459 FXUS62 KCHS 130739 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 339 AM EDT Fri Jun 13 2025 .SYNOPSIS... A series of upper level disturbances will affect the area through the weekend. Meanwhile, high pressure will expand over the western Atlantic and persist through next week. && .NEAR TERM /THROUGH TONIGHT/... Today: Aloft, the center of an anticyclone will be centered just to the south-southeast off the east coast of FL. At the surface, the area will continue to sit under the western extent of subtropical high pressure over the Atlantic. The day will likely start off similar to yesterday with small showers impacting areas along the coast within subtle lines of convergence. These showers will gradually shift inland through mid to late morning before the main convective initiation takes place around midday or just into the early afternoon. The best coverage for thunderstorms should then gradually shift inland through the rest of the afternoon. Similar to yesterday, the overall severe threat is low. MLCAPE values are expected to peak in the 1,500-2,000 J/kg range and DCAPE values are expected to be in the 500-700 J/kg. Getting a strong to marginally severe storm will likely again be dependent on boundary interactions to enhance updrafts. Model soundings do show a bit more flow through the mid-levels, meaning that storm motions should be slowly higher, more into the 10-15 mph range. There will still be a threat of locally heavy rainfall and minor flooding in areas where thunderstorms pass. Highs are expected to mostly be in the upper 80s, with a few low 90s possible mainly across southeast GA. This evening and tonight: Afternoon convection should shift inland and dissipate through the evening hours such that most of the area should be rain-free by the early morning hours. As the pattern has shown the last few nights we will likely have to deal with some degree of coastal showers through the overnight, or at least showers across the coastal waters. Lows are forecast to fall into the low to mid 70s. && .SHORT TERM /SATURDAY THROUGH MONDAY/... As the upper level high remains off to our south-southeast and the surface Atlantic high pressure well off to our east, chances for daily showers and thunderstorms continue throughout the weekend and into the beginning of next week. Highest probabilities and spatial coverage are expected through the late morning and into the afternoon hours as instability builds, with chances decreasing into the overnight hours. While severe weather can`t be entirely ruled out given 1-2 kJ of MUCAPE, the lack of strong forcing and weak mid- upper level flow will keep such activity isolated at best. This is further validated by various AI/ML models, as well as the SPC keeping chances for severe weather below 5%. As for temperatures, they are expected to slowly increase throughout the weekend given the persistent pattern underneath the aforementioned upper level high. Both the NAEFs and ECMWF ensemble situational awareness tables (ESATs) show the region remaining near/above the 90th percentile of climatology with respect to geopotential heights from 850mb up to 200 mb per the NAEFS and ECMWF, resulting in afternoon highs on Saturday and Sunday in the upper 80s to lower 90s and lower to mid 90s on Monday, while those near the coast remain in the mid/upper 80s. Heat index values in the mid 90s to lower 100s are also expected, possibly as high as mid 100s on Monday if dewpoints rise into the upper 70s. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... Models have slowed the previous westward shift of the ridge axis, with the 13.00 suite now suggesting that won`t happen until later next week. This keeps our pattern continuing, with daily chances for showers and thunderstorms, and temperatures remaining in the lower to mid 90s. Dewpoints have come in a touch lower with this cycle of the NBM, resulting in heat indices largely remaining below Heat Advisory criteria, though they start to appear on Thursday and again on Friday across the SC Lowcountry and southeast GA. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... The 06z TAF period begins with VFR conditions at KCHS and KSAV, but MVFR ceilings in place at KJZI. The first concern is for showers to soon move into the vicinity at KJZI. These showers could bring brief rainfall as well as MVFR ceilings. This activity should miss KSAV, but could come closer to KCHS through about 10z. Then attention turns to afternoon thunderstorm potential. Thunderstorms should start developing around 17-18z and could at least in the vicinity at all 3 TAF sites. Confidence in direct impacts is low, but if the terminals take a direct hit from a thunderstorm expect a brief period of heavy rain and MVFR or IFR conditions. Extended Aviation Forecast: Brief flight restrictions are possible in showers and thunderstorms each day, mainly in the afternoon. && .MARINE... Today and tonight: Southerly flow, mostly in the 10-15 knot range, will prevail through the period. There will likely be a modest enhancement along the land/sea interface with the sea breeze, perhaps producing gusts up to 20 knots at times in Charleston Harbor. Seas will mostly average 2-3 feet, except up to 4 feet at times in the outer waters. Saturday through Wednesday: Aside from daily shower and thunderstorm chances, no marine concerns as conditions remain below small craft criteria. Winds remain out of the south- southwest. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...BSH SHORT TERM...APT LONG TERM...APT AVIATION...APT/BSH MARINE...APT/BSH