textproduct: Charleston

WHAT HAS CHANGED

Aviation section was updated to reflect the 12Z TAFs.

KEY MESSAGES

- 1) Strong to severe thunderstorms are possible Monday and Tuesday.

- 2)Increasing rain chances mid to late week with the potential for locally heavy rainfall.

DISCUSSION

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

The overall pattern for today will be rather similar to yesterday, except that a rather subtle shortwave is expected to eject over the area during the mid to late afternoon. This subtle shortwave should result in slightly increased moisture across our area as PWATS climb to around 1.9 to possibly 2 inches along the coast. This coupled with very subtle ascent across the area and overall convective coverage should be a little more scattered than it was today. Given the better coverage and slightly better moisture, storms should be able to sustain themselves a little better leading to more clusters of storms developing along the seabreeze. However, the best ascent appears to miss just to the north of the area across eastern North Carolina into northeastern South Carolina. With this progression expect storms to likely start north of the area during the mid-afternoon with most of the area remaining dry through at least 4 pm. As the seabreeze moves slowly inland and boundaries from the north slowly move southward, we likely see the seabreeze begin to zipper from Charleston southward towards Savannah by the early evening. MLCAPE values look to range in the 3000-3500 range resulting in likely potent updrafts. With slightly less dry air, storms should be able to survive this environment unlike today when any attempt of a storm just fizzled as dry air entrained into the storm drying it out. With the upper shortwave in the area, some weak shear will be present in the 20 to 25 knots range which could support more multicellular clusters that would increase the potential for damaging winds across the area. With PWATS approaching 1.9 inches and DCAPE values in the 1200 to 1500 J/KG range, any storms that do develop will pose the threat of damaging winds. As a result, the entire area is under a Marginal (level 1 of 5) risk for severe storms.

Tuesday looks fairly similar to today, except that our moisture looks to be even more substantial with PWATs increasing in the 2 inch range as yet another wave moves into the area. Coverage looks to be slightly better on Tuesday; however, with the deeper moisture the overall signal for damaging winds might be a little lower. However, if storms are able to cluster up with time a few strong to severe wind gusts could be possible given PWATS approaching 2 to 2.1 inches allowing for heavy precipitation loading in storms. The more water in the middle of the cloud the more weight comes crashing down and the more weight the stronger the winds could be despite DCAPE values only in the 700 to 1000 J/KG range.

KEY MESSAGE 2: Increasing rain chances mid to late week with the potential for locally heavy rainfall.

Broad mid level troughing will reside over the eastern U.S. mid to late week, with a series of embedded shortwaves progged to pass through the region. At the surface, a weak boundary will drift into the region and likely stall in the vicinity. Deeper moisture will return with ensemble means indicating PWats reaching near 2 inches by late week. Given this and some larger scale forcing in play, in addition to mesoscale boundaries such as the sea breeze, scattered to numerous showers and thunderstorm are expected to develop each day. The threat for organized severe weather looks low, but a stronger storm or two cannot be ruled out. In addition, with slower storm motions, pockets of heavy rainfall will be possible which could lead to localized flooding concerns.

AVIATION /12Z MONDAY THROUGH FRIDAY/

24/12z TAFs: VFR conditions will prevail through much of the forecast. Isolated to scattered thunderstorms should develop during the late afternoon hours mainly along the coast. Confidence in storms is highest around KSAV this afternoon; however, storms could occur in and around CHS/JZI as well between 21Z and 00Z. Winds will remain light out of the southwest throughout the period becoming light and variable overnight.

Extended Aviation Outlook: Scattered showers and thunderstorms are possible each afternoon potentially bringing temporary restrictions at the terminals.

MARINE

Today 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.