textproduct: Charleston

WHAT HAS CHANGED

All sections have been updated.

KEY MESSAGES

- 1) Minor coastal flooding expected along portions of the Southeast South Carolina coast with the evening high tide cycles today and Monday.

- 2) Mostly dry conditions expected through midweek with increasing rain chances to occur late week.

DISCUSSION

KEY MESSAGE 1: Minor coastal flooding expected along portions of the Southeast South Carolina coast with the evening high tide cycle on Monday.

Astronomical influences associated with the new moon (5/16) and lunar perigee (5/17) along with a modest southeasterly onshore flow will continue to drive elevated tide levels early this week, leading to minor coastal flooding along the southeast South Carolina coast and potentially along the southeast Georgia coast. The latest forecast advertises a peak high tide around 7.0 to 7.2 ft MLLW Monday evening. A Coastal Flood Advisory for Coastal Colleton and Charleston Counties could be needed Monday evening. Astronomical tide levels then begin to fall and the potential for minor coastal flooding will diminish.

KEY MESSAGE 2: Mostly dry conditions expected through midweek with increasing rain chances to occur late week.

Surface high pressure will extend across the region through midweek, while ridging largely prevails aloft. Convection potential will be quite limited, with most areas staying dry Monday through Wednesday.

Beyond Wednesday, the pattern could become more active, although there is still a good bit of inconsistency between models. Shortwave energy will advance toward the area, but will compete with the deep Bermuda High offshore, which could deflect the better forcing north of the region. At the surface, a cold front will approach the area, with its eventual progression likely dependent on the strength of the ridge. Our current forecast indicates a slow progression of the front into southeast SC/GA over the course of several days (Thu- Sat), which would support increasing moisture and higher rain chances across the area. However, if the ridge remains stronger, the front and better forcing could remain farther to the west and north, resulting in lower rain chances than currently forecast. Ensemble mean indicates the probability for accumulated rainfall of >1" ending Saturday evening of only 10-40% (highest inland), so widespread significant rainfall seems unlikely at this time.

AVIATION /02Z MONDAY THROUGH FRIDAY/

VFR conditions will prevail at CHS/JZI/SAV terminals through 0Z Tuesday. However, gusty winds (14-17 kt) will accompany the afternoon sea breeze on Monday.

Extended Aviation Outlook: There are no high confidence concerns.

MARINE

Today and Tonight: High pressure will remain the dominant weather feature across local waters throughout the day and night, resulting in a typical summer-like southerly flow regime. In general, wind speeds will be no higher than 10 kt across most waters, although localized enhancement along the land/sea interface and Charleston Harbor is anticipated with any sea breeze enhanced this afternoon (~15 kt). Seas should range between 2-4 ft, largest beyond 20 nm from the coast overnight.

Monday through Friday: No marine concerns are expected. High pressure to the east will drive onshore east-southeasterly flow each day, with wind speeds mostly topping out in the 10-15 knot range. Each afternoon and evening there could be some local enhancement along the land/sea interface with the diurnal sea breeze. Seas should average 2-4 feet through the period.

Rip Currents: The combination of influences from the new moon cycle and persistent onshore flow will produce an elevated risk of rip currents through midweek. A Moderate Risk of rip currents is in effect at all southeast South Carolina and southeast Georgia beaches Monday and Tuesday.

CHS WATCHES/WARNINGS/ADVISORIES

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