE CONDITIONS THROUGH TUESDAY
NIGHT.
AS THE HIGH EXPANDS OVER THE REGION MONDAY NIGHT...CONDITIONS
APPEARS FAVORABLE FOR FREEZING TEMPERATURES TO PUSH TO THE COAST.
BY MIDWEEK...ANOTHER SOUTHERN BRANCH LOW PRESSURE WILL TAKE SHAPE
OVER THE N/W GULF OF MEXICO...AND OVERRUNNING MOISTURE/PRECIPITATION
WILL EXPAND E/NE ACROSS THE SOUTHEAST. RECENT GUIDANCE HAS TRENDED
TOWARD A FASTER ONSET OF PRECIPITATION...THUS INTRODUCED CHANCE POPS
WEDNESDAY AND CONTINUED CHANCE POPS THROUGH THURSDAY AS THE LOW
PRESSURE PASSES OVER OF JUST S/E OF THE FORECAST AREA.
MODEL AGREEMENT REGARDING THE TRACK/INTENSITY OF THE SURFACE LOW
REMAINS POOR...AND FORECAST UNCERTAINTY REGARDING MANY FORECAST
DETAILS REMAINS HIGH. DUE TO THIS UNCERTAINTY...MAINTAINED SLIGHT
CHANCE POPS FRIDAY.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
AT KCHS...PATCHY MVFR CIGS STILL IN THE VICINITY BUT OVERALL WITH
MODELS CONTINUING TO SHOW A DRYING TREND IN THE LOWER LEVELS...WE
HAVE OPTED TO MAINTAIN CIGS ABOVE 3 KFT FOR A FEW MORE HOURS. WE
BELIEVE THAT PATCHY FOG WILL ALSO REMAIN RELATIVELY SHALLOW UNTIL
IT DISSIPATES PRIOR TO DAWN. OTHERWISE CONDITIONS WILL BE VFR FOR
THE REMAINDER OF THE FORECAST PERIOD WITH LIGHT PREVAILING WINDS
BLO 10 KT.
AT KSAV...THERE IS A SLIGHT CHANCE THAT PTCHY MVFR CIGS AROUND
STATESBORO AND SYLVANIA DRIFT DOWN OVER THE TERMINAL IN THE NEXT
COUPLE OF HOURS BUT WE HAVE OPTED TO MAINTAIN VFR CONDITIONS
OVERNIGHT AND THROUGH THE REMAINDER OF THE 06Z TAF CYCLE WITH
LIGHT W TO NW SURFACE WINDS.
VFR THROUGH TUESDAY. MVFR OR LOWER POSSIBLE IN RAIN WED.
&&
.MARINE...
CONDITIONS IMPROVING THIS MORNING...THANKS TO AN OFFSHORE WIND
COMPONENT. THE STRONG STORM SYSTEM FRI WHICH BUILT SEAS ABOVE
15 FT BEYOND 20 NM HAS LONG DEPARTED BUT WAS STILL PRODUCING
SWELL WAVES ON REGIONAL BUOYS. WE HAVE OPTED TO MAINTAIN SMALL
CRAFT ADVISORIES FROM EDISTO BEACH NORTH AND OVER OUR OUTER
GEORGIA WATERS TO INITIALIZE. SEAS OFF OF CHARLESTON COUNTY SHOULD
DIMINISH BLO 6 FT THIS MORNING WHILE GEORGIA WATERS BEYOND 20 NM
WILL LIKELY TAKE UNTIL LATE TODAY OR EVEN EARLY THIS EVENING FOR
SEAS TO COME DOWN...ESPECIALLY IN LIGHT OF AN ONGOING SURGE AND
JETTING CONDITIONS FROM SAVANNAH SOUTHWARD.
MODERATE OFFSHORE SURGING WILL CONTINUE TONIGHT AS HIGH PRES BUILDS
FROM THE W. SEAS SHOULD AVERAGE 2-3 FT NEAR SHORE AND 3-5 FT
BEYOND 20 NM. OFF THE GEORGIA COAST THERE COULD BE SOME GUSTS TO
20 KT AT TIMES BUT WE THINK SCA
WINDS/SEAS WILL REMAIN BELOW SMALL CRAFT ADVISORY LEVELS SUNDAY INTO
SUNDAY NIGHT. THEN...ANOTHER SURFACE OF COLD ADVECTION WILL SUPPORT
STRONGER W/NW WINDS AND BUILDING SEAS BY MONDAY MORNING...AND SMALL
CRAFT ADVISORY CONDITIONS WILL LIKELY DEVELOP THROUGH MONDAY NIGHT
ESPECIALLY BEYOND 20 NM. THEN...00Z GUIDANCE SUGGESTS THAT WINDS
WILL VEER TOWARD THE NORTHEAST TUESDAY/WEDNESDAY...TEMPORARILY
SLACKENING TUESDAY BEFORE THE SURFACE PRESSURE GRADIENT TIGHTENS
WEDNESDAY BETWEEN HIGH PRESSURE CENTERED NORTH OF THE WATERS AND
LOW PRESSURE APPROACHING FROM THE SOUTHWEST WEDNESDAY. THUS...BUMPED
UP WINDS/SEAS SOMEWHAT FROM PREVIOUS FORECASTS FOR TUESDAY/
WEDNESDAY...AND SMALL CRAFT ADVISORY CONDITIONS COULD DEVELOP AROUND
MIDWEEK. BEYOND WEDNESDAY...LOW PRESSURE WILL TRACK TOWARD THE
SOUTHEAST COAST. FORECAST UNCERTAINTY REMAINS HIGH REGARDING THE
TRACK/STRENGTH OF THE LOW PRESSURE AND ASSOCIATED IMPACTS ACROSS THE
COASTAL WATERS. THE POTENTIAL EXISTS FOR HAZARDOUS WINDS/SEAS BUT
FORECAST DETAILS COULD REMAIN ELUSIVE UNTIL SOMETIME NEXT WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR AMZ374.
SMALL CRAFT ADVISORY UNTIL NOON EST TODAY FOR AMZ350.
&&
$$
