Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 090325
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1025 PM EST MON FEB 8 2016

.SYNOPSIS...
A SERIES OF REINFORCING COLD FRONTS WILL CROSS THE REGION THIS
EVENING THROUGH MID WEEK. AN ARCTIC COLD FRONT WILL THEN MOVE THROUGH
FRIDAY NIGHT...WHICH COULD BRING SOME OF THE COLDEST TEMPERATURES
OF THE SEASON EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
TONIGHT...A PRE-FRONTAL TROUGH HAS SHIFTED OFFSHORE AS OF LATE
THIS EVENING AND WINDS HAVE VEERED WEST-NORTHWEST IN ITS WAKE. THE
TRUE COLD FRONT HOWEVER APPEARS TO BE JUST UPSTREAM...MOVING
THROUGH THE EASTERN MIDLANDS AND CENTRAL SAVANNAH RIVER
AREA...WITH WINDS VEERING FURTHER TO THE NORTHWEST AND BECOMING
GUSTY AS STRONG COLD AIR ADVECTION DEVELOPS IN ITS WAKE. THERE IS
ALSO A CONSIDERABLE DROP IN DEW POINT VALUES AS MUCH DRIER AIR
FILTERS IN BEHIND THE FRONT. THIS FRONT SHOULD PROGRESS THROUGH
THE AREA LATE THIS EVENING AND INTO THE EARLY OVERNIGHT HOURS.

SHOWERS HAVE BASICALLY COME TO AN END AS OF LATE EVENING...WITH A
FEW LINGERING SPRINKLES ALONG THE COAST UP NEAR THE SANTEE RIVER
AND DOWN NEAR THE ALTAMAHA RIVER. THE REMAINDER OF THE NIGHT
SHOULD BE RAIN-FREE. SKIES WILL CLEAR INITIALLY...THEN SCATTERED
CLOUDS COULD SHIFT INTO WESTERN AREAS LATE TONIGHT ASSOCIATED WITH SHORT
WAVE ENERGY ALONG THE SOUTHERN PERIPHERY OF THE UPPER TROUGH.

WINDS WILL REMAIN ELEVATED THROUGH THE NIGHT WITHIN THE COLD
ADVECTION REGIME...CONSISTENTLY IN THE 10-15 MPH RANGE...SO
RADIATIONAL COOLING SHOULD NOT BECOME A FACTOR. NEVERTHELESS...AS
THE MUCH COLDER AIR RUSHES IN...TEMPERATURES WILL FALL INTO THE
LOWER AND MID 30S AWAY FROM THE BEACHES.

LAKE WINDS...GUSTY WINDS WILL CONTINUE ON LAKE MOULTRIE THROUGH
THE NIGHT AS STRONG COLD AIR ADVECTION DEVELOPS IN WAKE OF A
DEPARTING COLD FRONT. THEREFORE...A LAKE WIND ADVISORY IS IN
EFFECT.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
A BROAD UPPER TROUGH WILL ENVELOPE THE EASTERN U.S. THROUGH
WEDNESDAY BEFORE LIFTING OUT TO THE NORTHEAST WEDNESDAY NIGHT INTO
THURSDAY. THIS WILL RESULT IN MUCH COOLER THAN NORMAL TEMPERATURES
THROUGH THE PERIOD...LIKELY NOT GETTING OUT OF THE 40S FOR MOST OF
THE AREA MOST OF THE TIME. BEST CHANCE OF LOWER 50S WILL BE NEAR AND
SOUTH OF I-16 ON THURSDAY. OVERNIGHT LOWS TUESDAY NIGHT AND
WEDNESDAY NIGHT WILL BE IN THE MID TO UPPER 20S AWAY FROM THE
IMMEDIATE COAST...WITH EVEN THE IMMEDIATE COASTAL AREAS SEEING
TEMPERATURES NEAR FREEZING. IT WILL BE PRECIPITATION-FREE THROUGH
THE PERIOD GIVEN LIMITED MOISTURE...ALTHOUGH CANNOT COMPLETELY RULE
OUT A FEW SPRINKLES OR EVEN SOME SLEET AS LOW-MID LEVEL MOISTURE
INCREASES A BIT IN ASSOCIATION WITH A STRONG SHORTWAVE
TROUGH...MAINLY TUESDAY MORNING AND AGAIN TUESDAY EVENING.

