textproduct: Charleston

WHAT HAS CHANGED

All sections have been updated.

KEY MESSAGES

- 1) Scattered to numerous showers and thunderstorms are expected each afternoon and evening through this weekend.

DISCUSSION

KEY MESSAGE 1: Scattered to numerous showers and thunderstorms expected each afternoon and evening through this weekend.

Tonight: Afternoon and evening convection has steadily drifted either offshore or further inland with time and we are now mostly left with areas of light rain across the forecast area. Through the night the forecast area will remain in advance of an upstream front and within an airmass with precipitable water values around 2.25 inches. Therefore there could be shower or thunderstorm development just about anywhere at any time. Late tonight and sunrise Saturday, there are some hints in hi-res model guidance that convergence and instability will pool along the SC coast and potentially lead to a round of showers and thunderstorms. The highlighted area is mainly from around Beaufort up through Charleston County. Confidence isn't particularly high but if it were to occur, there is the threat for locally heavy rain given the degree of available moisture and the presence of convection.

A stationary front will remain draped over the Southeast Saturday before dissipating Sunday. Weak shortwaves aloft may continue scattered showers and thunderstorms Saturday morning. While there will likely be a break from the rain during the mid- morning to early afternoon hours, additional showers and thunderstorms are expected to develop Saturday afternoon as the sea breeze pushes ashore. Deep convection looks limited with 1000-1500 J/kg of SBCAPE anticipated. Also the lack of flow aloft will keep thunderstorms from becoming organized, maintaining a very low risk for strong thunderstorms. However, given the slow storm motions and precipitable water values in excess of 2 inches, locally heavy rainfall is a concern. Flooding is possible, especially for low-lying and flood-prone areas. HREF has scattered 50-70% chances for 2+ inches along and west of I-95, decreasing into the 20-40% probability range for 3+ inches. A few isolated locations could see rainfall amounts greater than 3 inches, with the greatest chances mainly along the coast. Flood Advisories and/or Flash Flood Warnings could be needed Saturday.

A similar set-up and environment is expected Sunday. With the nearby front expected to dissolve at some point during the day, we do not anticipate as much rainfall coverage as the previous days'. However, precipitable water values will still be elevated, which could lead to lingering heavy rainfall/flooding concerns.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/

The 00z TAF period begins with areas of light rain around the area with mostly VFR conditions. Current radar suggests that there will be little to no thunderstorm activity over the next several hours. However, late tonight, there are hints in model guidance that shower and thunderstorm coverage will increase along the SC coast. This could potentially impact KCHS and KJZI most likely, and we have maintained a PROB30 from 09-13z. Then for the afternoon, the thinking is that the best thunderstorm coverage will be around KSAV. There are also hints in model guidance that MVFR (or lower) stratus could develop and impact the terminals. This would mainly be an issue starting around 08-10z, potentially extending as late as midday.

Extended Aviation Outlook: Showers and thunderstorms could bring periodic flight restrictions through the weekend, especially during the afternoons.

MARINE

Tonight: The local weather pattern will generally support sustained winds of 10 kt or less. Seas should be in the 2-3 ft range. Additionally, thunderstorms could bring brief gusty winds along with cloud-to-water lightning.

Saturday through Wednesday: No large-scale marine concerns, with daily chances for showers and thunderstorms through at least the weekend. Winds and seas will remain below Small Craft Advisory criteria through the period.

CHS WATCHES/WARNINGS/ADVISORIES

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