textproduct: Columbia

WHAT HAS CHANGED

Cold Weather Advisory remains in effect for tonight. Updates for the long term forecast.

KEY MESSAGES

- 1) A Cold Weather Advisory tonight and well below normal temperatures through the week.

- 2) Following a stretch of calm but cold weather this week, an active stretch of weather is expected over the weekend with potential winter weather.

DISCUSSION

KEY MESSAGE 1: A Cold Weather Advisory tonight and well below normal temperatures through the week.

Very cold 1042mb arctic surface high centered over the Southern Plains will build eastward through tonight although the center of this high will remain to our west. Persistent west-northwest flow expected through tonight will keep strong cold advection over the region and an extremely dry air mass will settle over the area with PWATs falling to around a tenth of an inch with dewpoints likely falling into the single digits. Model guidance in agreement with 2m temp anomalies between 10-20 degrees below normal and NAEFS showing 1000mb temps well below the 10th percentile. Expecting low temperatures to fall into the teens tonight and combined with surface winds around 5 to 10 mph this should yield wind chills within our Cold Weather Advisory criteria and values ranging from 8F to 15F. Cold Weather Advisory continues from 10p tonight through 9am Tuesday.

Ensemble guidance shows a persistent upper trough across the east through the week with a very dry air mass in place with PWATs staying below a quarter inch. A cold well below normal period of temperatures will continue through the week with NAEFS showing temperatures at all levels at or below the 10th percentile and model 2m temp anomalies generally remaining around 10-15 degrees below normal. This will result in highs in the 40s and lows in the 20s through the week.

KEY MESSAGE 2: Following a stretch of calm but cold weather this week, an active stretch of weather is expected over the weekend with potential winter weather.

Below average temperatures are expected to last through the end of the week with broad trough in place across the eastern US. Generally daytime highs in the 40's with overnight lows in the 20's is expected through Friday. The pattern quickly begins to amplify Saturday as the lingering deep trough over the eastern US digs south and interacts with the jet draped across the southern US. The global ensembles and AI suite are in general agreement that this will rapidly drive cyclogenesis somewhere from the southeast US to the Mid-Atlantic. While these ensembles, and inferring from the AI output, are showing the potential for some snow as this low develops, caution should be taken in trusting any ensemble and model in this range yet, even those with internal ensemble consistency. The interaction between the digging trough (with its own internal dynamic shortwaves) and the southern jet is inherently chaotic from a prognostication standpoint; ejecting-decaying cutoff mid level troughs, like we see from Canada in this setup, are notoriously difficult to predict. So expect some notable changes in guidance the next few days, but snow potential cannot be ruled out this weekend. Regardless of where the low deepens, well below average temperatures are likely early next week behind whatever occurs from this system.

AVIATION /18Z MONDAY THROUGH SATURDAY/

Gusty northwesterly winds will continue helping scatter out lingering MVFR ceilings.

Clouds with a base hovering near 2000 to 2500 feet have been slow to fully scatter at Columbia and Orangeburg, but satellite trends and model forecast soundings suggest clearing is quickly impinging on CAE/CUB early this afternoon, and will likely take a few hours longer at OGB, which is within a more prominent axis of lingering cloud cover. Aside from these ceilings early in the period, no weather is expected through the TAF period. Northwest winds near 10 knots with gusts to near 20 knots may briefly diminish towards 00Z, then a secondary cold front will help boost these winds once again towards 03Z with a tendency to be more northerly. Winds then will diminish and gradually shift west-southwesterly with speeds remaining near 4-7 knots, mainly 10Z onward.

EXTENDED AVIATION OUTLOOK...Mainly SKC likely through early Friday, then impactful aviation weather becomes possible as a low pressure system likely moves somewhere near the region.

CAE WATCHES/WARNINGS/ADVISORIES

SC...Cold Weather Advisory from 10 PM this evening to 10 AM EST Tuesday for SCZ016-018-020>022-025>031-035-037-038-041- 115-116-135>137. GA...Cold Weather Advisory from 10 PM this evening to 10 AM EST Tuesday for GAZ040-063>065-077.