Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 091133
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
633 AM EST TUE FEB 9 2016

.SYNOPSIS...
A SERIES OF REINFORCING COLD FRONTS WILL CROSS THE REGION TODAY
THROUGH WEDNESDAY. WEAK HIGH PRESSURE EARLY THURSDAY WILL GIVE WAY
TO ANOTHER COLD FRONT THURSDAY NIGHT. AN ARCTIC COLD FRONT WILL THEN
MOVE THROUGH FRIDAY NIGHT OR SATURDAY...WHICH COULD BRING SOME OF
THE COLDEST TEMPERATURES OF THE SEASON INTO EARLY NEXT WEEK. A
FRONTAL SYSTEM COULD IMPACT THE REGION NEXT MONDAY OR TUESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
TODAY...THE PATTERN ALOFT WILL FEATURE A DEEP AND COLD UPPER TROUGH
ACROSS THE EASTERN CONUS AND THE FORECAST AREA WILL BE SITUATED
UNDER ITS SOUTHERN PERIPHERY AND WITHIN THE STRONG CHANNELED VORT
ENERGY ASSOCIATED WITH IT. AT THE SURFACE...THE REGION WILL REMAIN
WITHIN THE CYCLONIC FLOW AROUND THE LOW OVER THE GREAT LAKES WHICH
WILL RESULT IN A COLD AND BREEZY DAY. IN FACT...THE MAIN FORECAST
ISSUE WILL BE THE STRENGTHENING WEST WINDS IN WHAT WILL ULTIMATELY
BE A VERY CHILLY AND MOSTLY CLOUDY DAY. SKIES MAY START OFF CLEAR OR
PARTLY CLOUDY...BUT CLOUDS WILL INCREASE WITH SURFACE HEATING AND
INVASION OF MOISTURE IN THE 4-6 KFT LAYER. THE FORECAST IS DRY...BUT
WE CANNOT TOTALLY RULE OUT A FEW STRAY SPRINKLES OF RAIN OR EVEN
SLEET/GRAUPEL. WIND GUSTS WILL PICK UP SOON AFTER SUNRISE AND WILL
PEAK THIS AFTERNOON. FREQUENT GUSTS INTO THE 30-35 MPH RANGE ARE
EXPECTED...WITH A FEW ISOLATED HIGHER GUSTS. HAVE OPTED TO NOT GO
WITH A WIND ADVISORY FOR NOW AS WINDS ARE EXPECTED TO STAY JUST
BELOW CRITERIA...BUT WITH SATURATED SOILS THERE IS A CHANCE WE COULD
SEE ISOLATED DOWNED TREES. WITH THE AMOUNT OF CLOUD COVER AND THE
COLDER INCOMING AIR...HIGHS WILL TOP OUT IN THE UPPER 40S.
HOWEVER...WITH THE GUSTY WINDS AND CLOUD COVER...IT WILL FEEL LIKE
IT IS IN THE 30S VIRTUALLY ALL DAY.

TONIGHT...GUSTY WINDS WILL LINGER INTO THE EVENING BEFORE
DIMINISHING. STILL...WINDS WILL REMAIN ELEVATED THROUGH THE
OVERNIGHT THANKS TO THE PERSISTENT PRESSURE GRADIENT. SKIES WILL
CLEAR OUT THROUGH THE NIGHT...BECOMING MOSTLY CLEAR LATE.
TEMPERATURES WILL FALL INTO THE UPPER 20S...AND WITH THE ELEVATED
WINDS WIND CHILL VALUES WILL BE IN THE UPPER TEENS LATE.

