Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 220306
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1106 PM EDT TUE OCT 21 2014

.SYNOPSIS...
A COLD FRONT WILL CROSS THE REGION EARLY TONIGHT. HIGH PRESSURE WILL
DOMINATE THROUGH LATE WEEK.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
LATE THIS EVENING...NO CHANGES WERE NEEDED TO THE GOING FORECAST.
THE COLD FRONT CONTINUES TO APPROACH AND WILL BEGIN TO INFILTRATE
THE FORECAST AREA OVER THE NEXT FEW HOURS. PREVIOUS DISCUSSION
CONTINUES BELOW.

TONIGHT...AS A ROBUST AND DEEP-LAYERED GYRE NEAR KPIT THIS EVENING
WILL DROP TOWARD THE DELMARVA LATE AND SEND A MODEST COLD FRONT INTO
THE AREA THIS EVENING...BEFORE IT SLIDES INTO THE ATLANTIC
OVERNIGHT. THE FRONT WILL COME THROUGH DRY...WITH AT MOST A FEW
ALTOCUMULUS AND/OR STRATOCUMULUS CLOUDS...ESPECIALLY IN SC.
OTHERWISE SKIES WILL BE CRYSTAL CLEAR WITH THE VERTICAL VOID OF ANY
MOISTURE. COLD ADVECTION STARTS IN EARNEST AFTER ABOUT 03-05Z WITHIN
A DEEP NW AND NORTH FLOW...AND WE LOOK FOR A GOOD DROP IN TEMPS
OVERNIGHT. LOWS WILL RANGE FROM 47-50 ALONG THE NW TIER...TO THE
LOWER OR MIDDLE 50S NEAR THE US-17 CORRIDOR...TO THE UPPER 50S ALONG
THE IMMEDIATE SHORELINE.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
WEDNESDAY...MUCH COOLER AND DRYER AIR WILL PUSH INTO THE REGION
BEHIND A COLD FRONT WELL OFF THE SOUTHEAST COAST. HIGH TEMPS WILL BE
SOME 8-10 DEGREES COOLER THAN THE PREVIOUS DAY AS A NORTH/NORTHWEST
FLOW PERSISTS BETWEEN HIGH PRESSURE CENTERED OVER THE MIDWEST AND A
BROAD LOW PRESSURE SYSTEM JUST OFF THE MID-ATLANTIC AND NORTHEAST
COAST. IN GENERAL...HIGH TEMPS SHOULD RANGE IN THE LOW 70S...COOLEST
OVER SOUTHEAST SOUTH CAROLINA. WEDNESDAY NIGHT LOWS SHOULD ALSO BE
THE COOLEST OF THE WEEK...WITH PERHAPS SOME CONTRIBUTION FROM
RADIATIONAL COOLING INLAND. IN GENERAL...LOWS SHOULD DIP INTO THE
LOW/MID 40S INLAND TO LOW 50S NEAR THE COAST.

THURSDAY AND FRIDAY...VERY LITTLE CHANGE IS ANTICIPATED IN REGARDS
TO THE DRY WEATHER PATTERN...BUT WINDS WILL GRADUALLY BACK TO
NORTHWEST LATE WEEK. A FULL SUN ALONG WITH A MORE FAVORABLE
DOWNSLOPING WIND COMPONENT EACH DAY SUPPORTS GRADUALLY WARMING
TEMPS...WITH LATEST 1000-850MB THICKNESS VALUES SUGGESTING OVERALL
HIGH TEMPS IN THE LOW/MID 70S ON THURSDAY...THEN MID/UPPER 70S ON
FRIDAY. THURSDAY NIGHT LOWS WILL ALSO BE SLIGHTLY WARMER THAN THE
PREVIOUS NIGHT...IN THE MID/UPPER 40S AWAY FROM THE COAST.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
GLOBAL MODELS HAVE COME INTO FAIR AGREEMENT THROUGH MONDAY...BUT
THEN START TO DIVERGE BY TUESDAY. FRIDAY NIGHT AND SATURDAY...A WEAK
UPPER LEVEL SHORT WAVE TROUGH MOVES OFFSHORE BUT IS QUICKLY FOLLOWED
BY A SHARPER SHORT WAVE MOVING DOWN IN THE NORTHWEST UPPER FLOW.
THIS SHORT WAVE MOVES SOUTHEAST NEAR THE REGION SATURDAY...BUT
MODELS DIFFER SLIGHTLY ON ITS TRACK. IF THIS FEATURE REMAINS AS
SHARP AS MODELS CURRENTLY SHOW...AND MOVES CLOSER TO THE AREA..WOULD
NOT BE SURPRISED IF LATER FORECASTS NEED TO ADD AT LEAST SLIGHT
CHANCE POPS FOR FIRST PART OF SATURDAY. BY SUNDAY AND MONDAY...A
BROAD/DEEP LAYER RIDGE BUILDS ACROSS THE SOUTH AND SOUTHEAST STATES.
THIS UPPER RIDGE IS SLOWER TO MOVE EAST IN THE ECMWF THAN GFS ON
TUESDAY.

