675
FXUS62 KCHS 172325
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
725 PM EDT WED SEP 17 2025
SYNOPSIS
WEAK HIGH PRESSURE WILL EXTEND ACROSS THE REGION THIS WEEK.
STRONGER HIGH PRESSURE WILL BUILD INTO THE REGION OVER THE
WEEKEND AND EARLY NEXT WEEK, WHILE A COASTAL TROUGH DEVELOPS
OFFSHORE.
NEAR TERM /THROUGH THURSDAY/
THIS EVENING: A VERTICALLY STACKED LOW PRESSURE CENTER IN THE
MID AND UPPER LEVELS OF THE ATMOSPHERE IS LOCATED OVER THE
DELMARVA AREA OF THE MID-ATLANTIC THIS AFTERNOON. THIS FEATURE
WILL REMAIN NEARLY STATIONARY THROUGH TONIGHT. AT THE SURFACE A
LOW PRESSURE SYSTEM IS ALSO CENTERED OVER THE DELMARVA REGION.
THIS SYNOPTIC SET UP HAS LEAD TO BROAD TROUGHING OVER THE
SOUTHEASTERN STATES. THERE IS ENOUGH FORCING ASSOCIATED WITH THE
TROUGH ALOFT AND MOISTURE IN THE MID LEVELS FOR SOME WEAK
SHOWERS EXIST INTERIOR SC AND GA. LITTLE TO NO ACCUMULATION IS
EXPECTED WITH THESE WEAK SHOWERS.
TONIGHT: EVEN THOUGH THE BOUNDARY LAYER IS EXPECTED TO DECOUPLE
TONIGHT, HIGH CLOUDS WILL LIKELY LIMIT RADIATIONAL COOLING. THE
FORECAST FEATURES LOWS IN THE MID 60S INLAND WITH AROUND 70 ALONG
THE BEACHES.
SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/
ALOFT, A MID-UPPER LVL TROUGH WILL EXTEND ACROSS MUCH OF THE EASTERN
SEABOARD WITH AN AXIS RUNNING NORTHEAST TO SOUTHWEST ACROSS THE
INTERIOR OF THE MID-ATLANTIC AND SOUTHEAST ON THURSDAY BEFORE SUBTLE
HINTS OF RIDGING OCCUR ACROSS THE REGION LATE WEEKEND. AT THE SFC,
WEAK HIGH PRESSURE WILL PREVAIL INTO FRIDAY, PRIOR TO BEING
REINFORCED BY A STRONGER WEDGE OF HIGH PRESSURE FROM THE NORTH
STARTING SATURDAY. THE PATTERN WILL SUPPORT MAINLY DRY CONDITIONS
DURING THE PERIOD. HOWEVER, GUIDANCE CONTINUES TO SUGGEST A WEAK
LOBE OF H5 SHORTWAVE ENERGY TRAVERSING THE LOCAL AREA ALONG THE
SOUTHERN EDGE OF THE LARGE-SCALE TROUGH, POTENTIALLY BRINGING A FEW
SHOWERS AND/OR ISOLATED THUNDERSTORM ACROSS FAR INLAND LOCATIONS MID-
LATE AFTERNOON THURSDAY.
THE MORE NOTICEABLE CHANGE TO THE WEATHER WILL BE ATTRIBUTED TO
WARMING TEMPS INTO LATE WEEK, AS 1000-850 MB THICKNESSES INCREASE
THURSDAY AND FRIDAY PRIOR TO STRONGER/COOLER HIGH PRESSURE WEDGING
SOUTHWARD TOWARD THE LOCAL AREA LATE SATURDAY. IN GENERAL, HIGH
TEMPS SHOULD RANGE BETWEEN THE UPPER 80S/LOWER 90S AWAY FROM THE
BEACHES EACH DAY (WARMEST ACROSS SOUTHEAST GEORGIA). LOW TEMPS WILL
REMAIN SLIGHTLY MORE MILD THAN PREVIOUS DAYS, GENERALLY IN THE MID-
UPPER 60S INLAND TO LOWER 70S NEAR THE COAST EACH NIGHT.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
ALOFT, WEAK MID-LVL RIDGING WILL GRADUALLY GIVE WAY TO A MORE
SUBSTANTIAL TROUGH EARLY NEXT WEEK. AT THE SFC, HIGH PRESSURE WILL
WEDGE SOUTHWARD ACROSS THE MID-ATLANTIC INTO THE SOUTHEAST STATES,
LIKELY RESULTING IN NOTICEABLY COOLER CONDITIONS SUNDAY INTO MONDAY,
PRIOR TO COASTAL TROUGHING OCCURRING ON TUESDAY. LOWER-END RAIN
CHANCES REMAIN IN THE LATEST FORECAST EACH AFTERNOON (20-30%), WITH
THE BULK OF ACTIVITY OCCURRING ALONG COASTAL AREAS WHERE MOISTURE
CONVERGENCE IS HIGHEST ALONG A FRONT AND TROUGHING ACROSS THE NEARBY
ATLANTIC PROMOTES COASTAL SHOWERS ADVECTING ONSHORE WITHIN A
NORTHEASTERLY WIND. IN GENERAL, HIGH TEMPS SHOULD PEAK IN THE LOW-
MID 80S (WARMEST ACROSS INLAND SOUTHEAST GEORGIA) SUNDAY AND MONDAY,
FOLLOWED BY UPPER 80S/AROUND 90 ACROSS THE INTERIOR ON TUESDAY.
