FXUS62 KCHS 110912
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
412 AM EST SAT FEB 11 2012

...DANGEROUS FIRE WEATHER CONDITIONS TODAY...
...ARCTIC AIR POISED TO MAKE A BRIEF RETURN TO THE LOWCOUNTRY AND
COASTAL EMPIRE...

.SYNOPSIS...
AN ARCTIC COLD FRONT WILL PUSH ACROSS THE REGION TODAY. COLD HIGH
PRESSURE WILL BUILD FROM THE WEST AND SHIFT ACROSS THE AREA
THROUGH EARLY NEXT WEEK. AN UNSETTLED PATTERN WILL DEVELOP BY MID
WEEK...WITH SEVERAL WAVES OF LOW PRESSURE IMPACTING THE REGION
THROUGH THE LATE WEEK PERIOD.

&&

.NEAR TERM /THROUGH TODAY/...
THE INITIAL COLD FRONT HAS PUSHED WELL OFFSHORE. LINGERING 
SHOWERS OVER THE COASTAL WATERS ARE STEADILY DIMINISHING IN AREAL
COVERAGE AND WILL EXIT THE OFFSHORE MARINE ZONES WITHIN THE NEXT
HOUR. 11/08Z SURFACE OBSERVATIONS SHOWED THE ARCTIC COLD FRONT 
MOVING RAPIDLY ACROSS CENTRAL TENNESSEE AND NORTHERN ALABAMA AS
ITS SUPPORTING UPPER TROUGH DIGS ACROSS THE OHIO VALLEY. THE
FRONT IS ON TARGET TO PUSH ACROSS SOUTHEAST SOUTH CAROLINA AND
SOUTHEAST GEORGIA LATER TODAY WITH A SECONDARY/STRONGER SURGE OF
COLD AIR DRIVING SOUTH TONIGHT. THE ARCTIC FRONT WILL USHER IN
CONSIDERABLY COLDER AND DRIER AIR INTO THE REGION WHICH WILL
LINGER THROUGH MONDAY MORNING.

EXTENSIVE CLOUD COVER IN PLACE EARLY THIS MORNING WILL STEADILY
THIN AND CLEAR AFTER SUNRISE AS LOW/MID-LEVEL TRAJECTORIES BECOME
DOWNSLOPE DOMINATED. THERE ARE SOME INDICATIONS A LITTLE MORE IN
THE WAY OF CLOUDS COULD LINGER ACROSS THE CHARLESTON TRI- COUNTY
AREA INTO THE EARLY AFTERNOON HOURS...BUT GENERALLY EXPECT SUNNY
TO MOSTLY SUNNY SKIES TO DOMINATE. IMPRESSIVE COLD AIR ADVECTION
WILL ENSUE LATER THIS MORNING AS THE ARCTIC COLD FRONT PUSHES
OFFSHORE. THIS WILL HAVE A SIGNIFICANT IMPACT ON HIGH TEMPERATURES
AS H8 TEMPERATURES ARE FORECAST TO PLUMMET TO -7 TO -10C BY LATE
AFTERNOON. EXPECT TEMPERATURES TO PEAK BY LATE MORNING INTO EARLY
AFTERNOON WITH READINGS FALLING STEADILY THEREAFTER. HIGHS WILL
RANGE FROM THE MID 50S ACROSS FAR INTERIOR SOUTHEAST GEORGIA TO
THE UPPER 50S IN THE CHARLESTON-BEAUFORT-SAVANNAH-DARIEN CORRIDOR
WITH TEMPERATURES FALLING INTO THE MID-UPPER 40S INLAND TO LOWER
50S COAST BY LATE AFTERNOON.

IT WILL BE RATHER BREEZY TODAY AS COLD AIR ADVECTION INITIATES AND
THE PRESSURE GRADIENT TIGHTENS IN THE WAKE OF THE ARCTIC FRONT.
WINDS SHOULD REMAIN IN THE 15-25 MPH RANGE WITH GUSTS AS HIGH AS
35 MPH...BUT THERE IS A CHANCE WINDS COULD APPROACH WIND ADVISORY
CRITERIA ACROSS INTERIOR SOUTHEAST GEORGIA.

