As if we haven't said it enough but another winter storm is taking shape and has its sights set on Minnesota. But unlike other storms, this one is a bit more complex making it next to impossible to predict exactly what's going to happen. One of the main issues with forecasting a storm like this is the fact that this time temperatures will be close to freezing which makes it difficult to not only predict where the heaviest snow will fall and how much it will be, but also adding the melting factor into the mix which can take a seemingly huge storm and turn it into a big rain maker which lowers snow totals drastically. It's easiest if I show you what we are working with.
First off, temperatures will be close to or above freezing in the lowest layers of the atmosphere… this includes us at the surface and all the way to 7000+ feet. So how do we know this?? Well we can not only look at current analysis of the atmosphere, but those computer forecasting models show us warm air heading north. For example… here is what some of the lower level temperatures looked like this morning when the rain/sleet/snow was moving through the metro.
This is a snapshot of the atmosphere right around 5000 feet and those lines indicate a change in temperature of 1°C. That dark blue line represents the freeze mark with areas west of it above freezing and areas east of it below freezing. You can see that the line slices through the far west metro with the east metro in the subfreezing category. But most of the metro experienced a rain, freezing rain, sleet, snow mixture as opposed to all snow. This means that at some level in the atmosphere, temperatures were warm enough to melt most of the snow even though, according to this map, most areas should have seen snow. This is why current and forecast analysis cant be used as a concrete fact because the computers might be a little off, or there may even be a little hidden warm layer that we just can't see. So, whenever temperatures at the surface or above get to the upper 20's, you almost always have to approach the storm thinking that someone won't get all snow. This same type of design shows up on the forecast computer models for Tuesday…
The freezing line is drawn in red with temperatures above 32° to the east and below 32° to the west. Granted, these show much of western and central Minnesota below freezing with metro locations right on the freeze mark. This indicates that the metro will likely start with some sort of mix with the west staying all snow. But remember what I just told you… if temperatures fluctuate even a couple degrees, things can change either way. This makes it EXTREMELY difficult to forecast.
That being said… here is what we are looking at if models can hold their course and things go to the current plan. Looks like a pretty good swath of snow arcing northeastward from west central MN to the Arrowhead. IF it can stay all snow, there could be totals up to a foot. But if rain mixes in, the overall totals will be far less. Here is where 3 different models put their accumulation. The legends are at the bottom of each picture.
Surprisingly, these seem to be in relatively good agreement arcing the heaviest snow to the north and west of the metro. The hard part from there though is figuring out exactly who gets what. I would say a swath of 4 to 8 inches of snow somewhere in central and northern MN is a guarantee, but it's anyone's guess on where it ends up. Of course, most metro locations will likely have the largest variance in conditions. If the storm holds its course (which it very rarely does), most locations will be in that 2 to 5 inch range. If it drifts further south, we could be in the 6 to 10 inch range. But vice versa, if it drifts north, It might just be all rain and sleet. Quite a conundrum isn't it??
As I always say, more minds are better than fewer, so here is what some other experts in the field are thinking. The Weather Prediction Center issues their forecasts in probabilities. The following images show the probability of getting at least 2", 4", and 8" for our area. These of course, are also subject to change.
Right now, much of the area has at least a 70% chance of getting two inches of snow. But they also have the bulk of the heavy snow to the north of the metro with a 90%+ chance for 4" in Duluth, but only about a 50% chance for much of the metro. 8" is even scarcer, but still a 50%+ chance in northern Minnesota with only a 5% chance in the metro.
The conclusion?? Looks like some sort of precipitation is headed our way, but it will vary from place to place so hope for the best and plan for the worst. Stay tuned!