Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 081142
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
642 AM EST MON FEB 8 2016

.SYNOPSIS...
A SERIES OF REINFORCING COLD FRONTS WILL CROSS THE REGION THROUGH
MID WEEK. HIGH PRESSURE THURSDAY WILL GIVE WAY TO AN ARCTIC COLD
FRONT LATE IN THE WEEK...WHICH COULD BRING SOME OF OUR COLDEST
WEATHER OF THE SEASON INTO EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
TODAY...SHORTWAVE RIDGING WILL RIPPLE TO THE EAST AND OFF THE COAST
THIS MORNING AHEAD OF AN AMPLIFYING UPPER TROUGH THAT WILL CONTINUE
TO DIVE SOUTHEASTWARD AND CARVE OUT ACROSS MUCH OF THE EASTERN
CONUS. THIS WILL PUSH A WEAK AREA OF LOW PRESSURE AND A STRONG COLD
FRONT ACROSS THE SOUTHERN APPALACHIANS AND INTO THE FORECAST AREA
THIS AFTERNOON. DRY AIR AHEAD OF THE FRONT WILL RESULT IN CLEAR
SKIES FOR MUCH OF THE DAY. THEN AS THE FRONT APPROACHES AND
CROSSES...A RIBBON OF MOISTURE WILL BRING A BAND OF LOW AND MID
LEVEL CLOUDS AS WELL AS ISOLATED TO SCATTERED SHOWERS. THOUGH THE
MOISTURE IS RATHER NARROW THERE SHOULD BE ENOUGH FORCING ALOFT WITH
PVA AND CONVERGENCE ALONG THE FRONT TO SUPPORT LIGHT SHOWERS. POPS
HAVE BEEN MAINTAINED IN THE CHANCE RANGE AT THEIR HIGHEST AS
COVERAGE WILL BE SCATTERED AT BEST WITH RAINFALL AMOUNTS EXPECTED TO
BE NO MORE THAN A FEW HUNDREDTHS OF AN INCH. PLENTIFUL SUNSHINE AND
SOME COMPRESSIONAL HEATING AHEAD OF THE FRONT WILL ALLOW
TEMPERATURES TO RISE TO NEAR 60 OR THE LOW 60S ACROSS THE FORECAST
AREA. ALSO...THE TIGHTENING PRESSURE GRADIENT AND EXCELLENT MIXING
PROFILES WILL RESULT IN WEST-SOUTHWEST WINDS GUSTING INTO THE 25-30
MPH RANGE THIS AFTERNOON.

TONIGHT...THE DEEP TROUGH AXIS WILL SETTLE OVERHEAD AND THE COLD
FRONT WILL MOVE OFFSHORE. A FEW SHOWERS MAY LINGER IN THE EVENING
ALONG THE COAST AND ADJACENT COASTAL WATERS...BUT OVERALL RAINFALL
CHANCES WILL BE ON THE DECREASE. THE BAND OF THICKER CLOUDS ALONG
THE FRONT WILL SHIFT OFFSHORE AND MAINLY SCATTERED CLOUDS WILL
LINGER THROUGH THE NIGHT. WINDS WILL REMAIN ELEVATED THROUGH THE
NIGHT IN THE COLD ADVECTION...CONSISTENTLY IN THE 15-20 MPH
RANGE...SO IT WILL DEFINITELY NOT BE A RADIATIONAL COOLING NIGHT. AS
THE MUCH COLDER AIR RUSHES IN...LOWS WILL FALL INTO THE LOW 30S AWAY
FROM THE BEACHES.

LAKE WINDS...A STRONG COLD FRONT WILL PUSH ACROSS LAKE MOULTRIE THIS
EVENING AND WINDS WILL INCREASE BEHIND THE FRONT THROUGH THE
OVERNIGHT. FREQUENT GUSTS TO 25 KNOTS COULD OCCUR AND A LAKE WIND
ADVISORY MAY EVENTUALLY BE NEEDED.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
TUESDAY THROUGH WEDNESDAY...A BROAD AND DEEP LAYERED TROUGH WILL
EVOLVE OVER THE EASTERN STATES WHILE OCCASIONAL WEAK COLD FRONTS
AND/OR SURFACE TROUGHS PASS THROUGH THE AREA WITHIN DEEP WESTERLY
FLOW THROUGHOUT THE ATMOSPHERE. THESE FRONTS/TROUGHS WILL HAVE
LITTLE MOISTURE TO WORK WITH...BUT WITH SOME PERTURBATIONS ALOFT ON
TUESDAY AND LOW LEVEL CONFLUENCE THERE MIGHT BE A FEW SPRINKLES IN
SPOTS. OTHERWISE THE WEATHER PATTERN IS ONE THAT FEATURES A
CONTINUED SUPPLY OF COLD CANADIAN AIR...WITH DEEP MIXING AND A TIGHT
PRESSURE PATTERN TO RESULT IN BREEZY TO WINDY CONDITIONS INTO MID
WEEK.