GENERALLY DRY CONDITIONS WITH NO POPS MENTIONED THROUGH SUNDAY. SOME
MARGINAL DEEP LAYER MOISTURE BEGINS TO RETURN LATER MONDAY AND
TUESDAY WITH LOW LEVEL EAST-SOUTHEAST FLOW. THIS HAS PROMPTED
MENTION OF SLIGHT CHANCE POPS MONDAY NIGHT AND TUESDAY. TEMPERATURES
SLIGHTLY ABOVE NORMAL /ESPECIALLY MAX TEMPS/ THROUGH THE PERIOD.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
VFR. NORTHWEST TO NORTH WINDS MAY BE A BIT GUSTY WEDNESDAY
MORNING.

EXTENDED AVIATION OUTLOOK...VFR.

&&

.MARINE...
LATE THIS EVENING...INCOMING NEW MODEL DATA CONTINUES TO SHOW
WINDS BEING RIGHT ON THE CUSP OF SMALL CRAFT ADVISORY. NO
ADVISORIES HAVE BEEN ISSUED AND THE FORECAST CONTINUES TO FEATURE
15-20 KT...THOUGH A FEW GUSTS APPROACHING 25 KT CANNOT BE RULED
OUT. WINDS WILL PICK UP IN THE 06-08Z WINDOW AND WILL BE STRONGEST
THROUGH AROUND 12Z. SEAS WILL BUILD FROM NEAR 2 FT THIS EVENING
TO 3-5 FT LATE TONIGHT...GREATEST ACROSS AMZ374.

WEDNESDAY...A DRY COLD FRONT WILL CONTINUE TO SHIFT EAST OVER THE
WESTERN ATLANTIC WITH A FAIR AMOUNT OF COLD AIR ADVECTION OCCURRING
OVER THE COASTAL WATERS AS HIGH PRESSURE BUILDS FROM THE NORTHWEST.
AS A RESULT...WINDS/SEAS WILL BE ENHANCED THROUGH WEDNESDAY MORNING.
IN GENERAL...NORTH/NORTHWEST WINDS SHOULD RANGE BETWEEN 15-20 KTS
WHILE SEAS BUILD TO 3-5 FT...HIGHEST IN OFFSHORE GEORGIA WATERS.
THERE IS A LOW CHANCE WE COULD SEE A PERIOD OF MARGINAL SMALL CRAFT
ADVISORY LEVEL WINDS OVER NORTHERN SC WATERS WHEN COLD AIR ADVECTION
IS STRONGEST WEDNESDAY MORNING.

WEDNESDAY AFTERNOON THROUGH SUNDAY...WINDS AND SEAS ARE EXPECTED TO
REMAIN BELOW ANY HIGHLIGHTS AS A BROAD AREA OF HIGH PRESSURE REMAINS
NORTHWEST OF THE REGION THROUGH LATE WEEK AND IS THEN REINFORCED
SATURDAY AFTERNOON BEHIND AN UPPER LEVEL DISTURBANCE.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.

&&

$$

NEAR TERM...BSH
SHORT TERM...DPB
LONG TERM...RFM
AVIATION...BSH
MARINE...BSH/33/DPB




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