Sloshing air can cause quick temperature extremes
Several years ago, I did a bicycle trip on the Mikelson Trail located in the鈥� Black Hills鈥� of South Dakota. The trail is named after the former governor of South Dakota and the trip was in honor of a good friend and fellow biker who had passed away. It was springtime and it was beautiful with mild temperatures and sunshine. I had planned to do 100 miles of riding over a three day period.
The first day went fine, but on the second day, the wind was so strong, I could hardly make any forward progress. Morning temperatures would be in the 20s and by afternoon it would be 70. The third day the wind and cold got to me and I decided to cut the trip a bit short and see the rest of the area by car.
The Black Hills are truly interesting and beautiful and occasionally experience some very rapid changes in temperature when pockets of cold and warm air become trapped in the valleys with the air sloshing back and forth like water in a shallow bowl. This can result in dramatic changes of temperature measured in minutes rather than hours.
Spearfish, South Dakota, saw a temperature change from -4 degrees to a balmy 45 degrees in just two minutes. Within the hour, the temperature rose another 9 degrees to 54 and twenty seven minutes later it was back down to -4. All of this happened on January 22, 1943. On the same day, the town of Deadwood had a reading of -16 degrees, while the town of Lead just a mile away was reporting 52.
Christopher Burt in his book 鈥淓xtreme Weather鈥� tells of an 80 degree temperature rise in Kipp, Montana, in a period of just 15 hours entirely melting 30 inches of snow. This was part of a Chinook wind blowing down the mountain and warming the air. The Indians called these winds the 鈥渟now eaters.鈥�
Helena, Montana, once experienced a Chinook that raised the temperature from -36 to 54 in 50 hours. Topping all records, Loma, Montana, on January 14-15, 1972, experienced a temperature rise from 54 below zero to 49, a rise of 103 degrees in a 24-hour period. Now that蘑菇视频 some sloshing.