textproduct: Charleston

WHAT HAS CHANGED

All sections have been updated.

KEY MESSAGES

- 1) Daily thunderstorms are expected across southeast Georgia and southeast South Carolina this weekend and into early next week. An increase in rain chances is expected by the middle of next week, with cooler temperatures thereafter.

DISCUSSION

KEY MESSAGE 1: Daily thunderstorms are expected across southeast Georgia and southeast South Carolina this weekend and into early next week. An increase in rain chances is expected by the middle of next week, with cooler temperatures thereafter.

Sunday through Monday: Continued unsettled afternoons are expected as an upper level low over the Florida peninsula meanders around the next 48 hours. At the surface a weak boundary has slipped south of the area and is expected to slowly wash out. With very little upper forcing, storms will likely be more confined to any remnant boundaries and the slowly advancing seabreeze each afternoon. With the location of the upper low, continued moisture will stream up over the area as PWATS linger in the 2 inch range. Expect isolated to scattered storms to develop both this afternoon and Monday afternoon along the slow advancing seabreeze and work south with time. Overall, instability continues to remain meager and with very little deep layer shear strong to severe storms should be limited. While this means a stronger storm cannot be ruled out, not really expecting a widespread risk. With PWATS around 2 inches and slow moving storms a low end heavy rainfall threat cannot be ruled out with any storms.

Tuesday through the end of the week: Convective coverage and rain chances will increase Tuesday into Wednesday as a cold front approaches from the north. Deep moisture, with PWATS exceeding 2 inches, will create a threat of locally heavy rainfall during this period. In regards to the severe weather potential, guidance targets late Tuesday night for the initial push of the front, which should keep the severe weather threat low due to unfavorable overnight timing. However, a secondary, reinforcing cold front is timed to move across the region on Wednesday. Prior to the arrival of cooler air, dew points in the lower 70s and afternoon heating could build sufficient instability to support strong thunderstorms Wednesday afternoon, primarily across Southeast Georgia. Though, much of this will depend on the evolution of the front moving through Tuesday night.

Behind the cold front, noticeably cooler air is expected for the latter half of the week and into the following weekend. Highs in the upper 70s to low 80s for southeast SC and low to mid 80s for southeast GA look probable at this time, which would be a few degrees below normal for late September.

AVIATION /06Z SUNDAY THROUGH THURSDAY/

MVFR to VFR conditions continue across the area this evening with light northerly winds. VFR conditions should return during the mid morning timeframe with light winds out of the northeast turning more easterly as the seabreeze moves inland. Scattered showers and thunderstorms should develop along the seabreeze around 19Z to 21z and slowly progress southwestward. Temporary reductions to IFR or MVFR will be possible at each of the three TAF locations.

Extended Aviation Outlook: The main potential for sub-VFR conditions will come from afternoon and evening showers and thunderstorms each day. The best chance of showers and thunderstorms is expected to come Tuesday into Wednesday.

MARINE

Sunday: Very quiet conditions will continue across the local waters. Light northeasterly flow will continue through the day before turning more easterly overnight. Seas are expected to average around 2 ft. A few showers/thunderstorms are possible along the GA coast this evening, potentially producing gusty winds and frequent lightning.

Monday through Friday: Conditions across the local waters will remain quiet through Monday night with northeast or east flow generally no more than 10 knots. However, this will change during the middle of the week as a cold front pushes through. This will result in a strong surge of northeast flow beginning Wednesday and potentially continuing through Friday. There are increasing probabilities of gusts into the 25-30 knot range with seas building to 5-6 ft as well. Small Craft Advisories will likely be needed for most of the local waters, including the Charleston Harbor. Also of note, rounds of thunderstorms will be possible at times ahead of the front which could bring the potential for strong wind gusts and frequent lightning.

CHS WATCHES/WARNINGS/ADVISORIES

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