One of the wettest periods on record in Upper Michigan culminated in a snowstorm over many sections on May 6-7, 1960. Old timers in Negaunee and Ishpeming were unable to remember worse weather the first week of May. May Day was preceded by a sloppy four to eight inches of snow over central sections on April 30. After a brief dry spell, new low pressure formed from the Rockies into the High Plains on May 3, while a frontal boundary set up from the low into the Upper Great Lakes, paralleling the developing southwest flow aloft (Image 1 above). Waves of low pressure rippled along the stalled boundary, drawing abundant moisture northward, producing more unwanted rain over the waterlogged U.P. May 4-5.
Finally, the main storm lifted northeastward out of the Texas Panhandle, drawing in cold air from an extensive pool of chill trapped over central Canada by persistent high-latitude blocking to the north. The low lifted slowly northeastward to Wisconsin then the Lower Peninsula while deepening, providing a perfect set-up for heavy snow over Upper Michigan on May 6-7 (Images 2 & 3).
Snow amounts from this storm were worthy of a mid-winter snowfall. Marquette only tallied 8.8 inches because a good share of the precipitation mixed with rain. The higher elevations west of town had mostly snow. Ishpeming reported 14 inches with three-to-four-foot drifts. The high temperature there on Saturday, May 6 only made 32 degrees and on Sunday 33. The Marquette County Airport in Negaunee Township was buried under nearly two feet of wet, heavy snow. â??Extremely dangerousâ?? driving was reported down south in Dickinson County and up north the May chill allowed Houghton to retain a 3 inch snow cover on May 9, two days after the unseasonable storm.
It took 30 years before another storm of this magnitude hit the U.P. so late in the season. The big storm of May 9-10, 1990 followed unseasonably warm weather during late April and early May. Again, the Marquette County Airport site picked up nearly two feet of wet, heavy snow.
We have a developing storm, but it wonâ??t be a big one and it wonâ??t snow. However, it does look like a spring-like pattern is on the way. First, as the warm front from the low approaches it will be cloudy and raw with a chance of scattered showers; warm fronts struggle to pass through Upper Michigan at this time of year. Then as the front gets closer and the low-pressure, storm system passes west of the U.P. warmer air will be drawn up across the Peninsula. Highs by late in the week into the weekend will reach or exceed 60 degrees over most areas.