An historic fall storm system affecting the central U.S. on October 25 and 26 has established new record low October barometric pressure levels at Peoria and Springfield.
In fact, this system produced many monthly and all time record low pressure readings for individual sites and state records in the north-central U.S. In Minnesota, the lowest pressure observed was 28.21 inches of mercury (955.2 mb). It was one of the deepest low pressure systems ever observed in the continental U.S., outside of a hurricane. The NWS offices in Minnesota worked with the National Climatic Data Center to determine the status of any national records. Their results can be found at this link on the NWS Duluth web page.
The image below, from 1 PM Oct. 26, courtesy of the Hydrometeorological Prediction Center shows the infrared satellite image (background) overlaid with isobars, or lines of equal pressure, surrounding the center of the low in Minnesota. Winds blow with more velocity the tighter the isobars are packed, as nature tries to equalize the difference between regions of high and low pressure. This map shows the scope of the system and amount of wind energy affecting the central United States and Canada.