textproduct: Charleston

SYNOPSIS

A front will be situated inland of the area today. High pressure will prevail late week into the weekend.

NEAR TERM /THROUGH TONIGHT/

Today: Aloft, the pattern will transition as the main belt of westerlies retreats to the north and ridging builds in turning the flow more anticyclonic with time. At the surface, a subtle boundary will remain situated inland across central GA and the central Carolinas while the subtropical high over the Atlantic will take on more influence along the Southeast coast. Overall, the setup will transition to be more of a typical summertime pattern with weak large scale forcing and subtle mesoscale features serving as the main source of initiation for diurnal convection. For the morning, hi-res models suggest that land areas should be mostly free of any shower and thunderstorm activity with the focus for convection being off the coast over the coastal waters. Then as we move into the early afternoon, convection should start to fire along and just inland of the developing sea breeze. Model soundings reveal a significant difference in the near storm environment compared to previous days as mid-level flow will be 15 knots or less. This will result in slow-moving storms that will try to move back to the east or southeast, counter to the inland moving sea breeze. MLCAPE values look to be more on the order of 1,000 J/kg, with DCAPE in the 700- 900 J/kg. Overall, the severe risk is certainly lower than the last few days, but there could still be one or two strong to marginally severe storms especially where boundary interactions enhance updrafts. Current thinking is that coverage will warrant 40-60 percent rain chances this afternoon, but there are certainly differences in the hi-res solutions. Recent runs of the HRRR suggest considerably less coverage. We will continue to monitor and update as needed. Highs are forecast to top out in the upper 80s in most areas.

This evening and tonight: Lingering afternoon convection should gradually diminish through the evening and then pick up in coverage across the coastal waters through the late night hours. Lows are forecast to fall into the low 70s.

SHORT TERM /THURSDAY THROUGH SATURDAY/

Fairly typical summertime pattern for late week. Atlantic high pressure will be the dominant surface feature through the period with a stalled front over the region expected to dissipate on Thursday. Ridging largely prevails aloft, however weak shortwave energy is progged to rotate through the region at times. Forecast will be on repeat with showers and thunderstorms possible each day, with coverage peaking in the afternoon when instability is maximized. Organized severe weather is not expected with weak shear but cannot rule out a stronger storm or two. Temperatures will be seasonable, mainly in the upper 80s to around 90. Lows will be in the low to mid 70s, except upper 70s at the beaches.

LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/

Mid level ridge will persist over the Southeast early next week, although it could be briefly suppressed as a shortwave trough passes by to the north. This could bring another front towards the region but will likely stall in the vicinity into Tuesday. Showers and thunderstorms will be possible each day, especially during peak heating, but some activity could linger overnight as well. Highs average in the upper 80s to lower 90s, although humidity will make it feel even hotter. Heat indices will creep up into the 100-105 range in many locations, shy of Heat Advisory criteria.

AVIATION /08Z WEDNESDAY THROUGH SUNDAY/

The 06z TAF period begins with VFR conditions in place at KCHS, KJZI, and KSAV. Current thinking is that we shouldn't see any overnight shower or thunderstorm activity and the overall fog or stratus potential is low. KJZI did briefly report IFR ceilings, but that has since gone away. Attention then turns to the afternoon and the thunderstorm potential. It looks like thunderstorms will develop along the afternoon sea breeze and will not exhibit very much motion. Confidence in direct impacts is low, but there should be enough coverage of thunderstorms to warrant VCTS at all 3 sites. We have introduced VCTS at KCHS and KJZI starting at 18z, and at 20z for KSAV.

Extended Aviation Forecast: Brief flight restrictions are possible in showers and thunderstorms each day, mainly in the afternoon.

MARINE

Today and tonight: Winds are expected to be more southerly today with speeds mostly topping out in the 10-15 knot range. The strongest winds are expected along the land/sea interface with the development of the sea breeze. This should result in some gusts up to 20 knots along the coast including Charleston Harbor. Seas should mostly average 2-3 feet through the period.

Thursday through Monday: Marine conditions are expected to stay below Small Craft Advisory criteria through the period. Southerly flow will persist with speeds 15 knots or less. Seas will average 2- 3 feet.

CHS WATCHES/WARNINGS/ADVISORIES

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