This Demon Low is still intensifying, so don’t consider this the final word on it. Late this morning, Superior set a new Wisconsin state record for low pressure at 28.38″ of mercury (adjusted for sea level), breaking the old record of 28.45″ set in Green Bay on April 3, 1982.
Meanwhile, as of 3:13 pm, Orr, Minnesota had a low pressure of 28.22″ of mercury, shattering the previous non-tropical US record of 28.28″ measured just west of Cleveland on January 26, 1978. That is just 0.01″ above the North American non-tropical land record set in Sarnia, Ontario, and a bit above the Great Lakes record of 28.05″ on a buoy in Lake Huron, both measured during that same 1978 blizzard.
For a couple of points of reference, the minimum pressure of the storm that sank the Edmund Fitzgerald bottomed out at 28.95″, and a typical Category 3 hurricane is expected to have minimum pressures between 27.91″ and 28.47″.
Revisions/extensions (5:34 pm 10/26/2010) - Bigfork dropped to 28.21″ of pressure.
R&E part 2 (10:17 pm 10/26/2010) - And it’s a new land record at Bigfork – 28.20″ of pressure recorded at 5:13 pm.