Marine Weather and Tide Forecast for Rockville, SC

NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
Early Evening: Latest radar trends indicate isolated to scattered showers and thunderstorms occurring well inland, mainly across Allendale, Hampton, Screven and Jenkins Counties in wake of a sea breeze circulation that has already exited Southeast South Carolina zones, and will be exiting Southeast Georgia zones within the next hour. Although this feature has been the main contributor to convection occurring initially, boundary/outflow interactions will continue to promote additional shower/thunderstorm activity for the next hour or two within an environment marked by modest instability (SBCAPE around 1500-2000 J/kg) and weak shear (0-6 km Bulk Shear around 20-25 kt). Low-lvl lapse rates near 7.5-8.0 C/km and -10 to -30 C hail cape around 500 J/kg suggest a few thunderstorms capable of gusty winds and perhaps small hail, but activity is expected to remain sub-severe. Expect activity to slowly wane approaching sunset, then dissipate with the loss of diurnal heating within a weakly sheared environment early evening.

Overnight: Shower/thunderstorm activity will likely have ended prior to late evening hours. The forecast remains dry for the remainder of the night, although h5 shortwave energy rippling across the region could spawn a few isolated showers well inland. The main issue will once again focus on the potential for fog to develop across the area late, especially for locations that have experienced a heavier shower/thunderstorm during the day. Despite some mid/high clouds, light southeasterly winds going calm, favorable condensation pressure deficits and favorable low-lvl moisture south of a nearly stationary front placed just north of the local area suggests at least patchy fog potential for most locations away from the beaches and greater fog coverage in areas that have experienced rainfall. There is even some potential for a stratus build down scenario across northern and inland areas given very weak 1000 mb geostrophic winds and ample moisture. Given this expectancy, have increased fog coverage to areas across the Tri- County Area as well as inland SC/GA counties near the Savannah River. Expect another mild night with low temps in the low-mid 60s.

SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/
Friday: the surface high pressure slides southwards while remaining well off the coast, leading to south-southeasterly winds continuing. Aloft, we remain under weak west-southwesterly flow, with some weak shortwaves moving through. This, in combination with the sea-breeze may spark off another round of afternoon showers and thunderstorms, with highest probabilities (~30%)
inland and dropping towards the coast. Highs reach up into the mid to upper 80s across the region. Heading into the overnight hours, areas that see rainfall have a chance for seeing patchy fog as winds decrease, with overnight lows into Saturday in the lower to mid 60s.

Saturday: A cold front will be approaching the area from the north, but before it gets here daytime highs are expected to reach up into the mid 80s to lower 90s across inland regions, highest across eastern Georgia. Areas along the coast will get up into the upper 70s to lower 80s. As dewpoints remain in the mid to upper 60s, heat indices top out in the mid to upper 80s, again highest across eastern Georgia. However, the mid-level shortwave arrives well before the cold front, and will likely result in increased shower/storm activity (40-60% chances)...though timing of this feature is not well agreed upon. If the shortwave moves through a couple hours earlier, then the region may miss out on a few degrees of heating.
Heading into the overnight hours, the aforementioned cold front will be moving through the area, though models have now decreased chances for rainfall along the front as the rainfall is now expected with the passage of the mid-level shortwave.

Sunday: Surface high pressure will be moving down the east coast throughout the day, leading to winds shifting to become out of the east-northeast. This will bring slightly cooler air down into the region, with afternoon highs in the upper 70s across SE SC to mid 80s for inland SE GA.

LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
The aforementioned surface high pressure continues to move south into the coastal Atlantic water east of the region, with the cooler temperatures persisting across the region. Areas across southeastern South Carolina may only reach into the upper 70s, while southeastern Georgia will reach up into the mid 80s. Temperatures warm back up again on Tuesday as southerly surface flow returns and weak ridging occurs aloft, continuing to warm Wednesday and Thursday as highs approach 90 degrees.

AVIATION /22Z THURSDAY THROUGH TUESDAY/
KCHS/KJZI: VFR conditions are expected through the evening. There seems be some indication fog/or low stratus developing around ~08Z and lasting till 12-13Z Friday, thus MVFR conditions will be present until fog/low stratus dissipate in the early morning.

KSAV: VFR conditions prevail until ~10Z Friday when fog and/or low stratus develops and MVFR conditions overtake for a couple hours before returning back to VFR sometime after 12Z Friday.

Extended Aviation Outlook: Periodic scattered showers and thunderstorms Friday - Saturday may bring MVFR cigs and/or vsbys, with patchy overnight fog for areas that see rain possibly resulting in MVFR or even IFR conditions.

MARINE
Tonight: Atlantic high pressure centered well offshore will extend across local waters while a nearly stationary front is placed just north of the area. The pattern will support another quiet night across marine zones with conditions similar to the previous night.
In general, southeast/east winds will peak around 10-15 kt. Seas will range between 2-3 ft.

Friday: Winds will remain out of the east-southeast right around 10 to 15 knots, with wave heights near the coast remaining at or below 2 feet, getting close to 4 feet 60nm out to sea. Can't rule out some isolated afternoon showers and thunderstorms close to shore, but most activity looks like it should remain onshore.

Saturday through Monday: A cold front will be approaching throughout the day, swinging winds around to the southwest for the day. Cold front moves through overnight into Sunday, possibly bringing scattered showers and thunderstorms onto the near and offshore waters. Sunday will see winds out of the northeast strengthening throughout the morning, reaching up into the 15-20 knot range into the Monday. Waves of 3-4 feet are expected near shore, 5 feet 20 nm out, and 5-6 feet in the 20-60nm range offshore of Georgia.

Tuesday: The surface high pressure moves off to our east and southwards, swinging the winds around to become out of the south- southeast. Wave heights decrease back into the 2-3 foot range near shore, and 3-4 feet in the 20-60nm range offshore of Georgia.

TIDES/COASTAL FLOODING
Minor coastal flooding is possible with the evening high tides due to the elevated tides from the approaching New Moon Perigee. For Charleston, the astro tides rise above 6.5 feet with the evening tides Saturday through Wednesday. With the approaching surface high pressure Sunday and Monday, northeasterly to easterly surface flow may cause the waters to rise into minor flood stage with the evening high tides.

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