A typical summer pattern brings periods where you??ll see a chance of scattered showers in the forecast nearly every day. That??s because summer is characterized by ??convective?? precipitation. That means localized showers and thunderstorms pop up due to warm, humid air currents rising into the atmosphere until they cool sufficiently to form clouds and rain.
Often, the rain that falls is spotty in coverage under these conditions. Take for instance the evening of June 21, 1988. A small complex of thunderstorms fired over south-central Upper Michigan and moved eastward toward Lake Michigan. Bark River was directly in the path of heaviest rain, receiving a 2.77-inch dousing in a relatively short period of time. These were classic ??hit or miss?? thunderstorms. The vast majority of the U.P. stayed dry. Rainfall was at a premium over the U.P. and Great Lakes during May through July 1988. It was a hot and dry summer over the north-central U.S. (Image 1 above)
The rain that fell in Delta County of June 21 created a little island of green. Later in the summer pilots reported a V-shaped cone of green extending through Delta County from Bark River eastward toward the lake. The rest of the area was brown due to the drought. Finally in August, the pattern flipped. The National Weather Service near Negaunee measured 8.59 inches of rain, a record for the month of August.
A typical summery pattern has developed over the Upper Great Lakes region. This means the inclusion of scattered shower chances in the forecast nearly every day into next week. There have been more than just ??scattered?? showers the last two days as a front set up close by. A major disturbance rolled along it this morning and brought moderate to heavy rain over a good share of Upper Michigan. The front will be suppressed southward for a time. However, it appears that it will surge northward Saturday night. That??s when another batch of showers and thunderstorms may develop along the frontal boundary. On Sunday, we should be solidly in the warm sector as the front lifts north of Upper Michigan. That means a very warm and humid day??with a chance of ??hit or miss?? showers and thunderstorms.