textproduct: Charleston

WHAT HAS CHANGED

The aviation section has been updated for the 06z TAF issuance. Key Message 1 was updated to include strong winds across the coastal waters.

KEY MESSAGES

- 1) Strong winds expected across Lake Moultrie and the Atlantic coastal waters through Saturday morning.

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

DISCUSSION

KEY MESSAGE 1: Strong winds expected across Lake Moultrie and the Atlantic coastal waters through Saturday morning.

Surface analysis shows that a dry cold front is just upstream of the forecast area and will move in over the next hour or two. As it does, colder air and a tightening pressure gradient will produce strengthening winds across Lake Moultrie. Though lake temperatures are are only in the low 40s, there should still be sufficient mixing to produce a period of wind gusts into the 24-28 knot range this morning. A Lake Wind Advisory remains in effect through 1 pm, as winds should start to diminish by around midday as the gradient relaxes.

Similarly, winds will increase across the Atlantic coastal waters as the cold front passes through. Frequent gusts into the 25-30 knot range are expected across the nearshore waters and Charleston Harbor, with gusts up to gale force in the outer GA waters where a Gale Warning is in effect through 7 am. A Small Craft Advisory remains in effect for all other waters. The peak period of winds is expected to generally last through around sunset.

KEY MESSAGE 2: Cold temperatures with low wind chills across coastal South Carolina Sunday morning.

Unseasonably chilly temperatures are expected this weekend. The time period of greatest concern is Saturday night into Sunday morning when low temperatures are forecast to fall well into the 20s across much of southeast South Carolina and southeast Georgia. There looks to be enough gradient wind present (5-10 mph) to bring a concern for wind chills dropping to the upper teens to around 20, especially across the Charleston Tri-County where latest HREF highlights a 50- 80% chance for seeing apparent T < 21F. A Cold Weather Advisory could be needed for portions of the area.

Notably, the stretch of below normal temperatures will be short- lived as we will be on a warming trend during the upcoming week.

AVIATION /06Z SATURDAY THROUGH WEDNESDAY/

VFR conditions will prevail at KCHS, KJZI, and KSAV through 06z Sunday. Northwest winds will be breezy at KCHS and KJZI beginning just after sunrise and continuing into the afternoon. Frequent gusts into the 20-25 knot range can be expected.

Extended Aviation Outlook: There are no concerns.

MARINE

Through tonight: A dry cold front will sweep across the coastal waters over the next few hours, turning winds from westerly to northwesterly. Speeds will increase with frequent gusts into the 25- 30 knot range across the nearshore waters and Charleston Harbor, as well as a period of gusts up to gale force in the outer GA waters. The peak period of winds should come from the pre-dawn hours through about mid morning, then gradually diminish as the gradient relaxes and mixing profiles lessen. Then overnight, there should be another modest surge as winds turn northeasterly with the surface high building in. This will likely keep the Small Craft Advisory going for the Charleston County waters and the outer GA waters.

Sunday through Thursday: Marine conditions will continue to improve on Sunday, with no additional concerns through Thursday as winds/seas remain below Small Craft Advisory criteria.

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...Lake Wind Advisory until 1 PM EST this afternoon for SCZ045. MARINE...Small Craft Advisory until 1 PM EST this afternoon for AMZ330. Small Craft Advisory until 6 AM EST Sunday for AMZ350. Small Craft Advisory until 7 AM EST this morning for AMZ352- 354. Gale Warning until 7 AM EST this morning for AMZ374.