Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 100229
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
929 PM EST TUE FEB 9 2016

...LOW WIND CHILLS OVERNIGHT...

.SYNOPSIS...
A SERIES OF REINFORCING COLD FRONTS WILL CROSS THE REGION 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. A FRONTAL SYSTEM COULD
IMPACT THE REGION NEXT MONDAY OR TUESDAY.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
A DEEP...CYCLONIC FLOW WILL REMAIN IN PLACE ACROSS THE SOUTHEAST
STATES TONIGHT AS A POTENT LONG-WAVE TROUGH REMAINS ANCHORED TO
THE EASTERN THIRD OF THE UNITED STATES. A BAND OF ENHANCED
MOISTURE THAT PRODUCED SOME FLURRIES EARLIER ACROSS PARTS OF SOUTH
CAROLINA AND THE CSRA HAS EXITED THE COAST SO EXPECT DRY WEATHER
TO DOMINATE THE REMAINDER OF THE OVERNIGHT HOURS. THE RISK FOR
FLURRIES HAS GENERALLY ENDED. EXPERIMENTAL...HIGH RESOLUTION
1-MINUTE IR DATA SHOW SKIES RAPIDLY CLEARING FROM SOUTHWEST-
NORTHEAST THIS EVENING AS DRIER AIR IN THE 4-8 KFT LAYER FINALLY
ERODES ANY REMAINING MOISTURE. CLEAR SKIES WILL PREVAIL OVERNIGHT
WITH LOWS RANGING FROM THE UPPER 20S INLAND TO LOWER 30S BEACHES.
THE COMBINATION OF AN ENHANCED PRESSURE GRADIENT AND ONGOING COLD
AIR ADVECTION WILL KEEP RATHER BRISK WINDS IN PLACE WITH WIND
CHILLS POISED TO DROP INTO THE UPPER TEENS BY SUNRISE WEDNESDAY.
ATTM IT APPEARS WIND CHILL VALUES WILL REMAIN ABOVE BOTH OUR
INLAND AND COASTAL WIND CHILL ADVISORY CRITERIA.

LAKE WINDS...STRONG WEST WINDS WILL CONTINUE TO PRODUCE 25 KT
GUSTS ACROSS LAKE MOULTRIE THROUGH TONIGHT WITH PEAK GUSTS AROUND
30 KT. A LAKE WIND ADVISORY REMAINS IN EFFECT.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
A HIGHLY AMPLIFIED UPPER TROUGH WILL PERSIST OVER THE EASTERN
UNITED STATES WEDNESDAY THROUGH FRIDAY. A REINFORCING BLAST OF
COLD AIR WILL DROP SOUTHEAST INTO THE AREA ON WEDNESDAY BEHIND A
DRY COLD FRONT. 850 MB TEMPS OF -8 TO -10C ACROSS SOUTHERN SC WILL
YIELD A COLD MORNING ON WEDNESDAY WITH TEMPS ONLY WARMING INTO THE
LOWER TO MIDDLE 40S DURING THE DAY UNDER SUNNY SKIES. WITHOUT THE
DOWNSLOPE WIND COMPONENT...HIGHS WOULD STRUGGLE TO CLIMB OUT OF
THE 30S. 30-35 KT GEOSTROPHIC WINDS WITH 5-6,000 FT MIXING HEIGHTS
WILL RESULT IN A WINDY DAY ACROSS THE AREA THOUGH THE CURRENT
FORECAST KEEPS CONDITIONS BELOW WIND ADVISORY CRITERIA.

STRONG COLD ADVECTION CONTINUES INTO WEDNESDAY NIGHT WITH MAINLY
CLEAR SKIES AND LOWS IN THE MIDDLE 2OS. POSITIVE LOW-LEVEL
THICKNESS ADVECTION ON THURSDAY WITH MOSTLY SUNNY SKIES WILL ALLOW
TEMPS TO JUMP INTO THE LOW TO MID 50S DURING PEAK HEATING.

AN EMBEDDED SHORTWAVE WILL DROP TOWARD THE AREA LATE THURSDAY
NIGHT...PUSHING A MAINLY DRY COLD FRONT INTO THE AREA. WEAK LOW
PRESSURE WILL DEVELOP OFF OUR COAST ALONG THE FRONT. THERE MAY BE
ENOUGH MOISTURE AND FORCING MAINLY OVER OUR COASTAL WATERS TO
SUPPORT LIGHT RAIN FRIDAY MORNING. ELSEWHERE THERE WILL BE
ABUNDANT LOW AND MID CLOUDS BUT LITTLE CHANCE FOR RAIN. THURSDAY
NIGHT LOW TEMPS ARE TRICKY BASED ON THE EXACT LOCATION OF THE LOW
AND TIMING OF THE FRONT. WE BUMPED TEMPS UP A FEW DEGREES BASED ON
THE EXPECTATION OF EXTENSIVE CLOUD COVER AND DECENT LOW-LEVEL
MIXING. A RELATIVELY ZONAL FLOW ON FRIDAY WILL MAINTAIN MODERATE
TEMPS THOUGH THE CLOUDS WILL SOMEWHAT LIMIT SURFACE HEATING. HIGHS
WILL RANGE FROM LOWER 50S FAR NORTH TO LOWER 60S FAR SOUTH.

LAKE WINDS...CONDITIONS FAVOR A CONTINUATION OF THE LAKE WIND
ADVISORY ON LAKE MOULTRIE WEDNESDAY INTO WEDNESDAY EVENING.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
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 /02Z WEDNESDAY THROUGH SUNDAY/...
VFR. GUSTY WINDS WILL LINGER THROUGH WEDNESDAY AFTERNOON.

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

&&

.MARINE...
TONIGHT...VERY POOR CONDITIONS EXPECTED DUE TO A STRONG PRESSURE
GRADIENT...LOW-LEVEL JETTING AND COLD ADVECTION. WINDS WILL BE
WESTERLY GUSTING UP TO 30 KT ACROSS THE NEARSHORE WATERS AND UP
TO 40 KT BEYOND 20 NM. THUS...ADVISORIES CONTINUE FOR NEAR SHORE
WATERS WITH GALE WARNINGS BEYOND 20 NM. SEAS WILL GENERALLY BE 4-6
FT WITHIN 20 NM AND UP TO 10 FT BEYOND 40 NM NEAR THE GULF STREAM.

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. A MARGINAL GALE WARNING WILL CONTINUE THROUGH WEDNESDAY
EVENING FOR THE OFFSHORE GA WATERS...PRIMARILY FOR 34 KT GUSTS...
WHILE ALL OTHER WATERS HAVE A SMALL CRAFT ADVISORY THROUGH MUCH OF
WEDNESDAY NIGHT.

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 30 TO
35 MPH GUSTS OVER INTERIOR PORTIONS AND MINIMUM RELATIVE HUMIDITY
AS LOW AS 25-28 PERCENT. FIRE WEATHER AGENCIES INDICATE FUEL
MOISTURE IS TOO HIGH TO WARRANT A RED FLAG WARNING FOR WEDNESDAY.
HOWEVER LATER SHIFTS MAY CONSIDER A FIRE DANGER STATEMENT IF
WEATHER CONDITIONS ARE EXPECTED TO BE CLOSE TO RED FLAG CRITERIA.

&&

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

&&

$$

ST


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