textproduct: Charleston

WHAT HAS CHANGED

Key Message 1 was updated

KEY MESSAGES

- 1) Poor air quality due to smoke through tonight, and possibly Friday.

- 2) Above normal temperatures with low afternoon humidity expected 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 due to smoke through tonight, and possibly Friday.

An Air Quality Alert remains in effect for the Lowcountry until midnight. The South Carolina Department of Environmental Services has communicated that the alert will not be extended into Friday. There are no Air Quality Alerts in effect for Southeast Georgia. Refer to state air quality agencies for additional information on air quality.

Early evening Geocolor satellite imagery shows extensive smoke in place across the Lowcountry and Southeast Georgia. While most of the smoke is aloft, the smell of smoke is rather widespread with impacts to air quality occurring. Farther the south, satellite shows what appears to be an impressive blow- up at the Highway 82 fire burning in Brantley County, GA. The smoke plume is moving due north and has infiltrated parts of the Long County and will spread into parts of Tattnall, Liberty, Evans and Bryan Counties soon. Webcams out of Jesup are not too bad overall and the KJES AWOS has yet to report any reductions in vsbys; however, this may change later this evening as the nocturnal inversion sets up and mixing heights lower below 1000 ft. The forecast was updated to hit the smoke coverage a bit harder through midnight over parts of Long, Long, Tattnall and Liberty counties.

Some degree of smoke may linger into the day Friday given the ongoing flow pattern. The sea breeze may help conditions somewhat, but most of the smoke should remain aloft again as mixing heights rise.

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

The western periphery of Atlantic High pressure will prevail across our area through Friday, bringing dry weather. High temperatures Friday will be above normal, generally in the mid to upper 80s, except cooler at/near the beaches due to the sea breeze. Dry conditions will also prevail. Relative humidity values Friday afternoon could drop into the middle 20s west of I-95, but will be higher closer to the coast. However, overall winds won't be strong. Though, they could briefly gust to around 15 mph across inland locations with the passage of the afternoon sea breeze. Given the extremely dry fuels and the ongoing drought, the fire danger will remain elevated.

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

A mid level shortwave will shift into the eastern U.S. Saturday into Sunday, helping to send a cold front through the area. There looks to be enough moisture and instability to allow scattered to numerous showers and thunderstorms to develop, beginning Saturday afternoon, with coverage likely peaking in the evening into Saturday night. While any rain will certainly be beneficial, this event will not significantly improve the ongoing drought. Guidance has been consistent in showing average rainfall totals generally 0.25-0.50". NBM indicates the probability for 24 hour rainfall of greater than 0.50" is only 20-30%. The threat for severe weather is low.

There are some indications a weak wave could develop along the front offshore on Sunday, so rain chances will linger through the day. Another front could impact the area towards the middle of next week, bringing additional chances for rain. However lack of model consistency brings low confidence in the forecast at this range.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

24/00z TAF Discussion: KCHS/KJZI/KSAV: VFR through 25/00z.

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 linger over the coastal waters through late this week. Expect S to SW winds 10-15 kts, with higher gusts along the land/sea interface with the formation of the afternoon sea breeze. Wave heights will be 2-3 ft.

A cold front will approach and cross the waters over the weekend. Winds/seas during this time will stay below Small Craft Advisory criteria, with winds generally 15 knots or less and seas 2-3 feet. High pressure will build south into the area Sunday night and could produce a brief northeast surge of 15-20 knots into early Monday. Winds should settle thereafter as the pressure gradient eases and winds turn to the east and eventually south through Tuesday.

EQUIPMENT

The KCLX radar remains out of service. Parts are expected to arrive Friday. Adjacent radar sites: KCAE, KLTX, KJAX, KVAX and KJGX.

CHS WATCHES/WARNINGS/ADVISORIES

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