643
FXUS62 KCHS 202030
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
330 PM EST THU FEB 20 2025
SYNOPSIS
COLD HIGH PRESSURE WILL BUILD INTO THE REGION THROUGH THE START
OF THE WEEKEND. AN AREA OF LOW PRESSURE WILL DEVELOP OFF THE
COAST ON SUNDAY, FOLLOWED BY MORE HIGH PRESSURE INTO EARLY NEXT
WEEK.
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE LOCAL FORECAST
AREA FROM THE WEST THROUGH THIS AFTERNOON AND INTO THE OVERNIGHT
HOURS. ALOFT, A LARGE SCALE TROUGH IS POSITIONED OVER THE OHIO RIVER
VALLEY AND WILL SLOWLY TREK EASTWARD. WITH THE FLOW BOTH ALOFT AND
AT THE SURFACE OUT OF THE NW WILL YIELD DOWNSLOPE FLOW OFF OF
THE APPALACHIAN MOUNTAINS. AS THE AIR DRIES WITH THE DOWNSLOPE
FLOW SKIES WILL CONTINUE TO CLEAR. AS OF 3 PM MOST OF SE GA WAS
REPORTING CLEAR SKIES, WHILE SE SC IS STUCK IN PERSISTENT CLOUD
COVER. THE CLOUD COVER HAS MADE FOR A TRICKY TEMPERATURE
FORECAST, WITH A LARGE RANGE OF TEMPERATURES OVER THE FORECAST
AREA. AS OF 3 PM LOCATIONS NEAR THE ALTAMAHA RIVER, GA ARE NEAR
50F WHILE NEAR LAKE MOULTRIE, SC THE TEMPERATURE IS IN THE MID
30S. ADDITIONALLY SOME LIGHT DRIZZLE HAS BEEN REPORTED OVER THE
CHARLESTON TRI-COUNTY. TEMPERATURES ARE ABOVE FREEZING, HOWEVER
SOME LIGHT SNOW FLURRIES HAVE BEEN REPORTED IN ORANGEBURG COUNTY
JUST INLAND OF THE FORECAST AREA. THE FORECAST MENTIONS LIGHT
DRIZZLE THROUGH THE NEXT FEW HOURS, AND SOME STRAY SNOW FLURRIES
CANNOT BE RULED OUT IN COOLER LOCATIONS. AS THE EVENING
PROGRESSES CLOUD COVER SHOULD CONTINUE TO ERODE OVER THE ENTIRE
FORECAST AREA, WITH ALL LOCATIONS CLEAR BY AROUND MIDNIGHT.
TEMPERATURES TONIGHT WILL BE CHILLY AS THE ARCTIC HIGH PRESSURE
CONTINUES TO ADVECT COLD AIR INTO THE REGION. UNDER CAA AND CLEAR
SKIES TEMPERATURES WILL DROP INTO THE 20S, WHICH COMBINED WITH A
LIGHT BREEZE WILL YIELD APPARENT TEMPERATURES IN THE UPPER TEENS. A
COLD WEATHER ADVISORY IS IN EFFECT FOR THE ENTIRE FORECAST AREA FROM
10 PM TONIGHT THROUGH TOMORROW MORNING.
SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/
FRIDAY THROUGH SUNDAY: COLD AND DRY HIGH PRESSURE WILL PREVAIL
ACROSS THE AREA ON FRIDAY. OTHER THAN SOME THIN CIRRUS SPREADING IN
FROM THE WEST IN THE AFTERNOON, MOSTLY CLEAR SKIES ARE EXPECTED.
DESPITE PLENTY OF SUN, TEMPERATURES WILL BE QUITE CHILLY AND ON THE
ORDER OF 15-20 DEGREES BELOW NORMAL. HIGHS ARE EXPECTED TO TOP OUT
IN THE MID TO UPPER 40S ACROSS SOUTHEAST SC AND NEAR 50 FOR
SOUTHEAST GA. FRIDAY NIGHT WILL BE ANOTHER VERY COLD NIGHT, THOUGH
NOT AS COLD AS THURSDAY NIGHT. LOWS IN THE MID TO UPPER 20S ARE
FORECAST BUT THE LACK OF WIND WILL KEEP WIND CHILLS UP AND NO COLD
WEATHER ADVISORY IS EXPECTED. THE HIGH WILL BRIDGE ACROSS THE
APPALACHIANS AND EVENTUALLY OFF THE EAST COAST SATURDAY AND SATURDAY
NIGHT. A SURFACE LOW IS EXPECTED TO DEVELOP OFF THE SOUTHEAST COAST
SATURDAY NIGHT, BUT ANY PRECIPITATION ASSOCIATED WITH IT WILL REMAIN
OFFSHORE. TEMPERATURES WILL START TO REBOUND, BUT REMAIN BELOW
NORMAL, WITH HIGHS GETTING UP INTO THE UPPER 50S FOR PORTIONS OF THE
AREA. QUIET CONDITIONS THEN CONTINUE INTO SUNDAY WARMING BACK CLOSER
TO NORMAL. LOOK FOR HIGHS IN THE LOW TO MID 60S.
