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Terry’s Take: The challenges of predicting a snowstorm!

Posted on: 10:55 pm, November 28, 2013, by

Terry Swails Weather Blog

On my newscast Thanksgiving night I indicated the threat of a winter storm next week somewhere close to the Quad Cities. I was also quick to add this qualifier, “The bottom line is it’s very early in the game and we are going to see ebb and flow for 2-3 more days before a hard track is established. That said, at this early juncture there are strong signs that a significant snowstorm is in the making for some part of the Midwest next week”. End quote!

Tonight the signs of a major storm are even stronger with the latest run of the US. forecast model known as the GFS. However, the area to be impacted is in more doubt than ever. The models are struggling mightily determining where the storm will go. The afternoon run of the GFS went totally rogue on me and shifted the storm track about 700 miles northwest from its previous run. Instead of crossing southeast Indiana the center is now shown passing directly over Minneapolis. The central pressure gets down around 977mb. That’s a ripper but a radical departure in track from 6 hours earlier, far more ebb and flow than I wanted to see!

C 18Z GFS SURFACE

C 12Z GFS SURFACE

Previous to this morning’s data, I was pretty certain the storm would track across Iowa. However after the morning runs of the EURO and GFS both took the storm SE of the Quad Cities, I was having doubts. Now with the GFS shifting heavily north I’m really on the fence!

If I had to bet the farm today I would expect a more northern track similar to what the GFS depicts. Without cold air in place it will be difficult for the storm to pass SE of the Quad Cities unless a lead wave can force the baroclinic boundary further south. I don’t like the chances of that. Additionally, climatology for early December favors storms tracking through central or eastern Iowa.

C GFS SNOW

C GFS SNOW MORNING

Models are an essential part of my job but as you can see it’s unusual when they are consistent and accurate more than a few days out. Sometimes pattern recognition and patience are a forecasters best friend when tracking a storm more than 5 days away!

Anyway, there is not much to do now but wait and see what tomorrow brings. Again, I still see a major snowstorm for the upper Midwest next week but I have many questions about where it will go. I suspect the worst of the snow will end up northwest of the Quad Cities. Time will tell.