Marine Weather and Tide Forecast for Kiawah Island, SC

NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/
A large Atlantic high pressure continues to sit offshore and extend over southeastern SC and southeastern GA through the afternoon as southerly flow aloft remains. This strong ridging in place will begin to weaken this afternoon as a shortwave approaches from the west. Sea breeze has kicked off the coastline here, however the chance for any showers to develop along it remains minimal due to dry aloft. With an ample amount of sunshine today, temperatures were able to reach into the low to mid 80s.

Tonight: There is a chance for some showers to develop as this shortwave moves in, but if anything does develop, it will be very anti-climactic due to weak forcing and the onset of the nocturnal environment. Mentioned a chance of patchy fog and/or stratus developing just before sunrise (~09Z) as there will be calm winds and favorable condensation pressure deficits overnight. It looks to be another warm night with lows only dropping into the low to mid 60s (with it being a little warmer closer to the beaches).

SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/
Wednesday: Ridging aloft slowly loosens its hold on the area, as perturbations pass in or near the local vicinity, causing a subtle fall of heights locally. This in turn allows for advection of greater moisture out of the Gulf within a deep southwest flow out of the Gulf. PWat will climb to around 1.8 inches by afternoon, with a considerable amount of deep moisture to prevail. At the surface, Atlantic high pressure pulls further offshore, as a cold front slips into closer vicinity of the area from the north. That front and the sea breeze will be the main focus for convection, that generally holds off until we reach our convective temperature in the lower and middle 80s around 1-2 PM. MUCAPE reaches around 1500-2500 J/kg, with its associated axis atop the local counties. While shear isn't that impressive, mainly around 25 or perhaps 30 kt, steep lapse rates will occur. These conditions will yield a sufficient amount of showers and t-storms. Right now we have scattered to numerous coverage, but higher coverage could be required as trends develop.
The greatest chances will be over the inland counties, and locally heavy rains will occur given weak storm motion and high water content. Unless conditions change, the heaviest rains will stay inland from Charleston, Beaufort, and Savannah. As dry as it has been, the grounds can certainly handle any heavy rains that occur.
Cold temperatures aloft (around minus 14 to minus 15C), WBZ around 10-11K feet, and strong updrafts, could generate some marginally severe hail. DCAPE of 900-1000 J/kg can also generate some strong to marginally severe winds where boundary interactions occur. These chances are mainly inland during the afternoon. Prior to convection, temperatures will peak in the mid and upper 80s away from the cooling effects of the sea breeze closer to the coast.

Wednesday night: Withe sea breeze far inland and the nocturnal stabilizing influences, convection looks to fade quickly, especially as any weak short waves aloft pass offshore. Low level moisture and convergence from off the ocean with a southeast synoptic flow could result in some showers moving in off the Atlantic at times.
Otherwise, the main concern could be the formation of fog where the grounds remain wet from earlier rains. Lows won't be too different from the previous night.

Thursday: Models differ on how much convection will occur. The front in the vicinity would suggest a greater than normal chance for showers and t-storms. But CAPE and shear are less than on Wednesday.
Plus moisture isn't as abundant, and much of the day looks like there is little forcing aloft. This would point toward less coverage than on Wednesday, so our forecast of scattered to numerous activity could be a bit on the high side. But since that forecast meshes with surrounding offices, we'll leave as is for now. Boundary interactions that lead to stronger updrafts could some some locally strong storms inland. Temperatures are a tough call, dependent on how much convection actually occurs. But even so, they will be above climo with 850 mb temperatures of 12-13C.

Friday: There is more of a cap in place and with the remnants of the front no longer in the picture, we don't expect as much activity.
But with sufficient instability and moisture, we are holding onto isolated or scattered PoPs. Temperatures are again above normal, especially with lower convective chances in play.

LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
A cold front will approach from the northwest Saturday, leading to at least a chance of showers and t-storms. The front pushes through at night or early Sunday, but lingers near or over our southern coutnies during the rest of Sunday, so we need to hold onto at least some low end chances during that time. High pressure will then prevail both surface and aloft early next week, with little or no chances of convection to occur given the large scale subsidence.
Compressional heating ahead of the front yields a very warm Saturday, with temperatures a bi more temperature thereafter behind the front.

AVIATION /20Z TUESDAY THROUGH SUNDAY/
22/18z TAF Discussion: KCHS/KJZI/KSAV: VFR conditions through tomorrow morning. Some low stratus and/or fog may develop across the region overnight into Wednesday morning, although confidence is too low to include flight restrictions at this juncture.

Extended Aviation Outlook: Although there will be be showers and thunderstorms Wednesday and Thursday afternoons, the higher chances look to stay further inland. Gusty winds are possible Friday and Saturday afternoon at all terminals with the passage of the sea breeze.

MARINE
Tonight: Southerly winds will remain across the coastal waters through tonight. The aforementioned sea breeze has already pushed inland, thus no enhancement of wind speeds were made. Seas will be from 2 to 3 ft.

Wednesday and Wednesday night: A stationary front will meander nearby, resulting in a prevailing onshore flow no more than 10 or 15 kt. Seas are just 2 or 3 feet. A few showers or t-storms can occur, but the greater coverage will be inland.

Thursday through Friday: Atlantic high pressure is in control, with not much wind or wave action, except some gustiness in Charleston harbor and near the coast Friday afternoon. There is little in the way of convection during this time.

Saturday through Sunday: High pressure will give way to a cold front that approaches form the northwest at night and early Sunday, before stalling nearby into Sunday night. High pressure builds in behind the front, perhaps even bridging across the front. Even so, this will result in stronger winds and building seas late in the forecast period. There is at least some chance for t-storms during this time.

CHS WATCHES/WARNINGS/ADVISORIES
GA...None.
SC...None.
MARINE...None.