It wasn't quite like the Halloween blizzard of '91, but Tuesday night's snowstorm with biting winds roared in on the heels of Minnesota's lowest barometric pressure ever recorded.
Alex Lamers, assistant forecaster at the National Weather Service in Duluth, said that the previous low pressure record was broken in Aitkin, Minn. just after 10 a.m. on Tuesday and continued to drop. The final number and new record, measured in Bigfork, Minn., was 955.2 millibars or 28.21 inches of mercury.
"Once we initially broke the record ... every time the pressure dropped, just a little bit, we were continually setting the new record for most of the afternoon [Tuesday] until the low reached its maximum intensity at the north central Minnesota area near Bigfork just southeast of International Falls," Dan Miller, science and operations officer at the National Weather Service in Duluth, said.
The previous record had been set in Albert Lea and Austin in 1998.
Miller said that records had been based on what had been measured for about the past 120 years, and that they didn't apply to time periods before then.
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Geoffrey Grochocinski, meteorologist at the National Weather Service in Grand Forks, said, "This storm was equivalent in nature, as far as low in millibars, to a Category 3 hurricane."
"In terms of what northern Minnesotans are used to with the biggest of snowstorms, 4 to 8 inches of snow is not necessarily a big deal per se. But the thing that's really made this storm noteworthy is the strength of the low pressure and then the combination of the really strong winds with the heavy wet snow," Miller said.
Grochocinski said that low pressure systems impact a wide geographic area.
"Because it was so large and powerful it's been causing very nasty winds across much of the Plains, upper Midwest, and moving on to the Ohio Valley," he said.
"The amount of snow and precipitation isn't necessarily tied to the actual strength of the low pressure system," Miller said. "The one thing you are guaranteed when you get a really intense low pressure system like this is the strong winds."
Talk of unusually low pressure had accompanied another historic storm to hit Wadena several months ago. That was June 17.
"An area of low pressure is just simply the reflection at ground level of a strong atmospheric disturbance that's moving across a particular region," Miller said. "Typically low pressure systems are associated ... with significant weather that generally has high impact. During the fall and winter seasons often times that's strong winds and a big snowstorm that's followed by bitterly cold Arctic air. In June, if you get a system like that, typically you get severe thunderstorms and tornadoes."
Miller said that this winter would be in a La Nina pattern, which means that, once averaged out, it is somewhat colder and wetter than an El Nino pattern winter.