LAKE WINDS...WINDS WILL BEGIN TO PICK UP ON LAKE MOULTRIE LATER
THIS MORNING AS COLD AIR ADVECTION INITIATES IN THE WAKE OF AN
ARCTIC COLD FRONT. LOOKS LIKE WINDS WILL REACH SOLIDLY WITHIN
ADVISORY THRESHOLDS TODAY SO THE GOING LAKE WIND ADVISORY IS ON
TRACK. WAVES WILL BUILD 1 TO 2 FEET...HIGHEST EAST SECTIONS OF THE
LAKE. 

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...
A BITTERLY COLD NIGHT IS IN STORE FOR SOUTHEAST SOUTH CAROLINA AND
SOUTHEAST GEORGIA AS ARCTIC HIGH PRESSURE SETTLES INTO THE REGION.
ONGOING COLD AIR ADVECTION WILL HELP PUSH LOW TEMPERATURES WELL
INTO THE 20S ALL THE WAY INTO THE COASTAL WATERS RESULTING IN A
HARD FREEZE ALL AREAS. LOWS WILL RANGE FROM THE LOWER 20S WELL
INLAND TO THE MID-UPPER 20S AT THE BEACHES. THESE TEMPERATURES
WILL RESULT IN DAMAGE TO SENSITIVE/TENDER VEGETATION THAT HAS
ALREADY BEGUN TO GROW AS A RESULT OF THE UNUSUALLY WARM WINTER SO
FAR AND THE TYPICAL COLD WEATHER SAFETY PRECAUTIONS SHOULD BE
TAKEN. STIFF NORTHWEST WINDS WILL ALSO PUSH WIND CHILLS INTO THE
12-18 DEGREE RANGE EARLY SUNDAY WHICH WILL ONLY FURTHER
EXACERBATE THE COLD. ATTM IT APPEARS THE RECORD LOWS AT ALL THREE
CLIMATE SITES WILL NOT BE BREACHED...ALTHOUGH IT COULD COME VERY
CLOSE IN DOWNTOWN CHARLESTON WHERE THE RECORD IS 22 DEGREES.

SUNDAY WILL BE THE COLDEST DAY OF THE PERIOD...AS BROAD CANADIAN
HIGH PRESSURE STEADILY SHIFTS INTO THE SOUTHEAST STATES. DESPITE
ABUNDANT SUNSHINE...TEMPERATURES WILL REMAIN SUPPRESSED IN THE
UPPER 40S TO AROUND 50 DEGREES DURING THE AFTERNOON HOURS.
THE LOW LEVEL JET WILL BE EXITING TO THE NORTHEAST ON
SUNDAY...AND DO NOT EXPECT WINDS TO BECOME AS BREEZY AS SATURDAY.
HOWEVER...SUCH COLD TEMPERATURES COMBINED WITH 10 TO 15 MPH WINDS
WILL STILL SUPPORT WIND CHILLS IN THE LOWER 40S BY MID AFTERNOON.
LOW TEMPERATURES SUNDAY NIGHT WILL AGAIN FALL WELL BELOW SEASONAL
NORMALS...AS RADIATIONAL COOLING BECOMES QUITE EFFICIENT UNDER
LIGHT WINDS AND CLEAR SKIES. EXPECT TEMPERATURES TO REACH THE 20
DEGREE RANGE EVEN TOWARD THE COASTLINE.

