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      1-2-2013: The Heart of Winter is Upon Us

      A week later, the GFS model forecasts a deep trough centered over the Upper Great Lakes.

      January is here and with its arrival, we move into the heart of winter. The mean temperature across Upper Michigan reaches its low point and, at least on average, January is the snowiest month at most locations. Here are some figures on January from the National Weather Service (NWS) near Negaunee. Keep in mind that records from here have only been kept since 1961.

      Average high and low on Jan. 1: 23 7

      Average high and low on Jan. 31: 21 3

      Record high for the month: 53 on January 26, 1973

      Record low for the month: -32 on January 9, 1977

      Average snowfall: 42.5 inches

      Snowiest January: 1997 with 91.7 inches

      The mean temperature for the month is about 12.5 degrees. Back in the bitter winter of 1911-12, Januaryâ??s mean temperature stayed below zero at some locations. Ironwoodâ??s 5.3 degree below mean stands as the coldest Upper Michigan mean temperature of any month since records began. Arguably, the coldest winter on record may have been the winter of 1874-75. Intense cold set in just after Christmas and held through February, with only a brief moderation in early February as a massive blizzard across the U.P. and Upper Midwest. The last really cold January was four years ago. Back in 2009, the month averaged over five degrees below average with 16 days with low temperatures below zero at the NWS.

      Whatâ??s ahead this January? After a warm December (5.2 degrees above average, January has started cold. However, the cold is not exceptional and already a warm up is in the works. Image 1 above shows the upper-air forecast for the beginning of the weekend. The polar vortex with the coldest air over the continent is forecast to retreat to a position over northern Hudson Bay. For us, a relatively mild Pacific air flow should be in place. The question is, will this warmth hold like it did for most of December?

      Some evidence shows this warm-up may be transient. The GFS model shows a dramatic change developing in about ten days (Image 2). A huge trough is forecast to develop over central North America with ridges on either side off the West and East Coasts. This is a classic set up for intense cold over Upper Michigan. This is still a long way off in the weather world and things may change, but we are overdue for an arctic blast. It may be that we will experience some real cold in the â??Heart of Winterâ?? this year.