363
FXUS62 KCHS 151723
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1223 PM EST MON DEC 15 2025
SYNOPSIS
COLD CONDITIONS WILL CONTINUE INTO TUESDAY. HIGH PRESSURE WILL
PREVAIL THROUGH THURSDAY BEFORE A COLD FRONT PUSHES OFFSHORE
FRIDAY.
NEAR TERM /THROUGH TONIGHT/
AS THE SURFACE HIGH PRESSURE CONTINUES TO BUILD INTO THE SOUTHEAST,
TEMPERATURES WILL REMAIN WELL BELOW NORMAL. THEY WILL HOWEVER BE A
FEW DEGREES WARMER THAN THE RECORD LOW MAXIMUM TEMPERATURES FOR
TODAY (39 FOR CHS, AND 38 FOR BOTH CXM AND SAV), AS HIGH
TEMPERATURES TODAY CREST IN THE LOWER TO MID 40S THANKS LARGELY TO
THE ABUNDANT SUNSHINE. WITH DEWPOINTS REMAINING IN THE UPPER SINGLE
DIGITS TO MID TEENS, RELATIVE HUMIDITY VALUES ARE EXPECTED TO
REMAIN/DROP IN THE UPPER TEENS TO LOWER 20S, THOUGH GIVEN THE WEAK
WINDS FIRE WEATHER CRITERIA IS NOT BEING MET, SO NO FIRE HEADLINES
ARE EXPECTED AT THIS TIME.
FOR TONIGHT, THE AXIS OF THE SURFACE HIGH PRESSURE WILL SLIDE ACROSS
THE AREA, CONTINUING TO WEAKEN OUR WINDS. WITH THE ALREADY COLD
TEMPERATURES IN PLACE AND CLEAR SKIES, RADIATIONAL COOLING WILL
BRING ANOTHER NIGHT OF FRIGID TEMPERATURES TO THE REGION. INLAND
AREAS ALONG AND WEST OF I-95 HAVE A 60-80% CHANCE OF REACHING AT OR
BELOW 20 DEGREES TONIGHT WITH THE COLDEST TEMPERATURES IN THE MID
TEENS, SO HAVE ISSUED A COLD WEATHER ADVISORY FOR THE IMPACTED
LOCATIONS GIVEN THE EXPECTED COLD TEMPERATURES. NOTE, WHILE WINDS
ARE EXPECTED TO BE WEAK AND/OR CALM, ANY LIGHT PUFF OF WIND WILL
RESULT IN WIND CHILLS DOWN INTO THE LOWER TO MID TEENS. ELSEWHERE
EAST OF I-95, SURFACE TEMPERATURES WILL REMAIN WARM ENOUGH TO FORGO
ANY HEADLINES, WITH OVERNIGHT LOWS IN THE MID 20S TO LOWER 30S,
WARMEST ALONG THE COAST.
SHORT TERM /TUESDAY THROUGH THURSDAY/
TUESDAY AND WEDNESDAY: WEAK UPPER-LEVEL RIDGING WILL PASS ACROSS THE
AREA AS MODIFIED ARCTIC HIGH PRESSURE GRADUALLY PROPAGATES OFFSHORE
OF THE SOUTHEAST U.S COAST. THIS WILL BRING MODERATING TEMPERATURES
BOTH DAYS WITH RAIN-FREE CONDITIONS PREVAILING. HIGHS WILL WARM INTO
THE MID-UPPER 50S TUESDAY THEN WARM INTO THE LOWER-MID 60S
WEDNESDAY. IT IS POSSIBLE A WEAK RESULTANT SEA BREEZE COULD DEVELOP
ALONG THE BEACHES BOTH AFTERNOONS WITH WEDNESDAY AFTERNOON BEING THE
MOST PROBABLE. LOWS TUESDAY NIGHT WILL LIKELY BE DOMINATED BY STRONG
RADIATIONAL COOLING FOR MUCH OF THE NIGHT BEFORE HIGH CLOUDS
INCREASE FROM THE SOUTHWEST. LOWS WERE NUDGED DOWN SLIGHTLY FROM THE
15/13Z NBM GIVEN ITS WARM BIAS IN STRONG RADIATIONAL COOLING NIGHTS.
LOWS LOOK TO RANGE FROM THE UPPER 20S INLAND TO THE MID-UPPER 40S AT
THE BEACHES.
