000
FXUS62 KCHS 280530
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1230 AM EST TUE DEC 28 2010
.SYNOPSIS...
HIGH PRESSURE WILL PERSIST THROUGH WEDNESDAY. A WEAK BACKDOOR COLD
FRONT WILL SLIP INTO THE REGION WEDNESDAY NIGHT. THE CENTER OF
THE SURFACE HIGH WILL THEN MOVE OFF THE EASTERN SEABOARD LATE IN
THE WEEK. ANOTHER SYSTEM COULD APPROACH FROM THE WEST ON SUNDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
HIGH PRESSURE WILL REMAIN NEARLY STATIONARY OVER THE DEEP SOUTH
OVERNIGHT...RESULTING IN CLEAR SKIES ACROSS THE LOCAL AREA. 1000 MB
GEOSTROPHIC WINDS WILL DROP TO 10-15 KNOTS BY DAYBREAK INCREASING
THE RADIATIONAL COOLING POTENTIAL. THE VERY DRY AIR MASS IN
PLACE WILL LEAD TO VERY CHILLY TEMPERATURES BY DAYBREAK...
GENERALLY AROUND 20 INLAND...LOWER TO MID 20S IN THE CHARLESTON-
BEAUFORT-SAVANNAH CORRIDOR...AND AROUND 30 ALONG THE COAST. WE ARE
FORECASTING A RECORD LOW AT CHARLESTON AND CLOSE TO A RECORD LOW
AT SAVANNAH. REFER TO THE CLIMATE SECTION OF THIS PRODUCT FOR THE
RECORD LOW TEMPERATURES FOR DECEMBER 28.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY/...
SURFACE HIGH PRESSURE WILL MOVE OVER THE MID ATLANTIC AND
SOUTHEAST STATES TUESDAY AND WEDNESDAY...WITH NEARLY ZONAL FLOW
PERSISTING ALOFT. THIS PATTERN WILL SUPPORT DRY AND MOSTLY SUNNY
CONDITIONS...AS WELL AS GRADUALLY MODERATING TEMPERATURES. DAYTIME
HIGHS WILL RISE INTO THE 50 DEGREE RANGE TUESDAY AND WEDNESDAY
AFTERNOONS...STILL COOLER THAN SEASONAL NORMALS. ALTHOUGH
OVERNIGHT LOW TEMPERATURES WILL ALSO FOLLOW THIS WARMING
TREND...EXPECT CONDITIONS TO REMAIN QUITE CHILLY...AS CLEAR SKIES
AND LIGHT WINDS ENHANCE RADIATIONAL COOLING EFFICIENCY.
THE CENTER OF HIGH PRESSURE WILL SLIP OFF THE EAST COAST WEDNESDAY
NIGHT THROUGH THURSDAY...AHEAD OF SHORTWAVE ACTIVITY MOVING
NORTHEAST FROM THE GULF OF MEXICO. A WEAK BACKDOOR FRONT WILL DROP
SOUTHWARD...WHILE A DISTINCT INLAND WEDGE/COASTAL TROUGH PATTERN
BEGINS TO TAKE SHAPE LATE THURSDAY. WILL MAINTAIN ONGOING FORECAST
HIGH TEMPERATURES FOR THURSDAY...DEPICTING A DECENT GRADIENT
BETWEEN COOLER TEMPERATURES IN THE UPPER 50S FOR FAR INLAND AND
NORTHERN ZONES...AND WARMER CONDITIONS IN THE LOWER 60S ACROSS
SOUTHEAST GEORGIA. CHANCES FOR MEASURABLE PRECIPITATION WITH THE
SHORTWAVE APPEAR MINIMAL LACKING SUFFICIENT DEEP MOISTURE. WILL
THUS CAP POPS BELOW 15 PERCENT AND JUST INDICATE INCREASING CLOUD
COVER ON THURSDAY.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
GLOBAL MODELS ARE IN GENERALLY GOOD AGREEMENT THROUGH THE LONG
TERM PERIOD. HEIGHTS ALOFT WILL BE BUILDING OVER THE EAST COAST
STATES BY THURSDAY NIGHT...AS A DEEP UPPER TROUGH DIGS INTO THE
MOUNTAIN WEST STATES. EVEN THOUGH A WEAK SURFACE WEDGE PERSISTS
FOR GEORGIA AND THE CAROLINAS ON FRIDAY...THE PATTERN DOES NOT
FAVOR ANY STRONG LOW LEVEL MOISTURE ADVECTION. LATEST THINKING IS
THAT THERE WILL BE SOME SUNSHINE FRIDAY...AND TEMPERATURES SHOULD
RISE ABOVE CLIMATOLOGICAL NORMALS...WELL INTO THE 60S MOST AREAS.
OVER THE WEEKEND...MILD CONDITIONS ARE LIKELY WITH THE WEDGE BREAKING
DOWN AND SSE-SSW FLOW EXPECTED. HIGH TEMPERATURES FOR MANY AREAS AWAY
FROM THE MUCH COOLER BEACHES COULD TOUCH OR TOP 70 DEGREES BOTH DAYS.
THE NEXT SIGNIFICANT CHANCE OF RAIN APPEARS TO BE LATE IN THE
WEEKEND AHEAD OF A COLD FRONT THAT COULD ALSO INITIATE A COOLING
TREND BY MONDAY.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
VFR.
EXTENDED AVIATION OUTLOOK...VFR.
&&
.MARINE...
COLD AIR ADVECTION WILL CONTINUE TO WEAKEN OVER THE WATERS
THROUGH THE REST OF THE OVERNIGHT AND WITH DIMINISHING WINDS
PLAN TO CANCEL THE ADVISORIES FOR ALL WATERS EXCEPT THE
CHARLESTON COUNTY WATERS AND OUTER GEORGIA WATERS WHERE THE RISK
FOR 25 KT WINDS IS HIGHEST DUE TO BETTER MIXING POTENTIAL AND THE
LINGERING STRONGER LOW-LEVEL WINDS.
QUIETER MARINE CONDITIONS ARE EXPECTED BY TUESDAY...AS SURFACE
HIGH PRESSURE SHIFTS OVER THE MID ATLANTIC AND SOUTHEAST STATES.
OFFSHORE FLOW WILL VEER TO THE NORTHEAST WEDNESDAY NIGHT INTO
THURSDAY...WHEN A WEAK BACKDOOR FRONT DROPS THROUGH THE MARINE ZONES
AND A SURFACE WEDGE SETS UP INLAND. COASTAL TROUGH DEVELOPMENT IS
POSSIBLE THURSDAY INTO FRIDAY...WITH THE CENTER OF HIGH PRESSURE
MOVING OFF THE EAST COAST. WINDS AND SEAS ARE EXPECTED TO REMAIN
BELOW ADVISORY LEVELS THROUGH THE PERIOD.
&&
.CLIMATE...
RECORD LOWS FOR DEC 28...
CHS...24 DEGREES SET IN 2004
CHL...18 DEGREES SET IN 1925
SAV...21 DEGREES SET IN 1925
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST EARLY THIS MORNING FOR
AMZ350-374.
&&
$$
JRL
