Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
630 FXUS62 KCHS 201712 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 1212 PM EST Thu Nov 20 2025 .SYNOPSIS... Dry high pressure is expected to prevail across the area through the rest of the week. A cold front is expected to sweep across the region Saturday night, followed by more high pressure early next week. && .NEAR TERM /THROUGH TONIGHT/... Visible satellite and sfc-based observations indicated a large patch of stratus and fog across the CHS Tri-county. A weak front will slowly slip south along the GA/SC coast, expected to become stationary just north of the Savannah River this evening. Nearshore water temperatures range between 59 to 63 degrees, a degree or cooler than forecast dewpoints tonight. Areas to patchy fog may develop across the GA nearshore waters this evening, then spread north and inland late tonight. Dense Fog Advisories could be issued as early as this evening. Low temperatures are forecast to range in the mid to upper 50s. && .SHORT TERM /FRIDAY THROUGH SUNDAY/... Short term guidance shows a strong, nearly 590 dm, ridge centered over the Gulf on Friday. NAEFS indicates that Friday, llvl temperatures across portions of the Southeast U.S. will approach 2 units of standardized anomaly. Given the strong ridge over the region, temperatures will remain generally 10 to 12 degrees above normal with no precipitation. High temperatures Friday will reach near record highs (see Climate section), with near 80 across the SC Lowcountry to the low to mid 80s across SE GA. Guidance indicated that the H5 ridge will gradually flatten along the Atlantic coast by late day, resulting in an evening arrival of the cold front. The NBM based forecast is siding with the slower guidance, featuring near record high temperatures and afternoon SCHC PoPs for showers across the extreme inland zones. Temperatures may verify a degree or two warmer than Friday. GFS indicates that H85 temperatures across the region will cool by 3 to 4 degrees in the wake of the cold front Saturday night. Conditions should dry from the top-down, resulting in mostly clear to partly cloudy conditions. Low temperatures Sunday morning are forecast to range in the mid to upper 50s. High temperatures are expected to remain near normals, with near 70 across the SC Lowcountry to the mid 70s across SE GA. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... Early next week, medium range guidance indicates that the H5 ridge axis will ripple across the region on Monday. Conditions will remain dry with moderating temperatures. Through mid-week, the H5 pattern is forecast to feature a 588 DM ridge over the Bahamas as a longwave trough develops over the Great Plains. A large low pressure system over eastern Canada may sweep an elongated front across the region into the mid-week. Tuesday and Wednesday, the forecast will feature above-normal temperatures and SCHC to CHC PoPs for showers. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... Prior to the 18Z TAFs, visible satellite and sfc-based observations indicated a large patch of stratus and fog across the CHS Tri- county. Restrictive ceilings may linger of KCHS and KJZI until around 18Z, highlighted with TEMPOs. The rest of the afternoon will feature light east winds with VFR conditions. A weak front will slowly slip south along the GA/SC coast, expected to become stationary just north of the Savannah River this evening. Latest MOS and HRRR indicates indicates that areas of stratus and fog will develop near the coast this evening, then spread inland through the rest of the night. Restrictive ceilings and fog will be possible at each terminal, especially at KSAV. Much like today, forecast soundings indicate that stratus may not mix out until 18Z Friday. TAFs will indicate that by 18Z, southwest winds will develop around 5 kts and ceilings will improve to VFR. Extended Aviation Outlook: Prevailing VFR. It is possible that periods of ground fog may develop during the pre-dawn hours through Saturday. && .MARINE... Tonight: The primary concern overnight will be the potential development of fog and low clouds across the nearshore waters. A weak front will slowly slip south along the GA/SC coast, expected to become stationary just north of the Savannah River this evening. Areas to patchy fog may develop across the GA nearshore waters this evening, then spread north late tonight. It is possible that a DFA maybe issued tonight. Otherwise, conditions will feature winds around 5 kts with 1-2 ft wave heights. Friday through Sunday: Conditions should remain below Small Craft Advisory Criteria through the period. Broad high pressure should remain across marine zones Friday through much of Saturday, then a weak cold front should sweep across the region late Saturday. Southwest winds ahead of the front are expected to gradually strengthen, reaching 10 to 15 kts on Saturday. Behind the front, winds should veer from northwest Saturday night, then northeast on Sunday between 10 to 15 kts. Seas through the period should favor values between 1 to 2 ft. && .CLIMATE... Record High Temperatures: November 20: KCHS: 82/1942 KCXM: 78/1900 KSAV: 83/1942 November 21: KSAV: 82/2011 November 22: KCHS: 83/1942 KCXM: 79/1997 KSAV: 82/1997 && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...NED SHORT TERM...NED LONG TERM...NED AVIATION...NED MARINE...NED