739
FXUS62 KCHS 191805
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
105 PM EST TUE NOV 19 2024
SYNOPSIS
HIGH PRESSURE WILL PREVAIL UNTIL A STRONG COLD FRONT MOVES
THROUGH LATER WEDNESDAY. CANADIAN HIGH PRESSURE WILL BUILD
ACROSS THE AREA THURSDAY INTO SUNDAY.
NEAR TERM /THROUGH TONIGHT/
RECENT TRENDS CONTINUE TO SLOW A DELAY OF THE BEGINNING OF THE
UPSTREAM SHOWERS, WITH THE BETTER FEED OF MOISTURE STILL TO OUR
WEST, ALONG WITH HAVING TO RAISE TEMPERATURES ABOUT 1-3 DEGREES
FROM THE PREVIOUS FORECAST. DESPITE THESE ABNORMALLY HIGH
VALUES, THEY ARE SEVERAL DEGREES BELOW ANY RECORDS FOR THE DATE.
TODAY: ALOFT, THE UPPER RIDGE AXIS WILL SHIFT OFF TO THE EAST
THIS MORNING AS SHORTWAVE ENERGY SPREADS IN ACROSS THE REGION
WITH THE ARRIVAL OF SOUTHWESTERLY FLOW AHEAD OF A STRENGTHENING
TROUGH ACROSS THE CENTRAL CONUS. AT THE SURFACE, HIGH PRESSURE
WILL BE POSITIONED OVER THE SOUTHWEST ATLANTIC AS A COLD FRONT
GRADUALLY TRACKS EASTWARD ACROSS THE DEEP SOUTH. CLUSTERS OF
STORMS IN THE NORTHERN GULF COAST REGION AND INTO THE GULF OF
MEXICO, WHICH TO SOME EXTENT IS LIKELY ENERGY FROM FORMER TS
SARA, WILL SPREAD EAST AND EAST-SOUTHEAST. THIS MIGHT CUT OFF
THE SUPPLY OF THE BETTER MOISTURE INTO OUR REGION, WHICH IN TURN
CAUSES SOME CONCERNS WITH THE FORECAST. WITHE THE MAJORITY OF
THE MOISTURE AND FORCING TO REMAIN TO THE WEST THROUGH MUCH OF
THE DAY, WE HAVE SLOWED THE ONSET OF ANY SHOWERS BY ABOUT 1-3
HOURS FROM PREVIOUS. QPF THROUGH THE DAY IS MAINLY 1/4 INCH OR
LESS.
DESPITE CONSIDERABLE CLOUD COVER, THERE WILL BE SOME BREAKS OF
SUNSHINE, AND THAT ALONG WITH WARM ADVECTION WILL ALLOW FOR
TEMPERATURES TO PEAK IN THE MID AND UPPER 70S, EXCEPT FOR SOME
LOWER 70S ALONG THE NORTHWEST TIER WHERE THE SHOWERS ARRIVE
EARLIER AND CLOUD COVER IS MOST EXTENSIVE. A FEW COASTAL AREAS
WILL ALSO NOT GET ABOVE THE LOWER 70S WITH THE ONSET OF A WEAK
SEA BREEZE.
TONIGHT: FOR THE EVENING, THE LEFTOVER AREA OF SHOWERS IS
EXPECTED TO GRADUALLY MOVE EASTWARD ACROSS THE FORECAST AREA,
AIDED BY VORTICITY ALOFT AND THE PRESENCE OF UPPER-LEVEL
DIVERGENCE IN THE RIGHT ENTRANCE REGION OF THE UPPER JET.
COVERAGE OF SHOWERS SHOULD PEAK IN THE EVENING WITH THE BEST
OVERLAP OF MOISTURE (1.5-2" PRECIPITABLE WATER) AND FORCING.
MODEL CONSENSUS IS FOR THE SHOWER ACTIVITY TO DWINDLE THROUGH
THE LATE NIGHT HOURS AS THE BETTER FORCING AND MOISTURE SHIFTS
OFF THE COAST. THERE ISN'T ANY SUPPORT FOR INTENSE RAINFALL, AND
AMOUNTS ARE FORECAST TO BE A TENTH OF AN INCH OR LESS, AND NO
MORE THAN A FEW HUNDREDTHS IN MOST LOCATIONS. WITH THE COLD
FRONT STILL BACK TO THE WEST, EXPECT A VERY MILD NIGHT. LOWS ARE
FORECAST TO ONLY FALL INTO THE LOW 60S FOR MOST AREAS, WHICH
WOULD ONLY BE AROUND 5-7 DEGREES BELOW CLIMO HIGH TEMPERATURES
FOR THIS TIME OF YEAR.
SHORT TERM /WEDNESDAY THROUGH FRIDAY/
A DEEPENING MID LEVEL TROUGH WILL SHIFT INTO THE EASTERN U.S.
ON WEDNESDAY. AT THE SURFACE, A STRONG COLD FRONT WILL APPROACH
FROM THE WEST AND SWEEP THROUGH THE AREA LATER IN THE DAY INTO
WEDNESDAY EVENING. ISOLATED TO SCATTERED SHOWERS WILL BE
POSSIBLE, ESPECIALLY DURING THE MORNING AND INTO EARLY
AFTERNOON, BEFORE DRIER AIR MOVES IN AND BRINGS AN END TO
PRECIP. ALL AREAS SHOULD BE RAIN-FREE BY WEDNESDAY NIGHT. ONE
MORE WARM DAY WITH HIGHS LARGELY IN THE MID 70S. COLD AIR
ADVECTION WILL BEGIN WEDNESDAY NIGHT. LOWS ARE CURRENTLY
FORECAST TO SPAN THE 40S, COOLEST INLAND.