TEMPS BOTH TUESDAY AND WEDNESDAY WILL BE SIMILAR AND AROUND 12-15F
BELOW NORMAL GIVEN 850 MB TEMPS THAT AREA AS COLD AS -8 TO -9C.
TUESDAY NIGHT WILL BE COLD WITH A FREEZE EVERYWHERE INLAND FROM THE
INTRA-COASTAL...BUT IT/LL BE EVEN COLDER WEDNESDAY NIGHT WITH A HARD
FREEZE TO OCCUR WEST OF US-17 AND FREEZING TEMPS ALL THE WAY TO THE
BEACHES.

WINDS WILL PEAK AT 20-30 MPH WITH GUSTS NEAR 35 MPH BOTH TUESDAY AND
WEDNESDAY...PROBABLY JUST SHORT OF WIND ADVISORY THRESHOLDS. THERE
IS ENOUGH WIND BOTH TUESDAY NIGHT AND WEDNESDAY NIGHT TO GENERATE
WIND CHILLS DOWN IN THE UPPER TEENS/LOWER 20S TUESDAY NIGHT AND INTO
THE TEENS MOST COMMUNITIES WEDNESDAY NIGHT. THIS MIGHT COULD
POTENTIALLY LEAD TO A WIND CHILL ADVISORY FOR PARTS OF THE AREA.

FOR THURSDAY THE LARGE SCALE TROUGH IN THE EAST LIFTS INTO THE
ATLANTIC WITH DECENT HEIGHT RISES AND SOME WARM ADVECTION. BUT GIVEN
THE BITTERLY COLD START TO THE DAY OUR MAX TEMPS WON/T BE TOO MUCH
DIFFERENT THAN THE PREVIOUS TWO DAYS...AND AGAIN WELL BELOW NORMAL.

LAKE WINDS...COLDER AIR MOVING ATOP THE RELATIVELY WARMER WATERS OF
LAKE MOULTRIE WILL LIKELY BE STRONG ENOUGH TO RESULT IN A LAKE WIND
ADVISORY TUESDAY AND AGAIN ON WEDNESDAY.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
A QUASI-ZONAL FLOW WILL PREVAIL ALOFT INTO FRIDAY BEFORE AN
ANOMALOUS EASTERN TROUGH RE-ESTABLISHES ITSELF THIS WEEKEND. WE
GET A BREAK FROM THE COLDER WEATHER FRIDAY IN ADVANCE OF AN ARCTIC
COLD FRONT THAT SWEEPS THROUGH LATE IN THE WEEK AND OPENS THE DOOR
FOR A PENETRATION OF WHAT MAY TURN OUT TO BE OUR COLDEST AIR OF
THE SEASON FOR EARLY NEXT WEEK.

PRECIP CHANCES ARE SLIM IN ADVANCE OF THE ARCTIC FRONT LATE IN THE
WEEK...AND FOR NOW IT LOOKS TO BE LIQUID RATHER THAN ANYTHING ELSE.
OTHERWISE IT/S DRY THROUGH THE BULK OF THE EXTENDED PERIODS.

AT PRESENT THE CONSENSUS OF THE GUIDANCE IS THAT 850 MB TEMPS WILL
PLUNGE TO AS COLD AS -6 TO -10C SATURDAY...-10 TO -14C SUNDAY AS A
1040 MB OR GREATER HIGH BUILDS OUT OF THE NORTHERN GREAT PLAINS. OUR
FORECAST MIGHT NOT BE COLD ENOUGH...BUT FOR NOW WE HAVE TEMPS AS
MUCH AS 15-20F BELOW NORMAL AND NIGHT TIME LOWS AS MUCH AS 10-15GF
BELOW SEASONAL LEVELS.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
VFR AT KSAV AND KCHS THROUGH 12Z TUESDAY.

SW AND WEST WINDS WILL BECOME STRONGER AND QUITE GUSTY LATE THIS
MORNING INTO TONIGHT...WITH THE HIGHEST WINDS REACH AROUND 25-30
KT IN ADVANCE OF A COLD FRONT THAT MOVES THROUGH THIS EVENING.
THERE COULD BE A FEW SHOWERS AT EITHER OR BOTH AIRFIELDS WITH THE
FRONT...BUT NO REDUCTIONS IN VISIBILITY WILL OCCUR.

