textproduct: Charleston

WHAT HAS CHANGED

Key Message 1 was updated and the Aviation section was updated for the 00z TAFs.

KEY MESSAGES

- 1) Strong to severe thunderstorms are possible Tuesday.

- 2) Unsettled weather with the potential for locally heavy rainfall continues mid to late this week.

DISCUSSION

KEY MESSAGE 1: Strong to severe thunderstorms are possible Tuesday.

On Tuesday, conditions should change very little from today. However, the weak boundary inland should make some progress closer to the coast. This boundary in addition to the sea breeze may increase llvl moisture convergence, especially across SE GA. Scattered to numerous thunderstorms should develop during the heat of the afternoon. Given similar thermal profiles on Tuesday, one or two severe thunderstorms are possible.

KEY MESSAGE 2: Unsettled weather with the potential for locally heavy rainfall continues mid to late this week.

The mid-levels will consist of troughing over the eastern half of the U.S. midweek, followed by it shifting over the East Coast by the end of the week. Additionally, a series of shortwaves embedded within the trough will pass over our region. At the surface, a stationary front will be spread across or in the vicinity of our area mid to late this week. There will be deeper moisture along and south of the front, with PWATs ~2". These values are above normal for this time of year. The combination of regional and mesoscale lift along with the moisture will generate rounds of convection each afternoon and evening mid to late this week. The models are generally in good agreement on the convective coverage. But the day to day timing and locations of the stronger convection will need to be refined with future forecasts. The threat for widespread and organized severe thunderstorms looks low. But since it's summer, we cannot rule out stronger to marginally severe storms each day with damaging winds. But the main concern appears to be the heavy rainfall potential. If the storms are slow moving, train, or backbuild, then quite a bit of rain could fall, which could lead to localized flooding. WPC is highlighting our area in the ERO to account for this. Once again, the details will need to be refined with future forecasts.

AVIATION /21Z MONDAY THROUGH SATURDAY/

25/00z TAFs: KCHS/KJZI/KSAV: The risk for tstm impacts has ended at all terminals. The risk will increase again by early afternoon and peak mid-late afternoon at all terminals. TEMPO groups for MVFR conditions in TSRA were included from roughly 18-21z at KSAV and 19-22z at KCHS/KJZI as this is when confidence is highest for impacts. Refinements in timing/intensity will be needed in later TAF cycles.

Extended Aviation Outlook: Showers and thunderstorms could bring brief flight restrictions each afternoon.

MARINE

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.

Tuesday through Saturday: South to southwest winds will persist through the period. Conditions will remain below Small Craft Advisory levels, with winds averaging 15 knots or less and seas 2 to 3 feet. Any showers or thunderstorms that move over the waters have the potential to bring higher wind gusts and frequent lightning.

CHS WATCHES/WARNINGS/ADVISORIES

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