Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
402 FXUS62 KCHS 151112 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 712 AM EDT Tue Jul 15 2025 .SYNOPSIS... Atlantic high pressure will prevail through early next week. && .NEAR TERM /THROUGH TONIGHT/... Today: Aloft, ridging extending from the subtropical Atlantic will stretch across the area just to the north of the upper low associated with AL93. At the surface, the flow pattern across the region will be driven by the circulation around AL93, but then by the late afternoon the subtropical high will take hold and the low- level flow will become more southeasterly with time. This setup is quite different than yesterday and should yield a much different evolution of convection. For the morning, convection (thought most of it being showers) should occur mostly along the coast and seemingly primarily along the SC coast. Then into the afternoon under the influence of deep layered easterly flow, showers and thunderstorms should shift inland. Even still, model consensus is that the best corridor of instability will reside further inland across central GA and the SC Midlands. Overall coverage should be scattered across the area with a low threat for severe storms. Model soundings show less instability thanks to the onshore flow and warm profiles. Also as a result of the onshore flow, highs are forecast to mostly top out in the low 90s. This will also lower our heat index potential today, with most locations topping out in the low 100s. Tonight: The evening should be pretty quiet with most of the convection occurring well inland of the forecast area. An occasional shower or storm over the coastal waters could try to move onshore, but the coverage should be limited. Then late tonight, the low-level flow will become more southeast and then south-southeast. We should see an increase in shower and thunderstorm activity across the waters, with trajectory of this activity possibly making a run for the SC coast at times. Otherwise, pretty quiet with lows in the low to mid 70s inland and the upper 70s along the coast. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... Deep layered ridging will prevail mid to late week, maintaining a typical July weather pattern. Scattered showers and thunderstorms are expected each day, particularly in the afternoon and early evening. A gradual warming trend will occur, with highs in the lower 90s Wednesday, increasing to the mid 90s by Friday. Heat indices are currently forecast to remain just below Heat Advisory criteria. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... Toasty weather is in store for the weekend as the upper ridge axis shifts overhead. Highs will reach the mid to upper 90s away from the coast each day. Heat indices could approach 108F in a few spots each afternoon. Scattered diurnal convection anticipated, with a bit more coverage possible on Monday as the upper ridge starts to break down. && .AVIATION /11Z TUESDAY THROUGH SATURDAY/... The 12z TAF period begins with dense fog and low stratus at KSAV and VFR conditions at KCHS and KJZI. The dense fog and low stratus should dissipate by 14z for KSAV. Scattered showers and perhaps a thunderstorm will be possible near the terminals through late morning or early afternoon. Thereafter, the focus for showers and storms should shift inland and away from the TAF sites. If a shower or storm were to go over the terminals it could produce a brief period of rain and maybe MVFR conditions. Extended Aviation Outlook: VFR will mainly prevail throughout the period, however brief flight restrictions are possible within showers and thunderstorms that develop in the afternoon and/or evening hours. && .MARINE... Today and tonight: For the morning, the flow pattern along the Southeast coast will be driven by the weak surface low moving into the east coast of FL. Then by the afternoon and through the overnight, the subtropical high will take control. We should see widespread southeast flow across the local waters by early afternoon which will then continue through the overnight. Wind speeds today should top out as a solid 10-15 knots. Then overnight, speeds will gradually increase to become 15 knots or even 15-20 knots at times. Seas should average around 2 feet through today, then increase to become 3-4 feet late tonight. Showers and a few thunderstorms are expected across the coastal waters and near the coast this morning, but this activity isn`t expected to be particularly strong. Then through the afternoon, focus for showers and storms should shift inland. Moderate southerly flow will prevail Wednesday through Sunday. A decent sea breeze will develop along the coast each afternoon. Conditions expected to remain well below advisory criteria. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...BSH SHORT TERM...JRL LONG TERM...JRL AVIATION...BSH/JRL MARINE...BSH/JRL