842
FXUS62 KCHS 161720
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1220 PM EST THU JAN 16 2025
SYNOPSIS
HIGH PRESSURE WILL PREVAIL THROUGH THE WEEK. A LOW PRESSURE
SYSTEM AND ASSOCIATED COLD FRONT WILL IMPACT THE REGION THIS
WEEKEND. ANOTHER LOW PRESSURE SYSTEM COULD IMPACT THE REGION
EARLY TO MID NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
EARLY THIS AFTERNOON: NO CHANGE TO THE FORECAST. PREVIOUS
DISCUSSION CONTINUES BELOW.
LATE THIS MORNING: SATELLITE IMAGERY SHOWS THAT THE BACK EDGE OF
THE CLOUD SHIELD HAS PUSHED WELL TO THE EAST AND WE WILL SEE
COMPLETELY CLEAR SKIES THE REST OF THE DAY. THE MAIN FORECAST
CHALLENGES TODAY WILL BE GUSTY WINDS AND TEMPERATURES. WITH A
SURFACE TROUGH/FRONT MOVING INTO THE AREA TODAY, THE GRADIENT
WILL TIGHTEN. THE COMBINATION OF A TIGHTENING GRADIENT AND
MIXING HEIGHTS IN EXCESS OF 5 KFT WILL RESULT IN GUSTY WINDS
FROM AROUND MIDDAY ONWARD. FREQUENT GUSTS INTO THE 20-25 MPH
RANGE CAN BE EXPECTED. HIGH TEMPERATURES ARE EXPECTED TO BE
RIGHT AROUND NORMAL FOR MID JANUARY, WITH MOST PLACES AROUND 60
AND EVEN A FEW LOW 60S POSSIBLE FOR PORTIONS OF SOUTHEAST GA.
TONIGHT: THE PRESSURE GRADIENT ACROSS THE FORECAST AREA WILL
RELAX AS THE CENTER OF HIGH PRESSURE APPROACHES FROM THE WEST.
WINDS FROM THE WNW SHOULD FALL BELOW 5 MPH FOR MOST OF TONIGHT.
THE COMBINATION OF CLEAR SKY AND LIGHT WINDS SHOULD ALLOW FOR
FAIR RADIATIONAL COOLING CONDITIONS THROUGH MOST OF TONIGHT. LOW
TEMPERATURES ARE FORECAST TO RANGE FROM THE LOW 30S INLAND TO
THE UPPER 30S ALONG THE COAST.
SHORT TERM /FRIDAY THROUGH SUNDAY/
FRIDAY: HIGH PRESSURE AT THE SURFACE WILL SHIFT OFF THE
SOUTHEASTERN COAST AS LOW PRESSURE DEVELOPS IN THE VICINITY OF
ARKLATEX ASSOCIATED WITH AN UPPER LEVEL SHORTWAVE. A QUIET DAY
IS FORECAST OVER THE LOCAL REGION, WITH PLENTIFUL SUNSHINE AND
HIGH TEMPERATURES REACHING INTO THE UPPER 50S TO LOW 60S,
WARMEST IN SOUTHEASTERN GA. CLOUDS WILL BEGIN TO INCREASE FRIDAY
NIGHT AS THE LOW PRESSURE TREKS EASTWARD ALONG WITH ITS
ASSOCIATED COLD FRONT. DUE TO THE INCREASING CLOUD COVER
OVERNIGHT TEMPERATURES WILL BE NEAR NORMAL VALUES, WITH UPPER
30S INLAND AND LOW 40S ALONG THE COASTAL COUNTIES.
SATURDAY AND SUNDAY: THE PATTERN TURNS ACTIVE ON SATURDAY AS A
COLD FRONT APPROACHES THE REGION FROM THE WEST. A RATHER MOIST
AIRMASS WILL BE USHERED INTO THE REGION EARLY SATURDAY MORNING,
WITH PWATS SURGING TO AROUND 1.3-1.5". IF THESE VALUES COME TO
FRUITION THEY WOULD RIVAL THE DAILY MAX ACCORDING TO SPC'S
CLIMATOLOGY. SHOWERS WILL INITIALLY MOVE INTO THE FAR WESTERN
ZONES BY DAYBREAK SATURDAY MORNING, OVERSPREADING THE FORECAST
AREA BY SATURDAY AFTERNOON. SHOWERS WILL LIKELY PERSIST THROUGH
SATURDAY NIGHT, WANING SUNDAY MORNING. OVERALL STORM TOTAL
RAINFALL LOOKS TO BE AROUND 1-1.5 INCHES. TEMPERATURES EACH DAY
WILL REMAIN NEAR NORMAL, WITH HIGHS IN THE UPPER 50S TO LOW 60S.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
AS THE COLD FRONT PUSHES OFFSHORE, THE POTENTIAL FOR ANY
SHOWERS SUNDAY NIGHT BECOMES RATHER LOW LEAVING A MOSTLY DRY
FORECAST. HEADING INTO MONDAY AND MONDAY NIGHT, A COLD HIGH
PRESSURE SYSTEM WILL BUILD INTO THE REGION OVERHEAD AND ALLOW
STRONG CAA TO DOMINATE THE NEXT FEW DAYS.
