textproduct: Charleston

WHAT HAS CHANGED

The Winter Weather Advisory has been expanded in area to include Tidal Berkeley County and Charleston County. Freezing drizzle has been added to the forecast across areas away from the coast in SE SC. The aviation section has been updated to reflect the 06Z TAF issuance.

KEY MESSAGES

- 1) Freezing rain/freezing drizzle will be likely across far interior counties of SE SC and SE GA through this morning.

- 2) Arctic air will yield very cold temperatures Monday night into next weekend, with Cold Weather Advisories possible.

DISCUSSION

KEY MESSAGE 1: Freezing rain/freezing drizzle will be likely across far interior counties of SE SC and SE GA through this morning.

Analyzing both radar imagery from KJAX and infrared satellite imagery, low pressure has developed off the SE GA coast as of early this morning. Surface analysis depicts a strong Cold Air Damming (CAD) set up east of the Appalachian Mountains as a strong (1042 mb) high pressure center sits over New England. Temperatures have dropped below freezing in several locations across SE SC. The coverage of below freezing temperatures is expected to expand as diabatic processes from the precipitation cool the air further to the wet bulb. The Winter Weather Advisory has been expanded in area to include Tidal Berkeley and Charleston Counties as freezing drizzle could yield a trace of ice across areas away from the immediate coastline. Roads, especially elevated bridges and overpasses, could become slick for anyone traveling this morning. Temperatures are forecast to rise above freezing late this morning, however conditions will still remain chilly as the CAD will likely be slow to erode.

KEY MESSAGE 2: Arctic air will yield very cold temperatures Monday night into next weekend, with Cold Weather Advisories possible.

An arctic airmass will expand into the region on Monday behind the cold front. A reinforcing high will build in on Thursday behind a dry cold front. Overnight lows will be in the upper teens to lower 20s Monday night, then in the low/mid 20s through the weekend. With 5-10 kt winds each overnight period, wind chills will dip to 10-20F for a few hours straddling daybreak each day. We expect to need a series of Cold Weather Advisories during this period.

There remains a low chance that a southern stream low could bring wintry precipitation next weekend.

AVIATION /06Z SUNDAY THROUGH THURSDAY/

MVFR will initialize at KCHS/KJZI/KSAV to start the 06Z TAF period. Light rain has developed across portions of SE SC, and both KCHS & KJZI have mention of VCSH. IFR cigs are forecast to move into the region early this morning, lingering through the remainder of the TAF period at KCHS/KJZI. KSAV could see a return to MVFR cigs this evening.

Extended Aviation Forecast: VFR.

MARINE

A very tight NE gradient continues over the Atlantic waters as strong high pressure continues to wedge in from the north while surface low pressure develops off the GA/SC coast. We're still seeing gusts of 33-40 kt at several buoys so we extended the Gale Warnings for all waters (except Charleston Harbor) until 08Z. All indications are that the strongest gradient will move north of the area later tonight, at which point we'll likely replace the Gale Warning with Small Craft Advisories. Conditions should drop below advisory criteria by Tuesday morning.

EQUIPMENT

The KCLX radar will remain out of service. Critical parts are on order and should arrive on Monday. Users should use adjacent WSR-88D sites, including KCAE, KLTX, KJAX, KVAX and KJGX.

CHS WATCHES/WARNINGS/ADVISORIES

GA...Winter Weather Advisory until 1 PM EST this afternoon for GAZ087-088. SC...Winter Weather Advisory until 1 PM EST this afternoon for SCZ040-042>045. MARINE...Small Craft Advisory until 1 AM EST early this morning for AMZ330. Gale Warning until 4 AM EST early this morning for AMZ350-352- 354-374.