AFD_CHS

FXUS62 KCHS 251111 AFDCHS

Area Forecast Discussion National Weather Service Charleston SC 711 AM EDT Sat Apr 25 2026

.WHAT HAS CHANGED...

All sections have been updated.

.KEY MESSAGES...

- 1) A cold front will push across southeast Georgia and the

South Carolina Lowcountry tonight into Sunday, bringing increased rain chances.

.DISCUSSION...

KEY MESSAGE 1: A cold front will push across southeast Georgia and the South Carolina Lowcountry tonight into Sunday, bringing increased rain chances.

Through Saturday night, the upper pattern will feature mostly zonal flow will some embedded shortwave energy. At the surface, a cold front situated upstream of the forecast area will start to draw closer from the west, especially during the overnight. We will see moisture profiles improve through the period, with precipitable water increasing into the 1.25-1.50" range and likely peaking during the evening and early morning hours. The combination of some shortwave energy aloft and increasing moisture ahead of the approaching front should result in more shower and thunderstorm coverage than we have seen in quite some time. Hi-res model guidance would suggest that convection will start in the afternoon as some combination of upstream development moving in from the west ahead of the front, along with development along the sea breeze as well. Conditions shouldn't support robust coverage, with mainly isolated to scattered activity expected. Model soundings do not support much instability, supported by low probabilities noted in the HREF for CAPE values in excess of 500 J/kg. Therefore, the severe threat is virtually zero. Through the evening and overnight, we could continue to see isolated to scattered showers (and a thunderstorm or two) as the area continues to sit within the moisture feed ahead of the front. Therefore, rain chances continue through the night. While locations directly impacted by passing showers and storms could see rainfall amounts of a quarter of an inch or more, overall rainfall will be quite variable with most areas remaining dry. Expect another warm day with highs reaching the upper 80s for much of the area, running about 8-10 degrees above normal.

By Sunday morning, the front will extend across the Carolina Midlands and into central Georgia, gradually pushing toward the coast through the day. By this point, the deeper moisture will be pushing offshore with isolated, or at best, scattered showers expected ahead of the front prior to its offshore passage in the evening. Although instability has trended downward, SBCAPE values are still expected to reach around 1000 J/kg Sunday afternoon, which could support a few isolated thunderstorms. It wont be until Sunday night, when dry high pressure builds in from the north, that precipitation chances will fully diminish and skies begin to clear.

While any rainfall will be beneficial, this system is not expected to provide significant relief from ongoing drought conditions. Recent model trends indicate slightly lower rainfall totals, with most areas receiving between 0.10 and 0.25 inches. A few inland locations could see up to around 0.50 inches, particularly where the front slows and convection becomes more concentrated. However, given the isolated to scattered nature of convection, some areas could receive no measurable rainfall.

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...

The 12z TAF period begins with VFR conditions at KCHS, KJZI, and KSAV. Overall, VFR conditions should persist through the TAF period, though there is some potential for showers and thunderstorms near the terminals late this afternoon, through the evening, and even into the early morning hours. The best chance for showers and storms appears to come first at KSAV along the sea breeze late this afternoon. Confidence is still low, especially in the thunder potential, so we have only advertised VCSH starting at 22z. The shower potential will likely arrive later at KCHS and KJZI, more into the evening and the latter portion of the TAF period. Overall coverage is only expected to be isolated to scattered so the potential for direct impacts is still relatively low. Conditions do not look very unstable, so the potential for thunder isn't considered to be particularly high at this point. Shower activity should dissipate by the early morning hours.

Extended Aviation Outlook: Showers and isolated thunderstorms associated with a cold front could bring reduced vsbys/cigs Sunday and possibly again midweek.

.MARINE...

Through Saturday night: An inland cold front will begin to approach from the west though the subtropical high will remain the primary driver of the the flow pattern across the local waters. Southwest flow in the morning will turn more southerly in the afternoon with the onset of the sea breeze. We should then see modestly higher south to southwest flow through the overnight as the front draws closer. Speeds will mostly top out around 10-15 knots, except up to 15-20 knots along the land/sea interface and the Charleston Harbor in the afternoon and early evening. Seas are expected to average 2-3 feet through the period.

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 up to 25 kt and seas nearing 6 ft. Winds and seas diminish thereafter as the pressure gradient relaxes.

.CHS WATCHES/WARNINGS/ADVISORIES...

GA...None. SC...None. MARINE...None.

BRS/BSH