You don’t expect to see 75 or even 80-degree water in the Great Lakes in July or, in most years, anytime. But an exceptionally hot weather pattern pushed water temperatures in most of the lakes to the highest levels on records in the summer. Lakes Erie and Ontario, the water is the warmest it has been since the records began.
Surface water temperatures averaged over all of the Great Lakes, except the deep and choppy Lake Superior had risen well into the 70s to 80 degrees. That’s about the same water temperature as the surf off Virginia Beach, Va. Now due to upwelling, the surface temps have crashed.
The configuration of the wind over the course of the next day or so (Monday into Tuesday) will result in a plunge in water temperatures at the shore. Water temperatures have already cooled to the 50s and 60s as of Monday morning in many places. 50s water temperatures will become more common into Tuesday with 40s possible as well. The 70s water temperatures have pushed offshore towards mid-lake. It may take until this upcoming weekend to see an appreciable warm-up in water temps. Cold water shock can lead to drowning, so be aware of the situation if you are jumping into deeper water.
Winds blowing across the waters surface push water away. Water then rises up from beneath the surface to replace the water that was pushed away. This process is known as “upwelling.”
Upwelling occurs in the open waters and along coastlines. The reverse process, called “downwelling,” also occurs when wind causes surface water to build up along a coastline and the surface water eventually sinks toward the bottom.
Water that rises to the surface as a result of upwelling is typically colder and is rich in nutrients. These nutrients “fertilize” surface waters, meaning that these surface waters often have high biological productivity. Therefore, good fishing grounds typically are found where upwelling is common.
West Michigan saw quite a bit of rainfall over the weekend. Here is what fell over the last 3 days.
-- Showers remain possible through today -- A few light showers are persisting over the heart of the area early this morning. These showers are likely the result of the combination of the large scale forcing overhead ahead of the incoming upper trough, and the low level NE flow bringing some lake instability inland from Lake Huron. This upper low/trough is expected to progress through the region through today, and be exiting the eastern portion of the area toward 00z this evening. The low and associated cold pool aloft will lead to some light showers developing with the heating of the day. Thunder chances look almost zero with the sufficient instability expected to stay just east of the area. The showers should dissipate toward 00z as the low moves out, and we lose the diurnal heating/instability. -- Quiet and mild weather Wednesday through Saturday -- Wednesday looks like it should be quiet across the area. The area will be under the influence of ridging in between the departing low to our east, and the next short wave dropping SE over the region. This short wave will arrive on Thursday. However, it will be coming in just after a dry period with high pressure having been in control. Moisture will be quite limited with no influx of moisture expected. Sprinkles look to be about the extent of any possible precipitation. The trough on Thursday will move out, and upper ridging will take control of the weather for Friday and Saturday. Temperatures will gradually warm a little each day as return flow on the backside of the sfc ridge will gradually bring in a little warmer temperatures. -- Warmer with chances for showers/storms Sunday-Monday -- Rain chances will then slowly increase on Sunday, and probably peaking early Monday. Heights will build a little more toward the area, and a warm front will be trying to nose overhead. This will bring the instability axis closer, along with the forcing from the warm front. Temperatures will also increase a bit more as the area of warmth from the Plains moves in.