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      May: Let the Warm Season Begin

      May 11, 2006 in Gogebic County.

      Itâ??s May Day and the inexorable push toward the warm season continues. April sees the biggest jump in mean temperature during the month. However, in May snow is relatively rare and the month usually gives us a preview of summer weather at some point.

      The average high on the 1st is 56, the low above freezing at 35. By monthâ??s end, the high is 67 and the low is 45. The hottest temperature on record at the National Weather Service (NWS) near Negaunee is 95 set on May 28, 1969. By the way, on that same day, downtown Marquette hit the 100-degree mark. Both Ironwood and Iron Mountain reached the century mark during the peak of the sizzling, droughty 30s on May 31, 1934. As for cold, on May 9, 1983 the NWS reached 17 degreesâ??the lowest May temperature in over 50 years of record keeping. Ironwoodâ??s all-time record for May is 13 set on the 2nd in 1911.

      Of course, we do not get that cold in May because the nights are getting shorter and shorter. Also, in most years, the snow cover is gone by the time the month begins (Snow effectively refrigerates the air on a clear, calm night). There are a few rare exceptions. We brought up one of them up the other dayâ??May 1996. That year the winter snow cover did not leave the NWS until May 11. In 1972, the last inch of snow melted in Marquette on May 4. The average snowfall for May at the NWS is 1.5 inches. Occasionally, a big snow occurs. Most recently, nearly 8 inches of snow fell at the NWS on May 7-8, 2010. The west end around Ironwood had a significant snowfall during a real stem-winder of a storm on May 11, 2006 (Image 1 above). Of course the big one occurred on May 9-10, 1990. Much of Upper Michigan got accumulating snow out of this one with the NWS collecting a record-shattering 22 inches over 2 days. Youâ??ll notice that all these events occurred in the first half of May. Snowfall is exceptionally rare late in May. One of the latest accumulating snows on record occurred on May 28, 1965 (Image 2). A couple of inches fell in some of the higher elevations in the Copper Country and Ironwood received 3.7 inches.

      Speaking of snow, the far western U.P. is on track to receive heavy, wet snow tonight into Thursday evening. It was already snowing in some spots to the west and southwest and that precipitation will work in during the evening and night. The Gogebic Range could receive 6 to 10 inches of snow, with lighter amounts through the rest of the far west. At the same time, dry, mild weather will continue over far eastern Upper Michigan closer to a big, warm ridge of upper-level high pressure over the eastern U.S.