LAKE WINDS...STRONG WEST TO WEST-NORTHWEST WINDS WILL CONTINUE TO
PRODUCE 25 KT GUSTS ACROSS LAKE MOULTRIE TODAY AND TONIGHT. PEAK
GUSTS TO AROUND 30 KT WILL BE POSSIBLE THIS AFTERNOON ESPECIALLY
AROUND THE WESTERN LAKE SHORES. A LAKE WIND ADVISORY REMAINS IN
EFFECT THROUGH TONIGHT.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
WEDNESDAY...A HIGHLY AMPLIFIED LARGE SCALE PATTERN WILL
PERSIST...FEATURING A BROAD AND DEEP TROUGH OVER THE EAST AND
RIDGING IN THE WEST. A DRY COLD FRONT WILL CROSS THE REGION AND
REINFORCES THE PRE-EXISTING COLD AIR MASS...RESULTING IN BREEZY TO
WINDY CONDITIONS. WINDS WILL APPROACH WIND ADVISORY THRESHOLDS...AND
GIVEN THAT AND THE SATURATED GROUNDS WE CERTAINLY NEED TO CONSIDER
THE POSSIBILITY THAT ONE COULD BE REQUIRED. UTILIZING THE LOW LEVEL
THICKNESS SCHEME AND 850 MB TEMPS THAT RANGE FROM -6C SOUTH TO -10C
NORTH...MAX TEMPS WILL STRUGGLE TO EVEN REACH THE MID AND UPPER 40S.
THIS IS A SOLID 15F BELOW NORMAL LEVELS. COMBINED WITH THE BLUSTERY
CONDITIONS IT/LL FEEL SIGNIFICANTLY COOLER.

WEDNESDAY NIGHT WILL BE BITTERLY COLD WITH LOWS TO PLUNGE TO THE MID
AND UPPER 20S JUST ABOUT EVERYWHERE...WITH EVEN SUB-FREEZING TEMPS
FOUND AT THE COAST. ALTHOUGH WINDS WILL DIMINISH THROUGH THE NIGHT
AS THE PRESSURE GRADIENT GRADUALLY SLACKENS...THERE IS ENOUGH WIND
TO PERSIST THAT WILL CAUSE WIND CHILLS DOWN CLOSE TO OUR WIND CHILL
ADVISORY CRITERIA OF 15F OR COLDER ALONG THE COASTAL COUNTIES.

THURSDAY THROUGH FRIDAY...THE MULTI-LAYERED TROUGH IN THE EAST WILL
TEMPORARILY LIFTS INTO THE ATLANTIC...BEFORE IT RE-ESTABLISHES
ITSELF IN THE EAST ON FRIDAY. HIGH PRESSURE WILL BRIEFLY BUILD INTO
THE REGION FROM THE GULF OF MEXICO THURSDAY...BUT A SHORT WAVE
DIVING SE THROUGH THE MID MS VALLEY THURSDAY AND INTO THE SE BY
FRIDAY MORNING WILL TRIGGER A WEAK SURFACE LOW IN THE NORTHERN GULF
COAST REGION. THAT LOW HEADS EAST AND PASSES OFF THE GEORGIA OR
FLORIDA COASTS FRIDAY. THAT MIGHT BE JUST ENOUGH FORCING AND
MOISTURE IN ASSOCIATION WITH THAT LOW TO PRODUCE A LITTLE LIGHT
PRECIP THURSDAY NIGHT INTO EARLY FRIDAY. BUT POPS ARE HELD UNDER 15
PERCENT AND NO MENTION IS NECESSARY IN THE FORECAST AT THIS TIME.
WET BULB TEMPS ARE ACTUALLY BELOW FREEZING ALONG THE NW AND NORTH
TIER...AND SHOULD ANY PRECIP OCCUR THERE MIGHT BE A LITTLE SNOW
AND/OR SLEET AS WELL. BUT EVEN SO...NO IMPACTS WOULD OCCUR.

DUE TO WARM ADVECTION TEMPS WILL NOT BE AS BRUTALLY COLD AS THE
PREVIOUS COUPLE OF DAYS...BUT STILL FAR BELOW NORMAL FOR THIS TIME
OF YEAR.

