As we brace for a chilly, damp week ahead in the Western Carolinas, it’s important to remember that the rain is much-needed. Tonight, temperatures are expected to plummet into the upper 20s and low 30s, raising concerns about patchy black ice on roads that haven’t fully dried. While these slick spots are likely to be isolated, caution is essential as they can be unpredictable. Clearing skies after midnight could bring some patchy fog at daybreak, and certain sheltered valleys may even experience freezing fog between 5 AM and 7 AM. Stay safe and prepared as we navigate this wintry weather together!
Overall, Monday will be a quiet and mostly sunny day, with temperatures reaching the mid to upper 40s. Clouds will increase rapidly Monday night in advance of an approaching shortwave trough. As this weather system develops, high pressure will move through the Northeast, bringing shallow cold air down along the eastern side of the Blue Ridge Mountains. This creates a cold air damming (CAD) event, although it seems to be a weak one. The dominant high pressure is only temporary, which means this damming setup will not last long.
As low pressure develops along the Gulf Coast and moisture surges north ahead of the advancing frontal boundary, that shallow cold air will already be retreating. To have a high-impact winter ice storm, that high to the north would need to be locked in place and continue supplying cold air southward. That does not appear to be the case with this system.
One important piece of the puzzle is latent heat release. The process of ice accretion actually gives off heat. Fruit producers use this exact science to protect crops when temperatures drop below freezing during the growing season. When freezing rain turns to ice on contact, that phase change actually releases heat into the surrounding air. That release of heat is one of the reasons ice storms sometimes struggle to escalate when temperatures hover near or just below freezing. For Monday Night, as moisture rides up and over that shallow cold air into Tuesday morning, the higher elevations and ridgetops of Burke, Caldwell, McDowell, Wilkes, and the South Mountains will likely be just cold enough for rain to freeze on contact with elevated surfaces such as power lines, decks, bridges, overpasses, and trees.
The saving grace of this system, once again, is that transient high pressure. The supply of sub-freezing air will be limited mainly to Tuesday morning, even in the mountains. As the high releases its grip, temperatures will climb back above freezing, not warm by any stretch, but enough to knock down the ice threat fairly quickly. Northern areas may stay stuck in the upper 30s most of the day before rain ends from west to east between roughly 1 PM and 4 PM. Highs should manage to reach the low 40s across much of the foothills.
Rainfall totals of 0.50 to 1.50 inches look likely. Any area that sees freezing rain should have ice accretion limited to about 0.05″ to 0.20″, but the area around Jonas Ridge and Little Switzerland could see localized totals approaching 0.25 inch. Across the foothills, most of this will fall as a cold, raw rain with temperatures staying just above 32°. It will be close, and that’s a forecast we’ll work to fine-tune over the next 24 hours.
The weather should dry up in time for the Morganton Christmas Parade on Tuesday night, but it will not feel festive from a temperature standpoint. Snow will begin flying across the mountains Tuesday evening, and winds will pick up area-wide with gusts around 30 mph at times. Temperatures will fall back into the upper 20s and low 30s after sunset, and with the wind, wind chill values will drop into the teens across the foothills. So while it should be dry for the parade, it’s going to be cold and windy.
Wednesday and Thursday place us in between weather systems with mostly clear skies and diminishing winds. Highs on Wednesday will sit in the mid to upper 40s, while Thursday will warm a bit with some low 50s possible. By late Thursday, the next storm system will already be organizing back to our west.
A southern-stream shortwave will lift northeast through Mexico, while strong high pressure to the north once again funnels cold air south. By Friday morning at sunrise, high pressure is expected to be centered over the Delmarva, setting up another cold-air damming event. This one may have a stronger cold-air supply and could erode more slowly. Multiple precipitation types appear possible early Friday, and this system could be higher-impact in the foothills than the earlier events this week.
For now, just know that Friday looks unsettled, with a potential for a winter mix of snow, sleet, and freezing rain. Temperatures will likely be stuck in the 30s all day, with some areas remaining below freezing. Fine details of this system will be covered in later blog posts as confidence increases.
By early Saturday morning, low pressure should be deepening along the Carolina coastline and moving offshore, ending precipitation before daybreak. Sunshine should return by Saturday with highs rebounding into the mid-40s. If the system slows at all, some precipitation could linger into the very early part of Saturday — that remains something to watch. We will briefly warm up again on Sunday before another cooldown heading into days 9 and 10. Skies should stay mostly clear during that stretch.
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