It turns out that Thursday’s storm was one for the record books. While it did not bring much snow, the cold air associated with it caused temperatures to plummet from a high of 83 F on Wednesday in Denver to a low of 13 F on Thursday. This is a difference of 70 degrees F, and a two day temperature change of this magnitude or greater has only happened 4 other times in Denver Weather history. The largest 2 day temperature change was on December 14th, 2008 when the mercury dropped 76 degrees F from a high of 58 F to a low of -18 F. Brrrr!
Weather is a little like baseball. Meteorologists like baseball players and fans love statistics. So, here are a few more stats to chew on:
- This storm brought the greatest 24 hour temperature change ever seen in Denver in the month of October, a 64 degree F drop.The all time 24 hour temperature drop is 66 F set on January 25, 1872 (that was a long time ago).
- It set a record low temperature of 13 F for Thursday in Denver. The previous record low for October 10th was 17 F set in 2009.
- It set a record low temperature of 9 F for Friday in Denver. The previous record low for October 11th was 22 F set back 1942.
Here in Nederland, I had a high temperature of 67 F at 1 PM on Wednesday. The temperature dropped 44 degrees to 23 F by midnight. The temperature continued to drop to 10 F by 8 AM Thursday morning, giving us a 57 degree 24 hour temperature change.
Stats are can tell an important story. The National Weather Service put together a nice analysis of the 2 two day temperature drops in Denver:
One thing that this table tells us is that most of the largest temperature changes have occurred between November and February, the cold season here in Colorado. None of them are during the summer. To understand this, we need to understand why we experience these extreme temperature changes. In my recent post Everything You Wanted to Know about Cold Air Masses but were Afraid to Ask, I described how in the cold season, deep cold pools of air form over the far northern latitudes as the frigid arctic night settles in over Northern Canada and northeastern Russia (Siberia). The temperatures over the equatorial portions of our planet do not cool nearly as much. There is nothing between Denver and the North Pole, at least in terms of mountains or other geographic barriers, and this makes it very easy for bitter arctic air masses to slide southward into the Great Plains. Likewise, warm air masses from the south from regions such as the Gulf of Mexico can easily flow northward into the Great Plains. This makes Eastern Colorado and the Plains States a virtual battleground between extremely cold and warm air masses and big temperature swings, particularly during the winter.
Denver and cities such as Fort Collins and Colorado Springs also are warmed by west winds downsloping off of the Continental Divide. These winds, also know as Chinooks, can easily bump temperatures into the 60s F and 70s F during the winter. These winds frequently occur just before a strong cold front passes through. This results in very warm temperatures due to adiabatic heating followed by much colder – sometimes arctic air – blowing in on northerly winds once the front passes through. This helps to accentuate temperature drops.
The weekend weather continues to look great! Enjoy the sunshine and warming temperatures on Saturday and Sunday.