MONDAY...THE SURFACE HIGH WILL STEADILY DRIFT TOWARD THE COASTLINE
AND INTO THE ATLANTIC WATERS ON MONDAY...AHEAD OF RAPIDLY
APPROACHING SHORTWAVE ENERGY WITHIN NEARLY ZONAL FLOW ALOFT. WILL
INDICATE A WARMING TREND ON MONDAY...AS LIGHT WINDS SHIFT AROUND
TO THE SOUTH AND HEIGHTS ALOFT RISE SLIGHTLY. HIGH TEMPERATURES
WILL REACH THE MID TO UPPER 50S...WITH LOWS MONDAY NIGHT IN THE 30
DEGREE RANGE. ALTHOUGH THE SHORTWAVE ENERGY AND AN ASSOCIATED
SURFACE WAVE WILL BE JUST TO THE WEST/SOUTHWEST BY DAYBREAK
TUESDAY...PREFER TO INDICATE JUST INCREASING CLOUDS AND CAP POPS
BELOW 15 PERCENT THROUGH MONDAY.

TUESDAY...THE FORECAST AREA WILL FALL WITHIN THE WARM SECTOR OF A
DEVELOPING WAVE OF LOW PRESSURE APPROACHING FROM THE NORTHERN GULF
OF MEXICO ON TUESDAY. THIS WILL CONTINUE THE WARMING TREND INTO
THE EARLY WEEK PERIOD...AS HIGH TEMPERATURES ON TUESDAY AFTERNOON
WILL REACH THE UPPER 50S TO LOWER 60S WITHIN INCREASING SOUTHERLY
FLOW. ALTHOUGH THE TRACK AND STRENGTH OF THE SURFACE WAVE IS
HANDLED A BIT DIFFERENTLY BETWEEN THE MODELS...THERE IS DECENT
AGREEMENT THAT STRONG WARM ADVECTION AND SOUTH/SOUTHWEST FLOW WILL
TAP INTO ENOUGH GULF MOISTURE TO SUPPORT A CHANCE FOR SHOWERS ON
TUESDAY. 

LAKE WINDS...WINDS AND WAVES WILL PEAK TONIGHT AS THE MOST INTENSE 
COLD AIR ADVECTION PASSES THROUGH. LOW-LEVEL WIND FIELDS SUPPORT
WINDS AS HIGH AS 20-25 KNOTS...ALTHOUGH THERE MAY BE A FEW HOURS
WITH SPEEDS AS HIGH AS 25-30 KNOTS. WAVES WILL BUILD AS HIGH AS
2-4 FT WITH THE HIGHEST WAVES OCCURRING ALONG THE EASTERN SECTIONS
OF LAKE MOULTRIE.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
THE SURFACE WAVE AND ASSOCIATED WEAK FRONT WILL SHIFT OFF THE
COAST LATE TUESDAY NIGHT/EARLY WEDNESDAY....FOLLOWED BY TRANSIENT
SURFACE HIGH PRESSURE. UPPER LEVEL FLOW WILL REMAIN NEARLY ZONAL
BEHIND THE SYSTEM...BEFORE GRADUALLY TRANSITIONING INTO A NOTABLE
RIDGE ALOFT BY WEDNESDAY. THIS PATTERN WILL SUPPORT A CONTINUED
WARMING TREND INTO THE LATE WEEK PERIOD...WITH HIGH TEMPERATURES
REACHING THE UPPER 60S TO NEAR 70 DEGREES EACH DAY.

THE NEXT SYSTEM TO IMPACT THE AREA WILL APPROACH FROM THE WEST
THURSDAY THROUGH FRIDAY. MEDIUM RANGE FORECAST MODELS ARE
INDICATING SOME RAIN POTENTIAL AS THE FRONT CROSSES THE FORECAST
AREA LATE WEEK. PREFER TO REMAIN RATHER GENERIC WITH POPS DUE TO
TIMING UNCERTAINTIES THIS FAR OUT...AND JUST HIGHLIGHT BEST RAIN
CHANCES AROUND 30 PERCENT THURSDAY NIGHT UNTIL BETTER MODEL
CONSENSUS IS SEEN.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
VFR FOR THE NEXT 24 HOURS. INCOMING SHOWER ACTIVITY ON KCLX IS NOT
REACHING THE GROUND TO ANY SIGNIFICANCE. GUSTY WINDS WILL DEVELOP
CLOSER TO SUNRISE AND WILL PEAK THIS AFTERNOON WITH SUSTAINED
WINDS NEAR 20 KT AND GUSTS NEAR 30 KT. GUSTY WINDS WILL PERSIST
INTO THIS EVENING IN A STRONG COLD AIR ADVECTION REGIME.

