textproduct: Columbia

SYNOPSIS

Dry weather is expected to continue into Saturday with near to normal daytime temperatures. A cold front crosses the region Saturday night and Sunday morning ushering in an arctic air mass for Sunday night into early next week. Weak ridging should then allow for air mass recovery by the middle of next week.

NEAR TERM /UNTIL 6 AM SATURDAY MORNING/

Key message(s):

- Overnight lows remain near average tonight.

Flow aloft remains generally zonal across the region while winds in the lower levels continue out of the southwest. These southwest surface winds have allowed for a slight increase in moisture. This is noted in dewpoints in the mid 30s for many locations in the forecast area. The exception is in the far northern Midlands and PeeDee where dewpoints are in the upper 20s to lower 30s. These values highlight where lows are forecast to be lowest overnight, with near freezing temps in the northern areas. Lows are expected to be a bit warmer and near normal everywhere else where the current dewpoints are a bit higher.

SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/

Key message(s):

- Above average temperatures Saturday with isolated rain chances Saturday night.

Saturday will be a transition day and likely the nicest day of the forecast period. The deep trough across the upper Midwest is forecast to dig into the eastern CONUS as an upstream Ridge axis amplifies and shifts eastward. Sunny skies are forecast across the area for most of the day on Saturday, with southwesterly surface flow common. Near to slightly above normal temps are forecast across the area, with highs in the low to mid 60s. Some upper 60s are certainly possible but lets not get our hopes too high. Clouds are forecast to increase as the front approaches from the northwest with scattered showers potentially overspreading the area late on Saturday night/early on Sunday. Lows should be in the mid to upper 40s.

LONG TERM /SUNDAY THROUGH FRIDAY/

Key message(s):

- Arctic cold front ushers in the coldest air mass of the season.

- An Extreme Cold Watch has been issued this afternoon to highlight the dangerous cold expected on Monday morning, with an upgrade to a Cold Weather Advisory likely with later forecast packages.

The key messages remain unchanged with this period, as bitter cold is forecast to overspread the area Sunday night through Tuesday morning. Forecast guidance remains in great agreement on the overall setup, with strong mid/upper level convergence resulting in a strong surface high pushing southeastward out of the Ohio Valley and into the Carolinas and the Atlantic Coastal Plain. The cold front is forecast to pass through the area between 4p and 8p on Sunday, with strong surface pressure rises resulting in wind gusts of 30+ mph for a few hours. Thereafter, winds will likely remain elevated through the early morning hours of Monday, and with temps falling into the teens, wind chills may range from 8F-15F across the area. Both the NBM and LREF support this strongly. In an effort to better serve the public & partners, we have issued a long lead time Extreme Cold Watch for Sunday night and Monday morning to help advertise the cold more effectively. Tuesday night looks very cold as well, and went with cooler guidance than the NBM as ideal radiational cooling conditions should be present over the area. In general, this looks like a very robust cold snap that could be impactful. Be sure to drip your pipes on Sunday and Monday nights to avoid pipe freezes. And if you have any additional outdoor interests, be sure to protect those as well. Beyond this, temperatures begin moderating on Tuesday as upper level ridging overspreads the area from the west. Temps should get back to near normal values by the end of this period.

AVIATION /00Z FRIDAY THROUGH WEDNESDAY/

High confidence in mainly VFR conditions through the TAF period.

Only clouds to speak of through the next 24 hours will cirrus as it moves across the region in association with an upper level trough. At the surface, the airmass remains dry enough to inhibit any kind of widespread fog development. As usual though, we can not rule out brief patchy ground fog at both ags/dnl through sunrise with their nearby rivers. Winds overnight mainly light to calm, then by late morning Saturday they increase to around 5 knots out of the southwest to west.

EXTENDED AVIATION OUTLOOK...Patchy fog could be possible into Sunday morning as low level moisture continues to increase and a couple showers could be possible ahead of a cold front. Widespread restrictions look unlikely after Sunday as a cold and dry arctic airmass moves into the region.

CAE WATCHES/WARNINGS/ADVISORIES

SC...Extreme Cold Watch from Sunday evening through Monday morning for SCZ027>031-035-037-038-041-135>137. GA...Extreme Cold Watch from Sunday evening through Monday morning for GAZ065-077.