MID LEVEL LOW INITIALLY OVER THE GREAT LAKES WILL ROTATE TO THE
NORTHEAST THURSDAY INTO FRIDAY, WITH LARGER SCALE TROUGH
EXTENDING DOWN THE ENTIRE EAST COAST. SURFACE LOW WILL CONTINUE
TO MEANDER OVER THE NORTHEASTERN PART OF THE COUNTRY WHILE HIGH
PRESSURE BEGINS TO BUILD. TIGHT PRESSURE GRADIENT WILL LEAD TO
GUSTY WEST WINDS BOTH DAYS. GUSTS TO AROUND 25 MPH WILL BE
COMMON. DESPITE FULL SUN, HIGHS WILL BE SEASONALLY COOL,
GENERALLY IN THE UPPER 50S TO AROUND 60. LOWS THURSDAY NIGHT
WILL BE CHILLY WITH MANY INLAND LOCATIONS DROPPING INTO THE 30S.
TEMPS AND WINDS SHOULD STAY A BIT TOO ELEVATED FOR FROST.
LAKE WINDS: GUSTY WEST WINDS ARE EXPECTED TO DEVELOP OVER LAKE
MOULTRIE WEDNESDAY NIGHT INTO THURSDAY BEHIND A COLD FRONT. A
LAKE WIND ADVISORY IS LIKELY, WHICH COULD PERSIST INTO FRIDAY.
LONG TERM /FRIDAY NIGHT THROUGH MONDAY/
HIGH PRESSURE WILL CONTINUE TO BUILD OVER THE AREA OVER THE
WEEKEND AND REMAIN THE DOMINANT FEATURE THROUGH MONDAY. NO
THREAT FOR RAIN WITH A DRY FORECAST THROUGH THE ENTIRE PERIOD.
MAIN FORECAST CONCERN WILL BE THE POTENTIAL FOR FROST EARLY
SATURDAY MORNING AND AGAIN SUNDAY MORNING. PERHAPS THE BETTER
CHANCE WOULD BE SUNDAY MORNING AS WINDS COULD STAY A BIT TOO
HIGH FOR FROST DEVELOPMENT FRIDAY NIGHT/SATURDAY MORNING.
AVIATION /18Z TUESDAY THROUGH SUNDAY/
KCHS/KJZI/KSAV: VFR WILL PREVAIL THIS AFTERNOON AND EVENING AS
THE NORTHWEST EXTENSION OF ATLANTIC HIGH PRESSURE CONTINUES TO
HANG ON. EVENTUALLY SOME OF THE UPSTREAM SHOWERS ASSOCIATED
WITH A SHORT WAVE, ALTHOUGH OUR CONFIDENCE ON TIMING IS NOT
PARTICULARLY HIGH. CONFIDENCE THOUGH IS GREATER THAT MVFR
CEILINGS WILL DEVELOP; FIRST AT KSAV AROUND 07Z, THEN AT KCHS
AND KJZI AROUND 14Z WEDNESDAY. ALL TERMINALS COULD EVEN
EXPERIENCE IFR CEILINGS, BUT IT'S MUCH TOO EARLY TO SHOW THOSE
CEILINGS AT THIS TIME.
EXTENDED AVIATION OUTLOOK: FLIGHT RESTRICTIONS IN LOW CLOUDS
WEDNESDAY AFTERNOON IN ADVANCE OF A COLD FRONT. VFR WILL PREVAIL
THEREAFTER. GUSTY WEST WINDS ARE EXPECTED THURSDAY AND FRIDAY.
MARINE
THIS AFTERNOON AND TONIGHT: HIGH PRESSURE OVER THE SOUTHWEST
ATLANTIC WILL STILL BE THE PRIMARY FEATURE DRIVING A MODEST
SOUTH TO SOUTHWEST FLOW AROUND 10 KT OR SO THROUGH THE DAYLIGHT
HOURS. OVERNIGHT, A COLD FRONT WILL BEGIN TO APPROACH FROM THE
WEST AND THE LOCAL WATERS WILL BE SITUATED BETWEEN THE FRONT AND
THE HIGH. THE RESULT WILL BE INCREASING SOUTH TO SOUTHWEST FLOW
LATE TONIGHT, PEAKING AROUND 15-20 KNOTS IN THE GEORGIA WATERS
BY SUNRISE WEDNESDAY. SEAS WILL AVERAGE 1-2 FEET THROUGH TODAY,
THEN INCREASE LATE TONIGHT. BY SUNRISE WEDNESDAY WE SHOULD SEE
2-3 FEET ACROSS ALL THE WATERS, WITH 3-4 FEET IN THE OUTER
GEORGIA WATERS.
WEDNESDAY THROUGH SUNDAY: A STRONG COLD FRONT WILL MOVE THROUGH
LATER WEDNESDAY WITH INCREASING WINDS AND SEAS IN ITS WAKE.
SMALL CRAFT ADVISORIES ARE EXPECTED FOR ALL WATERS, INCLUDING
THE CHARLESTON HARBOR, BEGINNING WEDNESDAY NIGHT AND POTENTIALLY
CONTINUING THROUGH FRIDAY. WHILE A FEW GUSTS NEAR OR AT GALE
FORCE ARE POSSIBLE BOTH WEDNESDAY NIGHT AND THURSDAY NIGHT, IT
APPEARS TO BE BRIEF AND MARGINAL, SO NO GALE WATCH ANTICIPATED
AT THIS TIME. IMPROVEMENT IS EXPECTED ON SATURDAY AS THE
PRESSURE GRADIENT EASES.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
NEAR TERM...
SHORT TERM...ETM
LONG TERM...ETM
AVIATION...
MARINE...
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