Area Forecast Discussion
Issued by NWS Charleston, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KCHS 110911
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
411 AM EST THU FEB 11 2016

.SYNOPSIS...
HIGH PRESSURE TODAY WILL GIVE WAY TO A WEAK AREA OF LOW PRESSURE
AND ASSOCIATED COLD FRONT TONIGHT. THIS LOW WILL PULL AWAY FROM
THE REGION ON FRIDAY AND AN ARCTIC COLD FRONT WILL PUSH THROUGH ON
SATURDAY. HIGH PRESSURE WILL THEN REMAIN IN CONTROL UNTIL EARLY
NEXT WEEK WHEN THE NEXT FRONTAL SYSTEM WILL IMPACT THE REGION.
MORE HIGH PRESSURE WILL RETURN THEREAFTER.

&&

.NEAR TERM /THROUGH TONIGHT/...
SURFACE HIGH PRESSURE HAD NESTLED OVER SOUTH GEORGIA EARLY THIS
MORNING WHILE A LINGERING LOW LEVEL PRES GRADIENT HAS KEPT LIGHT
BREEZES STIRRING FROM AREAS NORTH OF I-16 INCLUDING MOST OF SE
SOUTH CAROLINA. SHELTERED TEMPS IN RURAL AREAS TENDING TO RUN
QUITE A BIT COLDER WHILE MORE URBAN AND EXPOSED SITES HAD BEEN
BOUNCING AROUND THE FREEZING MARK OVERNIGHT. CLEAR SKIES AND A
LIGHT WEST BREEZE FOR COASTAL AREAS NEARING DAWN...SOUTHERN AND
INLAND ZONES SHOULD DECOUPLE JUST ENOUGH TO SEE LOW TEMPS OCCUR
DURING THE DAYBREAK HOUR...MANY AREAS SHOULD BE DOWN TO THE MID TO
UPPER 20S.

TODAY A SURFACE HIGH PRES RIDGE WILL BUILD OVER THE FORECAST AREA
BEFORE WEAKENING LATE. TEMPS ARE EXPECTED TO MODERATE FROM THE COLD
READINGS ON WEDNESDAY THAT WERE STUCK IN THE LOWER 40S DURING THE
AFTERNOON MANY AREAS. LOW LEVEL THICKNESS PROGS SUGGEST HIGHS WILL
WARM INTO THE MID AND UPPER 50S TO THE SOUTH OF I-16 IN GEORGIA TO
AROUND 50 DEGREES AROUND THE SANTEE COOPER LAKES REGION. A WEAK
DOWNSLOPE COMPONENT MAY PUSH HIGHS AT CHARLESTON TO 52-53 DEGREES
WHILE SAVANNAH LIKELY REACHES THE MID 50S. THE BIGGER FACTOR
WILL BE MUCH LESS WIND THAN YESTERDAY WITH SPEEDS AVERAGING ONLY
AROUND 10 MPH. SUNSHINE MAY BE PUNCTUATED BY A FEW MID/HIGH CLOUDS
LATER IN THE DAY BUT NOT ENOUGH TO ALTER A MAINLY SUNNY FORECAST.