TRANSITIONING TO TUESDAY AND BEYOND, THE FORECAST BECOMES
INCREASINGLY TRICKY AND POTENTIALLY IMPACTFUL. THE COLD
TEMPERATURES SEEM TO BE THE ONLY PART OF THE FORECAST MET WITH
HIGH CONFIDENCE, AS FOR THE REST OF FORECAST IS WHERE CONFIDENCE
DECREASES SIGNIFICANTLY. WITH THE 00Z GFS/ECMWF DETERMINISTIC
MODEL RUNS SUGGESTING A MORE SUPPRESSED SOLUTION WITH THE
SURFACE HIGH PUSHED VERY FAR SOUTH AND REMOVING ANY CHANCE OF
PRECIPITATION FROM DEVELOPING. THIS IS WILDLY DIFFERENT FROM THE
LAST COUPLE MODEL RUNS WHICH WAS SHOWING SOME SORT OF COASTAL
LOW PASSING BY TO THE SOUTH OR JUST OFFSHORE AND BRINGING A
WINTRY MIX OF SNOW AND ICE ALONG WITH IT. HOWEVER, THE GFS/ECMWF
ENSEMBLE MEMBERS ARE STILL IN AGREEMENT WITH THIS SOLUTION.
THUS, CONSIDERABLE UNCERTAINTY REMAINS WITH THIS SYSTEM AND ALL
SCENARIOS ARE STILL ON THE TABLE.
AVIATION /17Z THURSDAY THROUGH MONDAY/
VFR CONDITIONS WILL PREVAIL AT KCHS, KJZI, AND KSAV THROUGH 18Z
FRIDAY. WEST TO WEST-SOUTHWEST WINDS WILL BE GUSTY THROUGH LATE
AFTERNOON, WITH FREQUENT GUSTS INTO THE 20-25 KNOT RANGE
EXPECTED.
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
THE MARINE ZONES WILL REMAIN BETWEEN AN AREA OF HIGH PRESSURE
CENTERED TO THE SOUTH AND A BROAD AREA OF LOW PRESSURE EAST OF
THE APPALACHIANS. THIS PATTERN WILL YIELD A 2-3 MB PRESSURE
GRADIENT ACROSS THE MARINE ZONE TODAY INTO LATE TONIGHT. AS A
RESULT, SOUTHWEST WINDS SHOULD STRENGTHEN THIS MORNING. BY THIS
AFTERNOON, THE NEARSHORE SC WATERS ALONG WITH THE OUTER GA
WATERS SHOULD SEE FREQUENT GUSTS BETWEEN 25-30 KTS. IN ADDITION,
SEAS WILL BUILD THROUGH THE DAY, REACHING 3-5 FT BY THIS
EVENING. AS HIGH PRESSURE APPROACHES FROM THE WEST TONIGHT,
WINDS SHOULD DECREASE TO AROUND 15 KTS. THE NEARSHORE SC WATERS
(OUTSIDE THE CHS HARBOR) ALONG WITH THE OUTER GA WATERS WILL BE
HIGHLIGHTED WITH SMALL CRAFT ADVISORIES FROM THIS AFTERNOON
UNTIL 4 AM FRIDAY.
FRIDAY THROUGH TUESDAY: AS A SURFACE HIGH PRESSURE MOVES ACROSS
THE WATERS FRIDAY, CONDITIONS WILL BECOME RATHER QUITE AS WINDS
DIMINISH TO AROUND 10 KT AND SHIFT MORE EASTERLY/SOUTHEASTERLY
FRIDAY NIGHT. MOVING INTO SATURDAY, WINDS SHIFT INTO A
SOUTHERLY/SOUTHWESTERLY FLOW AND BEGIN TO INCREASE AHEAD OF THE
APPROACHING COLD FRONT TO 10 TO 15 KT. BEHIND THE COLD FRONT,
WINDS BECOME NORTHWESTERLY AND PICK UP TO 15 TO 20 KT WITH GUSTS
UP TO 25 KT. SMALL CRAFT ADVISORIES APPEAR MORE LIKELY DURING
THIS TIME PERIOD. SEAS WILL VARY ACROSS THE FORECAST PERIOD, BUT
MAINLY WILL BE FROM 2 TO 4 FT UNTIL TUESDAY NIGHT WITH SEAS
INCREASING TO 4 TO 6 FT (AND 7 FT IN THE OUTER GEORGIA WATERS).
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST FRIDAY FOR AMZ350.
SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 4 AM EST
FRIDAY FOR AMZ352-374.
NEAR TERM...BSH/NED
SHORT TERM...CPM
LONG TERM...DENNIS
AVIATION...BSH/DENNIS
MARINE...DENNIS/NED
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