413
FXUS62 KCHS 050620
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
120 AM EST FRI DEC 5 2025
SYNOPSIS
A FRONTAL SYSTEM WILL MAINTAIN UNSETTLED WEATHER THROUGH EARLY
NEXT WEEK, THEN COLD HIGH PRESSURE WILL BUILD IN.
NEAR TERM /THROUGH TONIGHT/
SATELLITE WATER VAPOR SHOWED A THICK BAND OF DEEP MOISTURE
EXTENDING FROM THE FORECAST AREA SOUTHWEST TO A CLOSED LOW OFF
THE COAST OF BAJA. THE STREAM OF MOISTURE SHOULD CONTINUE
THROUGH THE DAY, PWS INCREASING TO 1.6 TO 1.8 INCHES BY THIS
AFTERNOON. THE H5 HEIGHTS WILL REMAIN ORIENTED FROM SW TO NE
ACROSS THE REGION, WITH A SERIES OF VORT MAXES TRACKING ACROSS
THE CWA THROUGH THE NEAR TERM PERIOD. AT THE SFC, A 1025 MB HIGH
CENTERED OVER THE COAST OF NEW ENGLAND WILL LIKELY SURGE SW
OVER THE FORECAST AREA TODAY, REINFORCED BY PERSISTENT RAINFALL
FALLING ACROSS THE SOUTHEAST U.S. HIGH RESOLUTION GUIDANCE
INDICATES THAT THE WEDGE FRONT WILL SLIP OFF THE SC/GA COAST BY
DAYBREAK THIS MORNING. A FRONTAL WAVE MAY FORM OVER THE FRONT
THIS MORNING, TRACKING NE ALONG THE WEDGE FRONT AND SLOWLY
DEEPEN OFF THE COAST OF SC. AS THE LOW DEVELOPS AND DEPARTS, A
THICK BAND OF 925-850MB FRONTOGENESIS SHOULD FORM ACROSS SE
GA/SC LATE THIS MORNING, PUSHING EAST ACROSS THE CWA THROUGH
THIS AFTERNOON. RAINFALL TOTALS DURING THE DAYLIGHT HOURS ARE
FORECAST TO RANGE BETWEEN .5-.75 INCHES. GIVEN STEADY NORTH
WINDS, THICK CLOUDS, AND ROUNDS OF MODERATE RAINFALL,
TEMPERATURES SHOULD REMAIN GENERALLY STEADY IN THE LOW TO MID
50S.
TONIGHT, THE ASSOCIATED COLD FRONT WILL PUSH EAST OFF THE COAST
DURING THE OVERNIGHT HOURS. WEST-SOUTHWEST FLOW ALOFT WILL MAINTAIN
DEEP MOISTURE ACROSS THE REGION. SLOW HEIGHT FALLS AND ROUNDS OF
UPPER DIVERGENCE SHOULD SUPPORT A BROAD AREA OF LIGHT RAINFALL
TONIGHT. OVERNIGHT RAINFALL MAY REMAIN A 0.25" OR LESS ACROSS THE
FORECAST AREA. LOW TEMPERATURES ARE FORECAST TO RANGE IN THE 40S,
WITH THE COOLEST READINGS IN THE LOW 40S SURROUNDING LAKE MOULTRIE.
SHORT TERM /SATURDAY THROUGH MONDAY/
THE SOUTHEAST WILL REMAIN ON THE EASTERN PERIPHERY OF A BROAD
LONGWAVE UPPER TROUGH SATURDAY THROUGH MONDAY. AT THE SURFACE, A
QUASI-STATIONARY FRONTAL BOUNDARY WILL REMAIN NEAR THE SC/GA
COAST. A SERIES OF SHORTWAVES EMBEDDED IN THE MEAN FLOW WILL
LIFT NORTHEAST THROUGH THE AREA DURING THE PERIOD, BRINGING
PERIODS OF LIGHT TO MODERATE RAIN. AT THIS POINT IT SEEMS THAT
THE BEST CHANCES FOR RAIN WILL BE DURING THE DAYTIME PERIODS.
MOST AREAS SHOULD SEE WIDESPREAD LIGHT TO MODERATE RAIN
SATURDAY, TAPERING OFF SATURDAY EVENING. THEN ANOTHER BATCH OF
RAIN MOVES IN FROM THE SOUTHWEST LATE SUNDAY MORNING,
CONTINUING THROUGH THE AFTERNOON. A FINAL ROUND OF SHOWERS WILL
MOVE THROUGH ON MONDAY AS THE MAIN UPPER SHORTWAVE LIFTS
NORTHEAST. HIGH PRESSURE WELL NORTH OF THE AREA WILL MAINTAIN
WEAK COLD ADVECTION. THIS, IN CONCERT WITH OVERCAST SKIES
THROUGH THE PERIOD, WILL KEEP HIGH TEMPERATURES GENERALLY IN THE
50S AND LOWS IN THE 40S. THE RAINFALL WILL NOT BE PARTICULARLY
HEAVY (3-DAY TOTALS GENERALLY LESS THAN 0.75"), WHICH SHOULD
MINIMIZE FLOODING CONCERNS.