THURSDAY: RAIN CHANCES WILL BEGIN TO INCREASE THURSDAY AS A COASTAL
TROUGH DEVELOPS OFFSHORE AND SOUTHERN STREAM IMPULSES ASSOCIATED
WITH A STRENGTHENING SUBTROPICAL JET PASS THROUGH ALOFT. PWATS ARE
FORECAST TO RISE TO 1.25-1.50" SUGGESTING PLENTY OF MOISTURE WILL BE
AVAILABLE. THIS SYSTEM COULD YIELD SCATTERED TO POSSIBLY NUMEROUS
SHOWERS WITH A RUMBLE OR TWO OF THUNDER OCCURRING NEAR THE LOWER
SOUTH CAROLINA COAST. POPS WILL RANGE FROM 30-40% INLAND TO 50-60%
ACROSS THE NORTHERN GEORGIA COAST INTO THE CHARLESTON TRI-COUNTY
AREA, HIGHEST AT THE BEACHES. LOWS THURSDAY MORNING WILL DROP INTO
THE LOWER 40S INLAND WITH MID 50S AT THE BEACHES. AFTERNOON HIGHS
WILL TOP OUT IN THE UPPER 60S/LOWER 70S WITH COOLER CONDITIONS AT
THE BEACHES.
LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/
RAIN CHANCES WILL PERSIST INTO THURSDAY NIGHT WITH A CONTINUED RISK
FOR SCATTERED SHOWERS. A LARGE SHORTWAVE WILL DIG ACROSS THE EASTERN
CONUS FRIDAY, WHICH WILL PUSH A COLD FRONT ACROSS THE AREA. SOME
TIMING DIFFERENCES ARE NOTED WHICH COULD KEEP SOME DEGREE OF RAIN
CHANCES GOING INTO THE DAY, MAINLY THE MORNING HOURS IF THE SLOWER
FRONTAL TIMING VERIFIES. THE NBM IS A BIT DRIER AND FASTER WITH THE
FRONT SHOWING NO RAIN CHANCES DURING THE DAYTIME HOURS. THE NBM WAS
USED AS THE BASIS FOR THIS FORECAST CYCLE, BUT LATER CYCLES MAY NEED
TO INTRODUCE MENTIONABLE POPS IF THE FRONT TRENDS SLOWER LIKE SOME
GUIDANCE WOULD SUGGEST. THE POST FRONTAL COOL DOWN WILL BE BRIEF
WITH TEMPERATURES LIKELY TO MODERATE BACK TO ABOVE NORMAL LEVELS FOR
THE WEEKEND.
AVIATION /18Z MONDAY THROUGH SATURDAY/
18Z TAFS - VFR CONDITIONS. WIND DIRECTION CHANGES ARE THE PRIMARY
AVIATION CONCERN, THOUGH NO QUICK SHIFTS ARE EXPECTED. LOCALIZED
STEAM FOG NEAR OUR LOCAL WATERWAYS CANNOT BE RULED OUT BUT IS NOT
LOOKING SIGNIFICANT AT THIS TIME.
EXTENDED AVIATION OUTLOOK: THERE IS AN INCREASED RISK FOR MVFR OR
LOWER CEILINGS AND VISIBILITIES IN SHOWERS THURSDAY.
MARINE
THROUGH TONIGHT: NORTH-NORTHEASTERLY WINDS WILL CONTINUE TO SUBSIDE
THROUGHOUT THE AFTERNOON HOURS, ALLOWING FOR THE SEAS TO SIMILARLY
SUBSIDE. SMALL CRAFT ADVISORIES WILL THUS BE ALLOWED TO EXPIRE AS
CONDITIONS IMPROVE THIS AFTERNOON AND EVENING. SEAS OF 3 TO 4
FT CONTINUE INTO THE OVERNIGHT PERIOD, WITH WINDS REMAINING WEAK
OVERNIGHT AS THEY SLOWLY SHIFT TOWARDS BECOMING OUT OF THE
NORTH-NORTHWEST BY DAYBREAK.
TUESDAY THROUGH SATURDAY: THE PERIOD OF LARGEST CONCERN CENTERS ON
THURSDAY NIGHT INTO FRIDAY AHEAD OF A COLD FRONT. GUSTY SOUTHWEST
WINDS AND POSSIBLY SEAS ARE LIKELY TO APPROACH SMALL CRAFT ADVISORY
THRESHOLDS AS A MODEST PRE-FRONTL LOW-LEVEL JET TRAVERSES THE
REGION. SMALL CRAFT ADVISORY CONDITIONS ARE THE MOST LIKELY ACROSS
THE SOUTH SANTEE-EDISTO BEACH NEARSHORE AND GEORGIA OFFSHORE WATERS
WHERE WARMER SEA SURFACE TEMPERATURES COULD PROMOTE A BIT MORE
MIXING. LREF PROBABILITIES ARE CURRENTLY RUNNING 20-40% CURRENTLY FOR
WIND GUSTS >25 KT IN THESE AREAS.
CHS WATCHES/WARNINGS/ADVISORIES
GA...COLD WEATHER ADVISORY FROM 8 PM THIS EVENING TO 9 AM EST
TUESDAY FOR GAZ087-088-099>101-115-116.
SC...COLD WEATHER ADVISORY FROM 8 PM THIS EVENING TO 9 AM EST
TUESDAY FOR SCZ040-042>045-047.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST TUESDAY FOR AMZ374.
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
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