919
FXUS62 KCHS 181121
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
621 AM EST MON NOV 18 2024
SYNOPSIS
HIGH PRESSURE WILL PREVAIL UNTIL A STRONG COLD FRONT MOVES
THROUGH MID WEEK. CANADIAN HIGH PRESSURE WILL BUILD ACROSS THE
AREA THURSDAY INTO SUNDAY.
NEAR TERM /THROUGH TONIGHT/
TODAY: ALOFT, THE PATTERN LOOKS NEARLY IDENTICAL TO YESTERDAY
WITH THE RIDGE CENTERED TO THE SOUTH NEAR THE FLORIDA KEYS AND
THE RIDGE AXIS EXTENDING NORTHWARD INTO THE GREAT LAKE REGION.
AT THE SURFACE, HIGH PRESSURE WILL GRADUALLY BECOME CENTERED OUT
OVER THE ATLANTIC BUT REMAINING THE PRIMARY FEATURE ACROSS THE
FORECAST AREA. WINDS WILL REMAIN QUITE WEAK THANKS TO THE WEAK
GRADIENT, WITH WIND DIRECTION STARTING OUT WESTERLY THIS MORNING
AND THEN BECOMING SOUTHWESTERLY IN THE AFTERNOON. THIN CIRRUS
WILL CONTINUE TO PASS ACROSS THE AREA THROUGH THE DAY, THOUGH WE
WILL STILL SEE PLENTY OF SUN. LOW-LEVEL THICKNESS VALUES
CONTINUE TO RISE, AND TEMPERATURES WILL CONTINUE TO MODERATE AS
WELL. HIGHS ARE FORECAST TO BE A FEW DEGREES WARMER, WITH
TEMPERATURES RISING INTO THE MID 70S JUST ABOUT EVERYWHERE. A
FEW UPPER 70S WILL BE POSSIBLE AS YOU GET CLOSER TO THE
ALTAMAHA.
TONIGHT: HIGH PRESSURE WILL REMAIN ANCHORED OVER THE SOUTHWEST
ATLANTIC AS A COLD FRONT MOVES INTO THE LOWER MISSISSIPPI VALLEY
LATE. MODEL CONSENSUS IS THAT ANY PRECIPITATION AHEAD OF THE
FRONT WILL REMAIN DISPLACED WELL TO OUR WEST THROUGH SUNRISE,
KEEPING THE REGION DRY THROUGH THE OVERNIGHT. HIGH CLOUDS WILL
START TO INCREASE FROM THE WEST LATE, BUT OVERALL WE SHOULD SEE
MOSTLY CLEAR SKIES. LOW TEMPERATURES WILL CONTINUE AN UPWARD
TREND FROM THE PREVIOUS FEW NIGHTS, WITH UPPER 40S AND LOW 50S
EXPECTED AWAY FROM THE IMMEDIATE COAST.
SHORT TERM /TUESDAY THROUGH THURSDAY/
SHORTWAVE ENERGY WILL PASS ACROSS THE REGION WELL AHEAD OF THE
MAIN TROUGH AXIS TUESDAY INTO TUESDAY NIGHT. AT THE SURFACE,
OFFSHORE HIGH PRESSURE WILL CONTINUE TO WEAKEN IN ADVANCE OF A
COLD FRONT AND POSSIBLY A WEAK WAVE OF LOW PRESSURE PASSING
ALONG THE GULF COAST STATES. MOST OF THE DAY WILL BE DRY THEN
RAIN CHANCES WILL INCREASE FROM THE WEST LATE AND INTO THE
OVERNIGHT. IT IS POSSIBLE THAT THE BULK OF ACTIVITY STAYS SOUTH
OF THE AREA OR CLIPPING OUR FAR SOUTHEAST GEORGIA ZONES. THIS IS
WHERE WE HAVE OUR HIGHEST POPS, GENERALLY PEAKING AROUND 50%.
LESSER COVERAGE AND INTENSITY EXPECTED FURTHER NORTH.
TEMPERATURES WILL AVERAGE IN THE MID 70S, WITH SOME SPOTS IN THE
UPPER 70S. LOWS WILL BE MILD WITH ABUNDANT CLOUD COVER IN
PLACE, ONLY FALLING TO AROUND 60/LOW 60S.
AFOREMENTIONED COLD FRONT WILL SWEEP THROUGH THE AREA LATER
WEDNESDAY. SHOWERS COULD LINGER THROUGH THE MORNING, THEN WILL
DECREASE DURING THE LATTER HALF OF THE DAY AS DRIER AIR MOVES IN
FROM THE WEST. LAND AREAS SHOULD BY RAIN-FREE BY WEDNESDAY
NIGHT. ONE LAST DAY OF SEASONALLY WARM TEMPERATURES IN THE MID
70S. LOWS WILL BE IN THE 40S.
DEEP UPPER TROUGH WILL REMAIN OVER THE EASTERN CONUS ON
THURSDAY, WHILE SURFACE LOW PRESSURE SPINS OVER THE NORTHEAST.
TIGHT PRESSURE GRADIENT WILL BE IN PLACE OVER THE LOCAL AREA
LEADING TO GUSTY WEST WINDS. OTHERWISE, TEMPERATURES WILL BE
NOTABLY COOLER DESPITE SUNNY SKIES. HIGHS WILL ONLY RISE TO THE
UPPER 50S TO LOWER 60S.
