textproduct: Charleston

WHAT HAS CHANGED

All Key Messages and sections were updated.

KEY MESSAGES

- 1) The risk for showers and thunderstorms will continue into next week.

DISCUSSION

KEY MESSAGE 1: The risk for showers and thunderstorms will continue into next week.

This Afternoon/Tonight: The airmass is slowly destabilizing across the area with visible satellite showing a distinct uptick in agitated cumulus. Convection has already started to develop with near term data supporting a clustering of showers/tstms near/ahead of the sharpening sea breeze circulation. A secondary area of showers/tstms is expected to initiate across interior Southeast Georgia later afternoon and march east/northeast through the early evening hours. Net pops 40-60% were highlighted with the greatest pops clustered inland of the US-17 corridor in the Lowcountry and along and just west of the I-95 corridor in Southeast Georgia. Similar to yesterday, there are no meaningful forcing mechanisms noted aloft with negligible shear. Tstms will remain mostly airmass driven and will be heavily influenced by mesoscale processes such as convective outflow collisions. A few stronger cells are certainly possible just about anywhere through early evening where updrafts can become locally enhanced in the vicinity of boundary collisions. Gusty winds, locally heavy rainfall and cloud-to-ground lightning will be the primary hazards. Convection will gradually wind down this evening; however, the tail end of a weak shortwave energy is forecast to cross the area overnight. This may spark off a few noctural showers/tstms into the early morning hours, especially east of I-95 and over the nearby Atlantic waters as low-level convergence builds near the beaches and along the west wall of the Gulf Stream.

This Weekend into Next Week: A shortwave trough aloft will ripple across the southeastern states towards the Mid-Atlantic Saturday into Sunday. At the surface a weak front will approach the region Saturday, likely fizzling out prior to arriving Sunday. Scattered to numerous showers and thunderstorms are in the forecast for Saturday and Sunday afternoons, with the greatest coverage likely on Saturday. Widespread severe weather is not forecast, however a strong to marginally severe thunderstorm cannot be ruled out. The greater threat will be heavy rainfall, as PWATs are forecast to increase to 2+ inches. Very weak storm motions could result in localized heavy rainfall, leading to minor flooding issues within low-lying and poor drainage areas. A more typical summertime pattern of isolated to scattered afternoon showers/storms will take shape Monday and dominate through the week as weak coastal troughing develops along the southeastern coast.

AVIATION /18Z FRIDAY THROUGH TUESDAY/

11/18z TAFs: KCHS/KJZI/KSAV: Risk for tstm impacts look greatest at KCHS through mid-afternoon as activity fires along the sea breeze. Another area of showers/tstms could approach KSAV from the west/southwest by late afternoon. A TEMPO group for TSRA was introduced for KCHS 18-21z and 22-01z at KSAV with a PROB30 for KJZI 18-20z. Conditions were limited to MVFR for now, but locally lower conditions could still occur given the nature of the convection. Amendments will be issued as needed. Otherwise, VFR should prevail for the remainder of the 18z TAF period. There is a low chance for a brief period of low stratus impacting mainly KCHS and KSAV just before daybreak Saturday. Confidence is too low to introduce at this time.

Extended Aviation Outlook: Periodic flight restrictions will be possible Saturday and Sunday afternoons as showers/storms could impact the terminals. The risk for periodic flight restrictions will linger into the week as a typical summertime pattern of afternoon showers/storms dominates.

MARINE

Through Tonight: The southerly flow regime will persist through tonight. Winds will average 10 kt with seas 2-3 ft. Convection could approach the Georgia nearshore and possibly the far southern South Carolina nearshore waters later this afternoon. These could produce gusty winds, locally heavy rainfall and cloud-to-water lightning. Special Marine Warnings could be needed.

Saturday through Tuesday: Conditions are forecast to remain below Small Craft Advisory levels through the weekend. Beginning next week a weak coastal trough will develop off/along the southeast coast, leading to a surge in NE wind gusts potentially as high as 25 knots. Small Craft Advisories may be required for portions of the waters beginning Tuesday.

CHS WATCHES/WARNINGS/ADVISORIES

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