A surface high pressure system and associated upper level ridge have been in firm control over Iowa's weather these past few days with hardly a cloud in the sky. Unfortunately, very hot and dry air have lead to numerous wildfires over northern Minnesota and into Canada. This "heat dome" system, as it is sometimes colloquially called, has been impressively strong. During the warm season, one measure of its strength can be found by the maximum height of the 500 hPa pressure surface. Due to the ideal gas law, a very warm lower atmosphere will vertically "push" the height of a pressure surface further away from the ground. Meteorologists like to consider a height of 6 kilometers has an impressive height for the 500 hPa pressure to be found. And that finally brings us to the subject of today's featured chart. The chart presents the 2026 observed heights and period of record ranges of the 500 hPa surface as recorded from the Minneapolis sounding. The monthly max and min values are labelled. The sounding from Monday evening (00 UTC 14 July) came in at 6,010 meters, which according to unofficial IEM archives is the highest height on record for the site. Typically, these very strong "heat domes" happen further south and particularly southwest with 6km heights happening a few times per year.

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