Friday, October 26, 2007
SNOW IN NOVEMBER?
The long range weather models are hinting at snow in the Great Lakes within the next 10 days. The first image you are seeing is a precipitation forecast for November 4. If you look over Lake Michigan, this model is showing some form of precipitation taking place. No you might be saying, Patrick...how do you know it's snow being forecast? Well, when you forecast you can't just look at just one thing and be done with it. You have to look at multiple models and levels of the atmosphere. When we are talking about winter weather you we have to see if temperatures will be cold enough to support snow or warm enough to support rain. 
A good level of the atmosphere to look at is the 850 mb level map. It does a great job of showing the movement of cold and warm air (otherwise known as cold air advection and warm air advection). Here is the forecast at the 850 mb level for the exact same date. Notice the strong push of cold air moving into Wisconsin, Northern Illinois and Michigan. This is very far into the future and models are known to exaggerate, but this is something that I noticed and I thought I would pass it along. I love forecasting snow. I have doing weather in Yuma, AZ for the past two years where snow is unheard of, but now I can get back to the forecast that I learned a great deal about when I went to Northern Illinois University.
Posted by Patrick Crawford at 6:04 PM
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