Blue Norther
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I'm Dave Thurlow and this is The Weather Notebook. Today on the show we look at cold fronts that are really cold fronts. Some of the most dramatic fronts on earth surge across the North American prairie each winter. The cold winds associated with these fronts are called blue northers in Texas, but their stomping ground ranges from Alberta to the Gulf Coast.

Blue northers get their start when a bitterly cold air mass builds up not far from the North Pole. This usually happens beneath a dome of high pressure which leads to light winds, clear skies, and successively colder nights. Sometimes the high pressure builds up enough to spread south through sheer gravity, like a blob of maple syrup rolling across your pancakes. However, for a really intense norther, you need the jet stream to help push the air south. When everything comes together, a newborn cold front can race south at speeds of 60 kilometers per hour or more, enough to move it from Canada to the Gulf of Mexico in less than two days.

A blue norther arrives with screaming winds that can push up a thick, ominous blanket of stratus clouds. These may look blueish grey as they approach, thus the colorful name. One classic blue norther hit the plains in November of 1911. In just a matter of hours after the front passed, temperatures in Oklahoma City dropped from a balmy record high of 83 Fahrenheit or 28 C, to a record low of 17, that's minus eight Celsius. Both readings still stand as testimony to what can happen when the wind comes sweeping down the plain.

The Weather Notebook is made possible by a grant from The National Science Foundation. Additional support comes from Subaru, maker of the all weather Legacy. Subaru, the beauty of all wheel drive.