LAKE WINDS: GUSTY WEST WINDS ARE EXPECTED TO DEVELOP OVER LAKE
MOULTRIE WEDNESDAY NIGHT INTO THURSDAY BEHIND A COLD FRONT. A
LAKE WIND ADVISORY APPEARS LIKELY.
LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/
SURFACE LOW PRESSURE OVER THE NORTHEAST ON FRIDAY WILL FINALLY
GIVE WAY, ALLOWING HIGH PRESSURE TO BUILD OVER THE AREA FOR THE
WEEKEND. ALOFT, MID LEVEL TROUGH OVER THE EASTERN U.S. WILL ALSO
EXIT WITH A RETURN TO ZONAL FLOW OR EVEN SUBTLE RIDGING LATE IN
THE PERIOD. DRY WEATHER WILL PREVAIL. GUSTY WEST WINDS WILL
LIKELY PERSIST INTO FRIDAY, POTENTIALLY MAINTAINING A LAKE WIND
ADVISORY OVER LAKE MOULTRIE, BEFORE THE PRESSURE GRADIENT
WEAKENS AND WINDS EASE. COOLER TEMPERATURES ARE EXPECTED THROUGH
THE PERIOD. OVERNIGHT TEMPERATURES ARE FORECAST TO FALL INTO
THE 30S OVER MANY INLAND LOCATIONS. WILL NEED TO MONITOR THE
POTENTIAL FOR FROST, ESPECIALLY SATURDAY NIGHT.
AVIATION /12Z MONDAY THROUGH FRIDAY/
VFR CONDITIONS ARE EXPECTED TO PREVAIL AT KCHS, KJZI, AND KSAV
THROUGH 12Z TUESDAY. SHALLOW GROUND FOG IS EXPECTED AT THE TAF
SITES AROUND SUNRISE, BUT NO FLIGHT RESTRICTIONS ARE EXPECTED AT
THIS TIME.
EXTENDED AVIATION OUTLOOK: PREVAILING VFR. BRIEF FLIGHT
RESTRICTIONS POSSIBLE IN SHOWERS TUESDAY NIGHT INTO WEDNESDAY IN
ADVANCE OF A COLD FRONT. GUSTY WEST WINDS ARE EXPECTED THURSDAY
AND FRIDAY.
MARINE
TODAY AND TONIGHT: VERY QUIET CONDITIONS WILL CONTINUE FOR THE
LOCAL WATERS. WINDS WILL BECOME A BIT MORE SOUTHWESTERLY THROUGH
THE PERIOD, BUT SPEEDS ARE EXPECTED TO BE 10 KNOTS OR LESS.
SEAS ARE FORECAST TO BE 1-2 FEET.
TUESDAY THROUGH SATURDAY: NO MARINE CONCERNS THROUGH TUESDAY
NIGHT. A STRONG COLD FRONT WILL MOVE THROUGH LATER WEDNESDAY
WITH INCREASING WINDS AND SEAS IN ITS WAKE. SMALL CRAFT
ADVISORIES ARE LIKELY FOR ALL WATERS, INCLUDING THE CHARLESTON
HARBOR, BEGINNING WEDNESDAY NIGHT AND POTENTIALLY CONTINUING
THROUGH FRIDAY. THERE REMAINS SOME RISK FOR GUSTS TO NEAR GALE
FORCE OVER PORTIONS OF THE WATERS, ESPECIALLY THURSDAY NIGHT,
BUT SEEMS PRETTY MARGINAL AND BRIEF AT THIS POINT. IMPROVEMENT
IS EXPECTED ON SATURDAY AS THE PRESSURE GRADIENT EASES.
TIDES/COASTAL FLOODING
UPCOMING MORNING HIGH TIDE (~9:30AM): WE ARE CURRENTLY AT LOW
TIDE IN CHARLESTON AND THE TIDAL DEPARTURE IS 0.8 FEET. PLUGGING
THIS INTO OUR LOCAL FORECAST TOOL SUGGESTS A HIGH TIDE OF 7.28
FEET MLLW AND ALL MODEL GUIDANCE SOURCES ARE IN THE 7.2-7.3 FEET
MLLW RANGE. THEREFORE, WE FEEL PRETTY CONFIDENT IN GOING 7.3
FEET MLLW AND ISSUING A COASTAL FLOOD ADVISORY FOR CHARLESTON
AND COASTAL COLLETON COUNTIES. FORT PULASKI LOOKS LIKE IT IS ON
TRACK FOR 9.2-9.3 FEET MLLW, JUST SHORT OF ADVISORY CRITERIA.
TIDES WILL BE CLOSE TO MINOR FLOODING LEVELS WITH THE TUESDAY
MORNING HIGH TIDE ALONG THE CHARLESTON AND COLLETON COUNTY
COASTS, BUT THE LATEST FORECAST KEEPS IT JUST SHY.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...COASTAL FLOOD ADVISORY UNTIL 11 AM EST THIS MORNING FOR SCZ049-
050.
MARINE...NONE.
NEAR TERM...BSH
SHORT TERM...ETM
LONG TERM...ETM
AVIATION...BSH/ETM
MARINE...BSH/ETM
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