{"id":70180,"date":"2026-05-01T22:15:38","date_gmt":"2026-05-01T22:15:38","guid":{"rendered":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/?p=70180"},"modified":"2026-05-01T22:18:48","modified_gmt":"2026-05-01T22:18:48","slug":"lake-influence-on-fair-weather-convection-in-the-upper-midwest","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/70180","title":{"rendered":"Lake Influence on Fair Weather Convection in the Upper Midwest"},"content":{"rendered":"\n

One of the defining characteristics of spring in the upper midwest is a land surface that warms up much more quickly than the many lakes do. There’s a couple of reasons for this: water itself has a higher heat capacity than soil does, sun penetrates into the lakes somewhat which distributes the energy over a greater depth than is possible in land, and currents (especially in the Great Lakes) can mix cold water to the surface. This combines to create a large amount of thermal inertia and thus the lakes are slow to warm in the spring and summer compared to the surrounding land. (The opposite happens in the fall and early winter, and is a primary contributor to lake effect snow). <\/p>\n\n\n\n

It doesn’t take a Great Lake to have an impact on local weather. We can see this happen even with more modestly sized lakes, and an excellent example was seen on 1 May 2026. Here is an animation from the GOES West (GOES-19) Band 2 visible imagery, depciting clouds over northern Minnesota and Wisconsin. Recall, Band 2 is the highest resolution band and is the best tool for identifying the size and extent of individual cumulus clouds during the day. Based on the direction that the clouds are moving, it’s clear that winds are from the north-northwest. However, as the clouds move over the lakes, they vanish. While it’s most apparent south of Lake Superior, many of the less pronounced lakes in Minnesota are also contributing to this downstream clearing. Even the small lakes in the southwest corner of the loop show this imapct.<\/p>\n\n\n\n

\"Animation<\/figure>\n\n\n\n

So what’s going on here? In short, the colder lakes are killing the surface fluxes that contribute to buoyancy and vertical cloud development. We’ve frequently discussed lake breezes<\/a> in various blog posts<\/a> over the years<\/a>, and while those circulations are driven by a similar difference in the land and water temperatures, that’s not quite explaining what’s happening here. If this were a lake breeze, we’d see the clearing happening on all sizes of the lake, not just the sides downstream of the prevailing synoptic flow. <\/p>\n\n\n\n

CIMSS’s Community Satellite Processing Package for Geostationary Data (CSPP Geo)<\/a> applies processing to geostationary satellite observations to create Level 2 products. One of these products is the land surface temperature, derived from the GOES-19 Advanced Baseline Imager (ABI) infrared channels. We can use that to see just how much of a surface temperature difference is present between the lakes and the land. While it’s only possible to measure the surface temperature in clear sky conditions, the areas downwind of the lakes offer plenty of opportunity to make those measurements in a cloud-free environment. This movie shows the CSPP Level 2 land surface temperature product as displayed on the CSPP Geosphere<\/a> site. Note how the lakes are a deeper blue than the surrounding land, indicating that they’re colder.<\/p>\n\n\n\n

\"Animation<\/figure>\n\n\n\n

Earlier we said that this was not a lake breeze case because the reduction in cloudiness doesn’t appear anywhere but the downstream sides of the lakes. However, that doesn’t appear to the case on the western point of Lake Superior as clearing can be seen both north and south of the lake. However, as the blog has discussed before<\/a>, Duluth is an unusual place. There’s over 800 feet of elevation difference between the lake surface and the airport up on the bluffs just five miles away. That results in cold air being trapped in the Superior basin and whatever lake breeze is being created by the temperature difference finds it challenging to deeply penetrate inland to the north due to the sharp elevation difference. Here’s the Band 13 (10 micron) infrared window view focusing on greater Duluth, with surface observations overlaid on top. Note the 6 degree air temperature difference between the lake and Duluth International Airport and the lack of surface winds coming from the lake, which seems to indicate that at best the lake breeze and the larger synoptic flow have battled to a stalemate. That convergence may also explain the band of enhanced convection paralleling Superior’s north shore.The northeasterly flow at Sky Harbor in the lake basin and Superior-Bong airport may also indicate a weak lake breeze funneled up the St. Louis River valley.<\/p>\n\n\n\n

\"Image<\/figure>\n\n\n\n

The meteorological impacts of the lakes on convective growth are small, but they are noticeable. On other days in which the larger-scale atmospheric instability is greater, we may see upscaling and precipitation in other regions but a lack of convection and precipitation in the downstream locations. <\/p>\n","protected":false},"excerpt":{"rendered":"

One of the defining characteristics of spring in the upper midwest is a land surface that warms up much more quickly than the many lakes do. There’s a couple of reasons for this: water itself has a higher heat capacity than soil does, sun penetrates into the lakes somewhat which distributes the energy over a […]<\/p>\n","protected":false},"author":22,"featured_media":70192,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[10,159,151,38],"tags":[],"class_list":["post-70180","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-general-interpretation","category-goes-19","category-l2_readouts","category-what-the-heck-is-this"],"acf":[],"_links":{"self":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/70180","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/users\/22"}],"replies":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/comments?post=70180"}],"version-history":[{"count":6,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/70180\/revisions"}],"predecessor-version":[{"id":70197,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/70180\/revisions\/70197"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media\/70192"}],"wp:attachment":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media?parent=70180"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/categories?post=70180"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/tags?post=70180"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}