Leap day. It is what we call February 29, the day added onto February every fourth year to keep the seasons from slowly drifting through time as the earth takes slightly longer than 365 days to revolve around the Sun. Leap day on occasion does impact climate statistics and this past winter was possibly one of those times.
Our recently completed winter was the 16th coldest on record, but the National Weather Service recently released a statement that this past winter was the 17th coldest on record. The difference? February 29, 1904. Including that day makes the winter of 1903-1904 average temperature 4.4 degrees. Without that day, the average temperature is 4.2 degrees. The winter of 2013-2014 that we just completed had an average of 4.3 degrees meaning that depending on if you include that leap day this winter’s ranking changes by one position. Is one statistic more accurate than the other?
Not necessarily, but leap day seems to get little respect, so I always include in all my analysis and most other researchers do as well.
This past winter season was definitely cold, but it certainly was not snowy. From December 1 through February 28, the official snow total from our cooperative observer in north Moorhead totaled 27.3 inches. That is 2.1 inches below the average of 29.4 inches for that time period. It was the second year in a row with snowfall being very close to the average during the three principal months of winter as last year 28.7 inches was recorded.
More important than the amount of snow is the water content in that snow. The 27.3 inches of snow that fell in the past three months contained 2.09 inches of liquid, right at the average of 2.14 inches. Meaning, this past winter was about as average as average gets for winter precipitation. The driest of the three winter months was February as only 1.5 inches was measured last month, the 8th lowest total on record for that month.
That snow contained only 0.11 inches of liquid making February 2014 the 7th driest since records began in 1881.
The average temperature this past winter (December through February) was 4.3 degrees. That ranks as the 16th coldest winter of the 133 winters on record in Fargo Moorhead (records began on January 1, 1881, therefore the first winter has incomplete data, meaning the first winter of record was the winter of 1881-1882).
The last colder winter in Fargo Moorhead was back in 1981-1982 when the average temperature was 3.3 degrees. Other fairly recent colder winters were in the late 1970s. The winter of 1978-1979 the average temperature was 0.6 degrees and the winter of 1977-1978 the average was 2.8 degrees. Those were the two coldest back to back winters since the 1880s. Even with such a cold winter being recorded, no record lows were set. Of interest, the coldest temperature of winter was just -25 degrees on January 2 which is 3 degrees above the average coldest temperature recorded in a year locally.
There have been colder winters, but if you are under 30, it was the coldest winter in your lifetime.
Yesterday in this space I mentioned that the low temperature at Hector Int’l recorded a low below zero on 65 of the 90 days during our just completed winter season. On most of those days, the air temperature remained below zero for many hours of the day and on some days; the temperature remained below zero the entire 24 hours of that day.
Using the hourly reports from the airport, the temperature in Fargo was below zero for approximately 900 hours December 1 to February 28. That many hours would total 37 complete days of the 90 days of meteorological winter. Put another way, approximately 40% of winter was below zero. Grand Forks’ total hours represented in days would be about 45 days below zero, the Twin Cities, 20 days and Bismarck 25 days.
It may not have been even close to the coldest winter on record, but it was still a very memorable one.
Yesterday was the last day of climatological winter. It was a cold winter, the coldest since the winter of 1981-1982. One of the most impressive stats these past three months has been the number of below zero days. From December 1 to February 28 the daily low temperature was below zero on 65 days which is nearly three out of four days over the past three months.
As of this morning this cold season is currently ranked as having the 19th highest number of days below zero since records began in 1881 (with more negative days to come). Yet, if you only include the three principal months of winter, the 65 days recorded last season would rank as the 6th highest. Plus, if you exclude the 1880s before temperature measurement standards were initiated in 1891, this past climatological winter would rank 3rd behind the winters 1935-1936 and 1949-1950 both tied with 66 negative days.
It has been a very cold winter, yet, not only have no record lows been set, we have not even come close. February will be ending quite cold but the odds of Fargo Moorhead recording a record low this week does not look likely. Although we are rapidly approaching March, the record lows are still near -30 degrees.
Back on February 20, 2008 the temperature at Hector Int’l dropped to -31 degrees which did set a record for that date and we would likely need a reading that low to break any records with our current cold snap. One factor that will hinder the temperature from breaking any records is our current snow pack. Although deep, it is crusty and hard and not as conducive to strong radiational cooling as fresh more powdery snow. In other words, hard crusty snow will help keep the temperature up this week, meaning, although it will likely be a very cold finish to February, had we recorded some fresh snow cover recently we would be even colder.
One of the most asked questions lately has been how does this winter rank in comparison to past winters. Snow wise, this winter has been quite ordinary, but of course when this question comes up, it is almost always referenced for temperatures. Through Monday, February 10, the average temperature since December 1 was 3.5 degrees. That would rank that period as the 23rd coldest on record.
As a comparison, it would be similar to the average temperature for the same period during the winters of 2008-2009, 1996-1997 and 1995-1996. The biggest difference would be all those winters had significantly more snowfall to this point. Based on the warmer temperatures that have moved into the area and are expected to remain for at least the next week (most days), that ranking will slowly drop. When climatological winter ends on February 28, we may not even finish in the Top 30, yet, no matter the ranking, this is clearly a noticeably colder than average winter.
The lack of snow in the past couple of weeks have made for excellent travel conditions on the main roads, but many city streets and parking lots remain ice covered. That will likely be changing soon and not necessarily for the reason you may think. The one obvious reason that the secondary roads will be improving soon would be the rise in air temperatures, but there is another more subtle reason, the Sun.
As the Sun angle slowly increases, you will notice even on days with an air temperature well below freezing, that melting will take place on area roads on a sunny day. Although the stronger Sun will help with clearing the roads and parking lots from the abundance of ice, it also tends to cause problems. The melting that occurs will freeze nearly every night meaning slick spots each night.
That melt and freeze cycle also creates something that will be very common in the coming weeks, potholes.
When I was a kid growing up in southern Minnesota, temperatures in the -10s impressed me. In December 1983, when I was home for Christmas while attending college, the temperature dropped to -30 on our home thermometer. From that point forward, temperatures in the -10s never impressed me again.
Then in late January and early February in 1996, this region was in the grips of the coldest weather in 60 years. Although Fargo dropped to -39 degrees during that cold snap, in Sioux Falls, where I was living at the time, the temperature dropped to just -33 degrees. Yet, ever since then, the -30s no longer seemed extraordinary.
When I was young, my father would always tell me that it was so much colder when he was a kid and would rarely think the weather was special. Now that I have experienced most of what my father did (except a 1936 type year), I can relate to his weather wisdom, although, I still ponder how he walked up hill to school both ways.
Since records began in 1881, the average number of days with a low temperature below zero during the cold season in Fargo Moorhead is 48 days. With winter only about one-half done, the airport has already recorded 37 such days.
Last year the metro recorded 43 below zero days and during the very mild winter of 2011-2012 the temperature dropped below zero on just 16 days all winter. As a reference, our recently completed December had more below zero days than that entire winter. Looking forward, we could easily record as many below zero days by the end of this month as we did all of last winter with another six weeks of negative potential left after this month. Although patterns can change quickly, it appears this winter may rival the 61 below zero days recorded back during the winter of 2008-2009.
Excluded data from the 1880s, the highest number of negative days in a cold season was set during the winter of 1964-1965 with 76 such days.