931
FXUS62 KCHS 261208
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
708 AM EST TUE JAN 26 2021
SYNOPSIS
A STORM SYSTEM WILL IMPACT THE REGION TODAY INTO WEDNESDAY,
BEFORE A STRONG COLD FRONT PUSHES OFFSHORE WEDNESDAY NIGHT.
HIGH PRESSURE WILL RETURN LATE WEEK, FOLLOWED BY ANOTHER COLD
FRONT EARLY NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
AS OF 7 AM: IR SATELLITE INDICATES STRATUS INCREASING FROM THE
WEST ACROSS THE FORECAST AREA. ALSO, A THIN AREA OF SEA FOG WAS
EVIDENT ALONG THE SC COAST. THE FORECAST UPDATE WILL FEATURE
FASTER ARRIVAL OF THE CLOUD COVER AND WILL CONTINUE A MENTION OF
PATCHY SEA FOG. OTHERWISE, TEMPERATURES WILL BEGIN THE DAY IN
THE 60S, STEADILY WARMING THROUGH EARLY THIS AFTERNOON.
AS OF 4 AM: LATEST IR SATELLITE DETECTED A LARGE SHIELD OF STRATUS
ADVANCING NE ACROSS GA. BASED ON SATELLITE TRENDS, THE LEADING EDGE
OF THE STRATUS SHOULD LIFT NORTH OF THE FORECAST AREA AROUND
DAYBREAK. CLOUD COVER IS FORECAST TO REMAIN MOSTLY CLOUDY TO CLOUDY
FOR THE REST OF THE DAY. TEMPERATURES ACROSS THE FORECAST AREA WILL
BEGIN THE DAY IN THE LOWER 60S. THE LOW LEVEL THERMAL PROFILES
SHOULD REMAIN VERY MILD AS RETURN FLOW STRENGTHENS AHEAD OF AN
APPROACHING COLD FRONT. HIGH TEMPERATURES ARE EXPECTED TO RANGE
WITHIN A DEGREE OR TWO OF VALUES REACHED YESTERDAY, GENERALLY UPPER
70S ACROSS GA AND MID 70S ACROSS THE SC LOWCOUNTRY. SEE CLIMATE
SECTION BELOW.
NEAR TERM GUIDANCE INDICATES THAT THE SFC COLD FRONT WILL APPROACH
FROM THE WEST THIS EVENING, THEN BECOMING STATIONARY OVER THE CWA
TONIGHT. A PRE-FRONTAL BAND OF CONVECTION SHOULD GRADUALLY WEAKEN AS
IT PUSHES EAST ACROSS GA/SC THIS MORNING. FADING SHOWERS MAY ARRIVE
OVER THE INLAND COUNTIES DURING THE DAYLIGHT HOURS THIS MORNING,
COVERAGE REMAINING ISOLATED TO SCATTERED. THIS EVENING, A AMPLIFIED
H5 TROUGH WILL RIPPLE EAST OVER THE SOUTHERN PLAINS. AT THE SFC, LOW
PRESSURE IS FORECAST TO ORGANIZE OVER THE DEEP SOUTH, TRACKING ENE
ALONG THE STATIONARY FRONT. AS THE LOW DEVELOPS AND APPROACHES, A
BAND OF FRONTOGENESIS WILL DEVELOP AND ALONG AND NORTH OF THE
STATIONARY FRONT. IN ADDITION, A BAND OF WEAK SBCAPE WILL LINGER
NEAR THE FRONT, WITH WEAK INSTABILITY PRESENT ACROSS SE GA AND THE
SC LOWCOUNTRY. HIGH RESOLUTION GUIDANCE SHOWS CLUSTERS OF SHOWERS
AND THUNDERSTORMS ARRIVING ACROSS SE GA THIS EVENING, ADVANCING
ACROSS THE LOWCOUNTRY DURING THE OVERNIGHT HOURS. USING THE
PLACEMENT AND TIMING OF THE SIMULATED REFLECTIVITY, I WILL SPREAD
CATEGORICAL POPS ALONG AND WEST OF THE I-95 CORRIDOR TONIGHT.
TEMPERATURES WILL WET-BULB DOWN TO THE LOW TO MID 60S LATE
TONIGHT.
