textproduct: Columbia

WHAT HAS CHANGED

Cancelled Freezing Fog Advisory for Pee Dee. Updated the aviation discussion.

KEY MESSAGES

- 1) Some black ice possible this morning.

- 2) Arctic air mass moves in early this week where multiple days with chilly overnight lows are expected. Tuesday night has been trending the coldest.

- 3) Trends need to be monitored for a potential impactful storm next weekend, but uncertainty is expectedly high.

DISCUSSION

Key Message 1: Some black ice possible this morning.

Residual moisture from Sunday's rain and strong cooling overnight will cause some black ice in spots through sunrise this morning.

Key Message 2: Well below average temps through mid-week, before slowly moderating late week.

Deep troughing will continue to dig into the eastern US through the first half of the week with well below average daytime and nighttime temperatures as result. Temps 10-15 degrees below average are expected during this period with daytime highs in the 40's. Overnight temps will likely be the most impactful falling down into the low 20's, Monday, Tuesday, and Wednesday mornings. While not quite to cold weather advisory criteria, these low temps are in the range where we typically start to see some frozen pipes concerns and the like. Temps moderate back around to average on Thursday and Friday.

Key Message 3: Trends need to be monitored for a potential impactful storm next weekend, but uncertainty is expectedly high.

Given the notable trends across the three major physics-based ensemble suites, next weekend will need to be monitored for a potentially impactful system. The overall synoptic pattern is driven by persistent deep troughing and an expected strong Canadian surface high digging into the north central US. This could provide sufficient low level cold air with strong CAD and a typical broad overrunning setup for wintry precip. However there are some notable disagreements across guidance, let alone the inherent uncertainty that comes with day 5-7 forecasting. So while the EC EFI and NAEFS show general agreement in this anomalous setup, prediction of very cold airmasses like this is tricky, especially as they dig down into the central US in both intensity and easterly extent; generally shallow cold airmasses dig further south than east and trend weaken in forecast time. For example, the AI models-ensembles show this idea (which have performed well this season so far) and are notably weaker with the surface high and therefore a less aggressive CAD setup compared to their physics based counterparts. So lots to monitor for next weekend but the inherent uncertainty with regards to wintry precip is very high.

AVIATION /12Z MONDAY THROUGH FRIDAY/

VFR Conditions Likely through the TAF Period.

Satellite and surface observations continue to indicate clear skies and P6SM across the region this morning. These conditions will prevail through the next 24 hours. Winds light and less than 5 knots this morning, then increasing to to 10-15 knots with gusts by late morning and through the afternoon hours on Monday, before decreasing once again near the end of the TAF period as high pressure builds in from the west.

EXTENDED AVIATION OUTLOOK...VFR conditions are expected to last through at least mid-week as cold, dry high pressure moves into the region. Potential restrictions return by Thursday with the approach of the next system.

CAE WATCHES/WARNINGS/ADVISORIES

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