textproduct: Charleston

WHAT HAS CHANGED

The Aviation Section has been updated for the 12Z TAF issuance.

KEY MESSAGES

- 1) Above normal temperatures with low afternoon humidity expected through the remainder of the work week.

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

DISCUSSION

KEY MESSAGE 1: Above normal temperatures with low afternoon humidity expected through the remainder of the work week.

Surface high pressure will remain centered over the western Atlantic through the rest of the work week. Aloft, a broad H5 trough over the region today will shift east over the Atlantic tonight, with heights rising as a ridge axis ripples over the forecast area on Friday. This pattern should yield a dry and warm pattern across SE GA and SC through the rest of the work week. High temperatures should favor values in the low to mid 80s today, warming to the mid to upper 80s on Friday. The warm afternoon temperatures is expected to support mixing in excess of 8 kft this afternoon and 10 kft on Thursday and Friday. The deep mixing should keep afternoon dewpoints in the 40s, with the lowest values across the I-16 corridor. The dewpoint forecast was constructed of a blend of the NBM deterministic and NBM10 each afternoon. Fortunately, the sfc pattern and warm temperatures should result in a sea breeze each afternoon and evening, providing some late day humidity recovery. Winds are forecast to remain between 10-15 mph during the daylight hours, gusts possible after the sea breeze. Given very dry fuels and low relative humidity, fire danger will remain the primary concern each afternoon through Friday.

KEY MESSAGE 2: A cold front could provide some much needed rainfall across southeast Georgia and South Carolina this weekend.

Medium range guidance indicates that a H5 shortwave is forecast to ripple over the Southeast U.S. on Saturday. At the sfc, a cold front is expected to approach from the west, stretching across the Fall Line of the Carolinas and Georgia by the afternoon. As a sea breeze develops Saturday afternoon, increasing moisture convergence and weak instability may support isolated to scattered showers and thunderstorms Saturday afternoon. The coverage of convection is expected to peak Saturday evening with the passage of the short wave and sfc cold front. ECMWF and GFS AI models indicates that rainfall may remain into Sunday as a area of low pressure develops along the front over the coastal waters. Rainfall this weekend does not look heavy, in fact, NBM indicates just a 30% of a half inch during the peak 24 hr rainfall. However, any rainfall will be beneficial as a severe to exceptional drought continues across SE GA and SC.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

VFR through the 12Z TAF period at KCHS/KJZI/KSAV. Gusty SE winds will develop this afternoon as the sea breeze pushes inland, with gusts as high as 20 knots possible. Gusts will wane with nightfall.

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

MARINE

High pressure centered across the Mid-Atlantic will slowly shift south with a weakening cold front during the next few days, favoring a southerly flow across local waters for much of the week. Wind speeds should generally remain around 10-15 kt or less with some slight enhancement along the land/sea interface where a daily sea breeze develops, then shifts inland. A few showers and thunderstorms could arrive this weekend.

CHS WATCHES/WARNINGS/ADVISORIES

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