textproduct: Charleston

WHAT HAS CHANGED

The Aviation Section has been updated for the 12Z TAF issuance. The Marine Section has been updated for a Small Craft Advisory issuance tonight.

KEY MESSAGES

- 1) Dry conditions with gusty winds this afternoon.

- 2) Freeze Watch in effect for early Sunday morning with frost/freeze conditions possible through Monday morning.

DISCUSSION

KEY MESSAGE 1: Dry conditions with gusty winds this afternoon.

Dry high pressure will build across the region today, continuing to usher in a cooler airmass behind a cold front well offshore. Cold air advection should help promote low-lvl mixing, taping into wind fields that support westerly sfc winds gusting upwards to 15-25 mph this afternoon and favor a slight mixing out of sfc dewpts across inland tier counties (Dorchester County, SC to Tattnall County, GA) suggesting RH levels dipping into the mid 30s for a few hours. This could pose a limited fire weather risk for a few hours this afternoon given continued drought/dry fuels, but weather conditions should fall just short of those needed for a Fire Danger Statement across the far interior today.

KEY MESSAGE 2: Freeze Watch in effect for early Sunday morning with frost/freeze conditions possible through Monday morning.

As cold air continues to advect into the region in the wake of the frontal passage, high pressure will continue to build into the region. Expect this setup to yield dry, breezy conditions through tonight and into Saturday morning. Overnight lows will dip into the mid to upper 30s across the inland areas with low 40s along the coastal corridor. The elevated winds combined with marginal temperatures will limit frost formation across the region and opted out of issuing a Frost Advisory for tonight/Saturday morning.

However, the pressure gradient should weaken on Saturday afternoon as the center of high pressure shifts across the Southeast and this will yield light to calm winds through Saturday night/Sunday morning. Alongside this, clear skies will allow for good radiational cooling to take place overnight with low temperatures dropping into the upper 20s to low 30s across the inland counties and upper 30s to low 40s along the coastal counties. Therefore, there was a good amount of confidence to issue a Freeze Watch for early Sunday morning across the interior southeast Georgia and southeast South Carolina counties. This will likely be upgraded to a Freeze Warning with later forecast updates. The forecast notes widespread to areas of frost on early Sunday morning to account for this.

There could be another chance of frost/freeze conditions across the inland counties through early next week as the cool air mass lingers across the region.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

VFR conditions are expected at CHS/JZI/SAV terminals through 12Z Saturday. However, west/west-northwest winds will become gusty at all terminals this afternoon, generally up to 15-18 kt between 18Z-23Z today.

Extended Aviation Outlook: Expect VFR conditions to prevail.

MARINE

Today through Tuesday: A brief period of weakening winds is expected across local waters this morning and afternoon with conditions expected to remain below Small Craft Advisory levels during daylight hours. However, a second episode of notable cold air advection and tightening of the pressure gradient is likely across coastal waters this evening and overnight, producing gusty west-northwest winds up to 25-30 kt and building seas up to 3-6 ft across offshore Georgia waters. A Small Craft Advisory has been issued for offshore Georgia waters from this evening through sunrise Saturday. High pressure will then continue to build across the region this weekend into early next week with wind/sea conditions remaining below Small Craft Advisory levels through daylight hours Monday. The next round of Small Craft Advisories could arrive across a bulk of local waters next Tuesday.

CHS WATCHES/WARNINGS/ADVISORIES

GA...Freeze Watch from late Saturday night through Sunday morning for GAZ087-088-099>101-114-115. SC...Freeze Watch from late Saturday night through Sunday morning for SCZ040-042>045-147. MARINE...Small Craft Advisory from 6 PM this evening to 7 AM EST Saturday for AMZ384.