FXUS62 KCHS 241102 AFDCHS
Area Forecast Discussion National Weather Service Charleston SC 702 AM EDT Fri Apr 24 2026
.WHAT HAS CHANGED...
The Aviation Section was updated for the 12Z TAFs.
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.KEY MESSAGES...
- 1) Above normal temperatures with low relative humidity inland
today. Isolated showers possible along the sea breeze over the South Carolina Lowcountry this afternoon.
- 2) A cold front could provide some much needed rainfall across
southeast Georgia and the South Carolina Lowcountry this weekend.
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.DISCUSSION...
KEY MESSAGE 1: Above normal temperatures with low relative humidity inland today. Isolated showers possible along the sea breeze over the South Carolina Lowcountry this afternoon.
Sunny to mostly sunny sky conditions will remain across the forecast through early this afternoon. Strong insolation should result in rapidly warming temperatures, peaking in the mid to upper 80s early this afternoon. The very warm temperatures combined with the approaching H5 shortwave may result in very deep mixing inland of the sea breeze. The mixing should keep inland dewpoints in the upper 40s to around 50, resulting in RH values below 30 percent. The low RH values combined with very dry fuels may lead to worsening fire danger conditions this afternoon, primarily inland of I-95. In addition, HRRR smoke guidance indicates that smoke sourced from ongoing GA wildfires may drift over the forecast area today. However, deep mixing should keep sfc concentrations limited, patchy smoke is possible before the sea breeze.
High resolution guidance indicates some convection along the sea breeze this afternoon. Given the ongoing severe to extreme drought across SE GA and SC, I am hesitant to add PoPs to the forecast. However, both the 0Z HREF and REFS both indicate 6 hr probabilities of 0.01 inches between 40 to 50 percent over portions of the SC Lowcountry this afternoon. Forecast soundings from recent runs of the HRRR indicates that SBCAPE will peak around 500 J/kg with little to no CIN over the SC Lowcountry, some CIN present across SE GA. Near term guidance times the H5 shortwave to ripple over the forecast area during the heat of the afternoon. The combination of upper forcing, weak instability, and a progressive sea breeze, it appears that isolated showers may occur over portions of inland SC this afternoon. The forecast will feature SCHC PoPs during the mid to late afternoon. Any convection that develops this afternoon should quickly dissipate with the loss of heating towards sunset.
KEY MESSAGE 2: A cold front could provide some much needed rainfall across southeast Georgia and the South Carolina Lowcountry this weekend.
A sharp, positively tilted shortwave will move into the eastern U.S. Saturday into Sunday, helping to push a cold front into the area. Deep moisture is progged to increase ahead of the boundary, with PWATs rising to around 1.5-1.6 inches by Saturday evening, supporting development of much needed rainfall. Isolated to scattered showers are expected to develop Saturday evening ahead of the front and persist into the overnight period as the boundary slows while dropping in from the northwest. This slower progression introduces some uncertainty in the timing of the FROPA. Showers could linger into Sunday, potentially into the afternoon, before the front pushes offshore. Instability remains limited Saturday night, but looks to increase to >1200 J/kg by Sunday afternoon, supporting isolated to scattered thunderstorms if convection continues into midday Sunday.
Although any rainfall will be beneficial, this system is not expected to significantly alleviate ongoing drought conditions. The NBM has been consistently indicating average rainfall totals between 0.25 and 0.50 inches, with only a 15-30% probability of 24-hour rainfall exceeding 0.50 inches.
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.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
12Z TAFs: VFR conditions expected across the terminals through the TAF period. The sea breeze should push inland at a slightly quicker pace this afternoon. The sea breeze should slide across the terminal between 17-19Z, turning winds from the south with a temporary surge. Winds should settle to around 5 kts around 0Z.
Extended Aviation Outlook: Scattered showers and/or thunderstorms could impact the terminals late Saturday into Sunday.
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.MARINE...
High pressure will remain centered over the western Atlantic today and tonight. The pressure gradient will remain generally weak, south winds between 10 to 15 kts. Some enhancement in the winds may occur near the coast with the formation of the sea breeze this afternoon. Wave heights are forecast to remain around 2 ft within 20 NM and 3 ft between 20-60 NM.
A cold front will push offshore Sunday. High pressure building in from the north Sunday night will bring a brief northeast surge of 15- 20 kt winds into early Monday. Conditions could approach Small Craft Advisory levels, with gusts nearing 25 kt and seas nearing 6 ft, mainly beyond 40-60 nm. Winds and seas diminish thereafter as the pressure gradient relaxes.
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.EQUIPMENT...
The KCLX radar remains out of service. Parts are expected to arrive Friday. Adjacent radar sites: KCAE, KLTX, KJAX, KVAX and KJGX.
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.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None. SC...None. MARINE...None.
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BRS/NED