Minimum Extremes

This month has brought some dramatic temperature changes to the area. One of most interesting to me has been the extreme range in low temperatures observed. Back on January 2 the official low in Fargo Moorhead was -33° which was a record for that date. Then three weeks later, on January 23, the official low was 33° above zero. That was also a record, but this time a record high minimum for that date.

So during this month our low temperatures have varied by 66° which is the 2nd highest such difference in our record books for this month. The greatest difference in minimum temperatures in January occurred in 1892 when the range was 67°. That year the lowest minimum temperature was -37° and the highest minimum was 30°.

The all-time record dates back to March of 1964 which experienced a minimum low temperature of -22° with a high minimum of 50° for a monthly difference of 72°.

The Windiest Place is…

The blizzard on Monday once again reminded us of how windy the Red River Valley can be. The wind gusted to over 50 mph at times (peak was 54 mph at Fargo’s Airport and 55 mph at Moorhead’s airport). But our wind potential pales in comparison to the weather station atop Mount Washington in New Hampshire.

Rising to over 6000 feet the same cold air masses the sweep through our area have a much greater impact on the weather station situated so high above sea level. Wind speeds exceeding 100 mph are common and in April, 1934 a gust measured to 231 mph was observed. This has been listed as the strongest wind speed ever directed measured by instrumentation until this month.

The World Meteorological Organization just announced that after a long review that a new world wind speed record has been verified. Back on April 10, 1996 Tropical Cyclone Olivia produced a gust of 253 mph as it passed near Barrow Island in Australia besting the long held Mount Washington record.

Below and Above

After a very cold start, this month has had a remarkable turnaround in temperatures. The first 10 days of the month ranked as the 10th coldest such period on record with temperature averaging 10-15 degrees below seasonal normals. Then the weather turned mild with the stretch from January 11 to January 21 recording temperatures about 15 degrees above normal. In fact, that stretch in the middle of the month was the 11th warmest such period on record.

So to this point, January is running slightly above average for temperatures. The storm over the weekend is part of another pattern change that is occurring over North America so at the moment it appears the rest of the month will trend to colder temperatures once again. The month of January could therefore finish reasonably close to the long-term average for temperatures with, in typical fashion for our climate, very little average weather occurring during the month.

Christmas Part II?

There has been much talk this week that this weekend’s storm is the same one that hit our area around Christmas. The mixing of warm tropical air with the colder weather in the arctic triggers waves to form in the upper-level wind flow over the Northern Hemisphere. These waves of varying shapes and sizes generally flow slowly from west to east around the globe. Low pressure systems tend to form on the troughs of these waves.

The wave that helped develop the snows around Christmas has been slowly circumnavigating the globe, but the original area of low pressure that triggered our heavy snow event around Christmas dissipated as it moved into northeastern Canada. But the atmospheric wave associated with the storm did trigger additional areas of low pressure of differing intensities as it moved around the globe. Therefore, one storm did not move completely around the world, but the same piece of atmospheric “energy” has reappeared in the United States.

Up, Up and Away

One of the most common questions asked this time of year deals with when the average high and low temperatures start to increase. There is something about the averages starting to rise that brings a sense of relief to many individuals. Starting today, the average high has started the slow climb upwards.

Yesterday the average high was 15° and today it is 16°. Our average low on the other hand will wait until tomorrow for the increase to begin. The average low today is -3° and tomorrow it will increase to -2°. The averages will increase very slowly the next couple of weeks. By the end of the month the averages will be 18° and 0°. In February we will gain a degree about every four days and on February 28 the averages will be 27° and 11°.

The milestone I look forward to is the day our average high finally reaches 32° and that will not occur until March 10.

Snow Depressions

On a recent excursion to a park to more accurately measure our local snow depth, I noticed depressions in the snow cover around every tree. This is a very typical occurrence each winter. As we know, snow is not a good absorber of visible light as a high percentage of the sunlight that strikes snow is reflected back into space. But snow does absorb almost all of the infrared energy that strikes it.

The bark of the trees absorbs the energy from the sun and emits infrared (long wave) radiation which the snow nearby absorbs. During this process this long wave radiation is converted to energy which in turn melts the snow near the tree trunk. This gradually creates the depressions in the snow that surrounds each tree.

As long as we maintain our fairly deep snow pack (currently around 12 inches with more possible this weekend) this affect will become even more noticeable in the coming weeks.

Big Swings

On January 2 the low temperature in Fargo Moorhead dropped to -33°. This week temperatures have been close to 30° which is over 60° warmer than that cold morning two weeks ago. Back in February 1996 we experienced an even greater short-term swing in temperatures. Nearly everyone living in this area then remembers the -39° recorded on February 1, 1996. It was the coldest temperature recorded locally since the 1910s and we almost accomplished something not experienced since the 1880s, a temperature of -40°.

But what many forget is that on February 10, 1996 the high reached 41 degrees. In fact, that was our 5th straight day with temperatures above freezing and a swing of 80 degrees in just 10 days. Great transitions like that are taken in stride in this area, but many locations around the world would not experience such a swing in an entire year, let alone in less than two weeks.


Deadly Blizzard Anniversary

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.

That blizzard was so intense, that surface friction with the strong wind and snow created so much static electricity, that stove pipes/chimneys were electrified in the storm creating sparks and glowing in the atmosphere.  This phenomenon is generally referred to as St. Elmo’s Fire and creates hissing and sparking sounds.  This of course, created fear and anxiety for many settlers that had never experienced such an event.

The record low for January 15 is -36 degrees set after that horrible blizzard ended in 1888.

Record Snow

There is some climate information that has only been available in great detail since the advent of satellites in the 1960s. Sea ice extend would be one example, with good information only available since 1979. Snow cover over the globe would be yet another example with a reliable database only going back to 1966. In those 44 years of records, December 2009 ranked as having the second highest aerial extent of snow cover over the Northern Hemisphere. Last month recorded peak snow coverage of nearly 46 million square kilometers (18 million square miles) with an average of 43 million square kilometers (17 million square miles) for the entire month.

Taken alone, North America set a record average December extent with nearly 16 million square kilometers (6 million square miles) of the continent covered by snow. To give some perspective to the abundance of snow cover, on several occasions, nearly two-thirds of the lower 48 states were snow covered last month.