LONG TERM /MONDAY NIGHT THROUGH THURSDAY/
COOL, DRY HIGH PRESSURE WILL BUILD IN FROM THE WEST MONDAY
NIGHT. OVERNIGHT LOWS WILL DIP BELOW FREEZING IN MANY AREAS AWAY
FROM THE COAST MONDAY NIGHT AND TUESDAY NIGHT. DAYTIME HIGHS
SHOULD PUSH BACK INTO THE 60S FOR MOST AREAS BY WEDNESDAY.
AVIATION /06Z FRIDAY THROUGH TUESDAY/
6Z TAFS: THE LEADING EDGE OF COLD AIR DAMMING WILL SPREAD ACROSS
THE TERMINALS AROUND DAYBREAK. NORTH WINDS SHOULD GENERALLY
REMAIN, SPEEDS BETWEEN 5 TO 10 KTS THROUGH THE TAF PERIOD.
DEEP FORCING AND MOISTURE SHOULD YIELD WIDESPREAD MODERATE
RAINFALL ACROSS THE REGION THROUGH MUCH OF THE DAY. FORECAST
SOUNDINGS INDICATE THAT CLOUD BASSES WILL GRADUALLY LOWERS
THROUGH THE DAY, REACHING IFR TO LIFR BY LATE THIS MORNING.
LINGERING CAD TONIGHT MAY YIELD SOME STRATUS BUILD DOWN,
HOWEVER, ONGOING RAINFALL MAY KEEP THE BL MIXED ENOUGH TO LIMIT
AND FOG FORMATION. EACH TAF WILL HIGHLIGHT THE POTENTIAL FOR
CEILINGS FALLING BELOW 500 FT.
EXTENDED AVIATION OUTLOOK: A RELATIVELY PROLONGED PERIOD OF
CEILING RESTRICTIONS EXPECTED SATURDAY THROUGH MONDAY.
PREVAILING MVFR WITH PERIODS OF IFR ARE EXPECTED. PERIODS OF
RAIN COULD OCCASIONALLY REDUCE VISIBILITIES AS WELL. IMPROVING
CONDITIONS LATER MONDAY OR MONDAY NIGHT.
MARINE
TODAY AND TONIGHT: AN AREA OF LOW PRESSURE IS EXPECTED TO DEVELOP
OVER THE MARINE ZONES THIS MORNING, TRACKING OFF TO THE NORTHEAST
THIS AFTERNOON. LIGHT WINDS WILL VARY DIRECTIONS THIS MORNING AS THE
LOW DEVELOPS. AS THE LOW DEPARTS, WINDS SHOULD SHIFT FROM THE NNW
WITH SPEEDS INCREASING TO AROUND 10 KTS. A BAND OF MODERATE SHOWERS
WITH ISOLATED EMBEDDED THUNDERSTORMS SHOULD PUSH ACROSS THE WATERS
LATE THIS AFTERNOON AND EVENING. RAINFALL RATES WITHIN THE RAIN BAND
MAY LIMIT VISIBILITY TO 2 SM OR LESS AT TIMES. WAVE HEIGHTS ARE
FORECAST TO RANGE BETWEEN 2-4 FT TODAY, DECREASING TO 2-3 FT
TONIGHT.
A BRIEF PERIOD OF MARGINAL SMALL CRAFT ADVISORY CONDITIONS
POSSIBLE FOR THE CHARLESTON NEARSHORE AND GA OFFSHORE WATERS
MONDAY AFTERNOON INTO MONDAY NIGHT. ANOTHER ROUND OF MARGINAL
ADVISORY CONDITIONS POSSIBLE WEDNESDAY NIGHT AND THURSDAY.
TIDES/COASTAL FLOODING
A COASTAL FLOOD ADVISORY HAS BEEN POSTED FOR CHARLESTON AND COASTAL
COLLETON COUNTIES UNTIL 9 AM THIS MORNING. OBSERVATION TRENDS AND
RECENT GUIDANCE INDICATES THAT TIDE LEVELS SHOULD PEAK BETWEEN 7.3-
7.4 FT MLLW. HIGH TIDE SHOULD OCCUR AROUND 7:43 AM.
FURTHER SOUTH, FROM BEAUFORT COUNTY THROUGH THE SOUTHEAST
GEORGIA COAST, HIGH TIDE SHOULD PEAK BELOW FLOOD STAGE AROUND
9.3 FT MLLW.
ASTRONOMICAL TIDES WILL REMAIN ELEVATED THROUGH THE WEEKEND.
COASTAL FLOOD ADVISORIES COULD BE NEEDED FOR MORNING HIGH TIDE
CYCLES, PRIMARILY AT CHARLESTON HARBOR (CHARLESTON AND COASTAL
COLLETON COUNTIES) THROUGH SUNDAY MORNING.
CLIMATE
RECORD PRECIPITATION:
DECEMBER 7:
KCHS: 1.14/1976
KCXM: 0.82/1976
KSAV: 0.79/2017
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...COASTAL FLOOD ADVISORY FROM 6 AM TO 9 AM EST THIS MORNING FOR
SCZ049-050.
MARINE...NONE.
NEAR TERM...NED
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...JRL/NED
MARINE...JRL/NED
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