textproduct: Charleston

WHAT HAS CHANGED

Key Message 1 has been updated for latest trends. The Aviation Section has been updated for the 00Z TAF issuance.

KEY MESSAGES

- 1) Another round of showers and thunderstorms will be possible east of I-95 late tonight.

- 2) A typical summertime pattern will remain in place through the upcoming weekend. Isolated strong to severe thunderstorms and the threat for localized heavy rainfall will be possible each day.

DISCUSSION

KEY MESSAGE 1: Another round of showers and thunderstorms will be possible east of I-95 late tonight.

Tonight: Activity well inland across Southeast Georgia is expected to wane and/or shift further inland this evening, but there are signals that another round of noctural convection could develop over the Atlantic overnight as low-level convergence refocuses closer to the west wall of the Gulf Stream. Latest models suggest that areas along/east of the I-95 corridor to be favored for experiencing shower and/or thunderstorm activity approaching daybreak Thursday morning, especially along the South Carolina Coast. Like earlier today, locations could see bouts of heavy rainfall and localized flooding, especially in urban or low-lying areas with poor drainage.

KEY MESSAGE 2: A typical summertime pattern will remain in place through the weekend. Isolated strong to severe thunderstorms and the threat for localized heavy rainfall will be possible each day.

The pattern aloft will be dominated by deep high pressure over the western Atlantic and the western CONUS through the weekend. This will support daily scattered convection, with the sea breeze and any remnant outflow boundaries serving as the primary focus for afternoon and evening thunderstorm development. Persistent southerly flow will continue to advect deep moisture into the region with PWATs near 2 inches and SBCAPE values as high as 3000 J/kg. These parameters will support efficient rainfall rates, with some storms capable of dropping a quick 1-2 inches of rain in a short period. In addition, slow storm motions of around 10 kt, combined with training or repeated rounds of convection, could increase the potential for isolated instances of minor flooding, especially in low-lying and poor drainage areas. Friday could be the exception, as somewhat drier air with pockets of PWATs around 1.5 to 1.7 inches should limit the flooding threat. Lastly, with little shear in the environment, storms will remain pulse-like. Although widespread severe weather is not expected, a few stronger storms could produce damaging wind gusts.

AVIATION /00Z THURSDAY THROUGH MONDAY/

VFR conditions should prevail at CHS/JZI/SAV terminals through 08Z Thursday. However, additional convection could reduce vsbys at CHS/JZI late tonight and through late morning with activity shifting onshore from the Atlantic. PROB30 groups have been included at CHS between 09-19Z Thursday at CHS for MVFR conditions produced by late night showers and late morning thunderstorms. Chances for flight restrictions are a bit higher at JZI with TEMPO MVFR conditions included in the latest TAF due to thunderstorms between 09-19Z Thursday. Conditions are not as favorable for convection at SAV tonight so shower/thunderstorm activity have been removed, but a PROB30 group has been introduced between 14-18Z Thursday for MVFR conditions during thunderstorms once heating takes place and a sea breeze shifts inland.

Extended Aviation Outlook: Periodic flight restrictions are expected in showers and thunderstorms this week and into this weekend.

MARINE

Through Tonight: Southerly flow will continue through the evening, with winds averaging 15 kts or less. Otherwise, look for another round of nocturnal convection to be possible overnight into early Thursday, with seas generally ranging between 2 to 4 ft.

Thursday through Sunday: Atlantic high pressure will be the dominant synoptic feature through the weekend. This will generate a typical summertime wind field with increased winds along the land/sea interface each afternoon associated with the sea breeze. Marine conditions are expected to remain below Small Craft Advisory criteria through the weekend.

CHS WATCHES/WARNINGS/ADVISORIES

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