939
FXUS62 KCHS 150552
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1252 AM EST WED JAN 15 2025
SYNOPSIS
HIGH PRESSURE WILL PREVAIL THROUGH THE WEEK. ANOTHER LOW
PRESSURE SYSTEM AND ASSOCIATED COLD FRONT WILL IMPACT THE
REGION THIS WEEKEND.
NEAR TERM /THROUGH TODAY/
AFTER MIDNIGHT, IR SATELLITE SHOWED A BAND OF HIGH CLOUDS
PASSING OVER THE FORECAST AREA. BASED ON SATELLITE TRENDS, SKY
CONDITIONS WILL REMAIN AT LEAST PARTLY CLOUDY, WITH PERIODS OF
MOSTLY CLOUDY CONDITIONS. THE FORECAST UPDATE WILL INCREASE SKY
COVER AND ALIGN HOURLY TEMPERATURES WITH RECENT OBSERVATIONS.
A ZONAL FLOW WILL PREVAIL ALOFT, WHILE A BROAD POSITIVELY
TILTED TROUGH IS FOUND DROPPING THROUGH THE NORTHERN AND CENTRAL
STATES. AT THE SURFACE, HIGH PRESSURE WILL EDGE INTO THE AREA
FROM THE NORTHWEST, PRECEDED BY A WEAK TROUGH THAT PUSHES
THROUGH DURING THE OVERNIGHT HOURS. MEANWHILE, MID AND HIGH
LEVEL CLOUDS WILL CONTINUE TO ADVANCE INTO THE LOCAL AREA FROM
THE WEST AND SOUTHWEST IN ASSOCIATION WITH A POWERFUL 185-195 KT
UPPER JET MOVING OFF NOT FAR TO OUR NORTH. THE AMOUNT AND
THICKNESS OF THESE CLOUDS WILL PLAY A HUGE ROLE IN LOW
TEMPERATURES, AS WILL THE TIMING OF A 25-30 KT LOW LEVEL JET
THAT COMES THROUGH. WE EXPECT THERE TO BE ADJUSTMENTS IN THE
HOURLY TEMPERATURE CURVE, BUT IN GENERAL LOWS WILL BE DOWN IN
THE LOWER AND MIDDLE 30S INLAND (SOME UPPER 20S IN BERKELEY
COUNTY AND MAYBE FAR NORTHERN DORCHESTER), WITH UPPER 30S CLOSER
TO THE OCEAN. WE'LL NEED TO KEEP AN EYE ON WINDS ACROSS LAKE
MOULTRIE, WHERE THERE WILL CERTAINLY BE SOME GUSTS CLOSE TO
ADVISORY LEVELS. BUT IT LOOKS TOO MARGINAL TO HOIST A LAKE WIND
ADVISORY.
SHORT TERM /TONIGHT THROUGH FRIDAY/
WEDNESDAY THROUGH FRIDAY: THE PERIOD WILL BEGIN WITH A DRY COLD
FRONT PASSING THROUGH THE AREA FROM NORTH TO SOUTH WEDNESDAY
MORNING, BRINGING A SHOT OF SOME COOLER AIR. THEN AS WE MOVE FROM
THURSDAY INTO FRIDAY HIGH PRESSURE WILL SPREAD IN FROM THE WEST AND
LIKELY BE POSITIONED RIGHT ON TOP OF THE AREA BY FRIDAY MORNING. DRY
WEATHER WILL PREVAIL, WITH PRECIPITABLE WATER VALUES LESS THAN HALF
AN INCH THROUGH THE PERIOD. TEMPERATURES WILL BE COOLEST ON
WEDNESDAY, WITH HIGHS RANGING FROM THE UPPER 40S AND LOW 50S ACROSS
SOUTHEAST SC TO THE MID AND EVEN UPPER 50S FOR SOUTHEAST GA.
THURSDAY AND FRIDAY WILL BE THE WARMER DAYS, WITH HIGHS STILL BELOW
NORMAL BUT ACTUALLY RISING INTO THE UPPER 50S AND POSSIBLY EVEN LOW
60S FOR SOME AREAS ALONG AND SOUTH OF I-16 IN GA. LOWS WILL BE
COLDEST WEDNESDAY NIGHT, WITH WIDESPREAD UPPER 20S AND LOW 30S.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
A CONSIDERABLY MORE ACTIVE PERIOD IS EXPECTED TO COMMENCE THIS
WEEKEND WITH THE PASSAGE OF A COLD FRONT SATURDAY NIGHT INTO SUNDAY.