TONIGHT A CHANNELED VORT WILL DROP INTO THE CAROLINAS AND SPUR A
SERIES OF WEAK SURFACE WAVES THAT WILL TRAVERSE A POORLY DEFINED
BAROCLINIC REGION ACROSS THE SE STATES. MOISTURE WILL INCREASE
BELOW 10K FT RESULTING IN AN EXPANSION OF CLOUDINESS OVER THE
REGION OVERNIGHT BUT WITH 00Z MODELS PAINTING HIGH 850 MB TO 500
MB CONDENSATION PRES DEFICITS...WE MAINTAINED A DRY FORECAST
TONIGHT ALTHOUGH A FEW BRIEF SPRINKLES LATE CANNOT BE RULED OUT.
THE INCREASE IN CLOUDS AND LOW LEVEL DEW POINTS SHOULD SPELL OUT A
MILDER OVERNIGHT...TEMPS THIS EVENING MAY BE TRICKY DEPENDING ON
WHAT TIME CLOUDS INCREASE. WE GRADUATED LOWS FROM THE MID 30S N TO
THE LOWER 40S S.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
FRIDAY AND FRIDAY NIGHT...THE FORECAST AREA WILL REMAIN WELL WITHIN
THE COLD TROUGH ALOFT. THE MORNING WILL START OFF WITH A WEAK AREA
OF LOW PRESSURE SITUATED JUST OFF THE COAST AND POISED TO PULL AWAY
FROM THE AREA INTO THE AFTERNOON. THE FIRST HALF OF THE DAY WILL
BRING MOSTLY CLOUDY SKIES BEFORE CLEARING OUT IN THE AFTERNOON AS
DRIER AIR MOVES IN QUICKLY BEHIND THE DEPARTING SYSTEM. MODELS ARE
IN PRETTY GOOD AGREEMENT THAT ALMOST ALL OF THE PRECIPITATION
ASSOCIATED WITH THE SYSTEM WILL STAY JUST OFFSHORE...THOUGH THERE IS
SOME VERY LIGHT QPF IN THE MORNING. THE FORECAST MAINTAINS THE FEW
HOURS OF SLIGHT CHANCE POP ACROSS EASTERN BERKELEY AND CHARLESTON
COUNTIES...BUT LITTLE TO NO MEASURABLE RAINFALL IS EXPECTED.
TEMPERATURES WILL DEPEND GREATLY ON HOW QUICKLY CLOUDS ERODE AND
INSOLATION CAN BEGIN. CLOUDS WILL LIKELY HANG ON IN THE EAST THE
LONGEST SO WE MAY END UP WITH QUITE A TEMPERATURE GRADIENT. THE
FORECAST FEATURES HIGHS FROM THE MID 60S ALONG THE ALTAMAHA TO THE
LOW TO MID 50S FOR THE FAR EASTERN ZONES. OVERNIGHT...HIGH PRESSURE
WILL BEGIN TO BUILD IN AND COLD NORTHWEST FLOW WILL PREVAIL. LOWS
WILL DIP INTO THE MID TO UPPER 30S INLAND...WITH LOW 40S AT THE
COAST.

SATURDAY THROUGH SUNDAY...THE WEEKEND WILL BE DEFINED BY A STRONG
ARCTIC COLD FRONT POISED TO CROSS THE REGION FROM THE
NORTH/NORTHWEST LATE SATURDAY AND SATURDAY NIGHT. THE RESULT WILL BE
A VERY COLD WEEKEND. AHEAD OF THE FRONT...SATURDAY HIGHS WILL RANGE
FROM AROUND 50 TO THE LOW/MID 50S ACROSS SOUTHEAST GEORGIA. SATURDAY
NIGHT WILL BE A COLD AND BLUSTERY NIGHT WITH LOWS DIPPING INTO THE
LOW 20S IN MANY AREAS...WITH MID TO UPPER 20S COMMON. WITH ELEVATED
WINDS SUNDAY MORNING...WIND CHILL VALUES WILL FALL INTO AT LEAST THE
LOW TO MID TEENS NORTH OF I-16 WITH UPPER TEENS TO LOW 20S FURTHER
SOUTH. A WIND CHILL ADVISORY MAY BE NEEDED AND WE WILL MAINTAIN THE
MENTION IN THE HAZARDOUS WEATHER OUTLOOK. FINALLY FOR SUNDAY...HIGHS
WILL BE 20 DEGREES OR MORE BELOW NORMAL. TEMPERATURES WILL STRUGGLE
TO REACH 40 AROUND THE CHARLESTON AREA...WITH MID 40S AROUND
SAVANNAH AND POINTS SOUTH.

LAKE WINDS...ANOTHER ROUND OF STRONG WINDS WILL BE POSSIBLE OVER
LAKE MOULTRIE LATE SATURDAY INTO SUNDAY. A LAKE WIND ADVISORY COULD
EVENTUALLY BE NEEDED.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
MODEL AGREEMENT REMAINS GOOD REGARDING THE MAIN FORECAST IN THE LONG
TERM WHICH IS SYSTEM EXPECTED TO PUSH THROUGH LATE MONDAY THROUGH
EARLY TUESDAY. THE PERIOD WILL START OFF WITH HIGH PRESSURE OVER NEW
ENGLAND AND A STRENGTHENING WEDGE INLAND AND A SHARPENING COASTAL
TROUGH OFFSHORE. LOW PRESSURE IS PROGGED TO MOVE INLAND THROUGH
CENTRAL GEORGIA AND THE CAROLINAS MONDAY NIGHT. THE BEST TIME PERIOD
FOR RAINFALL LOOKS TO BE DURING THIS TIME AS THE DEEP MOISTURE
ASSOCIATED WITH THE SYSTEM DOES NOT PRECEDE IT BY MUCH. MODEL
AGREEMENT IS GOOD ENOUGH TO GO WITH LIKELY POPS...THOUGH IT
SHOULDN/T BE A LONG DURATION EVEN THANKS TO THE PROGRESSIVE NATURE
OF THE MID/UPPER LEVEL TROUGH. BEHIND THIS SYSTEM...DRY HIGH PRESSURE
WILL RETURN. TEMPERATURES LOOK AS THOUGH THEY WILL MODERATE THROUGH
THE PERIOD...STARTING OFF BELOW NORMAL MONDAY WITHIN THE
WEDGE...THEN INCREASING THEREAFTER TO NEAR NORMAL BY MID WEEK.

