FXUS62 KCHS 060914
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
414 AM EST SUN DEC 6 2009
.SYNOPSIS...
HIGH PRES WILL REMAIN N OF THE REGION THROUGH MON. A COMPLEX
STORM SYSTEM WILL IMPACT THE REGION TUE INTO WED. HIGH PRES WILL
BUILD OVER THE REGION FOR THE LATTER HALF OF NEXT WEEK. ANOTHER
SYSTEM COULD AFFECT THE AREA ON SAT.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CERTAINLY A TRICKY FROST/FREEZE FORECAST THIS MORNING STILL TO
BE RESOLVED. TEMPERATURES HAVE BEEN HELD UP BY A SURGE OF N WINDS
ALONG COASTAL SOUTH CAROLINA AND FREEZING TEMPERATURES WERE MAINLY
CONFINED TO SHELTERED AREAS WHERE THE GROWING SEASON HAD ALREADY
ENDED OR JUST INLAND FROM OUR FREEZE WARNING AREA IN SE GEORGIA.
TO INITIALIZE...IT LOOKS LIKE SCATTERED FROST ALONG COASTAL
SOUTH CAROLINA IS UNLIKELY WITH THE WINDS AND CURRENT CONDITIONS
AND WE HAVE OPTED FOR PATCHY FROST AND CANCELLED THE ADVISORY FROM
BEAUFORT UP TO CHARLESTON. IN SE GEORGIA...WE HAVE LEFT OUR
ADVISORY/WARNING AREAS ABOUT THE SAME AND WE WILL SEE WHAT PANS
OUT AROUND SUNRISE.
MOST AREAS WILL START THE DAY WITH SUNSHINE AND SOME PASSING
HIGH CLOUDS. A FEW POCKETS OF EARLY MORNING STRATOCUMULUS WILL
LINGER AROUND THE CHARLESTON TRI-COUNTY AREA. A CHILLY START
TO THE DAY WITH AFTERNOON HIGH TEMPERATURES IN THE 50S...ON
AVERAGE 6 TO 8 DEGREES BELOW NORMAL VALUES FOR THIS TIME OF YEAR.
THIS AFTERNOON...WE WILL START TO SEE LOW LEVEL CONVERGENCE AND
MOISTURE RETURN INVOF OF A DEVELOPING SURFACE COASTAL TROUGH
OFF THE S GEORGIA/NE FLORIDA COAST. STRATOCUMULUS DECKS WILL
LIKELY BEGIN TO INCREASE ALONG THE I-95 CORRIDOR S OF SAVANNAH
AS THE AFTERNOON WEARS ON. EVEN A LIGHT LATE DAY SPRINKLE IS
POSSIBLE AROUND THE GEORGIA BARRIER ISLANDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
MANY INLAND AREAS WILL SEE LOW TEMPERATURES REALIZED PRIOR TO 2
OR 3 AM MON MORNING AS LAYERED CLOUDS THICKEN AND SPREAD NW AND N
WITH TIME. LOW LEVEL WARM AIR ADVECTION PROCESSES ASSOCIATED WITH
THE WEAK OFFSHORE COASTAL TROUGH MAY PRODUCE SOME LIGHT SHOWERS
ALONG THE SOUTH CAROLINA COAST OVERNIGHT BUT RAINFALL AMOUNTS
SHOULD BE SPOTTY AT BEST WITH LACK OF SIGNIFICANT HIGHER RH
PROFILES. COOLEST TEMPERATURES IN THE MID TO UPPER 30S WELL
INLAND WITH RISING READINGS THROUGH THE 40S ALONG THE COAST PRIOR
TO DAWN A GOOD BET.
ON MON...ANY REAL RISK FOR SHOWERS SHOULD MAINLY BE CONFINED TO
AREAS TO THE N OF CHARLESTON AS THE NOSE OF THE COASTAL TROUGH SHIFTS
UP THE CAROLINA COAST. A WEAK WEDGE PATTERN WILL DOMINATE MUCH OF
OUR FORECAST AREA INLAND TIER NW OF CHARLESTON AND SAVANNAH AND TO
THE N OF I-16 IN GEORGIA. OUR TEMPERATURES APPEARED TOO WARM IN
THE LOW TO MID 60S AND WE LOWERED INLAND HIGHS TO THE CLOSER TO
59-60 DEGREES IN RESPECT TO THE CLOUDS AROUND DURING THE DAY AND
THE DEFIANT SHALLOW COOL AIR MASS. WE MAY NEED TO LOWER HIGHS EVEN
A BIT FURTHER DOWN THE ROAD.
TO THE S OF I-16...THE NAM SUGGESTS SOME SUNSHINE MAY POKE THROUGH
IN THE AFTERNOON ON MON AND WE HAVE MAINTAINED SOME HIGHS IN THE
MID 60S THERE.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
A PROGRESSIVE FLOW WILL MAINTAIN A RELATIVELY WET PATTERN FOR MUCH
OF THE PERIOD. HIGH PRESSURE NORTH OF THE REGION WILL BE THE PRIMARY
FEATURE MONDAY NIGHT BEFORE THE UPPER FLOW BACKS AND ALLOWS A FEW
SHORTWAVES TO RIPPLE THROUGH THE SOUTHEAST STATES TUE AND WED. MOIST
ISENTROPIC ASCENT WILL RAMP UP QUICKLY ON TUESDAY WITH A FRONTAL
BOUNDARY DRAPED ACROSS THE AREA AND A SHORTWAVE MOVING UP FROM THE
GULF COAST. TUE NIGHT THE FRONT SHOULD LIFT NORTH AS A WARM FRONT
ONCE THE LONGWAVE TROUGH AXIS SHIFTS INTO THE OHIO VALLEY AND A
SHORTWAVE LIFTS THROUGH CENTRAL GA/SC.