OVERNIGHT LOWS REMAIN IN THE MID-UPPER 60S INLAND TO LOWER 70S
CLOSER TO THE COAST.
AVIATION /00Z THURSDAY THROUGH MONDAY/
PRIOR TO THE 0Z TAFS, KCLX DOPPLER RADAR DETECTED A FADING
CLUSTER OF SHOWERS TRACKING ACROSS KSAV. THESE SHOWERS SHOULD
END WITHIN THE FIRST HOUR OF THE TAF. THROUGH THE REST OF THE
NIGHT, CONDITIONS SHOULD REMAIN VFR WITH LIGHT SW WINDS. A WEAK
SEA BREEZE SHOULD ACROSS THE TERMINALS EARLY THURSDAY AFTERNOON,
TURNING WINDS FROM THE SSE AROUND 10 KTS.
EXTENDED AVIATION FORECAST: VFR CONDITIONS ARE EXPECTED AT
CHS/JZI/SAV TERMINALS THROUGH SATURDAY. GUSTY NORTHEASTERLY WINDS
(15-20 KT) ARE POSSIBLE WITH A WEDGE OF HIGH PRESSURE EACH AFTERNOON
SATURDAY THROUGH MONDAY. BRIEF FLIGHT RESTRICTIONS ARE ALSO POSSIBLE
WITH SHOWERS ON SUNDAY AND MONDAY.
MARINE
THOUGH TONIGHT: WINDS THIS AFTERNOON AND THROUGH TONIGHT WILL
GENERALLY BE SW/S AROUND 10 KNOTS. SOME GUSTS THIS AFTERNOON
COULD APPROACH 15-20 KNOTS ALONG THE IMMEDIATE COASTLINE
ASSOCIATED WITH THE AFTERNOON SEA BREEZE. SEAS ARE FORECAST TO
AVERAGE 2 TO 3 FT THROUGH TONIGHT.
THURSDAY THROUGH MONDAY: WEAK HIGH PRESSURE WILL PREVAIL ACROSS
LOCAL WATERS THROUGH EARLY SATURDAY, RESULTING IN NO MARINE
CONCERNS. IN GENERAL, SOUTHERLY WINDS WILL BE NO HIGHER THAN 10-15
KT WITH SEAS RANGING BETWEEN 1-3 FT, LARGEST ACROSS OUTER GEORGIA
WATERS. HIGH PRESSURE WILL BEGIN TO WEDGE SOUTH ACROSS THE REGION
OVER THE WEEKEND, PLACING A STRONGER PRESSURE GRADIENT ACROSS LOCAL
WATERS BETWEEN A WEDGE FRONT TO THE NORTH AND TROUGHING EAST OF
FLORIDA. THE FRONT SHOULD ARRIVE ACROSS LOCAL WATERS OR JUST INLAND
MONDAY, ALLOWING AN ENHANCED PRESSURE GRADIENT TO PERSIST INTO EARLY
NEXT WEEK. CONDITIONS COULD SUPPORT SMALL CRAFT ADVISORIES ACROSS A
PORTION OF LOCAL WATERS STARTING AS EARLY AS SATURDAY NIGHT, THEN
PREVAIL ACROSS MOST LOCAL WATERS SUNDAY, BEFORE IMPROVEMENT OCCURS
ON MONDAY. DURING THE PEAK OF THE EVENT (SUNDAY), NORTHEASTERLY
WINDS GUSTING AROUND 25 KT AND SEAS BETWEEN 4-6 FT ARE
ANTICIPATED.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
NEAR TERM...CPM
SHORT TERM...DPB
LONG TERM...DPB
AVIATION...NED
MARINE...CPM/DPB
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