November is truly the transition month from mild fall weather to winter. Itâ??s illustrated in the average high and low temperatures. On the first, itâ??s 45 and 29. By the end of the month, the average high is only 31 at the National Weather Service (NWS) near Negaunee, while the low is down to 17.
As the month progresses, cold air and snow cover builds in the northern latitudes of North America (Image 1 above). At the same time, warmth lingers in the south where a tropical storm can still form in the warm Caribbean and Gulf of Mexico. This increasing temperature contrast is the breeding ground for storms. Some of the most severe storms on record have developed during the month of November. These expansive cyclones can breed blizzards on their cold side and severe weather in their warm sectors as well as storm-force winds on the Great Lakes. Historically, the most famous storms seem to hit around Veteranâ??s Day.
On average, the northern U.P. highlands establish a permanent winter snow cover at about the end of the third week of the month. In places like Marquette and southern sections, the winter snow cover usually holds off until the tail end of the month or even early December.
One of the latest arriving winters occurred in 1994. That year, the first measurable snow held off until November 21st at the NWS site. The next year, most of the U.P. had a permanent winter snow cover by Thanksgiving.
The average snowfall for November is up to 22.6 inches at the NWS. Thatâ??s because of some hefty snow totals over the last couple of decades. Lately, November snow has been a scarce commodity. In 2010 only 8.2 inches fell. The year before, only 4.6 inches was measured for the entire month and a permanent winter snow cover wasnâ??t laid down until December 9th.
That has been the trend latelyâ??mild, relatively snowless winters. November 2002 was the last really cold 11th month. It came in nearly four degrees below average. Since then, Novembers have been warm with only a couple of exceptions. The warmest relative to average during this time was in 2009 with a monthly mean of 37.2 degrees---7.9 degrees above average. By the way, the warmest November at the NWS was set in 2001 with a balmy mean of 39.9 degrees. Since 2003, the aggregate November mean is running 2.7 degrees above average.Iâ??ve pointed out a number of times over the last few years how a warm November (3 degrees or more above average) strongly correlates to a warmer than average winter. It has certainly held true the last three years. What about November 2012. NOAA does not provide much insight (Image 2). It shows â??Equal Chancesâ?? over much of the eastern U.S. including the Upper Peninsula. From my perspective, there are number of climate factors that are different than last year at this time. Among them are sea surface temperatures and the general circulation that has set up this fall in the Northern Hemisphere. My bet is that we will have near to below average temperatures this month.