THE SUITE OF MODEL SOLUTIONS DEPICT A HEALTHY FRONTAL BAND PUSHING
INTO THE AREA FROM THE WEST SATURDAY MORNING WITH PRECIPITATION
POTENTIAL LINGERING INTO SUNDAY MORNING. WIDESPREAD SIGNIFICANT
RAINFALL AMOUNTS WILL BE POSSIBLE, WITH POTENTIAL TOTALS OF 0.75-
1.50" FOR THE ENTIRE WEEKEND. THEN BEHIND THIS FRONT, THERE IS
WIDESPREAD AGREEMENT THAT AN IMPRESSIVE ARCTIC HIGH WILL SPILL A
BITTERLY COLD AIRMASS ACROSS MUCH OF THE CONUS WITH HIGH
PROBABILITIES FOR WELL BELOW NORMAL TEMPERATURES.
ATTENTION THEN TURNS TO THE VERY END OF THE FORECAST PERIOD WHERE
THERE IS INCREASING CONFIDENCE IN A WIDESPREAD PRECIPITATION EVENT
IN ASSOCIATION WITH A COASTAL LOW TRACK, POTENTIALLY BEGINNING AS
EARLY AS TUESDAY. THIS EVENT WOULD BE UNFOLDING IN THE PRESENCE OF
THE ARCTIC AIRMASS NOTED ABOVE, YIELDING THE POTENTIAL FOR WINTER
WEATHER. MODEL GUIDANCE, BOTH OF THE DETERMINISTIC AND ENSEMBLE
VARIETY, SUGGESTS A THREAT OF WINTER WEATHER FOR THE FORECAST AREA
AND THE REGION AS A WHOLE. IT MUST BE STRESSED THAT CONSIDERABLE
UNCERTAINTY REMAINS, ESPECIALLY REGARDING SUCH IMPORTANT ITEMS AS
POSSIBLE PRECIPITATION TYPES, POSSIBLE PRECIPITATION AMOUNTS, AND
SPECIFIC IMPACTED AREAS.
AVIATION /06Z WEDNESDAY THROUGH SUNDAY/
6Z 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 EARLY 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
OVERNIGHT: SURFACE HIGH PRESSURE BUILDS DOWN INTO THE SOUTHEAST
REGION THROUGH THE PERIOD. THIS WILL RESULT IN A TIGHTER
PRESSURE GRADIENT ACROSS THE COASTAL WATERS. THIS OCCURS IN
TANDEM WITH SMALL ISALLOBARIC PRESSURE CLIMBS AND SOME COLD
ADVECTION THAT DEVELOPS BEHIND A SURFACE TROUGH FROM THE NORTH.
THIS TURNS WINDS TO THE NW AND INCREASES THEM UP NEAR 15-20 OR
EVEN 20 KT, WITH STRONGER GUSTS. THE HIGHER PROBABILITIES OF
THE GUSTS OF 25 KT OR MORE WILL OCCUR ON THE CHARLESTON COUNTY
ATLANTIC WATERS, WHERE WE HAVE HOISTED A SMALL CRAFT ADVISORY.
THE OTHER WATERS WILL BE CLOSE, BUT CURRENTLY THE SITUATION
LOOKS TO MARGINAL FOR AN ADVISORY. SEAS WILL BE LIMITED
SOMEWHAT BY THE OFFSHORE FETCH, BUT STILL ENOUGH TO GET 2-4
FEET WITHIN 20 NM AND UP TO 3-5 FEET FURTHER OUT.
WEDNESDAY THROUGH SUNDAY: MARINE CONDITIONS WILL IMPROVE ON
WEDNESDAY AS WINDS DIMINISH, ESPECIALLY LATE MORNING AND
AFTERNOON. THE NEXT PERIOD OF STRONG WINDS WILL COME THURSDAY
AND THURSDAY NIGHT WHEN CONDITIONS COULD APPROACH SMALL CRAFT
ADVISORY THRESHOLDS, ESPECIALLY IN THE CHARLESTON COUNTY WATERS
AND THE OUTER GA WATERS. FINALLY, A COLD FRONT IS EXPECTED TO
PASS THROUGH THE WATERS THIS WEEKEND. WINDS AND SEAS WILL
INCREASE SATURDAY FIRST IN SOUTHERLY AHEAD OF THE FRONT,
FOLLOWED BY WESTERLY FLOW BEHIND IT ON SUNDAY. SMALL CRAFT
ADVISORY CONDITIONS DON'T LOOK PARTICULARLY LIKELY BUT CAN'T BE
RULED OUT AT THIS TIME.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR AMZ350.
NEAR TERM...NED
SHORT TERM...BSH
LONG TERM...BSH
AVIATION...NED
MARINE...
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page