EXTENDED AVIATION OUTLOOK...VFR CONDITIONS WILL PREVAIL.

&&

.MARINE...
TODAY...WINDS AND SEAS HAVE DIMINISHED ACROSS THE LOCAL WATERS AS
THE DEEP CYCLONE PULLS AWAY TO THE NORTHEAST. THIS IMPROVEMENT WILL
BE TEMPORARY HOWEVER AS A STRONG COLD FRONT APPROACHES THE REGION
FROM THE NORTHWEST TODAY. THE PRESSURE GRADIENT WILL TIGHTEN AHEAD
OF THE FRONT AND WEST-SOUTHWEST WINDS WILL RAMP BACK UP INTO THE
SMALL CRAFT ADVISORY RANGE THROUGH THE AFTERNOON FOR ALL MARINE
AREAS. ADVISORIES GO INTO EFFECT THROUGH THE AFTERNOON WITH
DIFFERING START TIMES AND FREQUENT GUSTS TO 25 KT ARE
EXPECTED...WITH EVEN SOME 30 KT GUSTS POSSIBLE OVER THE CHARLESTON
COUNTY WATERS.

TONIGHT...WINDS WILL CONTINUE TO RAMP UP AND BECOME MORE WEST-
NORTHWEST WITH TIME. HIGH END 25-30 KT SMALL CRAFT ADVISORY
CONDITIONS WILL BE WIDESPREAD THROUGH THE NIGHT AS COLDER AIR RUSHES
IN BEHIND THE FRONT. IN FACT...THERE IS A CHANCE FOR MARGINAL GALES
OVER THE OUTER GEORGIA WATERS TONIGHT. CONFIDENCE ISN/T HIGH ENOUGH
TO HOIST A GALE WATCH...THOUGH SUBSEQUENT FORECAST UPDATES MAY NEED
TO EVENTUALLY GO WITH A GALE WARNING FOR A PERIOD OF TIME.
REGARDLESS...HAZARDOUS MARINE CONDITIONS WILL CONTINUE THROUGH THE
NIGHT.

TUESDAY THROUGH WEDNESDAY...A DEEP TROUGH OF LOW PRESSURE WILL
SUPPLY THE COASTAL REGIME WITH A CONTINUED INFLUX OF COLDER AIR AND
A TIGHT PRESSURE PATTERN...RESULTING IN A LONG DURATION OF ELEVATED
WINDS AND SEAS. WE/RE EASILY LOOKING AT SMALL CRAFT ADVISORIES ON
ALL WATERS...BUT INDICATIONS FROM SOUNDING PROFILES SUPPORT THE
POTENTIAL FOR GALES AND THIS WILL BE INCLUDED IN THE HAZARDOUS
WEATHER OUTLOOK.

THURSDAY THROUGH SATURDAY...MUCH QUIETER CONDITIONS ARE ANTICIPATED
AS WEAK HIGH PRESSURE DEVELOPS INTO EARLY FRIDAY...ALLOWING FOR
WINDS AND SEAS TO REMAIN BELOW ANY ADVISORY CRITERIA. BUT ANY
IMPROVEMENT IS LIMITED AS WINDS AND SEAS WILL CLIMB AGAIN BEHIND AN
ARCTIC COLD FRONT LATE IN THE WEEK...PERHAPS AGAIN RESULTING IN
ADVISORY CONDITIONS FOR THE WEEKEND.

&&

.TIDES/COASTAL FLOODING...
HIGH TIDE IN THE CHARLESTON HARBOR WILL REACH 7.1-7.3 FT MLLW
WITH THE 8-830 AM HIGH TIDE...AND A COASTAL FLOOD ADVISORY HAS
BEEN ISSUED.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...COASTAL FLOOD ADVISORY UNTIL 10 AM EST THIS MORNING FOR
     SCZ048>050.
MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 5 AM EST
     THURSDAY FOR AMZ352.
     SMALL CRAFT ADVISORY UNTIL 5 AM EST THURSDAY FOR AMZ350.
     SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 5 AM EST
     THURSDAY FOR AMZ354.
     SMALL CRAFT ADVISORY UNTIL 11 AM EST THURSDAY FOR AMZ374.
     SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO MIDNIGHT EST
     TUESDAY NIGHT FOR AMZ330.

&&

$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
TIDES/COASTAL FLOODING...


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