textproduct: Charleston

WHAT HAS CHANGED

The Aviation Section was updated for the 12Z TAFs.

KEY MESSAGES

- 1) Poor air quality with smokey conditions to linger through today, possibly longer.

- 2) Above normal temperatures with low afternoon humidity expected today and Friday.

- 3) A cold front could provide some much needed rainfall across southeast Georgia and the South Carolina Lowcountry this weekend.

DISCUSSION

KEY MESSAGE 1: Poor air quality with smokey conditions to linger through today, possibly longer.

The South Carolina Department of Environmental Services (SCDES) has issued an Air Quality Alert for all of the Lowcountry through late this evening.

Infrared satellite detected two large wildfires over southern GA early this morning. So far this morning, sfc observations indicated little to no issues with low visibility due to wildfire smoke. However, given high pressure centered over the western Atlantic and the development of the nocturnal inversion, smoke concentrations may increase across the region, especially over SE GA. The forecast will continue to feature a mention of patchy smoke this morning.

HRRR smoke guidance indicates that vertically integrated smoke will linger or increase across the region today, carried by the southwest winds around the sfc high. As the sea breeze develops this afternoon, smoke concentration may increase along and ahead of the sea breeze. However, deep mixing should aid in keeping smoke limited to patchy. Some degree of smoke may linger into early this weekend depending on the coverage of showers and thunderstorms and wind speed.

KEY MESSAGE 2: Above normal temperatures with low afternoon humidity expected today and Friday.

Quiet weather conditions will prevail across the region through tomorrow while surface high pressure remains centered across the western Atlantic. Aloft, ridging will continue to build from the west-southwest. High temps will peak above normal this afternoon and Friday afternoon, generally in the mid-upper 80s away from the coast (warmest across inland Georgia). Dry conditions will prevail, with RH values forecast to drop into the low-mid 20s west of I-95 each afternoon as strong surface heating promotes deep mixing into drier air aloft. Although RH values are considered critical, surface winds are only expected to gust up to around 15 mph across inland locations. The stronger gusts (around 20 mph) are forecast to occur with the afternoon sea breeze and are correlated with higher RH values. Given very dry fuels and low RH, fire danger will remain the primary concern today and tomorrow (Friday).

KEY MESSAGE 3: A cold front could provide some much needed rainfall across southeast Georgia and the South Carolina Lowcountry this weekend.

A shortwave trough is forecast to ripple through the flow aloft on Saturday, with a surface cold front approaching the region Saturday into Saturday night. Ahead of the front increasing moisture convergence combined with some weak instability and the afternoon sea breeze could trigger isolated to scattered showers/thunderstorms. Coverage of precipitation is expected to increase Saturday evening into Sunday morning. While the rainfall is desperately needed across the region, this will not be a drought buster. Guidance has been consistent in amounts generally 0.25-0.5" across the region.

AVIATION /12Z THURSDAY THROUGH MONDAY/

12Z TAFs: VFR conditions expected across the terminals through the TAF period. Large wildfires over southern GA and FL have generated a large plume of smoke across the Southeast U.S. HRRR smoke guidance indicates that the smoke will remain across the region as sfc high pressure remains centered over the western Atlantic. Near sfc smoke concentrations may peak just ahead of the sea breeze this afternoon. The KCHS and KSAV TAFs will feature VFR visibility in smoke between 17-21Z. Following the sea breeze, smoke should decrease as winds turn from the south- southwest.

Extended Aviation Outlook: VFR conditions will prevail through Friday with a sea breeze likely to occur during afternoon hours. Scattered showers and/or thunderstorms could impact the terminals late Saturday and Sunday.

MARINE

High pressure will remain centered over the western Atlantic through the rest of the work week. The pressure gradient will remain generally weak, SSW winds between 10 to 15 kts. Some enhancement in the winds may occur near the coast with the formation of the sea breeze each afternoon. Wave heights are forecast to remain between 2- 3 ft.

A cold front will approach the waters from the west on Saturday, timed to push across the marine zones late Saturday night into Sunday morning. As the front passes late Saturday night, winds will veer from the NNW, remaining between 10 to 15 kts. Seas should remain between 2-3 ft into early next week.

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...Air Quality Alert until midnight EDT tonight for SCZ040- 042>045-147>152. MARINE...None.