textproduct: Charleston

WHAT HAS CHANGED

High temperatures for today have been adjusted down a few degrees to account for the lingering wedge. Low temperatures tonight were adjusted down a degree or two, and a Cold Weather Advisory has been issued for the entire SC Lowcountry and SE Georgia from 10 PM tonight through 9 AM Tuesday morning. Introduced chance of snow for Friday night through Sunday morning now that models are more consistently showing low pressure developing along the SC coast this weekend. The aviation section has been updated to reflect the 06Z TAF issuance.

KEY MESSAGES

- 1) An arctic air mass will yield very cold overnight temperatures tonight and into the weekend. A Cold Weather Advisory is in effect for SE SC from 10 PM tonight through 9 AM Tuesday morning. Additional Cold Weather Advisories are likely through the week.

DISCUSSION

KEY MESSAGE 1: An arctic air mass will yield very cold overnight temperatures tonight and into the weekend. A Cold Weather Advisory is in effect for SE SC from 10 PM tonight through 9 AM Tuesday morning. Additional Cold Weather Advisories are likely through the week.

Strong high pressure (~1040) will build into the region from the west today behind a departing cold front. This high pressure will usher in an anomalously cold airmass into SE SC and SE GA. 850 hPa temperatures are forecast to dip below 0C across the region tonight. In addition to these cold temperatures winds are forecast to remain slightly elevated tonight, generally around 5 to 7 mph as the high pressure builds into the region. The combination of the cold temperatures and the elevated wind will yield wind chill values in the low to mid teens across the region. A Cold Weather Advisory is now in effect from 10 PM this evening until 9 AM Tuesday morning across the SC Lowcountry and SE Georgia. There is some model guidance that shows temperatures across portions of inland SE GA a tad colder, with apparent temperature values dropping into the single digits. However, this is a low confidence forecast and any potential dip into the single digits would be short lived.

The building high pressure at the surface will continue through the week, Cold low temperatures will remain the forecast highlight through the week and headed into the weekend, with overnight apparent temperatures dropping into the upper teens to low 20s each night. Additional Cold Weather Advisories will likely be required for at least portions of the forecast area through the week.

AVIATION /06Z MONDAY THROUGH FRIDAY/

Cigs across KCHS/KJZI/KSAV to start the 06Z TAF period are bouncing between VFR/MVFR and even IFR. The TAFs air on the more pessimistic side, with prevailing MVFR at KCHS and prevailing IFR at KJZI/KSAV. Gusty NW winds will develop around daybreak, with gusts around 20 knots. Restrictive cigs will stick around until mid morning when VFR conditions are expected to move into the region. By this evening cigs should be FEW or even SKC.

Extended Aviation Forecast: VFR.

MARINE

Based on discussions with the Charleston and Savannah Pilots Associations as well as monitoring coastal web cams, the sea fog seems to have dissipated, so we dropped the Dense Fog Advisory over the waters. Winds remain relatively weak over the waters early this morning since the warm front has still not lifted north. Winds should swing around to the SW briefly close to daybreak, then quickly shift to the WNW after the cold front shifts offshore. We have a marginal Small Craft Advisory continuing through tonight for all of the Atlantic waters except Charleston Harbor. Occasional wind gusts of 25 kt and/or 6 ft seas will persist through tonight before diminishing 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...Cold Weather Advisory from 10 PM this evening to 9 AM EST Tuesday for GAZ087-088-099>101-114>119-137>141. SC...Cold Weather Advisory from 10 PM this evening to 9 AM EST Tuesday for SCZ040-042>045-047>052. MARINE...Small Craft Advisory until 6 AM EST Tuesday for AMZ350-352-354. Small Craft Advisory until 10 AM EST Tuesday for AMZ374.