AFD_CHS

FXUS62 KCHS 300631 AFDCHS

Area Forecast Discussion National Weather Service Charleston SC 231 AM EDT Thu Apr 30 2026

.WHAT HAS CHANGED...

All sections have been updated.

.KEY MESSAGES...

- 1) Showers and thunderstorms expected to move through

southeast Georgia and southeast South Carolina this morning bringing the potential for gusty winds and locally heavy rainfall.

- 2) A disturbance will bring much-needed rain to the region

Friday night through Saturday, though no significant impacts are expected at this time.

.DISCUSSION...

KEY MESSAGE 1: Showers and thunderstorms expected to move through southeast Georgia and southeast South Carolina this morning bringing the potential for gusty winds and locally heavy rainfall.

Aloft, zonal flow is in place from the Desert Southwest to the Southeast Coast. An well defined shortwave embedded within the zonal flow will push to the east early this morning and spread across the forecast area through mid morning. At the surface, a cold front stretches from the East Texas to the Carolina Foothills. Ahead of this front, several clusters of convection are ongoing and tracking to the east within a solid 25-30 knots of steering flow. The main forecast challenge for the day revolves around this upstream convection and its eventual passage through the forecast area later this morning.

There is good agreement among hi-res models that upstream convection will begin to approach our southeast GA counties in the predawn hours. There is also good agreement that convective activity will expand in coverage around the Savannah River and then spread across southeast SC with high coverage of showers and thunderstorms from sunrise through the mid morning hours. Availability isn't particularly impressive, but enough to support storm development, but pockets of mid-level lapse rates approaching 7 C/km and mid- level flow of around 40 knots could yield a strong to marginally severe thunderstorm. Damaging wind gusts will be the primary threat. Also of note is the potential for locally heavy rainfall. The HREF depicts are with 3-hour QPF mean well in excess of 0.50" with probabilities up to 50% of an inch or more in 3 hours. The best rainfall potential seems to align across southeast SC, with lesser amounts expected across southeast GA.

Convection is expected to shift offshore by late morning. In its wake, conditions should be pretty stable heading into the afternoon with the aforementioned front sinking southward. Hi- res models are in good agreement that the afternoon will be quiet except for some possible convection further south along the front for the southeast GA coast.

KEY MESSAGE 2: A disturbance will bring much-needed rain to the region Friday night through Saturday, though no significant impacts are expected at this time.

Confidence is increasing that beneficial rains will fall across the drought-stricken Lowcountry and Southeast Georgia Friday night into Saturday. A weak area of low pressure looks to develop along a remnant front draped across the Southeast coast and along the Florida Panhandle Friday. Deep moisture will increase with PWATs forecast to reach 1.5-1.7" by daybreak Saturday. As forcing for ascent increases ahead of a potent southern stream disturbance, widespread rains will begin to spread in from the west Friday night and impact the entire area Saturday. Rain will gradually end from west-east late Saturday afternoon into the evening hours as the developing surface low moves away, passing just south of Cape Hatteras and eventually out into the open Atlantic Saturday night.

There are signals that a corridor of heavier rainfall could set up across the interior within a region of enhanced lift induced by a dual-jet structure between the polar jet to the north and a weaker subtropical jet to the south. Current model guidance focuses this potential over the SC/GA Midlands, which may clip the far interior portions of the forecast area. However, the exact placement of the axis of heavier rain remains uncertain. Latest NBM guidance shows a 40-60% chance of rainfall exceeding 1.5 inches, and a 15-30% chance of totals exceeding 2 inches for the entire area. We do not anticipate much of a threat for flooding at this time, given that soils are parched, and rain rates should be low enough to minimize the risk of rapid downpours.

Surface-based instability is virtually nonexistent with the region likely remaining well embedded in the cold sector, but a few elevated tstms are certainly possible given the degree of forcing noted aloft.

.AVIATION /06Z THURSDAY THROUGH MONDAY/...

The 06z TAF period begins with VFR conditions at KCHS, KJZI, and KSAV. The main forecast challenge for the period will be the potential for thunderstorms to move through the terminals later this morning. Showers and thunderstorms are expected to develop in a few hours and track to the east through the mid morning hours. The threat will come at KSAV first, followed by KCHS and KJZI. Overall, the main time period of concern is generally between 10-15z. These storms could produce strong wind gusts, as well as a period of IFR conditions. Once this activity ends, the afternoon hours should be mostly quiet and VFR. There could be additional storm development across coastal southeast GA in the late afternoon, but should stay to the southwest of KSAV.

Extended Aviation Outlook: Flight restrictions are possible within showers/thunderstorms, especially Friday night into Saturday as a system moves across the region.

.MARINE...

Through tonight: Southwest flow will prevail across the waters early this morning ahead of a cold front sagging in. As the front moves through today, winds across the SC waters will start to turn more northeasterly with southerly flow across the GA waters. By tonight, a more uniform northeast flow will take hold. Winds and seas will both remain well below Small Craft Advisory thresholds. Likely of more interest is the potential for thunderstorms this morning along the coast that could produce strong wind gusts. The main time period of concern is approximately 5-10am, with the best chance for strong storms along the SC coast.

There is a risk for winds to reach marginal Small Craft Advisory levels Saturday as low pressure develops offshore and pulls away from the region. Gusts to 25 kt may linger over parts of the offshore waters through Saturday night into early Sunday morning. Seas look to peak around 3-5 ft within the nearshore waters and 4-6 ft within the offshore waters late Saturday afternoon into early Sunday morning.

.CHS WATCHES/WARNINGS/ADVISORIES...

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

BRS/BSH