LONG TERM /MONDAY THROUGH THURSDAY/
A SYSTEM IS EXPECTED TO PASS BY TO THE SOUTH ACROSS THE GULF SUNDAY
NIGHT AND MONDAY. WHILE MOST OF THE PRECIPITATION ASSOCIATED WITH IT
WILL REMAIN DISPLACED TO THE SOUTH, THERE IS SOME MODEL SUPPORT FOR
RAIN TO EXTEND UP TO ALONG THE GA COAST. THE FORECAST ADVERTISES 20
PERCENT CHANCES ALONG THE GA COAST AND THE ADJACENT COASTAL
WATERS. THEREAFTER, DRY CONDITIONS WILL PREVAIL WITH MODERATING
TEMPERATURES. WE COULD BE BACK TO NEAR NORMAL BY MONDAY WITH LOW
TO MID 70S POSSIBLE THROUGH MID WEEK.
AVIATION /20Z THURSDAY THROUGH TUESDAY/
KCHS/KJZI: BOTH TERMINALS WILL INITIALIZE WITH MVFR CIGS AS
CLOUD COVER REMAINS PERSISTENT ACROSS THE AREA DESPITE THE
DOWNSLOPE FLOW. CONDITIONS SHOULD RETURN TO VFR LATER THIS
AFTERNOON, WITH SKC EXPECTED BY MIDNIGHT. SOME GUSTY NW WINDS
ARE POSSIBLE THIS AFTERNOON AS WELL, WANING AROUND NIGHTFALL.
KSAV: THE 18Z TAF WILL FEATURE VFR CONDITIONS THROUGHOUT, WITH
SOME GUSTY NW WINDS THIS AFTERNOON WANING BY NIGHTFALL. SKC IS
EXPECTED BY MIDNIGHT.
EXTENDED AVIATION OUTLOOK: VFR CONDITIONS ARE EXPECTED TO
PREVAIL.
MARINE
TONIGHT: GUSTY NW WINDS WILL PERSIST ACROSS THE WATERS AS HIGH
PRESSURE BUILDS INTO THE REGION FROM THE WEST. GUSTS ARE
FORECAST TO RANGE BETWEEN 25 TO 30 KTS ACROSS THE CHARLESTON
COUNTY NEARSHORE AND OUTER GA WATERS. SEAS WILL RANGE BETWEEN 3
TO 6 FT. SMALL CRAFT ADVISORIES WILL REMAIN IN EFFECT TO
HIGHLIGHT THE WIND AND WAVE HEIGHTS.
FRIDAY THROUGH TUESDAY: NORTHERLY WINDS WILL PEAK FRIDAY MORNING
THEN STEADILY DIMINISH THROUGH THE DAY AS THE PRESSURE GRADIENT
RELAXES. AS CONDITIONS IMPROVE, THE ONGOING SMALL CRAFT ADVISORIES
FOR THE CHARLESTON COUNTY WATERS AND THE OUTER GA WATERS WILL COME
TO AN END. WINDS AND SEAS WILL THEN REMAIN WELL BELOW ADVISORY
THRESHOLDS THROUGH EARLY NEXT WEEK.
CLIMATE
RECORD LOW MAXIMUM TEMPERATURES:
FEBRUARY 21:
KCHS: 47/2020
RECORD LOW TEMPERATURES:
FEBRUARY 21:
KCHS: 22/1958
CHS WATCHES/WARNINGS/ADVISORIES
GA...COLD WEATHER ADVISORY FROM 10 PM THIS EVENING TO 10 AM EST
FRIDAY FOR GAZ087-088-099>101-114>119-137>141.
SC...COLD WEATHER ADVISORY FROM 10 PM THIS EVENING TO 10 AM EST
FRIDAY FOR SCZ040-042>045-047>052.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST FRIDAY FOR AMZ350.
SMALL CRAFT ADVISORY UNTIL 5 PM EST FRIDAY FOR AMZ374.
NEAR TERM...CPM
SHORT TERM...BSH
LONG TERM...BSH
AVIATION...BSH/CPM
MARINE...BSH/CPM
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