If you're a snow lover and you were a fan of the month of January from a snow perspective, then this article is for you. After a break from the snow over the last week or so, coupled with several days of widespread above normal temperatures (60's downstate) and several rain and freezing rain systems, we continue to eye an interesting weather pattern going forward, not only across the Midwest but across all of North America. By doing this an analyzing the large scale features at play, we can get a good idea on the overall pattern expected for a span of potentially several weeks across a given area. What we see as we get into the heart of February or the middle of the month, could be a pattern that is quite snowy along with more regular visits of below normal temperatures. This will not be a super detailed and long post, at least not yet but more a heads up of what we can expect going forward and what will be causing it.
We still have several more weather disturbances or systems to get through over the next few days across the Midwest and here in Illinois but I'm not here to talk about those. I'm going to focus on the pattern that looks to begin by this Sunday or so, give or take a day and a pattern that could deliver multiple accumulating snow systems if things work out right. As we get into this weekend and what will continue into next week, we will continue to see troughs of low pressure or upper level lows diving into the western U.S, with the first one doing so this weekend. This will set the stage for what could be a parade of systems coming out into the heart of the United States beginning on Saturday and continuing well into the heart of February.
By the time we get well into next week, a fairly textbook large scale pattern will begin to establish itself across North America as you'll see in the image below. First, a strong mid-upper level ridge will develop into the Gulf of Alaska, what we like to call a -EPO ridge. This will help force cold air from western and central Canada southward into portions of the northern and northwest United States. It will also mean that storm systems will crest that ridge and continue to dive into the western U.S. as previously mentioned above. So we have the cold air supply to the northwest and we have a feed of systems into the western part of the country. What else do we need? To get an active and favorable storm track here, it is usually helpful to get what's called a Southeast ridge or a -PNA ridge centered off the southeastern U.S. or the East Coast. This leads to a ridge across the eastern U.S. and helps steer storms to the left of it, up into the Midwest and Ohio Valley.
Another thing to look at to get a good idea of the potentially favorable pattern is the placement and orientation of the 850mb temperature anomalies (which is a temperature from the mean). These are temperatures we look at aloft, about 5,000ft above the surface. As you can see below, the very cold temperatures show up to our north and northwest, driven by the ridge into the Gulf of Alaska, allowing that cold air reservoir to seep southward. Also, with the ridge off the southeastern U.S. we can see an area of above normal temperatures, pretty typical with a strong ridge as shown. This then leads us to the orientation of these. I circled this in red and the orientation and placement of these temperature anomalies can sometimes signify or show where a potential active storm track will eventually be for a given period of time.
Now to end this, we can just at one operational model below to just show POTENTIAL that this pattern could muster up and by no means is this a forecast. This model is showing five different snow systems that run across the Midwest and affect portions of Illinois in about a 10 day period beginning this Sunday. Now, could we see five snow systems? Possibly yes. Could we see less? Definitely. This article was written to bring the potential to you of what could be a very snowy pattern but even when a pattern looks good for something, it doesn't always produce.