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      Historic Warmth: March 2012

      March 18, 2012 500 millibar map...This is as warm a pattern as one can see during the spring.

      After this historic winter, it seems like a long time ago. Yet, it was only two years ago to the day that Upper Michigan was in the midst of a prolonged stretch of summery weather.

      March 2012 began with a snowstorm that struck the north-central U.P. the hardest. Over 20 inches of snow fell at the National Weather Service (NWS) near Negaunee on March 2-3 leaving a snow cover of 47 inches on Monday morning March 4 (Image 1 above). After a cold day and the last below zero morning of the winter the next day, the pattern began to reverse. The warmth set in to stay after the 10th as a huge ridge of upper-level high pressure built over the central and eastern portion of North America (Image 2).

      The heat really ramped up starting on St. Pattyâ??s Day as the ridge reached its peak. Here are high and low temperatures over five historic days in March 2012:

      17: 75 44

      18: 78 54

      19: 78 49

      20: 78 53

      21: 81 52

      During these five days, the mean temperature was 39.4 degrees above average! As cold as itâ??s been this winter and early spring, it has not been anywhere near as cold as it was warm two springs ago. The month ended with a mean temperature of 39.7, far and away the warmest March on record at the NWS. The only other third month that compares with it was March 1878 which had a 40.3 mean temperature in Marquette. By the way, that month followed an incredible February where the mean temperature was 16 degrees above average. The irony of this warm February and March was that it occurred in the midst of an otherwise very cold stretch of years for the Upper Peninsula.

      It is also rather ironic that just two years after that unforgettable March, this month may be heading for the record books on the cold side of the ledger. Cold air will settle back in over this weekend and may stay with us for a while. Image 3 above is the forecast upper air for next Tuesday. It shows a huge, cold upper-air trough centered from the arctic into Upper Michigan. Obviously, it is the exact opposite of the pattern two years ago and will mean much below average, possibly record-cold temperatures.