Amazing Facts About Cold Fronts

Cold fronts can cause amazing and drastic weather changes. When a cold front passes through your location, you can smell and feel the change. Sometimes a cold front will bring in a dust storm with high winds or even a blizzard with a temperature drop of 40 degrees. 


Cold fronts that move south into the central United States can cause amazing weather changes and even be life threatening. These intense cold fronts during the winter months have names like Blue Norther, Alberta Clipper, Alaska Blaster, Siberian Express and Saskatchewan Screamer. 


Cold Fronts Explained


During the United States winter, very cold air can accumulate to the north in Alaska and Canada and will eventually slide south. These intense cold fronts usually slide south between the eastern slopes of the Rocky Mountains and the central high plains all the way south to Mexico.  A cold front is a difference in air masses with cold air behind the cold front and warmer air in front of the approaching cold front with normally a southwesterly wind.

As a cold front approaches, the barometer will fall since a cold front is a low pressure system. Once the cold front passes, the barometer will usually start to rise rapidly along with a shift in wind direction out of the north. High pressure will be on the back side or behind the cold front and many times, the higher the barometric pressure, the colder the air can be and the center of the high pressure is usually where the coldest temperatures occur. The temperature and weather changes can be dramatic and amazing as a cold front passes your location.

You can see and feel the weather change when a cold front approaches. As you sit in the sun basking in warm temperatures, you can look to your north and see a billowing cloud of dust and clouds moving towards you. When the cold front gets closer, you can smell the air change and the wind will start to shift. As the intense cold front passes your area, the temperature will drop rapidly and a heavy burst of snow and wind can result in blizzard conditions after the cold front passes.

Arctic cold front
Arctic cold front as seen from an airline over Colorado / Amanda Wicks

The Blue Norther of 1911


There is a saying in Texas that claims “The only thing between the Arctic Circle and Texas is a barbed wire fence”. And when a Blue Norther moves south, there can be amazing changes in temperature and the weather.

On November 11, 1911, an intense cold front or Blue Norther dropped south into the United States causing dramatic temperature drops and blizzard conditions. As is common ahead of an approaching cold front, the temperatures were warm. In Kansas City, Missouri, the high temperature for the afternoon was a balmy 76º F (24º C). Within an hour of the cold front passing, the temperature dropped to 45º F (7º C). By midnight, the temperature had fallen to 11º F (-12º C), which is a 65 degree temperature drop in just 10 hours. Temperature drops of 50 degrees within an hour were common throughout the area.

This Blue Norther brought even more extreme weather to the northern tier of states as nine tornadoes were reported in Wisconsin, Illinois, Indiana and Michigan. An F4 tornado struck the town of Janesville, Wisconsin, killing nine people and within a couple of hours the area was then hit with a blizzard and the temperature falling to 0º F (-18º C).

The intense cold front also affected the western High Plains, where in Denver, Colorado, the temperature dropped 68 degrees from a high of 66º F (19º C) to a low of -2º F (-19º C) the next morning. One of the largest temperature drops occurred in Jefferson City, Missouri, where the temperature fell 71 degrees from a high of 80º F (27º C) to a low of 9º F (-13º C) the next morning. This cold front was so intense that many cities actually set record highs and record lows in the same 24-hour period.



US weather map
Cold front moving across the US in 2011

The 1989 Alaska Blaster


During January 1989, bitterly cold air had been pooling in Alaska and was started to sag south towards the lower United States. Record temperatures in Alaska were as low as 76º F below zero. High pressure or high barometric readings are associated with these severe cold outbreaks and the 1989 cold wave was no exception. The highest barometric reading ever recording in North American occurred during this cold wave in Alaska with a reading of 31.85 inches.

By February 1, this bitter cold air sank into the United States and was called the Alaska Blaster, dropping temperatures by 70 degrees or more. When the cold front went through Valentine, Nebraska, the temperature dropped 33 degrees in one hour and from 70º F (21º C) degrees to 0º F (-18º C) in just 12 hours.

Denver, Colorado saw temperatures stay below zero for 69 straight hours and a number of people being treated for hypothermia and frostbite including one person that died from hypothermia. As usually happens, when the cold pool of air drained out of Alaska, their temperatures rose by 50 degrees and became warmer than many places in the lower United States

The cold wave eventually moved east with the cold front as warm chinook winds blowing off of the Rocky Mountains warmed Denver from a low of -24º F (-31º C) to 32º F (0º C) in just a couple of hours. Other rapid warm ups included Cheyenne, Wyoming warming 75 degrees in two days and Scottsbluff, Nebraska warmed 84 degrees from a low of -42º F (-41º C) to a high of 42º F (5º C).


Cold front from satellite
Cold front in SE Colorado as seen from satellite (NWS)

Cold Fronts Can Be Dangerous


Intense cold fronts can cause rapid temperature drops and blizzard conditions to occur almost immediately and are dangerous if you find yourself trapped outdoors walking or driving. I have been in a number of these intense cold fronts including the 1989 Alaska Blaster.

The most memorable for me was in 1980, when I was outside working in the yard and the temperature was in the 60s. Within two hours a cold front came through and the temperature dropped into the teens with blizzard conditions. The National Weather Service issued a bulletin that said an extremely severe blizzard was occurring and all roads were closed. 

The temperature had actually dropped from the 60s down to a wind chill temperature of -40º F in just a couple of hours. The National Guard was called out to rescue thousands of stranded motorists throughout the area before people froze to death in their cars.

Cold Front Conclusion


As you can see, intense cold fronts can cause dramatic and rapid temperature and weather changes that can be dangerous. Knowing when a cold front is coming into your area is important and the weather service is getting better at timing these cold fronts. Even if you only drive to work every day, you should carry a winter survival kit in your car since these intense cold fronts can cause you to be stranded even between your home and your job.

Copyright © 2011 Sam Montana
 

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