Meteorology: Understanding the Atmosphere            Ackerman and Knox



A Mid Latitude cyclone, also known as an Extratropical Cyclone (meaning not occurring in the tropics) is a cyclonic storm that often develops along a front in the mid and high latitudes. Another way to think of them is as a well developed low pressure system.

Things you should understand about Mid-Latitude Cyclones:

Isobar structure
Isotherm structure
Wind patterns
Precipitation patterns
Satellite view
Life Cycle

It is very important to see these storms as having a life cycle --They are not fixed in time and space; They rotate as they trek eastward (in our latitudes), almost as if you were holding a pinwheel and walking along with it. (This is quite apparent on satellite loops ) They usually go through stages where they develop, mature or strengthen and die out, although it is important to note that not all areas of low pressure become fully developed Extratropical cyclones.

 The Life Cycle of the Extratropical Cyclone on November 10-11 1998.

Satellite observations are a relatively new way of studying storms. So, recent that it is difficult to find satellite data in 1976! However, the cyclone that developed over the central U.S. during the period 9 to 11 November 1998 was similar to the storm that sank the "Edmund Fitzgerald -- the tracks of the two storms are nearly parallel. The storm rapidly intensified, deepening at a rate of between 1 and 2 mb per hour over a 24 hour period, and was accompanied by severe weather (including tornadoes) in the southern U.S. and severe winter weather (blizzard condition) in the upper plains. Below is an animation of the IR images for the November 10-11 1998 storm. Compare these infrared images to those given in Table 10.1 to identify the different life stages of this storm. You may also want to look at satellite images of the 6.7 micron.


The stormtracks graphic was created by Don Rolfson, National Weather Service Marquette, for more information see the NOAA web page at .