EXTENDED AVIATION OUTLOOK...SHOWER POTENTIAL ASSOCIATED WITH A
FRONTAL SYSTEM TUESDAY COULD RESULT IN REDUCED CEILINGS AND
VISIBILITIES.

&&

.MARINE...
DANGEROUS MARINE CONDITIONS WILL DEVELOP ACROSS THE COASTAL WATERS
TODAY AND PEAK TONIGHT AS ARCTIC HIGH PRESSURE BUILDS IN FROM THE
WEST. THE ONSET OF STRONG COLD AIR ADVECTION LATER THIS MORNING
WILL RESULT IN A RATHER ABRUPT INCREASE IN WINDS WITH BOTH WINDS
AND SEAS PEAKING TONIGHT AS THE MOST INTENSE COLD AIR ADVECTION
OCCURS. NAM/GFS BOUNDARY LAYER WIND GUIDANCE SHOWS A POTENTIAL FOR
AT LEAST FREQUENT GUSTS TO 35 KT GALES ACROSS THE NEARSHORE WATERS
WITH SUSTAINED GALES OF 30-40 KT LIKELY OVER THE GEORGIA OFFSHORE
LEG WHERE WATER TEMPERATURES ARE THE WARMEST. MMG GUIDANCE FOR
SPAG1 AND SPKG1 SHOW WINDS NEAR 40 KT FOR SEVERAL HOURS THIS
EVENING WHICH SEEMS REASONABLE. PLAN TO HOIST GALE WARNINGS FOR
ALL ZONES WITH THE EXCEPTION OF THE CHARLESTON HARBOR PER
COORDINATION WITH THE OCEAN PREDICTION CENTER AS WELL AS WFO/S
JACKSONVILLE AND WILMINGTON. THERE IS CERTAINLY A POTENTIAL FOR
WIND GUSTS TO REACH GALE WARNING CRITERIA IN THE CHARLESTON
HARBOR...BUT THE RISK LOOKS TOO LOW TO JUSTIFY A GALE WARNING
ATTM.

SEAS WILL PEAK 3-6 FT NEARSHORE WATERS WITH 7-12 FEET OVER THE
GEORGIA OFFSHORE LEG. WAVES IN THE CHARLESTON HARBOR COULD REACH
AS HIGH AS 3 FEET AT TIMES...ESPECIALLY NEAR THE HARBOR ENTRANCE.
BLOW OUT TIDES NEAR -1.0 TO -1.5 FT MLLW COULD OCCUR WITH THE LOW
TIDE EARLY SUNDAY MORNING.

SUNDAY THROUGH WEDNESDAY...MARINE CONDITIONS WILL GRADUALLY
IMPROVE AS THE DAY PROGRESSES ON SUNDAY...AS COLD ADVECTION
DIMINISHES AND THE PRESSURE GRADIENT WEAKENS UNDER BUILDING HIGH
PRESSURE. WINDS AND WAVES ARE EXPECTED TO DROP BELOW SMALL CRAFT
ADVISORY CONDITIONS BY MIDDAY SUNDAY FOR THE NEARSHORE
WATERS...WHILE ELEVATED SEAS COULD KEEP THE OUTER WATERS WITHIN
CRITERIA FOR A FEW HOURS INTO THE LATE AFTERNOON/EARLY EVENING.
CONDITIONS WILL CONTINUE TO IMPROVE SUNDAY NIGHT THROUGH MONDAY
NIGHT WITH THE CENTER OF THE SURFACE HIGH TRACKING INTO THE
ATLANTIC AND MAINTAINING A WEAK PRESSURE GRADIENT. ALTHOUGH THE
WEATHER PATTERN BECOMES A BIT MORE UNSETTLED BY MID WEEK...MARINE
CONDITIONS LOOK TO REMAIN BELOW ADVISORY CRITERIA THROUGH THE
REMAINDER OF THE PERIOD. 

