Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 082107
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
407 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/...
LATE MONDAY AFTERNOON...A COLD FRONT WAS APPROACHING INLAND
COUNTIES...AND SHOWERS WERE INCREASING IN COVERAGE AHEAD OF THE
FRONT. AN AMPLIFYING LONGWAVE UPPER TROUGH WILL DRIVE THIS STRONG
SURFACE COLD FRONT AND ASSOCIATED RAIN SHOWERS THROUGH THE REGION
THIS EVENING. WHILE HIGH RESOLUTION GUIDANCE SUGGESTS THAT
LIKELY/CATEGORICAL POPS COULD BE NEEDED...SHOWERS HAVE THUS FAR
BEEN FALLING FROM CLOUD BASES OF 5-8 KFT AGL AND SOME RAIN HAS
LIKELY EVAPORATED WITHIN THE DRY SUB-CLOUD LAYER. GIVEN THE LOW
LEVEL DRY AIR WHICH WILL PERSIST AHEAD OF THE FRONT...CAPPED
MAXIMUM POPS AT AROUND 50 PERCENT INTO THIS EVENING. OF
INTEREST...SHOWERS COULD PRODUCE WIND GUSTS 35-40 MPH. IN MOST
CASES...RAINFALL AMOUNTS EXCEEDING 0.10 INCH SHOULD REMAIN HIGHLY
LOCALIZED. ALSO OF NOTE...STRONG FORCING FOR ASCENT AND STEEPENING
MID LEVEL LAPSE RATES PROMOTED BY THE APPROACHING UPPER TROUGH
COULD SUPPORT A FEW LIGHTNING STRIKES...THUS MAINTAINED A MENTION
OF ISOLATED THUNDERSTORMS INTO THIS EVENING. THE POTENTIAL FOR ANY
SEVERE WEATHER REMAINS VERY LOW...LESS THAN 10 PERCENT...BUT
SUBTLE INVERTED-V SOUNDING SIGNATURES AND RAPID COOLING ALOFT
COULD SUPPORT A STRONGER WIND GUST AND/OR SMALL HAIL IN AN
ISOLATED THUNDERSTORM.

LATER THIS EVENING AND OVERNIGHT...A FEW SHOWERS MAY LINGER
INTO MID TO LATE 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 OVERNIGHT. WINDS WILL REMAIN
ELEVATED THROUGH THE NIGHT WITHIN THE COLD ADVECTION
REGIME...CONSISTENTLY IN THE 15-20 MPH RANGE...SO RADIATIONAL
COOLING SHOULD NOT BECOME A FACTOR. NEVERTHELESS...AS THE MUCH
COLDER AIR RUSHES IN...TEMPS WILL FALL INTO THE LOWER 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 AT LEAST THROUGH
THE EVENING. ISSUED A LAKE WIND ADVISORY UNTIL MIDNIGHT TO ACCOUNT
FOR FREQUENT GUSTS TO 25 KNOTS ON THE LAKE.

&&

.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 10-15GF
BELOW SEASONAL LEVELS.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
LOW PROBABILITY FOR BRIEF FLIGHT RESTRICTIONS IN SHOWERS AND EVEN
ISOLATED THUNDERSTORMS THIS EVENING. OTHERWISE...VFR THROUGH TUESDAY.

WIND GUSTS ARE INCLUDED THROUGHOUT 18Z TAFS. STRONGEST GUSTS FROM
THE WEST EXCEEDING 25 KNOTS ARE EXPECTED AFTER 15Z TUESDAY.

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

&&

.MARINE...
SOLID SMALL CRAFT ADVISORY CONDITIONS WILL PREVAIL TONIGHT. AS A
STRONG COLD FRONT CROSSES THE WATERS THIS EVENING...GUSTY SOUTHWEST
WINDS WILL VEER TOWARD THE WEST. CAPPED STRONGEST WINDS AT 30
KNOTS OVERNIGHT...ESPECIALLY AROUND 20 NM AND BEYOND.
HOWEVER...THERE IS A LOW PROBABILITY FOR GALE FORCE GUSTS WITHIN
AMZ374 OVERNIGHT...ESPECIALLY BEYOND 40 NM. 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 MIDNIGHT EST TONIGHT FOR SCZ045.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST THURSDAY FOR AMZ352.
     SMALL CRAFT ADVISORY UNTIL 5 AM EST THURSDAY FOR AMZ350.
     SMALL CRAFT ADVISORY UNTIL 5 AM EST THURSDAY FOR AMZ354.
     GALE WATCH FROM TUESDAY MORNING THROUGH THURSDAY MORNING FOR
     AMZ374.
     SMALL CRAFT ADVISORY UNTIL 6 AM EST TUESDAY FOR AMZ374.
     SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TUESDAY NIGHT FOR
     AMZ330.

&&

$$
SYNOPSIS...
NEAR TERM...SPR
SHORT TERM...RJB
LONG TERM...
AVIATION...RJB/SPR
MARINE...RJB/SPR
FIRE WEATHER...RJB


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