Many comparisons have been made between the strong el nino years of 1982-1983 and 1997-1998. While many similarities exist during these respective winter months, both had mild winters and above normal precipitation during the spring, lets hope one pattern doesn't repeat itself. The following December in 1983 saw an unprecedented cold wave that not only broke records for the coldest December on record by several degrees, but also broke records for the longest continuous period with temperatures of zero degrees or colder in both Sioux Falls and Sioux City.
A snowstorm occurred between November 26 through the 29th 1983 bringing widespread heavy snows of 9 inches at Huron South Dakota, 11.4 inches in Sioux Falls and 13.6 inches at Sioux City Iowa. With deep snow cover of around 10 inches at all three locations at months end, the stage was set for a potentially cold December.
With deep snow cover at the beginning of December and a persistent jet stream pattern that brought one cold Arctic blast after another, a month that started out cold only got colder and it wasn't until after Christmas when temperatures moderated and even then temperatures remained will below normal. An indication of just how cold it was in December 1983 was the fact that both Huron and Sioux Falls never saw the mercury climb to 30 degrees and Sioux City struggled to hit 32 degrees on December 4th. The monthly high of 29 degrees in Huron was also set on the 4th while in Sioux Falls, the monthly high of 27 degrees was reached on the 4th, 10th, 11th and the last day of the month.
The average temperature for the month of December 1983 in Sioux Falls was 2.1 degrees, 17.6 degrees below normal. This broke the previous coldest December by 5.9 degrees when the average temperature of 8.0 degrees was established in 1917. The average high for the month was 10.9 degrees and the average low was 6.7 degrees below zero. There were 24 days when the mercury fell to zero degrees or colder, 11 days of 10 below zero or colder including 10 days in a row between the 16th and 25th and 8 days with 20 degrees below zero or colder on 8 consecutive days between the 17th and 24th. The coldest temperature, 26 degrees below zero, occurred on the 18th and 22nd.
In Sioux City, the average temperature for the month of December 1983 was 6.0 degrees which was 17.3 degrees below normal. The previous record coldest December of 12.8 degrees set in 1909 was smashed by a whopping 6.8 degrees! The average high for the month was 13.4 degrees and the average low was 1.4 degrees below zero. There was a total of 17 days where the temperature fell to zero degrees or colder, 9 consecutive days of 10 below zero or colder which occurred between the 17th and 25th and one day with 20 below zero or colder which occurred on the 23rd when the mercury plunged to 21 degrees below zero.
In Huron, the average temperature for December 1983 was 2.8 degrees which was 16.2 degrees below normal. The average high was 11.1 degrees and the average low was 5.6 degrees below zero. There were 24 days of zero degrees or colder during the month, 10 consecutive days of 10 degrees below zero or colder between the 16th and 25th, and 4 consecutive days of 20 degrees below zero or colder between the 21st and 24th. The coldest temperature for the month was 28 degrees below zero which occurred on the 23rd.
The coldest period occurred during a ten day stretch beginning on the 16th and ending on Christmas day. In Sioux Falls the average temperature during this period was 14.2 degrees below zero which was 32.3 degrees below normal! The average high during this ten day period was 6.2 degrees below zero and the average low, 22.1 degrees below zero. Contrast this with what the average high should be during this period, around 26 degrees, and the average low during this period, around 7 degrees, and you begin to understand the magnitude of this unusually harsh cold spell.
During this same ten day period the average temperature in Sioux City was 9.5 degrees below zero which was 31.3 degrees below normal. The average high was 3.3 degrees below zero and the average low 15.7 degrees below zero. Normally during this period the high temperature should be around 29 degrees and the low around 11 degrees.
In Huron, the average temperature between December 16th through Christmas day was 12 degrees below zero which was 29.5 degrees below normal. The average high during this ten day period was 5.3 degrees below zero and the average low 18.8 degrees below zero. Normal high and low during this period would be around 27 and 6 degrees respectively.
It was also during this ten day Arctic invasion that both Sioux Falls and Sioux City broke their records for most consecutive days with temperatures at or below zero, 9 1/2 days in Sioux Falls and 8 1/2 days in Sioux City.
In Sioux Falls, the mercury dropped to zero degrees shortly before midnight December 15th and it wasn't until shortly after noon on Christmas day before the mercury would climb above zero degrees.
In Sioux City, the temperature fell to zero degrees during the late evening on December 16th and it wasn't until shortly before noon on Christmas day when the mercury climbed above zero.
In Huron, the temperature fell below zero degrees shortly before midnight on the 15th and remained below zero until around 10 am Christmas day.
Because of the extreme cold during December 1983 no snow melt occurred and additional snows that fell were of the dry fluffy variety that blows and drifts a lot. On the 20th, from 3 to 4 inches of dry fluffy snow fell across the area which served as ammunition for the biggest Arctic blast of the month which occurred late on the 23rd and continued into the 24th. High winds and loose snow produced zero and near zero visibilities through much of the day in Sioux Falls on the 24th. Shortly after midnight the temperature in Sioux Falls was 22 degrees below zero which when combined with a northwest wind averaging 30 mph combined to produce an apparent wind chill temperature of 82 degrees below zero. The high temperature that day was only 13 degrees below zero and the barometric pressure rose to a near record high 31.06 inches. In Sioux City, howling northwest winds produced zero or near zero visibilities through much of the morning with an apparent wind chill temperature of 80 degrees below zero around 3 am when the air temperature was 17 degrees below zero and the average wind speed was 41 mph! The high temperature that day in Sioux City was 11 degrees below zero. In Huron, visibilities were zero or near zero through the early morning with an apparent wind chill temperature of 77 below zero shortly after midnight on the 24th with a temperature of 20 below zero and a northwest wind averaging 29 mph. The high temperature on the 24th in Huron was 10 degrees below zero.
Will December 1998 follow the trend and be well below normal? Time will tell but even if December 1998 does turn out to be colder than normal it will be hard to break the record cold set in December 1983.