&&

.AVIATION /09Z THURSDAY THROUGH MONDAY/...
VFR AT KCHS/KSAV THROUGH 06Z FRIDAY.

EXTENDED AVIATION OUTLOOK...A BRIEF PERIOD OF MVFR CEILINGS IS
POSSIBLE FRIDAY AFTERNOON AND EVENING AS A COLD FRONT MOVES
THROUGH.

&&

.MARINE...
AT 330 AM EST WE LOWERED ADVISORIES FOR NEAR SHORE WATERS SOUTH
OF EDISTO BEACH AND EXPECT THE OUTER FRINGES OF THE NEAR SHORE
CHARLESTON WATERS WILL BE READY TO COME DOWN BY DAYBREAK AS WILL
THE OFFSHORE GEORGIA WATERS.

THIS MORNING...OFFSHORE FLOW WILL CONTINUE TO DIMINISH AS A SURFACE
RIDGE BUILDS OVER THE WATERS RELAXING THE PRES GRADIENTS. W FLOW
WILL FALL BELOW 10 KT LATER THIS MORNING THEN THE FLOW SHOULD BECOME
LIGHT AND VARIABLE BY THIS EVENING. SEAS WILL FALL TO 2 FT OR LESS
OVER THE NEAR SHORE WATERS DURING THE AFTERNOON.

WEAK LOW PRES WILL SHIFT INTO THE WATERS BY DAWN ON FRIDAY...THE
FLOW SHOULD REMAIN MOSTLY LIGHT AND CHAOTIC AS THIS FEATURE
APPROACHES OVERNIGHT. WARM AIR ADVECTION WILL RE-ESTABLISH A
STRONGER LOW LEVEL INVERSION TONIGHT BUT AN INCREASING SW JET
OVER WARMER OUTER GEORGIA WATERS CLOSER TO THE GULF STREAM SHOULD
INCITE AN UPTICK IN SW FLOW BEYOND 40 NM OFFSHORE BUT WINDS AND
SEAS LIKELY WILL REMAIN BELOW SMALL CRAFT ADVISORY LEVELS.

FRIDAY THROUGH MONDAY...A WEAK AREA OF LOW PRESSURE WILL PULL AWAY
FROM THE LOCAL WATERS ON FRIDAY AND COULD LEAD TO A SHORT PERIOD OF
NEAR SMALL CRAFT ADVISORY WINDS ACROSS THE OUTER GEORGIA WATERS.
BEHIND THIS SYSTEM...A STRONG ARCTIC COLD FRONT WILL PUSH THROUGH
SATURDAY NIGHT AND HIGH PRESSURE TO THE NORTH WILL RESULT IN A
PERSISTENT NORTHEAST FLOW THROUGH THE REMAINDER OF THE WEEKEND. THE
SURGE BEHIND THE FRONT SATURDAY NIGHT WILL RESULT IN SOLID SMALL
CRAFT ADVISORY CONDITIONS ACROSS ALL WATERS WHICH WILL CONTINUE
THROUGH AT LEAST SUNDAY MORNING. OTHERWISE...CONDITIONS SHOULD
IMPROVE INTO MONDAY WHEN A COASTAL TROUGH WILL DEVELOP AND
EVENTUALLY LIFT NORTHWARD AHEAD OF AN APPROACHING LOW PRESSURE
SYSTEM.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST THIS MORNING FOR AMZ350-
     374.

&&

$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...BSH
LONG TERM...BSH
AVIATION...
MARINE...BSH


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.