CONVECTIVE SHOWERS ARE EXPECTED TUE NIGHT BEHIND THE WARM
FRONT...THEN THERE IS THE POTENTIAL FOR SOME DRYING WED MORNING
BEFORE A SOMEWHAT MOISTURE-STARVED COLD FRONT MOVES THROUGH IN THE
AFTERNOON. IT IS HARD TO GET EXCITED ABOUT THUNDERSTORM POTENTIAL AT
THIS POINT GIVEN THE FACT THAT THE SHORTWAVE ENERGY WILL MOVE
THROUGH AT NIGHT AND THE MODELS ARE SHOWING FAIRLY WEAK MOISTURE
RETURN AHEAD OF THE COLD FRONT. MID-LEVEL LAPSE RATES DO NOT BREAK
THE 6C MARK AND MODEL CAPE VALUES ARE CURRENTLY LESS THAN 250
JOULES. MAINTAINED SLIGHT CHANCE TSTMS FOR WEDNESDAY ACCOMPANYING THE
COLD FRONT.
DRIER AND COOLER WEATHER EXPECTED THURSDAY INTO FRIDAY UNDER HIGH
PRESSURE. ANOTHER SYSTEM COULD DEVELOP IN THE GULF AND MOVE THROUGH
FRIDAY NIGHT AND SATURDAY.
&&
.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS WILL CONTINUE THROUGH THE 06Z TAF PERIOD FOR KCHS
AND KSAV. FOR THE FIRST COUPLE HOURS OF THE 06Z TAF CYCLE...THERE
ARE SOME CHANCES THAT MVFR CIGS COULD BRUSH BOTH TERMINALS BUT
CONFIDENCE WAS NOT HIGH ENOUGH FOR PREVAILING OR TEMPO MENTIONS.
EXTENDED AVIATION OUTLOOK...OCCASIONAL MVFR CONDITIONS POSSIBLE
MONDAY THROUGH TUESDAY. IFR OR LOWER CONDITIONS POSSIBLE IN RAIN
TUESDAY NIGHT INTO WEDNESDAY. VFR SHOULD RETURN WEDNESDAY NIGHT OR
THURSDAY.
&&
.MARINE...
A FEISTY LITTLE N SURGE HAS BEEN MOVING DOWN THE COAST THIS MORNING
AND WINDS ALONG THE SOUTH CAROLINA COAST AND ADJACENT TO THE
GEORGIA COAST HAVE BEEN ELEVATED IN THE 15 TO 20 KT RANGE SINCE
MIDNIGHT. N TO NE WINDS WILL CONTINUE TODAY BUT PROBABLY LAY DOWN
A BIT AFTER THE NOCTURNAL/EARLY MORNING SURGE. WE HAVE EXTENDED
OUR SMALL CRAFT ADVISORY FOR GEORGIA WATERS 20-60 NM THROUGH THE
MORNING IN RESPECT TO CURRENT CONDITIONS.
TONIGHT COULD BE REAL TRICKY AS THE COASTAL TROUGH PACKS A GRADIENT
UP ALONG THE SOUTH CAROLINA COAST. THERMAL/MOISTURE GRADIENTS WILL
BE QUITE TIGHT AND WE MAY SEE NNE WINDS SURGE ONCE AGAIN. OUR
FORECAST OF 15G20 KT MAY BECOME CLOSER TO 20 KT AND WILL NEED TO
KEEP AN EYE ON IT. SEAS MAINLY 3-5 FT...WAVEWATCH NOT DEPICTING
THE LOCAL EFFECTS EARLY MON. N WINDS SHOULD GRADUALLY DECREASE IN
THE AFTERNOON WITH SEAS 3 TO 4 FT.
HIGH PRESSURE WILL STRENGTHEN NORTH OF THE WATERS MONDAY NIGHT AND
TUESDAY BEFORE A WARM FRONT LIFTS NORTH TUESDAY NIGHT AND SOUTHERLY
LOW-LEVEL JETTING DEVELOPS. SOLID SMALL CRAFT ADVISORY WINDS WILL BE
POSSIBLE WEDNESDAY INTO THURSDAY ACROSS PORTIONS OF THE WATERS
ASSOCIATED WITH THE SOUTHERLY JETTING AND THEN WITH COLD ADVECTION
BEHIND A FRONTAL PASSAGE WEDNESDAY NIGHT.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...FROST ADVISORY UNTIL 9 AM EST THIS MORNING FOR GAZ118-140.
FREEZE WARNING UNTIL 9 AM EST THIS MORNING FOR GAZ087-099>101-
114>116-137-138.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EST THIS MORNING FOR AMZ374.
&&
$$
JRL
