Bill’s Blog: Forecast for the rest of the summer

GRAND RAPIDS, Mich. (WOOD) — The rest of the summer should continue to be warmer than average. Rainfall is always quite variable in the summer, but overall, average rainfall is expected.

The first week of July was about as warm in Grand Rapids (with an average temperature of 79.4 degrees) as it was in Mobile, Alabama (79.8 degrees). We had the sunniest June ever and the combination of above-average sunshine, warmer-than-average temperatures and light winds has boosted water temperatures to near record level. On Tuesday, the surface water temperature reached 83 degrees at the South Haven buoy and inland Reeds Lake reached 85 degrees.

Rainfall has been below average in most areas since the start of meteorological summer on June 1. Grand Rapids has had 2.86 inches of rain since June 1, which is 1.74 inches below average. Kalamazoo has had 2.22 inches, 2.07 inches below average.

Radar at 1:25 pm June 10, 2020 – Showing strong to severe storms

Despite the below average rainfall, many rivers are still a touch above average flow. As I type this, the flow on the Grand River at Grand Rapids is at 2,930 cubic feet per second, compared to the average flow for July 8 of 2,590 cfs.

Drought monitor – July 2

Despite the dry pattern, there is no significant drought in Michigan due to the cool and wet pattern we had for much of the spring, as the drought monitor map above shows. This map will be updated July 9.

Much of the “Corn Belt” and the growing areas east of the Rockies have ample soil moisture. Many crops in the West (apples in Washington State and vegetables in California) are irrigated.

Graphic from the Grand Rapids National Weather Service.
Graphic from GR NWS – Warm summers follow warm winters.

The graphic above is from the Grand Rapids National Weather Service. When we have a warm winter, we are very likely to have an above-average number of 90-degree days in the following summer. That’s what’s happening this summer. This time, Muskegon and the lakeshore are getting into the act because of the warmer water of Lake Michigan and the light wind pattern keeping the lake-effect cooling west of the Muskegon Airport at times.

Number of 90-degree days in Grand Rapids.

The number of 90-degree days in Grand Rapids varies quite a bit from year-to-year. The average is nine, but we’ve ranged everywhere from none (1951 and 2014) to 37 (1988).

This year we are up to 10, and I think we have a good shot at reaching 20 or more.

Sea surface temperature anomaly map

Above is the latest map showing sea surface temperature anomalies (difference from average). Yellow, orange and red areas are warmer than average and blue areas are colder than average.

Note the warmer than average water in the “hurricane belt” from Africa to Florida. This favors an above-average number of hurricanes this summer and fall in the Atlantic, Caribbean and Gulf of Mexico.

Second, look at the plume of colder-than-average water temperatures along the equator west of South America (and west of Africa). There, the wind has increased, stirring up colder water from below the surface. This is called La Nina.

Here’s what a typical La Nina means for the following winter:

La Nina Winter Pattern for North America

Just this much would lead you to think that next winter will be at least a little cooler and snowier than last winter in Lower Michigan, but it’s too early to make a winter forecast. We usually do that in late October.



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