Oymyakon, Siberia managed to hit -76 degrees Fahrenheit twice in December, a temperature that had been reached only one other time in the last 25 years. The generation of such extreme cold air originates with the lack of sunlight far northern latitudes receive this time of year, which means they radiate heat to space without any solar energy offsetting that infrared cooling.
Water vapor content in the air also plays a role in the creation of extremely cold air. Contrary to what many people think, cold air does not become dry because it is cold, but instead air becomes cold because it is dry. The reason air can get so dry is because it has been slowly sinking from high in the atmosphere, where very little water vapor is present.
The constant shifting of air masses in the northern hemisphere usually keeps any one region from experiencing the extreme cold for more than a week or two.
Researchers working in the Soudan Mine near Tower, Minnesota, have discovered a strong correlation between cosmic rays and temperatures in the stratosphere. This research showed that sudden increases in cosmic radiation during the winter corresponded to rapid changes in stratospheric temperatures.
It has been known for years that Sudden Stratospheric Warming (SSW) occurs, but it was always based on balloon or satellite data. SSW events tend to generate strong surface high pressure systems near the North Pole which gradually move into the mid-latitudes leading to strong arctic outbreaks in our area. If cosmic rays could be used to see a SSW coming in advance, it would give more lead time to the possibility of a severe cold snap moving into the United States.
A SSW has just occurred in the past week, which may lead to bitterly cold weather, similar to what we had two weeks ago moving into our area around the middle of February.
Although December was well below average locally, it was no where near the top ten coldest on record in Fargo Moorhead. But if you include all the reporting sites for both Minnesota and North Dakota both states as a whole did record one of the ten coldest Decembers on record.
The National Climatic Data Center just released their official data for December with Minnesota recording its seventh coldest and North Dakota its eighth coldest December in the 114 years that such statistics have been taken. Both Wisconsin and Iowa recorded their eleventh coldest. Although cold stories have dominated the news in recent weeks, some parts of the country have been warm.
Georgia for example had their seventh warmest December on record and South Carolina had their fifth warmest. Although it has recently been quite cold in the southeastern United States, that part of the country will likely experience above average temperatures this winter.
On January 12, 1888, after days of brutally cold weather, temperatures moderated enough to allow the kids to go to school again and for others to go into town for supplies. But by the end of the day the region was struck by a fierce blast of arctic air behind an Alberta Clipper that brought wind to 70 mph, three to six inches of snow and zero visibility.
It struck at the worst possible time when kids were in school or heading home. Teachers stuck between sending the kids home or keeping them in school without enough heat for the night, often choose to send them home. By the next morning, over 200 people died in the blizzard, most of them school children. This storm is often referred to as “The Children’s Blizzard” because of the high death toll among school kids. The record low for January 15 is -36 degrees set after that horrible blizzard in 1888.
Fargo Moorhead like all cities has an urban heat island. The buildings, pavement and industrial output all alter the landscape which will induce warmer temperatures in the city than that of the surrounding countryside. The effect is most noticeable at night and during the winter in most urban areas.
The heat island of Fargo Moorhead tends to be the most noticeable in the winter when we have a light southerly wind. Because Fargo Moorhead is a long narrow community built along the Red River, a light south wind will have to pass across several miles of the city before reaching the airport. Winter nights with a light south wind may induce the temperature at Hector International to be anywhere from three to six degrees warmer than the temperature at the Moorhead Municipal Airport which has no urban heat influence to its south.
When forecasting, I usually take this effect into account when forecasting our overnight low temperature this time of year.
Fargo Moorhead’s average temperature in 2008 was 3.2 degrees colder than what was recorded in 2007. This was not only a local phenomenon as this cooling trend was observed nationally as well. Preliminary data from the National Climatic Data Center, the repository of all climate records, indicated that nationally the average temperature dropped 1.34 degrees from 2007 to 2008.
This significant drop in temperatures ended a streak of several years when national temperatures were above average. The United States as a whole has, in recent years, been experiencing average temperatures last seen during the 1930s. The temperature decline in 2008 brought the average temperatures nationally back to the long-term normal temperature observed during the 20th century.
If this trend toward more average temperatures nationally continues is unknown. Considering some of the long-term climatic shifts that have occurred in recent years, my hunch is more 2008 type years will become increasingly common in the years ahead.
Several phone calls and emails have come into the weather center asking why the sunset times have increased by nearly twenty minutes, yet the sunrise times have been static since the Winter Solstice. Because the earth orbits the sun in an ellipse, not a circle, the earth’s orbital speed differs throughout the year. These different speeds make most days longer or shorter than 24 hours.
To eliminate confusion, our clocks run at a steady speed ignoring these daily time differences. This causes the Sun to lose time in reference to our clocks this time of year when the Earth is closer to the Sun. The effect of this is that the Sun rises and sets later and later this time of year when referenced to our clocks. So our sunsets get later this time of year, but it is our clocks being out of sync with the Sun that keeps the sunrises static until next week.
December 2008 will always be remembered for the record breaking snowfall. Last month was not only the snowiest December on record, but the snowiest month recorded as well. Somewhat forgotten with all the snowfall, was how bitterly cold much of the month was. December finished with an average temperature of just 5.9 degrees, 6.6 degrees below the monthly average of 12.5 degrees.
Twenty-three of the thirty-one days in December had temperatures below average. Twenty days last month saw temperatures below zero with the coldest being the -24 degree reading recorded on the last day of the month. Of those twenty days with below zero temperatures, four of those days saw both the low and high temperatures remain in negative territory. With an average temperature of only 5.9 degrees, December was also the coldest month in 2008 besting January, 2008 by 0.6 degrees for that honor.
2008 finished below average for temperatures, but well above average for rainfall. Last year the combination of melted snow and rain added up to 30.82 inches. That made 2008 the seventh wettest on record and only the ninth time in 128 years of record keeping that Fargo Moorhead received more than thirty inches of rain.
2008 started dry with January being the fourth driest on record. February and March continued this trend with only average rainfall. April and May traded places with April being a bit wet and May being a bit dry. So we entered summer with very average precipitation with some areas even experiencing drought conditions. But the second half of 2008 brought 24.80 inches of rain, more than the yearly average 21.19 inches, and 10.22 inches above normal for that time period.
The autumn of 2008 was the wettest on record and that induced a rare autumn flood on the Red River.