THE MAIN CONCERN THIS PERIOD WILL BE STRONG WINDS TUESDAY AND
WEDNESDAY WITH GUSTS OVER 30 MPH EACH DAY...GENERALLY HIGHEST EACH
AFTERNOON. THERE IS A SMALL RISK OF GUSTS AT LEAST REACHING 40 MPH
AND THUS A WIND ADVISORY MAY BE NEEDED FOR PART OF THE AREA...MAINLY
FOR COASTAL AREAS. HOWEVER...A WIND ADVISORY COULD BE NEEDED FOR
AREAS FARTHER INLAND AS WELL GIVEN THE WET SOIL WHICH COULD MAKE IT
EASIER FOR SOME TREES TO FALL. EVEN AT NIGHT WINDS WILL BE ELEVATED
ENOUGH TO PRODUCE WIND CHILLS INTO THE TEENS FOR MOST AREAS EXCEPT
MAYBE RIGHT ALONG THE COAST. THUS...WIND CHILL ADVISORIES MAY BE
NEEDED...AGAIN MOSTLY FOR COASTAL AREAS WHERE THE ADVISORY CRITERIA
IS 15 DEGREES COMPARED TO 10 DEGREES INLAND.

LAKE WINDS...STRONG WINDS WILL CONTINUE ACROSS THE AREA...INCLUDING
LAKE MOULTRIE...IN THE COLD ADVECTION REGIME THROUGH MID WEEK. A
LAKE WIND ADVISORY WILL LIKELY BE NEEDED FOR AT LEAST THE DAYTIME
PERIODS THROUGH WEDNESDAY.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
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 10-15F
BELOW SEASONAL LEVELS.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS ARE EXPECTED TO PREVAIL AT KCHS AND KSAV THROUGH
00Z WEDNESDAY. BREEZY CONDITIONS WILL OCCUR BEHIND A PASSING COLD
FRONT WITH GUSTS OF 20-25 KT THROUGH TUESDAY MORNING...THEN WINDS
WILL STRENGTHEN FURTHER WITH GUSTS REACHING AS HIGH AS 30 KT TO
EVEN 35 KT AT TIMES BEGINNING MIDDAY TUESDAY.

EXTENDED AVIATION OUTLOOK...GENERALLY VFR ALTHOUGH STRONG/GUSTY
WINDS ARE EXPECTED TUE/WED.

&&

.MARINE...
TONIGHT...A COLD FRONT WILL MOVE ACROSS THE WATERS...WITH A
STRONG OFFSHORE FLOW DEVELOPING IN ITS WAKE. A GALE WARNING HAS
BEEN RAISED FOR THE OUTER GEORGIA WATERS AND SMALL CRAFT
ADVISORIES REMAIN IN EFFECT FOR ALL COASTAL WATERS AND CHARLESTON
HARBOR. SEAS WILL RANGE FROM AS HIGH AS 5-7 FT NEAR 20 NM TO 7-9
FT BEYOND 20 NM.

TUESDAY THROUGH SATURDAY...VERY POOR MARINE CONDITIONS EXPECTED MOST
OF THE PERIOD AS A SERIES OF COLD FRONTS TRAVERSE THE AREA. SCA/S
ARE LIKELY FOR ALL WATERS INTO EARLY THURSDAY THEN AGAIN FOR AT
LEAST THE OFFSHORE WATERS FRIDAY NIGHT/SAT. GALES WILL BE POSSIBLE
TUESDAY THROUGH WEDNESDAY NIGHT ...ESPECIALLY AROUND 20 NM AND
BEYOND AND THIS IS WHERE WE HAVE RAISED A GALE WATCH.

&&

.FIRE WEATHER...
BREEZY CONDITIONS ARE EXPECTED TUESDAY AND WEDNESDAY WITH GUSTS
OVER 30 MPH EACH DAY. HUMIDITY LEVELS SHOULD REMAIN ABOVE 30
PERCENT TUESDAY BUT DROP TO NEAR CRITICAL LEVELS /25 PERCENT/ AWAY
FROM THE COAST WEDNESDAY. THUS...DEPENDING ON FINE FUEL MOISTURE
LEVELS WHICH WILL BE COORDINATED WITH LAND MANAGEMENT AGENCIES...A
FIRE DANGER STATEMENT AND/OR RED FLAG WARNING MAY BE NEEDED.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...LAKE WIND ADVISORY UNTIL 6 PM EST TUESDAY FOR SCZ045.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST THURSDAY FOR AMZ350-352-
     354.
     GALE WARNING UNTIL 7 AM EST THURSDAY FOR AMZ374.
     SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TUESDAY NIGHT FOR
     AMZ330.

&&

$$

NEAR TERM...JAQ
SHORT TERM...RJB
LONG TERM...
AVIATION...JAQ/RJB
MARINE...JAQ/RJB
FIRE WEATHER...RJB


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