textproduct: Charleston

WHAT HAS CHANGED

All sections were updated.

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.

Overall yet another tricky forecast today as conditions look to be fairly similar to the last two days. The only main difference between Tuesday and the last two is that moisture will continue to steadily increase compared to Monday and Sunday. As a result, confidence in convective coverage is slightly increased compared to the last few days. Best chances for storms looks to be across Georgia and the immediate coastline of South Carolina during the late afternoon with some remnant drier air in subsidence possibly keeping storms more isolated to scattered closer to Charleston and the tri-county area. MLCAPE values are expected to climb to around 2000-2500 J/kg across the area which is a tick lower than the past few days. With rather deep moist profiles, today should feel more like a standard summer afternoon as storms will likely need to cluster up and have a few boundary collisions to really get strong to severe. However, like most summer afternoons we do expect at least a couple clusters to develop and a few strong to severe wind gusts cannot be ruled out. This appears to be true for areas across coastal Georgia including the Savannah metro area. Also much like any summer day, PWATS are expected to be in the 2 to 2.1 inch range which would be enough to support rather heavy rain rates with the strongest of storms. IF any of the clusters are able to linger around for more than 30 min to an hour on the wrong metro area, then some minor flooding concerns could arise.

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

Upper level trough holds tight across the Ohio River Valley, with a series of shortwaves progged to graze the region through the end of the week. Meanwhile, at the sfc, will see a stationary front linger across the SE CONUS before a stronger cold front advances over the weekend. As noted in the previous discussion, there is ample moisture to work with, as PWATs near 2 inches, which is above normal for this time of year. This combined with regional and mesoscale lift along the aforementioned boundaries will yield daily chances for showers and thunderstorms. While most guidance agrees that convection will be diurnally driven and isolated to scattered in nature, overall confidence in exact location still remains fairly poor. Thus, further refinements to the forecast are expected in the coming shifts as model consistency improves. In regard to severe weather, can't rule out seeing a few strong to severe thunderstorms capable of producing damaging winds and lightning. However, think the main hazard to watch for will be heavy rainfall - given the stationary front in place. Slow moving, training, or back building storms are favorable in these setups, which could result in localized flooding or flash flooding, especially in urban or low- lying areas.

AVIATION /06Z TUESDAY THROUGH SATURDAY/

25/06z TAFs: VFR conditions should persist through the overnight and into the morning once again with light southwesterly winds. expect shower and thunderstorm activity to increase once again along the slowly moving seabreeze during the afternoon leading. Confidence in thunderstorms appears highest around KSAV from 19Z to 22Z with lower confidence at JZI and CHS. As a result, carried the TEMPO group at KSAV given the higher confidence in coverage and a PROB30 group at KJZI AND KCHS for lower confidence in coverage. Storms should subside by the evening as conditions return to VFR.

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

MARINE

Today: Winds should relax some during the day with southwesterly winds around 5 to 10 knots becoming easterly during the late afternoon and early evening hours. Wave heights are forecast to remain between 2 to 3 ft.

Wednesday through Saturday: South/southwesterly winds continue through the period, with winds averaging 15 knots or less and seas 2 to 3 feet. While Small Craft Advisories are not expected at this time, do want to highlight that any showers or thunderstorms moving over the waters will be capable of producing higher gusts and frequent lightning.

CHS WATCHES/WARNINGS/ADVISORIES

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