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The analog method is one of the tools a meteorologist uses in putting together a forecast.  We now can look at computer forecast models from America, Europe, Canada, Japan—the list is gradually growing with the access of the internet.  Hopefully, these models will at least show a trend in the same direction as they forecast the positions of the main troughs and ridges that bring us our storms, warm spells and cold waves. 

The Climate Prediction Center (CPC), a division of NOAA, has assembled a computer data base of upper-air maps going back to the 1950s.  The 8-day upper-air forecast (the evening of November 27^th) of the Global Forecast Model (the GFS) is then compared to this huge data base and the best fits or “analogs” are then separated out.  The top five analogs from last night’s runs were in order, 11/30/66, 12/9/2010, 11/24/1995, 12/15/1955 and 12/8/1977 (Image 1 above).  I looked back at all these dates and the days following and I found one thing in common—COLD.  Immediately following the first date was one of the great early December arctic outbreaks in 1966.  The high in Marquette on December 1 only reached 7 and the low was 3 below.  The next day, the high was 13 and the low minus 2.  Both days were over 20 degrees below the long-term average. 

More recently in 2010, December 9 had a high of 23 and a low of 3 below at the National Weather Service (NWS), which was 10 degrees below average.  The third-best match was November 24, 1995.  That day the high was 21 and the low zero.  The mean temperature was a bone-chilling 15 degrees below average.  The next two days moderated a bit, but were still below average.  The month as a whole was over 7 degrees below normal.  Finally on December 8, 1977, the high and low in Marquette was 23 and 17 or six degrees below average.  The next two days were 7 and 19 degrees below normal respectively.  In addition, 10.6 inches of snow fell in the city on December 9-10.  The highlands west of town got buried under 30.8 inches during that same time. 

So bottom line, the pattern for the end of the month looks wintry if you believe the GFS.  CPC also compares the upper-air maps to Canadian Global GEM forecast model (Image 2).  Its analog dates and years are similar with the only different one being November 23, 1964.  That particular day was two degrees below average in Marquette.  However, the next two days were two above average and 10 above respectively.  On the other hand, the four days preceding the 23^rd were all over 10 degrees colder than average and the final five days of the month plus the first week of December 1964 were well below normal.