textproduct: Charleston

WHAT HAS CHANGED

The Aviation section was updated for the 17/12z TAFs.

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 above normal temperatures.

- 3) 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 cycles today and Monday.

Astronomical influences including the new moon (5/16) and the perigee (5/17) along with a modest southeasterly onshore flow will help drive elevated tide levels early this week. The best chance for minor coastal flooding will be at the Charleston Harbor tide gage, with much lower potential at Fort Pulaski. Additional Coastal Flood Advisories will likely be needed today and possibly Monday. 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 above normal temperatures.

High pressure will maintain its influence on the region today as upper ridging holds aloft. Most guidance is similar in showing a pronounced northwest-southeast oriented 850 hPa theta-e axis setting up from east-central Georgia into far Southeast Georgia later this morning and persisting into this evening. This axis of increased theta-e coupled with building diurnal instability will likely support the development of scattered convection, centered mostly southwest of the local forecast area. Some activity could drift into the far interior Georgia zones by late afternoon, mostly along/south of a Metter- Claxton-Ludociwi line. Pops 20-30% were highlighted for these areas (highest over western Tattnall County) with rain-free conditions elsewhere. Highs today will range from the upper 80s/lower 90s inland to the mid-upper 70s at the beaches.

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. Temperatures will continue to trend on the warmer side of normal each day, with highs peaking in the upper 80s to around 90 away from the immediate coast. Lows will be mild.

KEY MESSAGE 3: Increasing rain chances to occur late week.

Later in the week, the pattern could become more active, although still a good bit of inconsistency between models. Mid level heights will fall in response to shortwave energy moving towards/into the region. This will bring a cold front towards the area, possibly stalling nearby, favoring higher rain chances. If the ridge holds stronger, and better forcing remains further to the west, our current PoP scheme could be too high. 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 /09Z SUNDAY THROUGH THURSDAY/

17/12z TAF Discussion: KCHS/KJZI/KSAV: VFR through 18/12z. Gusty winds will accompany the sea breeze.

Extended Aviation Outlook: There are no high confidence concerns.

MARINE

Through Tonight: No concerns with high pressure centered well offshore keeping a typical summer-likely southerly flow regime in place. Sea breeze enhancements are likely along the land/sea interface and Charleston Harbor this afternoon. Winds will largely remain less than 10 kt (except 10-15 kt in the Charleston Harbor this afternoon) with seas 2-4 ft.

Monday through Friday: No marine concerns are expected. High pressure to the east will drive onshore 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 upcoming new moon cycle and persistent onshore flow will produce an elevated risk of rip currents into early next week. A Moderate Risk of rip currents is in effect at all southeast South Carolina and southeast Georgia beaches today and Monday.

CHS WATCHES/WARNINGS/ADVISORIES

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