textproduct: Charleston

WHAT HAS CHANGED

The aviation section has been updated for the 0z TAF issuance. The Small Craft Advisory for the Charleston County nearshore waters has been extended to 9 AM Sunday.

KEY MESSAGES

- 1) Cold temperatures with low wind chills across coastal South Carolina Sunday morning.

DISCUSSION

KEY MESSAGE 1: Cold temperatures with low wind chills across coastal South Carolina Sunday morning.

As a cold front associated with the low exiting off of the Mid- Atlantic coastline dives across the Carolinas this afternoon, unseasonably cold temperatures will prevail through the weekend. Also, an expansive surface high will continue build into the region and allow for clear skies tonight and tomorrow. This set-up will support strong radiational cooling tonight with low temperatures ranging into the low to mid 20s across SE South Carolina and upper 20s to low 30s across SE Georgia. ESAT NAEFS highlights this well with a standard deviation of -3.0 to -3.5 for minimum temperatures on Sunday morning. Mixed the NBM/NBM25 into the overnight temperatures as the 07/13Z NBM appeared to be struggling to realize the strength of the radiational cooling regime. 12Z.HREF probabilities indicate 40-60% chance for seeing wind chills below 21F, with the highest chance in areas along the Santee River (specifically the towns of Awendaw, Saint Stephen, Jamestown, and McClellanville). However, the wind chills will be short-lived (less than 2 hours), and therefore it did not seem warranted to issue a Cold Weather Advisory for tonight.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

VFR conditions will prevail at KCHS, KJZI, and KSAV through 0z Monday.

Extended Aviation Outlook: VFR prevails.

MARINE

Through tonight: Northwesterly winds will prevail through the evening as conditions slowly improve across the Atlantic waters. As the low exiting off the Mid-Atlantic coastline continues to race further away, the pressure gradient continues to relax allowing for winds to dial back earlier than expected. Recent buoy data indicates wind speeds have diminished quite a bit here in the last couple hours and the Small Craft Advisory for AMZ374 will expire at 18Z (1PM) this afternoon. As we head into the overnight, surface high pressure will expand into the region from the northwest and produce a modest surge of winds across the nearshore Charleston waters. This will yield a wind shift out of the northeast. Therefore, a Small Craft Advisory has been extended into AMZ350 until Sun. 14Z (9AM). Not much of a swell out there at the moment with seas ranging 2 to 3 ft in the nearshore waters and 3 to 4 ft in the offshore waters.

Sunday through Thursday: As high pressure continues to build into the local waters, marine conditions will stay benign as some east- northeasterly swell surges into the local waters on early on Sunday morning before tapering back in the afternoon. Afterwards, marine conditions remain quite and conditions remain under SCA thresholds through the remainder of the week.

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...None. MARINE...Small Craft Advisory until 9 AM EST Sunday for AMZ350.