LAKE WINDS...CONDITIONS FAVOR A CONTINUATION OF THE LAKE WIND
ADVISORY ON LAKE MOULTRIE WEDNESDAY INTO WEDNESDAY EVENING.
HOWEVER...KEEP IN MIND THAT SHOULD ANY LAND BASED WIND ADVISORY BE
REQUIRED FOR BERKELEY COUNTY THAT WOULD SUPERSEDE THE LAKE WIND
ADVISORY. EITHER WAY...CONDITIONS ARE NOT SUITABLE FOR MARINERS ON
THE LAKE.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
THE LARGE SCALE EAST COAST TROUGH WILL PERSIST INTO EARLY
SUNDAY...FOLLOWED BY A PROGRESSIVE SHORT WAVE RIDGE LATER SUNDAY
INTO EARLY MONDAY...WITH AGAIN THE EAST COAST TROUGH IN PLACE
NEXT TUESDAY.

AN ARCTIC BLAST IS STILL EXPECTED TO OCCUR BEHIND AN ARCTIC COLD
FRONT THAT TRAVERSES THE REGION SATURDAY...AS A 1048 MB HIGH PUNCHES
SOUTH/SE FROM THE NORTHERN GREAT PLAINS LATE IN THE WEEK. THE CORE
OF THE HIGH REACHES THE CAROLINAS ON SUNDAY...THEN PULLS INTO THE
ATLANTIC ON MONDAY...GIVING WAY TO ANOTHER FRONTAL SYSTEM EITHER
MONDAY OR TUESDAY.

STRONG COLD ADVECTION ARRIVES LATER SATURDAY AND CONTINUES INTO
SUNDAY...BEFORE STARTING TO WANE SUNDAY NIGHT. WE/RE STILL NOT
COMPLETELY CERTAIN ON THE DEGREE OF MAGNITUDE OF THE COLD AIR...BUT
IT/LL CERTAINLY BE COLD ENOUGH WHERE HARD FREEZES ARE ANTICIPATED
MOST INLAND SECTIONS BOTH SATURDAY AND SUNDAY NIGHT. HIGHS ON SUNDAY
WILL BE FORTUNATE TO EVEN REACH THE LOWER AND MIDDLE 40S...IF THAT.
WIND CHILLS SATURDAY NIGHT AND SUNDAY COULD FLIRT WITH WIND
CHILL ADVISORY THRESHOLDS.

WARM ADVECTION IN ADVANCE OF THE EARLY NEXT WEEK FRONTAL SYSTEM WILL
ALLOW FOR A LITTLE WARMER WEATHER...BUT ALSO THE RISK FOR SOME
PRECIP.

LAKE WINDS...ANOTHER ROUND OF STRONG WINDS WILL BE POSSIBLE OVER
LAKE MOULTRIE THIS WEEKEND. ANOTHER LAKE WIND ADVISORY COULD
EVENTUALLY BE NEEDED.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS ARE EXPECTED TO PREVAIL AT KCHS AND KSAV THROUGH
12Z WEDNESDAY. BREEZY CONDITIONS WILL DEVELOP 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
IN THE AFTERNOON. THERE COULD EVEN BE A FEW ISOLATED GUSTS TO
AROUND 35 KT. VFR CEILINGS WILL LIKELY DEVELOP IN THE AFTERNOON
WITHIN AN EXPANSIVE STRATOCUMULUS DECK...BEFORE SKIES CLEAR OUT
LATER TONIGHT.

EXTENDED AVIATION OUTLOOK...GENERALLY VFR...ALTHOUGH STRONG AND
GUSTY WINDS WILL OCCUR AGAIN ON WEDNESDAY.