SHORT TERM /WEDNESDAY THROUGH FRIDAY/
A STALLED COLD FRONT WILL BE POSITIONED OVER OR NEAR THE AREA AT THE
START OF THE PERIOD WEDNESDAY. A WAVE OF LOW PRESSURE IS EXPECTED TO
TRACK ALONG THE BOUNDARY THROUGH THE DAY AND EVENTUALLY OFF THE
COAST WEDNESDAY EVENING. AMPLE LIFT AND MOISTURE WILL SUPPORT
WIDESPREAD SHOWERS AND PERHAPS SOME EMBEDDED THUNDERSTORMS, ALTHOUGH
INSTABILITY IS QUITE MARGINAL. AN ADDITIONAL 0.50 INCH OF RAINFALL
IS FORECAST, WITH LOCALLY HIGHER AMOUNTS POSSIBLE. THERE WILL LIKELY
BE A DECENT TEMPERATURE GRADIENT AS THE FRONT WAVERS IN THE
VICINITY. CURRENT FORECAST FEATURES HIGHS RANGING FROM LOW 60S
ACROSS THE NORTHERN ZONES TO AROUND 70/LOW 70S CLOSER TO THE
ALTAMAHA.
A TRAILING COLD FRONT WILL PUSH OFFSHORE WEDNESDAY NIGHT, WITH
MOISTURE STRIPPING OUT QUICKLY AND RAIN COMING TO AN END. MOST
PRECIPITATION SHOULD HAVE EXITED THE AREA BY MIDNIGHT. INCREASING
COLD AIR ADVECTION WILL BRING TEMPERATURES DOWN TO THE UPPER 30S TO
LOW 40S, ALTHOUGH BREEZY NORTHWEST WINDS BEHIND THE FRONT WILL MAKE
IT FEEL A BIT COLDER.
COOL AND DRY HIGH PRESSURE WILL EXPAND INTO THE REGION ON THURSDAY
AND WILL PERSIST THROUGH FRIDAY. ALOFT, THE AREA WILL REMAIN UNDER
NORTHWEST FLOW IN BETWEEN RIDGING BUILDING OVER THE CENTRAL AND
SOUTHERN PLAINS AND TROUGHING TO THE EAST. QUIET WEATHER CONDITIONS
ARE EXPECTED, ALTHOUGH WINDS WILL REMAIN A BIT GUSTY ON THURSDAY
BEFORE THE PRESSURE GRADIENT RELAXES. DESPITE CLEAR SKIES,
TEMPERATURES WILL REMAIN BELOW NORMAL. HIGHS BOTH DAYS WILL TOP OUT
IN THE LOW TO MID 50S. GOOD RADIATIONAL COOLING CONDITIONS THURSDAY
NIGHT WILL ALLOW LOWS TO DROP BELOW FREEZING ACROSS MOST LOCATIONS
INLAND OF THE COAST.
LAKE WINDS: STRONG COLD AIR ADVECTION BEHIND A DEPARTING COLD FRONT
WILL PROMOTE GOOD MIXING PROFILES OVER LAKE MOULTRIE WEDNESDAY NIGHT
INTO THURSDAY. WIND GUSTS IN EXCESS OF 25 KNOTS ARE POSSIBLE, AND A
LAKE WIND ADVISORY WILL LIKELY BE NEEDED.
LONG TERM /FRIDAY NIGHT THROUGH MONDAY/
HIGH PRESSURE WILL PREVAIL ON SATURDAY, ALLOWING QUIET AND DRY
WEATHER TO CONTINUE. AN AMPLIFYING MID LEVEL TROUGH AND ASSOCIATED
SURFACE LOW WILL THEN MOVE INTO THE REGION EARLY NEXT WEEK. WHILE
THERE ARE STILL TIMING DISCREPANCIES BETWEEN MODELS, A COLD FRONT
WILL EVENTUALLY PASS THROUGH, BRINGING THE NEXT CHANCE OF RAIN TO
THE AREA. TEMPERATURES WILL BE NEAR TO ABOVE NORMAL THROUGH THE
PERIOD.