&&

.FIRE WEATHER...
THE COMBINATION OF INCREASING WINDS...LOW HUMIDITY...DRY FUELS AND
ONGOING EXCEPTIONAL DROUGHT CONDITIONS WILL SUPPORT A POTENTIALLY 
DANGEROUS FIRE WEATHER SITUATION TODAY. INCREASING COLD AIR
ADVECTION IN THE WAKE OF AN ARCTIC COLD FRONT AND THE RESULTING
FALLING TEMPERATURES THIS AFTERNOON COULD TEMPER RELATIVE
HUMIDITY VALUES SOMEWHAT...HOWEVER ITS STILL APPEARS MINIMUM
VALUES OF 22-25 PERCENT WILL OCCUR COINCIDENT WITH NORTHWEST WINDS
OF 15-25 MPH. WIND GUSTS COULD APPROACH 30-35 MPH AT TIMES. GIVEN
THE FAVORABLE FIRE WEATHER PARAMETERS THAT WILL BE IN PLACE...THE
FIRE WEATHER WATCH WILL BE UPGRADED TO A RED FLAG WARNING FOR ALL
FIRE ZONES. THE WARNING WILL RUN FROM NOON UNTIL 8 PM THIS
EVENING.

SOME RH RECOVERY WILL OCCUR TONIGHT...BUT VALUES WILL GENERALLY
REMAIN 50 PERCENT OR LESS THROUGH SUNRISE SUNDAY. WINDS WILL
ALSO REMAIN ELEVATED AND GUSTY THROUGH MUCH OF THE OVERNIGHT PERIOD.

EVEN LOWER HUMIDITY VALUES ARE EXPECTED FOR SUNDAY AS ARCTIC HIGH
PRESSURE HOLDS FIRM. THERE WILL BE CONSIDERABLY LESS WIND...BUT
WITH DRY FUELS AND ONGOING DROUGHT CONDITIONS AN ELEVATED
FIRE DANGER WILL CONTINUE. ALTHOUGH RED FLAG CRITERIA WILL NOT BE
MET GIVEN THE LACK OF WINDS...A FIRE DANGER STATEMENT MAY BE
NEEDED AFTER COORDINATION WITH STATE/FEDERAL LAND MANAGERS LATER
TODAY.

&&

.CLIMATE...
RECORD LOWS FOR SUNDAY FEBRUARY 12...
CHARLESTON AIRPORT.... 12/1973
DOWNTOWN CHARLESTON... 22/1955
SAVANNAH AIRPORT...... 19/1973

RECORD LOWS FOR MONDAY FEBRUARY 13...
CHARLESTON AIRPORT.... 22/1955
DOWNTOWN CHARLESTON...  9/1899
SAVANNAH AIRPORT......  8/1899

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...RED FLAG WARNING FROM NOON TODAY TO 8 PM EST THIS EVENING FOR 
     GAZ087-088-099>101-114>119-137>141.
SC...RED FLAG WARNING FROM NOON TODAY TO 8 PM EST THIS EVENING FOR 
     SCZ040-042>045-047>051.
     LAKE WIND ADVISORY FROM 11 AM THIS MORNING TO 5 AM EST SUNDAY 
     FOR SCZ045.
MARINE...GALE WARNING UNTIL 5 AM EST SUNDAY FOR AMZ350-352-354.
     GALE WARNING UNTIL 11 AM EST SUNDAY FOR AMZ374.
     SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 5 AM EST 
     SUNDAY FOR AMZ330.

&&

$$