textproduct: Charleston

WHAT HAS CHANGED

KEY MESSAGE 1 has been updated to reflect trends tonight. The Aviation Section has been updated for the 00Z TAF issuance.

KEY MESSAGES

- 1) Unsettled weather will continue, with increasing chances of showers and thunderstorms this weekend.

DISCUSSION

KEY MESSAGE 1: Unsettled weather will continue, with increasing chances of showers and thunderstorms this weekend.

Tonight: Mid-level troughing dominates the synoptic pattern aloft, while a stationary front remains positioned over the SC Midlands. With these two features influencing the region scattered to numerous thunderstorms continue near the southern Southeast South Carolina and Southeast Georgia coast this evening, but are likely to shift offshore by around midnight tonight. Much of the night will then remain dry for most areas, but some HIRES guidance suggests few to scattered showers/thunderstorms attempting to redevelop a few hours prior to daybreak, mainly across coastal South Carolina, before shifting offshore and possibly interacting with a land breeze. Given PWATS in excess of 2.0 inches, activity could result in brief heavy downpours prior to daybreak.

Friday through Monday: The mid-levels will consist of a trough over the eastern third of the U.S. on Friday. It'll quickly weaken and lift north on Saturday, with gradually building heights overhead Sunday into Monday. At the surface, a stationary front should be located well to our west and northwest on Friday, with surface troughing also near our area. This general pattern will remain in place on Saturday, followed by a cold front potentially moving through on Sunday. There will be a deep plume of moisture ahead of the front, and across the Southeast U.S. PWATs will be around 2", but there could be brief periods where it peaks around 2.3". These values are well above normal for this time of year. The combination of regional lift, aided by the nearby front, and the sea breeze will generate an active weather pattern. Models are in fairly good agreement showing numerous to widespread showers and embedded thunderstorms Friday and Saturday afternoons, with perhaps slightly less coverage Sunday afternoon and again Monday afternoon. High temperatures will be near normal, but that'll still provide decent instability for late August. Therefore, we can't rule out strong to marginally severe storms each afternoon. The main concern will be the potential for locally heavy rainfall Friday and Saturday. Friday appears to be the day with more flooding potential given the overall synoptic and mesoscale setup. Regardless, there could certainly be slow moving, training, or back building storms both days that could drop significant amounts of rainfall locally. These details will need to be refined with future forecasts, especially when it comes to flash flooding. Also, WPC has our area highlighted in the ERO both days.

AVIATION /02Z FRIDAY THROUGH TUESDAY/

TEMPO MVFR conditions remain at CHS/JZI/SAV terminals through 03Z Friday, although additional activity could temporarily impact CHS/JZI terminals a few hours prior to daybreak. Outside this activity, expect mainly VFR conditions at all terminals through late morning hours Friday, before scattered shower/thunderstorms develop across the region during afternoon hours. PROB30 groups for thunderstorms and MVFR conditions have been introduced Friday between 18-24Z at CHS, 19-23Z at JZI, and 19-24Z at SAV.

Extended Aviation Outlook: Showers and thunderstorms will bring brief flight restrictions through the weekend, especially during the afternoons.

MARINE

Through Tonight: The pressure pattern will generally support southwest winds between 10 to 15 kts across the marine zones. Wave heights are forecast to remain between 2 to 3 ft. Showers and storms could form along the land breeze early Friday morning, with the potential for waterspouts.

Extended Marine: A stationary front should be located well inland on Friday, with surface troughing also near our area. This general pattern will remain in place on Saturday, followed by a cold front potentially moving through on Sunday. No Small Craft Advisories are expected, with sustained winds generally 10 kt or less and seas 2-3 ft. However, some thunderstorms may bring brief periods of higher winds along with frequent lightning.

CHS WATCHES/WARNINGS/ADVISORIES

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