Every year the point is made that there are more accidents with the first couple of snow events because people are not use to driving in the wintry conditions. Do we really forget how to drive in snow or could it be something else?
The first snows of the season usually occur with temperatures near the freezing point creating a wet sloppy snow which tends to make the roads more slippery than they are with the drier snows we get later in the season. Plus, all that moisture on the roads produces quite a bit of spray reducing visibility. In addition, in autumn the ground is still warm, which can keep the roads wet and free of ice, but the bridges, being surrounded by air, cool off much more quickly often catching drivers off guard as they suddenly drive over ice.
So perhaps it is not our skills we lose, but rather early winter storms having more difficult driving conditions.
The satellite image below shows a clear sky over all of North Dakota and western Minnesota, the white streak running through central and part of northeastern North Dakota is snow sitting on the ground. The deepest snow is west and north of Devils Lake.
Thanksgiving, the day set aside each year to give thanks, most years we can add weather to our list of things to be thankful about. Since 1950, it has snowed one inch or more only four times on Thanksgiving Day and on 46 of those 57 years no measurable precipitation fell, including thirteen out of the last fourteen. That one exception was back in 2003 when one-half inch of snow fell in Fargo Moorhead.
The heaviest Thanksgiving Day snow was 7.8 inches that fell back in 1993. That was part of a stretch of seven straight days of snow that added up to over a foot with snow falling over the entire four day weekend that year. Historically, about one-half of all years will have a weather event during the four day weekend that makes travel difficult, but as pointed out, the bad weather is usually not on Thanksgiving Day.
During our warm season, the main weather warnings issued are for severe thunderstorms and tornadoes with an occasional flood statement. In the winter months the situation gets much more confusing. Advisories are issued for snow, sleet, freezing rain, heavy snow, blowing snow, winter weather, plus, winter storm and blizzard warnings and watches are also used.
In the past, several different advisories may have been issued in an area at the same time, often leading to some confusion as to what they all meant. In order to streamline the many winter advisories, the National Weather Service offices around the nation will be issuing primarily winter weather advisories this season and eliminate the use of some advisories. Winter storm warnings and blizzard warnings will still be issued for the more serious situations, but for less severe conditions, a winter weather advisory will be used instead of the numerous other types previously issued.
The earliest weather records in the United States are from individual dairies. Many of our founding fathers, including Thomas Jefferson, Benjamin Franklin and George Washington are some of the sources of these early weather records.
The first attempt at an organized weather network started in 1814 when the Federal Government ordered the United States Army medical corps to collect weather data. When Fort Snelling was established at the confluence of the Minnesota and Mississippi Rivers in 1819 recording the weather became part of the daily routine. That data set gives us some of the earliest weather information for this region.
An attempt at a coordinated national network was not tried until 1870 when the U.S. Army Signal Corps began a program which evolved into the National Weather Service. Temperature and precipitation records started in 1881 in Fargo Moorhead when an observation post in Moorhead was established as part of that original national network.
Last weekend I flew to Springfield, Missouri to help with our broadcast of the Bison football game. On our descent to the airport we flew through a deck of clouds around 6000 feet. That particular cloud layer was composed of supercooled water droplets that froze immediately to the wing surfaces upon contact.
Supercooled water is the name give to water that remains liquid below the freezing point. You probably have noticed insects walking on water because of the strong surface (vapor) tension properties of water. Round cloud droplets have a higher vapor tension than a flat surface and the greater the tension the lower the water droplet can be cooled before it will freeze. These supercooled water droplets are common in low clouds in winter creating a hazard for aircraft.
Our time spent in that cloud was too short to cause problems, but ice buildup on the wings of airplanes causes problems with lift and is the principle cause of crashes during the cold season.
More than any other season of the year, most people are curious what a winter will bring. I get an occasional what does the summer look like question, but every autumn I rarely have a conversation without the winter forecast being mentioned.
My personal take is the upcoming cold season, from December through March is probably going to be colder than average, just like last year. We have a number of factors against us this winter season. A La Nina has formed once again and most La Nina winters are colder than average locally. Other signs include a rapid snow cover build up over the Northern Hemisphere this autumn, changes in both an Arctic and Tropical circulation pattern, the sun being in solar minimum and some other factors as well.
Precipitation-wise, atmospheric signals at this time do not give me enough confidence to give an educated guess on snow totals for this winter, but I would lean toward snowfall of less than 60" (so near average) for the winter if I were to give a guess.
Although temperatures have been seasonally warmer the past couple of months, 2008 as a whole is still running below the long term average in eastern North Dakota and all of Minnesota. These cooler temperatures have been widespread, as about two-thirds of the lower 48 states have recorded below average temperatures so far this year.
The largest anomalies below average have been observed in Iowa, Kansas and gulf coast areas of Alabama and northern Florida. The only areas running above average in 2008 have been in southern California (away from the immediate Pacific coast), southern Arizona and the Atlantic coastal cities running from Washington D.C. up toward Boston. Weather patterns change in yearly and decadal cycles, so having a cold year is just normal weather.
With some recent oceanic and atmospheric changes over the globe, I would not be surprised if we experience more frequent cooler periods in the future than we have observed in recent years.
The wet start to November in combination with all the rain since Labor Day now makes this the wettest autumn on record. The additional one inch of rain this month has also been enough to place 2008 in the top ten wettest years on record.
So far this year 29 inches of rain has fallen in Fargo Moorhead placing 2008 as the ninth wettest since 1881. The wettest year recorded was back in 2000 when 34.75 inches fell, mainly attributed to the over seven inches of rain that fell during one night in June of that year. Including 2008, four of the top ten wettest years have been recorded during our recent wet cycle that started back in 1993.
This area had a similar wet period during the early to mid-1800s, so it is not unprecedented. A drier weather pattern will eventually return it is just a matter of when.