Confidence Increasing On Sunday Storm

The two main forecast models that I look at, the GFS and ECMWF, have now largely come into agreement for the first time with regards to the track of the upcoming winter storm on Sunday. My confidence is increasing that this storm will have adverse impacts on SE Michigan, and here's why.

First, I'll look at the latest (00z) run of the GFS model. If you recall from my last post yesterday evening, this model was the one with the southernmost track. Since my last post, the GFS (and other models, as I'll get to shortly) no longer favors a transfer of energy from a primary low pressure system to a secondary low pressure system (if you want a more detailed explanation on this scroll down to my previous post). The latest run of the GFS now favor a single main low pressure system tracking from Paducah, Kentucky to Columbus, Ohio to Pittsburgh, Pennsylvania. This is usually a fairly ideal storm track for SE Michigan to receive good snowfall, and it looks like if that track happens for this storm, that will again be the case, as the GFS shows a period of Moderate/Heavy snow occuring from Sunday Morning through Sunday Evening. The image below shows the storm total precipitation from the latest run of the GFS. This is about 0.5" of liquid, which using the typical 10:1 snowfall ratio, would result in about 5" of snow. However, since temperatures would likely be fairly cold if this storm track took place, I am betting that snowfall ratios would be higher than normal, meaning more than 5" of snow would likely fall.



Next, I'll look at the latest (00z) run of the ECMWF model. As you may recall, as of my last blog post this model was the main outlier, showing a storm track from Chicago to Saginaw, which would result in a very sloppy rain/snow storm for SE Michigan, which would severely limit snow accumulations. I mentioned that I favored the GFS track over the ECMWF track, but that I was still unconfident. As it turns out, it appears that yesterdays GFS track will be closer to being correct than the ECMWF track (although neither of them will likely end up being perfectly correct). This is because, relative to yesterday, the ECMWF model has made a significant southward shift, and now also shows a significant snow storm for SE Michigan. The exact center of low pressure is fairly difficult to depict on the ECMWF, but I will say it likely tracks from Evansville, IN to Dayton, OH to Erie, PA. This is slightly north, but still fairly similar to, the track of the the latest GFS, and the ECMWF now also shows SE Michigan getting Moderate/Heavy snow all day Sunday. While I can't post images of precipitation from the ECMWF, I can say that it shows SE Michigan getting around 0.6" of liquid, which would translate to around 6" of snow using standard 10:1 snowfall ratios. While the ratios if the ECMWF track were to occur would be less than the ratios using the GFS track, they would still likely be above 10:1, meaning more than 6" of snow would likely fall.

Finally, I'd also like to mention two other models that I also take into consideration, the GGEM and UKMET. The GGEM model shows the storm tracking from Evansville, IN to Columbus, OH and also gives SE Michigan a significant snowstorm, as shown in the image below. The UKMET model is currently a large southern outlier, taking the system from Nashville, TN to Raleigh, NC...which is obviously significantly further south than the other three models I look at. For this reason, I doubt that track will happen, but it is something to keep in mind.



In summary, the forecast models seem to be coming into agreement on a potentially significant winter storm that could impact SE Michigan on Sunday. The main timeframe for snowfall would likely be from Early Sunday Morning through Early Sunday Evening. While this may not be the best timeframe to get a snow day on Monday, I do believe that IF this storm occurs as currently shown on most of the models (and that's still definitely not a sure thing), there would be a good chance of a snow day on Monday. This is because I believe that SE Michigan could possibly see totals well above 6", and also because I believe there will be a significant wind component with this storm system, which would lead to blowing and drifting of snow, and likely subzero wind chills. So, while a snow day is far from a sure thing at this point (and it never really is 5 days out), it's definitely something to keep an eye on. I still have some reservations w/ regards to this storm, but I am much more confident than I was in my last post.

I will likely have another post up tomorrow afternoon. Until then, feel free to leave questions/comments in the comments section below.