AVIATION /12Z TUESDAY THROUGH SATURDAY/
12Z KCHS UPPER AIR SOUNDING OBSERVED SW WINDS AT 40 KTS AT 1KFT
AND SW AND 40 KTS AT 2 KFT. A COLD FRONT WILL APPROACH FROM THE
WEST THIS MORNING. AS THE FRONT APPROACHES, LLVL WINDS WILL
LINGER AROUND 40 KTS ACROSS THE SC LOWCOUNTRY THROUGH MOST OF
THE MORNING. LLWS IS EXPECTED OVER KCHS BETWEEN UNTIL 13Z, THEN
SFC WIND GUSTS SHOULD DEVELOP AND END LLWS. PRIOR TO THE 12Z
TAFS, IR SATELLITE INDICATED IFR/MVFR CEILINGS APPROACHING BOTH
TERMINALS. BASED ON SATELLITE TRENDS, I WILL INDICATE PERIODS OF
LOW CEILINGS UNTIL MID-DAY. IN ADDITION, SW WINDS MAY GUSTS TO
AROUND 20 KTS THIS AFTERNOON, ESPECIALLY AT KCHS. THE SFC COLD
FRONT WILL SLOW AND BECOME STATIONARY OVER THE FORECAST AREA
THIS EVENING. LOW PRESSURE WILL DEVELOP OVER THE DEEP SOUTH,
TRACKING NE ALONG THE STATIONARY FRONT. A BAND OF SCATTERED TO
NUMEROUS SHOWERS AND THUNDERSTORMS IS TIME TO REACH KSAV THIS
EVENING. CEILINGS SHOULD CONTINUE TO LOWER THROUGH THE EVENING
AND OVERNIGHT, REACHING IFR BY LATE THIS EVENING AT BOTH
TERMINALS. LOW CEILINGS AND CONVECTION WILL REMAIN THROUGH THE
REST OF THE 12Z TAFS.
EXTENDED AVIATION OUTLOOK: FLIGHT RESTRICTIONS LIKELY IN LOW CLOUDS
AND MODERATE RAIN THROUGH WEDNESDAY EVENING. GUSTY WINDS EXPECTED
WEDNESDAY NIGHT INTO THURSDAY BEHIND A STRONG COLD FRONT.
MARINE
TODAY AND TONIGHT: A COLD FRONT WILL REMAIN WEST OF THE MARINE ZONES
THROUGH TODAY AND TONIGHT. AS A RESULT, WINDS WILL REMAIN OUT OF THE
SW THROUGH NEAR TERM. WIND GUSTS COULD APPROACH SMALL CRAFT ADVISORY
LEVELS ACROSS THE CHARLESTON COUNTY WATERS THIS AFTERNOON.
OTHERWISE, SW WINDS COULD GUSTS AROUND 20 KTS THROUGH THE DAYLIGHT
HOURS, SETTLING TO 10-15 KTS TONIGHT. IN ADDITION, PATCHY SEA FOG
COULD DEVELOP FROM TIME TO TIME NEAR THE COAST TODAY. ROUNDS OF
THUNDERSTORMS ARE FORECAST TO TRACK OVER THE NEARSHORE WATERS
TONIGHT, ESPECIALLY OFF THE SC COAST.
WEDNESDAY THROUGH SUNDAY: LOW PRESSURE WILL PASS OVER THE REGION ON
WEDNESDAY, FOLLOWED BY A STRONG COLD FRONT WEDNESDAY EVENING/NIGHT.
WINDS AND SEAS WILL DETERIORATE IN ITS WAKE, AND AT THE LEAST, SMALL
CRAFT ADVISORIES WILL BE NEEDED FOR ALL WATERS. THE WORST CONDITIONS
LOOK TO OCCUR BETWEEN MIDNIGHT AND DAYBREAK THURSDAY, WHEN GALE
FORCE GUSTS WILL BE POSSIBLE, PARTICULARLY OVER THE CHARLESTON
COUNTY NEARSHORE WATERS AND OUTER GEORGIA WATERS. GALE
WATCHES/WARNINGS COULD EVENTUALLY BE NEEDED. THERE WILL BE A GRADUAL
IMPROVEMENT ON THURSDAY AS THE PRESSURE GRADIENT RELAXES. NO
ADDITIONAL CONCERNS ARE ANTICIPATED THROUGH SATURDAY AS HIGH
PRESSURE EXPANDS OVER THE REGION. A COLD FRONT WILL APPROACH FROM
THE WEST ON SUNDAY AND WILL BRING INCREASING WINDS AND SEAS.
CLIMATE
RECORD HIGHS FOR 26 JANUARY:
KCHS: 80/1949
KCXM: 79/1949
KSAV: 81/1974 AND 1962
RECORD HIGH MIN FOR 26 JANUARY:
KCHS: 59/1949
KCXM: 60/1974
KSAV: 62/1974
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
NEAR TERM...NED
SHORT TERM...ETM
LONG TERM...ETM
AVIATION...NED
MARINE...NED
CLIMATE...
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