textproduct: Charleston

WHAT HAS CHANGED

Key Message 1 has been updated to reflect shower and thunderstorm trends today. The Aviation Section has been updated for the 12Z TAF issuance.

KEY MESSAGES

- 1) Scattered showers/thunderstorms expected across the area today with isolated/minor flooding possible.

- 2) Minor coastal flooding possible during this evening's high tide cycle along the South Carolina and Georgia coast.

- 3) Hot and humid conditions are expected to return to the area late this week through early next week. Heat Advisories could be needed.

DISCUSSION

KEY MESSAGE 1: Scattered showers/thunderstorms expected across the area today with isolated/minor flooding possible.

Today and Tonight: A weak trough/coastal low positioned off the Southeast Georgia Coast should slowly meander nearby this morning, but gradually shift further offshore and/or dissipate this afternoon. A few showers and thunderstorms could redevelop near and just north of this feature across coastal waters, then shift onshore this morning, but latest trends in model guidance suggest the bulk of precip activity is more likely to start up early afternoon in the vicinity of a sea breeze during peak heating hours, mainly across the coastal corridor in Southern Southeast South Carolina and Southeast Georgia. Activity could make slightly more inland progress across Southeast Georgia depending on the location of a weak/remnant boundary. Although convection is not expected to be particularly strong today, gusty winds and brief heavy downpours are possible in some locations. This could pose a limited risk for flooding this afternoon, especially if activity is slow moving and occurs across areas that have experienced heavy rainfall during the past 24 hours.

KEY MESSAGE 2: Minor coastal flooding possible during this evening's high tide cycle along the South Carolina and Georgia coast.

While the highest astronomical tides have passed, a 6.46 ft MLLW astro tide Wednesday evening in the Charleston Harbor brings another chance for coastal flooding. Weak and variable surface winds will likely keep tidal departures below 1 foot, resulting in total water levels in 7.2-7.4 ft MLLW range, which will likely necessitate a coastal flood advisory later this evening. At Fort Pulaski, an 8.37 ft MLLW astro tide with similar tidal departures below 1 foot expected, will likely keep total water levels below minor coastal flood criteria. If heavy rainfall were to occur near or during the time of the evening high tide cycles, flooding concerns would increase as total water levels would similarly increase, which looks most likely for southeast Georgia given the higher coverage of showers and thunderstorms expected this evening.

In the absence of strong tidal departures on Thursday, coastal flood issues are not anticipated.

KEY MESSAGE 3: Hot and humid conditions are expected to return to the area late this week through early next week. Heat Advisories could be needed.

Temperatures will be increasing Thursday as strong ridging builds aloft, with hot and humid conditions expected to remain across the region into next week. Thursday will see temperatures in the lower to mid 90s, and with dewpoints remaining in the lower to upper 70s (highest along the coast), widespread heat index values of 100+ return to the region. Areas along the coast may breach the 108 deg F mark for a few hours, bringing the potential for Heat Advisories. Expect a marginally warmer day for Friday as high temperatures in the mid 90s expand, with another round of heat advisories possible as heat index values peak in the 105-110 degree range along the coast.

While an upper level trough moves towards the area on Saturday before moving through on Sunday, the associated surface low pressure will remain well north of the region, with hot and humid conditions continuing across the region. Heat index values of 105-110 degrees will be possible along the coast each afternoon, and Heat Advisories could be needed. As for rain chances, typical summertime isolated to scattered showers are possible along the afternoon sea breeze dissipating into the evening hours.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

VFR conditions should prevail at CHS/JZI/SAV terminals through morning hours. Chances for showers and thunderstorms increase during the afternoon with TEMPO groups between 18-21Z at CHS/JZI terminals and 18-22Z at the SAV terminal. TEMPO flight restrictions due to linger showers/thunderstorms are possible at SAV and could need to be extended 1-2 hours in future TAF issuances/amendments. VFR conditions should then prevail at all terminals between 00-12Z Thursday.

Extended Aviation Outlook: Typical summertime pattern will result in diurnally driven showers and thunderstorms, resulting in isolated risks of lowered cigs and vsbys Thursday into the weekend.

MARINE

Today: A weak front/boundary will remain in the vicinity into the middle of the week, which will continue chances for scattered showers and thunderstorms throughout the period. Surface flow will be variable as a result of the front. In general, strong thunderstorms are not expected, though an isolated strong thunderstorm cannot be ruled out.

Thursday - Friday: South-southwesterly surface flow is expected to develop on Thursday and continue into Friday as a subtropical high develops, with winds and seas expected to remain below Small Craft Advisory criteria.

Saturday - Sunday: Over the weekend, the surface pressure gradient is expected to strengthen between an inland trough and the aforementioned high to the east. This will produce stronger southwest to south flow, with speeds getting more into the 15-20 knot range and an increasing chance of gusts up to 25 knots, mainly for the SC coast and Charleston Harbor. We could even need some short duration Small Craft Advisories over the weekend.

CHS WATCHES/WARNINGS/ADVISORIES

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