802
FXUS62 KCHS 151411
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
911 AM EST WED JAN 15 2025
SYNOPSIS
HIGH PRESSURE WILL PREVAIL THROUGH THE WEEK. A LOW PRESSURE
SYSTEM AND ASSOCIATED COLD FRONT WILL IMPACT THE REGION THIS
WEEKEND. ANOTHER LOW PRESSURE SYSTEM COULD IMPACT THE REGION
EARLY TO MID NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
TODAY: A WEAK BACKDOOR COLD FRONT WILL DISSIPATE NEAR THE
SAVANNAH RIVER TODAY AS HIGH PRESSURE OVER THE OHIO VALLEY NOSES
DOWN THROUGH THE CAROLINA PIEDMONT AND COASTAL PLAIN. VARIOUS
DEGREES OF CIRRUS WILL GRADUALLY DIMINISH THROUGH DAY WITH DRY
CONDITIONS PREVAILING. HIGHS WILL RANGE FROM THE UPPER 40S/LOWER
50S ACROSS SOUTHEAST SOUTH CAROLINA TO THE MID-UPPER 50S ACROSS
SOUTHEAST GEORGIA. NO MAJOR CHANGES WERE MADE FOR THE MID-
MORNING UPDATE.
TONIGHT: NEAR TERM GUIDANCE INDICATES THAT A SHORT-WAVE
TROUGH WILL RIPPLE EAST OF THE SOUTHERN APPALACHIANS LATE
TONIGHT, REACHING THE GA/SC COAST AROUND 12Z THURSDAY. NAM12
SHOWS A BELT OF H5 VORTICITY ADVANCING ACROSS THE CWA LATE
TONIGHT. AS A RESULT, CLOUD COVER SHOULD GRADUALLY INCREASE
TONIGHT, ESPECIALLY ACROSS SE GA. A WEAK PRESSURE GRADIENT
SHOULD ALLOW WINDS TO WEAKEN BELOW 5 MPH LATE TONIGHT. AREAS
UNDER THE THICK CLOUD COVER SHOULD FAVOR LOWS IN THE MID TO
UPPER 30S, WITH VALUES AROUND 30 DEGREES ARE POSSIBLE OVER
INLAND SC.
SHORT TERM /THURSDAY THROUGH SATURDAY/
THURSDAY AND FRIDAY: A DRY COLD FRONT WILL PUSH THROUGH THE REGION
ON THURSDAY AS A SHORTWAVE TROUGH RIPPLES OVER THE SOUTHEASTERN
STATES ALOFT. FRIDAY HIGH PRESSURE WILL BUILD INTO THE REGION,
CENTERED OVER THE SOUTHEASTERN STATES AS ZONAL FLOW DEVELOPS ALOFT.
BOTH DAYS WILL FEATURE RAIN-FREE CONDITIONS ALONG WITH PLENTIFUL
SUNSHINE. HIGH TEMPERATURES WILL RETURN TO NEAR NORMAL VALUES, WITH
DAYTIME HIGHS IN THE UPPER 50S TO AROUND 60 AND OVERNIGHT LOWS IN
THE 30S INLAND AND AROUND 40 AT THE COAST.
FRIDAY NIGHT INTO SATURDAY: THE QUIET WEATHER PATTERN WILL BEGIN TO
CHANGE ON FRIDAY NIGHT AS CLOUDS BEGIN TO INCREASE AHEAD OF THE NEXT
APPROACHING COLD FRONT. LARGE SCALE TROUGHING WILL DEVELOP ALOFT
FRIDAY NIGHT AND PERSIST INTO SATURDAY AS THE COLD FRONT APPROACHES.
MODELS ARE IN FAIRLY GOOD AGREEMENT ON A PERIOD OF SHOWERS PUSHING
THROUGH THE REGION ON SATURDAY, WITH THE HEAVIEST PRECIPITATION IN
THE AFTERNOON HOURS. MODELS ARE DEPICTING PWAT VALUES SURGING TO
AROUND 1.4" ON SATURDAY AFTERNOON, WHICH WOULD RIVAL THE DAILY
MAXIMUM ACCORDING TO SPC CLIMATOLOGY. RAINFALL TOTALS ARE GENERALLY
BETWEEN 0.75" AND 1" THROUGH SATURDAY EVENING. TEMPERATURES ON
SATURDAY ARE FORECAST TO BE IN THE UPPER 50S TO NEAR 60.
LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/
THE ACTIVE PATTERN WILL CONTINUE THROUGH THE REMAINDER OF THE
WEEKEND AS BROAD TROUGHING PERSISTS OVER THE EASTERN HALF OF THE
CONUS. SHOWERS WILL PERSIST THROUGH SATURDAY NIGHT AND INTO SUNDAY
AFTERNOON, ASSOCIATED WITH THE AFOREMENTIONED COLD FRONT. HIGH
TEMPERATURES ON SUNDAY WILL LIKELY REACH INTO THE LOW 60S BEFORE
PLUMMETING INTO THE 30S OVERNIGHT POST FROPA.
