Long Winded Weekend Snow Breakdown
Good morning folks! I thought skipping yesterday's scheduled posting and taking the extra 12 hours to allow the model runs to slowly work toward a solution would help when writing this discussion, but here we are on Thursday morning and I (and other outlets as well) are not any the wiser. We still do not know how much snow will fall, if and when sleet or freezing rain will mix in and where the highest totals will be located. That being said, we will definitely experience a wintry weekend and one that is likely to cause issues for many of us across SW NC, especially the higher elevations where totals could exceed 6 - 10". Not to cause panic as a sizeable portion of us will be on the sidelines with paltry amounts of snow, sleet, and freezing rain, but I do advise folks to prepare as reasonably as they can. We are not talking about week long outages or travel delays, but we are likely to see the entire region shutdown Monday morning, possibly extending through the day and into Tuesday for the higher elevations, whereas the valleys should be back to normal by late Monday.
The most important take home from today's discussion is that things will change between Thursday morning and Saturday morning. This is not a weather industry wide conspiracy to keep you on the hook, but an actual plea to not freak out based on one model run or one snowfall map you saw somewhere on social media. Always check the timestamps and follow legitimate outlets like WLOS, NWS, or even our more independent outlets like Asheville Wx with Hunter Ward or perhaps a lone meteorologist like Evan Fisher, both covering with in depth detail the Asheville and French Broad Valley. I will be shifting to daily updates (a rarity now a days with family and work responsibilities increasing) through Sunday morning, ensuring I capture the forecast changes so you can stay ahead of the event, or perhaps plan for an epic outing in the snow!
We'll keep Thursday and Friday short to focus on the weekend system. Expect high clouds today (Thursday) with temps managing to reach the mid - upper 30's above 5000', while the valleys push to the upper 40's. A round of NW flow snow occurs tonight, favoring the western slopes more than the NW facing slopes but a swath of 0.10 - 2" of snow is possible for the favored locations, with Mt LeConte in the Smokies picking up the 2" total, while Cataloochee Ski Area sneaks out a dusting. Temps bottom out to the low - upper 20's overnight, with snow showers ending before sunrise.
Friday offers up a breezy day before the main event with sunny skies overhead and temps warming to the low - mid 30's above 5000', mid - upper 40's in the valleys; similar to today. NW winds around 10 - 20mph will persist throughout the day, but flip over to a southerly flow overnight into Saturday, with temps settling into the mid - upper 20's under mostly cloudy skies.
Disclaimer: Any timeline discussed between Saturday morning and Monday morning is likely to change, including totals and subsequent impacts. Please check back in each morning before noon for a new event update or follow your favorite weather outlet each day as we approach the main window of precip; Saturday afternoon into Sunday evening.
According to the models, we could see light snow begin to fall as flurries as soon as the early - mid afternoon hours on Saturday. We will have dry air in place from a cold air damming setup that should be strong enough to push enough dry and cold air into our region before the precip arrives Saturday afternoon. This will allow the onset of precip to fall as snow and for some time as we move into the evening hours. I expect snow to be the dominant precip type overnight into Sunday, however the dreaded warm nose will rear its ugly head as some point during the pre dawn hours. It's likely that at some point before or after sunrise we will begin to see sleet and freezing rain mixing in with snow, possibly becoming the predominant precip type for our deeper valleys closer to midday. Keep in mind Cold Air Damming is a process brought on by high pressure to our northeast, funneling cold and dry air into the region on northeasterly winds. These winds and overall flow struggle most of the time to climb over and/or go around the Great Balsams (Jackson/Haywood Co line) and Highlands Plateau, essentially cutting off or reducing the supply of cold and dry air into our deeper valley towns like Bryson City, Dillsboro, Franklin, and Sylva. On the flip side, Waynesville and most of all of Haywood Co bodes quite well during CAD events, as they have very little interruption from the Newfound Mountains during northeasterly flow and benefit on the tail end of the event with the Great Balsams slowing down or minimizing the warm nose impact to precip types. I say all of this because it seems we may fall victim to a similar setup, where the valley floor in Graham, Cherokee, Clay, Macon, Swain, and Jackson counties struggle to maintain an all snow precip type, ultimately dealing with a wintry mix of sleet and snow, while the higher elevations above 3500 - 4000' across all of SW NC should experience snow.
As of now this is the likely playbook, however as the low pressure system races out of the region late Sunday, all precip will kick back over to snow regardless of elevation as temps crash behind the departing low, with scattered snow coverage that will extend into the pre dawn hours Monday. All of SW NC could pick up a light amount of snow during the second half of the event and its likely the favored NW flow locations will be pick up several more inches of snow overnight into Monday.
Temps this weekend will go from the mid 30's - mid 40's on Saturday to the upper 20's - mid 30's Sunday and mid 20's - mid 30's for Martin Luther King Jr. Day (Monday). Overnight lows match this declining trend with temps in the valleys bottoming out to the mid 20's Saturday night, low 20's Sunday night, and mid teens Monday night; low - upper teens above 4500' all three nights.
I won't discuss totals at this point and you should take any snowfall maps you see today with a grain of salt as they will undoubtedly change from today into Friday, likely changing again right before the event on Saturday morning. To prevent this whiplash and the likely frustration from those who didn't get 6" inches in their backyard because they say a map on Thursday that said it would, I will hold off till Friday to produce the SNOWCAST map. I will go out on a limb and say above 3500' will see 3 - 5" of snow or more, especially for those who live closer to the TN line. If you live above 4500' you should see all snow, if you live along the valley floor (1900') then expect snow at the onset, eventually mixing in with sleet, followed up by spotty snow showers Sunday afternoon/night.
I'll circle back Friday morning, hopefully around the same time (8:30am). Stay calm and enjoy the ride!