textproduct: Columbia

WHAT HAS CHANGED

Updated forecast discussion and aviation section.

KEY MESSAGES

- 1) Well-below normal temperatures are expected to continue the rest of the week and into early next week. Multiple Chilly nights expected this week.

- 2) We continue to monitor the potential for an impactful winter storm this weekend.

DISCUSSION

Key Message 1: Well-below normal temperatures are expected to continue the rest of the week and into early next week. Multiple Chilly nights expected this week.

Temperatures 10-20 degrees below normal can be expected to continue through the work week and behind this weekend's potential system. An extended period of troughing over the Eastern US and cold/dry high pressure remaining in place will aid in bringing these conditions where high temperatures generally peak in the 40s into the late week with multiple nights where lows into the 20s are expected. Right now overnight low values are expected to remain above Cold Weather Advisory criteria but taking steps to ensure that pipes are protected by dripping faucets will likely be needed. This weekend the next system is expected to move in and this will likely bring continued cold conditions where low temperatures behind this system could drop back into the teens, but how cold it gets will partly be dependent on if snow is seen across the FA with this weekend's system.

Key Message 2: We continue to monitor the potential for an impactful winter storm this weekend.

Not much change regarding the potential for an impactful winter storm across the forecast area this weekend. Most of the guidance continues to favor cyclogenesis off the South Carolina coast in response to phasing of the northern and southern jets and the amplification of the upper pattern across the Eastern CONUS. Timing differs between the guidance, but precipitation may begin as early as late Friday with Saturday into Saturday night being the most likely time period for significant impacts. Unlike the previous storm system, ample cold air is already in place across the region with model guidance not showing any warm air intrusion aloft (at this time) and snow being the predominant precipitation type. Precipitation type meteograms from the Euro suggest that precipitation may begin as either rain or a rain/snow mix as colder air wraps into the storm, especially if the models showing an earlier start time pan out. Temperatures could potentially warm up enough for a rain/snow mix in the CSRA on Saturday, as indicated by the NBM, which would lower any snowfall amounts. As seen with the last event, the placement, strength, and timing of the upper pattern would shift the area of heaviest precipitation, therefore it remains too early to nail down a specific corridor for potential heavy snowfall. The latest WSSI-P for moderate impacts from snow amounts ranges from 20% in Burke County to 50% in Chesterfield County suggesting the the threat of an impactful snowfall increases the further north and east you go across our forecast area. This makes sense given the offshore coastal low setup presented by the majority of model guidance.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

VFR conditions expected through the 24hr forecast period.

High pressure will continue to reside over the area during this period with mostly sunny skies through today with some increasing high clouds overnight. West southwesterly winds expected around 10 knots today but an increased pressure gradient should result in some wind gusts up to 20 knots through the afternoon before winds diminish a bit overnight. Winds should stay up a bit though through the night with a 30 knot low level jet forecast. Air mass too dry for fog concerns.

EXTENDED AVIATION OUTLOOK...VFR conditions likely through early Friday, then impactful aviation weather becomes possible as a low pressure system likely moves somewhere near the region bringing the possibility of wintry precipitation.

CAE WATCHES/WARNINGS/ADVISORIES

SC...None. GA...None.