Latest news, weather, high school sports for Michigan’s Upper Peninsula

Winter is on its way.  There’s already been a preview of the season for a good share of Upper Michigan.  Two system snows have occurred.  This is encouraging for snow lovers and also for those concerned about long-term water issues.  Over the last few years, there have been few widespread snowstorms from low-pressure areas coming in out of the west or southwest.  That means little precipitation and resulting snow cover over southern areas.  Even in the north, snow totals have fallen short of average the last two years in most locations. 

This year is the second year of the La Nina—the cold phase of the equatorial Pacific waters off the Coast of South America.  This cycle of cold and warm in that region is called ENSO.  Image 1 above shows the sea surface temperatures (SSTs) relative to average at this time last year.  Compare this to SSTs this year (Image 2).  Note that this year; there is nowhere near the depth or breadth of cold water in the equatorial Pacific as there was last year.  This means the La Nina is weaker.  A strong ENSO event tends to lock in a weather pattern over the Northern Hemisphere.  We saw that to some extent last year in that the storm track stayed predominantly down to the south of us.  This storm track was likely also influenced by a good deal of blocking in northeastern Canada and the North Atlantic. 

Speaking of the North Atlantic, notice that the waters there are not as warm compared to average as they were last year.  This will probably mean less tendency for blocking high pressure systems to develop in this region.  Less blocking could mean a more northern storm track—another plus for snow lovers in the U.P. 

As for temperatures, bitter cold air masses have formed early and persisted over Alaska and the Yukon.  That means an abundant supply of frigid air ready for transport southeastward into the U.P.  However, the colder-than-average water over the Gulf of Alaska means a tendency for big storms to form there.  Low pressure in that region is generally a warm signal for us in that it gives us a mild westerly flow aloft.  We’re seeing an extreme example of that this Thanksgiving. 

Another factor to consider is the sun.  The last couple of years, the sun was in a deep, extended minimum of activity.  Studies have shown that low solar activity seems to correlate to high-amplitude “blocky” patterns over the Northern Hemisphere as well as a tendency for these blocking features to stay in one place for long periods of time.  This occurred with the summer heat wave in Russia two years ago as well as the extreme blocking that produced the record snowy winter in the Mid-Atlantic States in 2009-10.  The sun is more active now, heading toward a solar maximum in the next couple of years.  An active sun seems to correlate to a more active “zonal” jet stream.  This fast jet stream points to more variable weather conditions. 

Since the turn of the 20^th century, there have been six second-year La Ninas following strong first-year events.  They are the winters of 1917-18, 1955-56, 1974-75, 1989-90 1999-2000 and most recently 2008-09.  The first one was a very cold winter for the U.P.  On the other hand, the winters of 74-75, 89-90 and 99-00 were quite mild.  A composite of the winters (Image 3), shows no tendency for either warm or cold winters.  However, the overall mild spell we've been in over the last few years tilts things to the mild side of average in my book.  At the same time looking at the analogs, this winter could see some very cold periods.  For instance, December 1989 was very cold.  Then things flipped around after the New Year and the rest of the winter was warmer than average.  We’ll probably see a lot of variability.  In January 1975, a huge storm developed in the Plains and moved to the west of Upper Michigan.  That’s very unusual during the heart of the winter season.  We would up in the warm sector with record highs in the 40s.  To the west, parts of Minnesota had their “Storm of the Century” with heavy snow and bitter cold.  It then turned very cold here, but only for a brief period. 

Another factor to consider is something I brought up last year.  Warm Novembers correlate very strongly to milder than average winters in Upper Michigan.  Novembers that were 3 degrees or more above average produced milder than average winters 83 percent of the time.  Those are pretty good odds.  Up to yesterday, we were only 1.6 degrees above average for the month.  It will be interesting to see what happens through the end of the month.  Temperatures will be way above average through at least Friday and it looks at least somewhat above through the end of the month.  So this may figure in the mix, too.