AFTER SUNDAY THE FORECAST BECOMES VERY UNCERTAIN AS THERE ARE VAST
RUN-TO-RUN DIFFERENCES. ALL GUIDANCE DOES POINT TO AN ANOMALOUSLY
DEEP UPPER LEVEL TROUGH OVER A LARGE PORTION OF THE CONUS, ALONG
WITH A VERY COLD ARCTIC AIRMASS AT THE SURFACE. A LOW PRESSURE SYSTEM
COULD DEVELOP OFF THE SOUTHEASTERN COAST EARLY TO MID NEXT WEEK,
BRINGING PRECIPITATION TO THE FORECAST AREA. THE COMBINATION OF THE
ARCTIC AIRMASS AND THE POSSIBLE PRECIPITATION YIELDS THE POTENTIAL
FOR WINTER WEATHER. AT THIS JUNCTURE, MODEL GUIDANCE DOES SUGGEST A
THREAT OF WINTER WEATHER ACROSS THE FORECAST AREA. HOWEVER, AN ABOVE
NORMAL AMOUNT OF UNCERTAINTY EXISTS REGARDING VERY IMPORTANT
FORECAST DETAILS SUCH AS POSSIBLE PRECIPITATION TYPES AND AMOUNTS,
TIMING, AND SPECIFIC IMPACTED AREAS.
AVIATION /14Z WEDNESDAY THROUGH SUNDAY/
12Z TAFS: HIGH PRESSURE WILL REMAINED RIDGED ACROSS THE
TERMINALS THROUGH THE TAF PERIOD. A DRY BACKDOOR COLD FRONT IS
TIMED TO PUSH SOUTH ACROSS THE TERMINALS THIS MORNING,
RESULTING IN WINDS TO SHIFT FROM THE NORTH. SOME DEGREE OF MID
TO HIGH CLOUDS WILL CONTINUE TO STREAM ACROSS THE TERMINALS
THROUGH THE PERIOD.
EXTENDED AVIATION OUTLOOK: VFR CONDITIONS ARE EXPECTED TO
PREVAIL THROUGH THE END OF THE WEEK. A FRONT IS EXPECTED TO
BEGIN IMPACTING THE AREA SATURDAY, BRINGING THE POTENTIAL FOR
SHOWERS AND BRIEF PERIODS OF FLIGHT RESTRICTIONS.
MARINE
TODAY: WINDS ARE STILL GUSTING AROUND 25 KT OFF THE CHARLESTON
COUNTY COAST BEHIND A WEAK BACKDOOR COLD FRONT. IT WILL LINGER A
BIT LONGER THAN EXPECTED, SO THE SMALL CRAFT ADVISORY FROM
SOUTH SANTEE-EDISTO BEACH OUT 20 NM HAS BEEN EXTENDED UNTIL
NOON. WINDS WILL GRADUALLY DIMINISH OVER ALL WATERS THROUGH THE
DAY.
TONIGHT: HIGH PRESSURE IS FORECAST TO INCREASE ACROSS THE
MARINE ZONES TONIGHT, DECREASING THE PRESSURE GRADIENT. WINDS
SHOULD SETTLE BETWEEN 5 TO 10 KTS WITH SEAS BETWEEN 1 TO 2 FT.
THURSDAY THROUGH MONDAY: A DRY COLD FRONT WILL PUSH THROUGH THE
WATERS ON THURSDAY, WITH HIGH PRESSURE BUILDING IN ON FRIDAY.
THURSDAY NIGHT COULD FEATURE A SHORT TIME PERIOD OF 25 KNOT GUSTS
ACROSS THE CHARLESTON NEARSHORE WATERS AND THE 20 TO 60 NM OFFSHORE
GA WATERS, POSSIBLY NECESSITATING A SHORT-LIVED SMALL CRAFT
ADVISORY. NW WINDS ARE FORECAST TO WANE INTO FRIDAY WITH 10 TO 15
KNOTS BY FRIDAY AFTERNOON. A COLD FRONT WILL PUSH THROUGH THE REGION
THIS WEEKEND, HOWEVER WINDS ARE FORECAST TO REMAIN BELOW SMALL CRAFT
ADVISORY CRITERIA. SEAS THROUGH FRIDAY ARE FORECAST TO AVERAGE 2 TO
4 FT, INCREASING TO 3 TO 5 OVER THE WEEKEND AS THE COLD FRONT PUSHES
THROUGH.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 12 PM EST THIS AFTERNOON FOR AMZ350.
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