&&

.MARINE...
TODAY AND TONIGHT...THE PATTERN WILL REMAIN NEARLY STEADY STATE WITH
STRONG WEST TO WEST-NORTHWEST WINDS THROUGH THE PERIOD. WINDS WILL
CONSISTENTLY BE 25-30 KT ACROSS THE NEARSHORE WATERS...WITH FREQUENT
GUSTS TO 35 KT OVER THE OUTER WATERS. WINDS IN AND AROUND THE
CHARLESTON HARBOR WILL INCREASE ESPECIALLY THIS AFTERNOON AND GUSTS
TO 30 KT WILL BE COMMON. THERE ARE NO CHANGES TO THE ONGOING SMALL
CRAFT ADVISORIES AND GALE WARNING. THERE COULD BE A FEW ISOLATED
GUSTS TO GALE FORCE IN THE NEARSHORE WATERS...BUT THEY ARE EXPECTED
TO BE FREQUENT ENOUGH TO CONSIDER EXPANDING THE GALE WARNING AS OF
YET. SEAS WILL STEADILY INCREASE AS WELL...WITH 4-6 FT COMMON IN THE
NEARSHORE WATERS AND 5 TO 8 FT COMMON ACROSS THE OUTER WATERS.

WEDNESDAY AND WEDNESDAY NIGHT...BLUSTERY CONDITIONS WILL PREVAIL
ACROSS THE MARINE COMMUNITY WITH A TIGHT PRESSURE GRADIENT BETWEEN
LOW PRESSURE OFF NEW ENGLAND AND HIGH PRESSURE IN THE GULF OF
MEXICO. FOR NOW A GALE WARNING ON THE OUTERMOST GA WATERS WITH HIGH-
END SMALL CRAFT ADVISORIES ELSEWHERE. HOWEVER...MARGINAL GALES ARE
CERTAINLY POSSIBLE ON THE OTHER WATERS.

THURSDAY THROUGH FRIDAY...MUCH BETTER CONDITIONS WILL PREVAIL...AS
HIGH PRESSURE MOVES IN ON THURSDAY...THEN GIVES WAY TO A COLD FRONT
AND WAVE OF LOW PRESSURE BY EARLY FRIDAY. FOR THE MOST PART WINDS
AND SEAS WILL BE BELOW ANY ADVISORY LEVELS.

SATURDAY THROUGH SUNDAY...AN ARCTIC COLD FRONT WILL SWEEP THROUGH
SATURDAY...FOLLOWED BY A POWERFUL 1040-1045 MB OR GREATER HIGH THAT
BUILDS FROM THE PLAINS SATURDAY TO THE EASTERN STATES SUNDAY. WE/LL
MOST LIKELY EXPERIENCE AT LEAST SMALL CRAFT ADVISORY CONDITIONS YET
AGAIN.

&&

.FIRE WEATHER...
BREEZY TO WINDY CONDITIONS ARE EXPECTED AGAIN WEDNESDAY WITH GUSTS
OVER 30 MPH TO OCCUR. HUMIDITY LEVELS COULD FALL TO NEAR CRITICAL
THRESHOLDS /25 PERCENT/ AWAY FROM THE COAST WEDNESDAY. THE MOST
RECENT FUEL MOISTURES ARE GREATER THAN 20 PERCENT OR VERY WET...BUT
WE STILL WILL COORDINATE WITH LAND MANAGEMENT AGENCIES TO SEE IF A
FIRE DANGER STATEMENT AND/OR RED FLAG WARNING MAY BE NEEDED.

&&

.TIDES/COASTAL FLOODING...
A STRONG OFFSHORE FLOW WILL PRODUCE BLOW OUT TIDES NEAR AND DURING
EACH LOW TIDE CYCLE THIS AFTERNOON THROUGH WEDNESDAY NIGHT.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...LAKE WIND ADVISORY UNTIL 11 PM EST WEDNESDAY FOR SCZ045.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST THURSDAY FOR AMZ350-352-
     354.
     GALE WARNING UNTIL 11 PM EST WEDNESDAY FOR AMZ374.
     SMALL CRAFT ADVISORY UNTIL 11 PM EST WEDNESDAY FOR AMZ330.

&&

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


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