For some of us it may feel like it’s been really dry in the past month. Here’s a look at how the Great Lakes water levels are reacting to recent weather. You might be surprised.
First off, let’s look at if it really has been dry over the Great Lakes drainage basin in the past month.
Total rainfall from June 28 to July 28, 2020
The total rainfall over the Great Lakes drainage basin hasn’t actually been overall dry. The southern half of Lower Michigan has been drier than average, but northern Lower and especially the U.P. have been hammered with heavy rain.
Another good way to look at abnormal amounts of rain is to look at the rain deviation from normal.
Rainfall deviation from average rainfall from June 28 to July 28, 2020
Lake Michigan and Lake Huron have a drainage basin that covers most of Lower Michigan, small parts of Wisconsin, Illinois and Indiana, and part of Ontario. The rainfall pattern looks split over the Lake Michigan and Lake Huron drainage basin. Some of the drainage basin has had three to five inches more rain than normal. The other part of the drainage basin has had one to three inches less rain than average.
So what have the Great Lakes water levels done over the past month? Remember this is a time of year when the Great Lakes typically reach their highest level of the season, and start to decline.
Great Lakes daily water levels for July 2020
These are daily numbers, but the official water levels are taken from monthly averages. So we will have to scan down the table and see a trend.
Lake Superior looks like it actually has been rising steadily over the past month. The numbers you see are arbitrary numbers pegged to a benchmark level from the 1980s. So the level listed as 602.78 on July 1 is just a number to compare later numbers with. But it’s easy to see the last two weeks of July has Lake Superior water levels generally over 603. That’s why I say Lake Superior is rising this July.
Lake Michigan and Lake Huron are the lakes with the most concern on water levels right now. A scan of the lake level numbers for July shows no real trend through the month. We certainly can’t see a downward trend. There may be a very slight increase in the past week. But I think it’s safe to say there hasn’t been a big movement up or down on Lakes Michigan and Huron this July.
Lake Erie appears to be going down slightly, and Lake Ontario has a definite trend downward.
Lake Superior typically goes down in July, so the rise is an abnormality. Lakes Michigan and Huron usually start to fall in summer, but it could be July or August.
MORE READING:
Lake Michigan and Huron water levels peaking short of 1986 record
Moderate drought takes over 10 Michigan counties, numerous others ‘abnormally dry’
Michigan rivers spewing record water amounts into Great Lakes
The Link LonkJuly 29, 2020 at 03:00AM
https://www.mlive.com/weather/2020/07/has-recent-dry-weather-affected-great-lakes-water-levels.html
Has recent dry weather affected Great Lakes water levels? - MLive.com
https://news.google.com/search?q=dry&hl=en-US&gl=US&ceid=US:en
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