textproduct: Charleston

WHAT HAS CHANGED

All sections have been updated.

KEY MESSAGES

- 1) Scattered showers and thunderstorms will continue to impact portions of southeast Georgia and southeast South Carolina daily through the weekend, with localized heavy rainfall possible at times.

- 2) Locally dense fog is possible across inland southeastern Georgia late tonight and early Thursday morning.

- 3) The potential for coastal flooding will persist into Friday, primarily for portions of the southeast South Carolina coast.

DISCUSSION

KEY MESSAGE 1: Scattered showers and thunderstorms will continue to impact portions of southeast Georgia and southeast South Carolina daily through the weekend, with localized heavy rainfall possible at times.

Through Tonight: Surface high pressure building across the region from the Mid-Atlantic will favor a southeasterly flow locally, which could allow isolated/scattered coastal showers to drift onshore at times overnight. Activity should remain rather progressive with lighter precip accumulations, before eroding/diminishing in coverage during the second half of the night.

A more typical summertime pattern takes hold Thursday as subtropical high pressure builds to the east. This will support daily scattered showers and thunderstorms. Convective coverage is expected to peak Friday into Saturday as upper-level shortwave energy traverses the Southeast. Southerly flow will transport deep moisture into the region beginning Thursday, elevating PWATs above 2.0 inches and supporting efficient rainfall rates through the weekend. Instability looks to be modest with daily SBCAPE values peaking around 2200-2500 J/kg. This could support periods of heavy rain at times, especially within thunderstorms, leading to the potential for locally heavy downpours and minor flooding issues.

KEY MESSAGE 2: Locally dense fog is possible across inland southeastern Georgia late tonight and early Thursday morning.

Sfc winds will become light/calm across the region overnight while ample moisture (sfc dewpts in the low-mid 70s) remain, setting up an environment conducive for fog near locations that experienced some rain/showers earlier today. Some guidance places a favorable stretch of condensation pressure deficits across southern southeast South Carolina into Southeast Georgia late tonight, where HREF probabilities for visibilities <0.5 mi are generally around 30%. Patchy to areas of fog is possible late night, some of which could become locally dense heading into daybreak Thursday.

KEY MESSAGE 3: The potential for coastal flooding will persist into Friday, primarily for portions of the southeast South Carolina coast.

Astronomical tide levels have peaked with with this evening's high tide, but will remain elevated through Friday. This could support minor coastal flooding along the southeast South Carolina coast during the next 1-2 evening high tide cycles given recent positive tidal departures that will be slow to change while winds weaken and turn more southerly. Thursday evening should see the best chance for reaching 7.0 FT MLLW in the Charleston Harbor before conditions improve further. A Coastal Flood Advisory could eventually be needed.

AVIATION /01Z THURSDAY THROUGH MONDAY/

VFR conditions should prevail at CHS/JZI/SAV terminals through 00Z. However, there are few exceptions during the next 24 hours. Fog could develop across the terminals late tonight, particularly at SAV given recent rains and light/calm winds anticipated overnight. TEMPO MVFR vsbys have been introduced between 09Z-13Z Thursday at SAV. The next round of flight restrictions could arrive with showers and/or thunderstorms that develop during afternoon hours Thursday. PROB30 groups have been introduced between 16-22Z at JZI and 17-23Z at CHS for showers and MVFR conditions. At SAV, a PROB30 group has been added from 17-23Z for thunderstorms and MVFR conditions.

Extended Aviation Outlook: Periodic flight restrictions will be possible each day through the weekend within showers and thunderstorms, mainly during the afternoon hours.

MARINE

Through Tonight: Easterly flow between 15-20 kt will slowly weaken during evening hours, becoming east-southeast around 10 kt or less after midnight tonight. Seas between 3-5 ft will also subside during the period, generally to 2-4 ft by late night.

Thursday through Monday: Tranquil marine conditions arrive Thursday and persist through the weekend under light southerly to southwesterly flow. Seas will hold steady at 2 to 3 feet throughout the period.

Rip Currents: Conditions will slowly improve with winds weakening and turning more southerly by daybreak Thursday. However, lingering swell and the light onshore flow supports a Moderate Risk for rip currents along all beaches Thursday, before conditions improve to a Low Risk Friday.

CHS WATCHES/WARNINGS/ADVISORIES

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