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An area of low pressure moved out of the Southern Plains and rapidly deepened into Minnesota during the early morning hours of October 26th.  As it moved north, shower and thunderstorm activity provided rainfall amounts of one-half to just over one inch in some locations.  More importantly though,the central pressure of the low continued to fall causing an increase in winds as the day progressed.  By late in the morning of October 26th, sustained wind speeds of 25 to 35 mph, with gusts of 40 to 50 mph, were reported over parts of western Minnesota.  By early afternoon, wind gusts of 50 to 55 mph were common across southeast Minnesota, northeast Iowa, and into western Wisconsin causing sporadic wind damage to roofs and trees. The winds continued  during the evening and overnight hours, with reported gusts near 60 mph around 2 a.m. at many locations (including 61 mph at Spring Valley, MN).

The low pressure system's central pressure slowly began to increase (or weaken) early in the morning on the 27th as it started to move into southern Canada. However the pressure gradient, or the difference between the central low pressure and the pressure surrounding the storm, did not weaken much. Therefore, the winds did not weaken and some locations experienced their strongest wind gusts from this wind event during the early morning hours. The stronger pressure gradient is indicated by the tight "packing" of the isobars (lines of constant pressure) seen in the loops below. By the evening of the 27th, winds diminished with gusts falling below 45 mph, due to the system continuing to weaken and moving farther away from the region.

While this storm set records for the lowest pressure ever recorded in Minnesota (Bigfork, MN - 955.2 mb / 28.21" - 5:13 p.m. October 26, 2010) and Wisconsin (Superior, WI - 961.3 mb / 28.39" - 11:15 a.m. October 26, 2010), it did not have the higher end winds seen in the November 10 1998 storm. The 1998 storm, which held the previous records for lowest pressure, produced sporadic 60-80 mph winds. One of the contributing factors for the higher wind gusts in 1998 was the greater difference in the pressure from outside the storm to the center - or a stronger pressure gradient. This pressure difference is the force that accelerates the air into the low pressure center. As an example, the 1998 storm had a pressure difference from Kansas City, Missouri (outside the storm) to Duluth, Minnesota (center of the storm) of around 40 millibars. For this storm, that measured difference from Kansas City to Duluth was around 30 millibars (about 25% less).

A High Wind Watch was issued by the National Weather Service in La Crosse on Sunday afternoon, October 24th.  The following day, the watch was replaced with High Wind Warnings (issued at 3:27 p.m. CDT October 25th) that covered Tuesday and Wednesday.  A webinar was also held with Emergency Management partners to assist with planning.

Other links about this storm include:

Track of the low pressure area that produced record low pressure levels and extreme winds.
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