Winter Storm Likely Monday. Heavy Snow Accumulation and Travel Impacts Expected.

It’s the active weather pattern that just keeps on giving. In anticipation of what is looking more and more like a high impact winter storm (at least by Tennessee Valley standards) across the area beginning late Sunday night and peaking in impact and intensity on Monday, the local National Weather Service offices have placed almost all of our viewing area (Morgan County AL not included yet, but this may be expanded) in a WINTER STORM WATCH valid into Tuesday morning. This is for the likelihood of significant snow accumulations across the area that are expected to cause widespread travel concerns and may even cause the possibility of some isolated power outages in the localized heaviest snow areas. The counties in blue on the map at left are included in this Winter Storm Watch.

Our current first shot at a snow totals forecast as of early this Saturday morning causes for a band of heavy snow totals covering a large part of southern middle Tennessee, back through northwest Alabama and into north Mississippi. Within the white shaded area on the map, current projects are for 4+ inches of snow accumulation. There is a very real chance that some locations in this zone may actually be greater than 6 inches based on consistent model data and the overall setup involved, but we aren’t yet comfortable putting an upper bound number on the highest totals zone just yet. Within the dark blue area that stretches down as far as Athens, Russellville, and Red Bay in north Alabama, our current forecast projection as of early this morning is for 2 to 4 inches of accumulation, and we can’t rule out localized areas of higher totals. We should caution that there’s a very real chance both of these higher accumulation zones may have to be expanded a little deeper into northwest Alabama than currently shown in this forecast map based on data coming in early this morning. We want to wait to get all of the morning data in before making a judgement call on that, but whatever judgement call that’s made will be shown in our updated forecast LIVE on social media and the Tennessee Valley Weather Channel today at Noon. Even south of those heavier accumulation areas, 1-2 inches of snow accumulation are possible deeper into north central Alabama, and these areas may have to be nudged a little southward as well.

Overall, this is a potentially high impact winter storm with an increasing likelihood of heavy snow accumulation that will cause a significant risk of widespread travel problems, and because we are talking about heavier snow totals now, there may be some localized power outages in those heavier snow zones. Take the time now to prepare for the possibility of losing power during this winter storm event.

We are just now getting into the timeframe where the full scope of the event is getting into our high resolution Futurecast computer modeling. We will be able to start showing that later today and this evening. For now, here’s a rough and general breakdown of the timeline:

Sunday evening and overnight: Light snow or snow showers look to start moving into the area as early as sundown or the early evening hours of Sunday. Even though temperatures will be below freezing, snow may be light enough that it may not significantly accumulate for a little while, and there’s the possibility that initial low-level dry air may help to evaporate a little of that early snow. Still, there is the potential for light snow accumulation during the evening and overnight hours, before sunrise on Monday.

Monday morning into the midday: This is when winter storm conditions really begin to ramp up across the area. Banding features of heavy snow begin to set up with temperatures well down into the 20s. This will set the stage for fast and significant snow accumulation, and the rates of it falling from the sky may be heavy enough at times to reduce visibility. Driving will become dangerous because of rapidly deteriorating road conditions and reduced visibility.

Monday afternoon into the evening: The exact ending point of the heaviest snow is still a little uncertain, but winter storm conditions are likely to carry on into the afternoon and possibly after dark hours. Heavy snow accumulations will have already been ongoing by this time, and this is when we may start to see enough snow weighing on tree limbs weakened by recent high wind events to start causing localized power outages.

Monday overnight into Tuesday morning: Heavy snow tapers off during the overnight Monday into early Tuesday morning, but light snow showers or flurries may continue into Tuesday morning. Little to no additional accumulation would be expected from this activity. Because of the cold temperatures, even if the sun breaks out on Tuesday, road conditions may not improve very much at all… even on main roads unless there is significant treatment operations by road crews. Back roads in hilly and shaded areas may not begin to see improvement until after Wednesday.

Aside from the winter storm conditions, the well-advertised and consistently forecasted arctic air next week is the other primary concern. Once we go below freezing Sunday evening (and there is increasing doubt that we even climb above freezing in many areas on Sunday for daytime highs), we don’t come back above freezing again until briefly for a few hours Thursday afternoon. That extended period of several days of non-stop day and night below freezing air, with overnight lows Monday and Tuesday nights down into the single digits and lower teens, is pipe bursting type cold. In addition, wind chill values may run near or below zero during this period, making this also a dangerous cold for anyone outside without protective layers of clothing for any significant period of time. This would also be a dangerous cold to elderly and others that may not have the best indoor heating, as well as to pets or livestock outside if not provided proper shelter from the cold.

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