The Snow Storm of May 27-29, 1947


On the morning of May 27, 1947, two areas of low pressure were located over the United States while a strong arctic high pressure system was located over the Mackenzie Basin in northwest Canada. This high would provide the cold air needed for a winter storm to develop. The strongest area of low pressure was located over central Nevada, and it was this low which would be responsible for the snow storm over the Central Plains, Upper Mississippi Valley, and Upper Michigan.

On the morning of May 28th, the high pressure center had moved rapidly south to southern Saskatchewan. This area of high pressure brought freezing temperatures to the Northern Plains, with temperatures as cold as 15 degrees at Eckman, ND. The sub freezing temperatures caused a partial to total loss of fruits and tender plants. During the day, this cold air surged southward across eastern Nebraska, Iowa, southern Minnesota, and Wisconsin. Many record cold maximum temperatures were established across the region for the day.

At the same time this was occurring, the area of low pressure was continuing to strengthen as it moved east through southern Kansas. From the evening of the 27th through the 28th, this low produced a 6-12" snow band from southeast Wyoming east across northern Nebraska into northwest Iowa. The heaviest snow in this band was found in Alliance and Harrison, NE where 12" had fallen.

During the late afternoon and evening of May 28th, the surface low began to move northeast across northern Missouri, northwest Illinois, and southeast Wisconsin. The reason for this change in direction was due to a strong upper level disturbance that had dropped into the base of the upper level trough over Nebraska during the day. This upper level disturbance caused an amplification of the upper level ridge over the Ohio Valley and much of New England. On the cold side of the system, over the Upper Mississippi River Valley, temperatures remained in the 30s and 40s. The cold temperatures changed the rain to snow across southern Minnesota, northeast Iowa, and across much of Wisconsin. This was the latest snow ever reported in a season in this area, with some places experiencing their biggest May snow storm on record.

Approximate snowfall totals.
Fig 1. Approximate snowfall totals from May 28-29, 1947.

From the late afternoon of the 28th into the early morning hours of the 29th, 7-10" of snow fell across Allamakee County in northeast Iowa, and Vernon, Crawford, southern Monroe, and Richland Counties in southwest Wisconsin (Fig. 1). The heaviest snowfall amount was 10" in Gays Mills, WI. Meanwhile, a 7-9" band of snow fell across northern Adams, Waushara, Winnebago, Outagamie, and Waupaca Counties in central and east central Wisconsin. The weight of the heavy snow caused severe damage power lines, telephone lines, bushes, and trees.



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