textproduct: Charleston

WHAT HAS CHANGED

Key Message 1 has been updated to reflect ongoing trends tonight. The Aviation Section has been updated for the 00Z TAF issuance. The Marine Section has been updated to reflect ongoing trends tonight.

KEY MESSAGES

- 1) Scattered showers and thunderstorms possible along coastal areas late tonight.

- 2) A typical summertime pattern will prevail this weekend into next week. The threat for isolated strong to severe thunderstorms and localized heavy rainfall will exist each day.

DISCUSSION

KEY MESSAGE 1: Scattered showers and thunderstorms possible along coastal areas late tonight.

Latest radar trends indicate a slow waning of convection across the local area early this evening, but likely diminishing across remaining locations during the next hour or two due to the loss of daytime heating. Similar to the past several nights, convection is expected to redevelop over the Atlantic through the night as low-level convergence shifts back along the west wall of the Gulf Stream after midnight. Activity does not look as extensive as the past few nights, but some degree of isolated to perhaps scattered showers/tstms will make a run for the coast during the early morning hours Friday.

KEY MESSAGE 2: A typical summertime pattern will remain in place through the upcoming weekend. Isolated strong to severe thunderstorms and the threat for localized heavy rainfall will be possible each day.

The pattern will be dominated by deep high pressure over the western Atlantic and Eastern Seaboard. While upper subsidence likely suppresses most convective activity Friday, the pattern will support daily scattered convection each day thereafter. There is increasing confidence that Saturday will begin with morning showers and storms, especially along the GA beaches, with outflow potentially developing new activity north and westward through the late morning and early afternoon Saturday. Then, Sunday and into next week, the sea breeze and any remnant outflow boundaries will serve as the primary focus for afternoon and evening shower and thunderstorm development.

Persistent southerly flow will continue to advect deep moisture into the region. Moderate instability looks to develop each afternoon, with SBCAPE values rising to 2500-3000 J/kg. PWAT values near or slightly above 2 inches each day from Saturday onward will support efficient rainfall rates, with some storms capable of dropping a quick 1-2 inches of rain in a short period. In addition, slow storm motions of around 10 kt, combined with training or repeated rounds of convection, could increase the potential for isolated instances of minor flooding, especially in low-lying and poor drainage areas. Lastly, with little shear in the environment, storms will remain pulse-like. Although widespread severe weather is not expected, a few stronger to marginally severe storms could produce damaging wind gusts.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

VFR conditions should prevail at CHS/JZI/SAV terminals through 00Z Saturday. However, scattered showers/thunderstorms could arrive from the Atlantic and impact the terminals during the 12-18Z timeframe Saturday, potentially resulting in TEMPO MVFR conditions. At this time, confidence is too low to include in the latest TAF issuance.

Extended Aviation Outlook: Periodic flight restrictions are expected in showers and thunderstorms this week and into this weekend.

MARINE

Through Tonight: Generally quiet marine conditions are expected with winds/seas remaining well below Small Craft Advisory levels. However, rounds of showers/tstorms are likely across the marine zones tonight/early Friday morning.

Friday through Tuesday: Atlantic high pressure will be the dominant synoptic feature through the weekend. Light to moderate winds prevail with gusty winds along the land/sea interface each afternoon associated with the sea breeze. Be alert for the potential for nocturnal jetting to set up Sunday into early next week, keeping breezy conditions in place along the beaches overnight. This feature is typically poorly resolved by models, but the combination of the weak surface trough shifting inland with persistent strong high pressure offshore and very warm water makes for a favorable setup.

CHS WATCHES/WARNINGS/ADVISORIES

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