The Science behind the artic blast! 01/14/09

As most of you should know A major cold air outbreak is under way! The models have been quite consistent about this for at least a week now. A great deal of the midwest is in the cross hairs as well as the northeast and especially the great lakes region! NOAA and the NWS are saying this is the biggest outbreak of artic air since 2000 and 1997.


There are two main reasons for this. But the main one is the strength and size of a high pressure system now over Saskatchewan. The high is right now around 1050 millibars!!! WOW! Its forecast to fill in some and move into the states by 0z or 6:00pm CST. In the mean time a Low pressure system is now positioned over IN and is forecasted to move to the northeast. This sets the stage for major cold air advection to flow in behind the Low. The High is pushing in the artic air mass, which in turn is getting pulled downward and eastward by the Low. The Low is being fueled by a somewhat warmer air mass that was pulled in and around it from the southwest.


The blue line is the cold front the red is the warm front. The warm front will be the area of snow fall.

After the cold air sets in and the snow falls the skys will clear mostly due to sinking in the atmosphere. Most of the snow that did fall was in part due to the long wave troughing, and some ascent due to dynamic forcing. If you look at the map above you will see the black lines which are isobars. The pressure is rapidly rising. Which will cause the wind to pick up and since the sir mass is artic it will cause some intense wind chills!

Look at the temps for Thursday above, ouch! Major wind events are also forecast to bring wind chills down to -30 and below to some places. Wind chills and drifting snow should make for some interesting morning commutes on thursday for some. I wouldnt want to be in Chicago right now thats for sure.

So far its been a colder winter than normal and somwhat dry for the most part. It will be interesting to figure out why and what it holds for the future. Major patterns are at work and this is an important time for collecting data! Be safe out there!