Having grown up on the east coast, I have experienced a variety of Nor'easters, which are intense storms that literally blow up off the eastern seaboard, producing rather strong winds, heavy rain/snow and beach erosion. Typically for one of these storms to "bomb out", it needs to have the jet stream aligned in a deep trough, an accompanying wave of low pressure at the surface and a clash of warm & cold air. We pretty much had these ingredients come together in the Upper Midwest on Tuesday as the jet stream dipped across the western Great Lakes, with low pressure driving northbound out of the southern Plains and combining with a second wave of low pressure along the US/Canadian border in the Northern Rockies.
First the significance of the intensity of this storm. It set the record for the 2nd lowest barometric pressure ever recorded in Wausau at 28.64" (969.9 mb), the lowest pressure ever in Wisconsin, measured at Superior of 28.39" (961.3 mb) and the 2nd lowest pressure ever recorded by a land based low pressure in the lower 48 states of the U.S. of 28.21" (955.2 mb). This is stronger than the storm that sank the Edmund Fitzgerald in November 1975 (28.95"/980.4 mb), the March 1993 Superstorm (aka "Storm of the Century"), the Blizzard of 1978 and on par with the pressure of a Category 3 hurricane. Based on research through the National Climatic Data Center, the lowest pressure ever observed in the U.S. was with the Labor Day Hurricane on September 2, 1935 at 26.34" (892 mb) in Matecumbe Key, FL. The lowest non-tropical storm pressure was 28.20" (955.0 mb) on January 3, 1913 in Canton, NY and March 7, 1932 at Block Island, RI. Also of note with this storm, the pressure dropped about 1.3 mb/hr going from 966 mb at 9am on 10/26 down to 957 mb at 3pm. Perhaps not as rapid in deepening as a Nor'easter, but still very impressive. By the same token, late October and November tend to be the time of the year for intense storms to traverse through the Great Lakes, thus the term "November Gales". This relates back well to the storm that sank the Edmund Fitzgerald on November 10-11, 1975 and the wind storm of November 10, 1998. You can learn more about this storm by checking out the info from the NWS La Crosse. Here are a few snapshots of the historic maps of this storm from October 26, 2010.
Surface Map at 2:29pm on Tuesday, October 26th
Here's a close up look at the center of low pressure in NE Minnesota
Here's the 300 mb (Jet Stream Chart) of the U.S. on 10/26/10
The different atmospheric conditions came together, but what will be most memorable outside of the deep area of low pressure? Let's start with the winds. One of the basic aspects of figuring out how strong the winds are is how close the isobars (lines of equal pressure) are to each other. Check out the surface map above. Very tightly packed lines into the western Great Lakes, which is what you may see on a map in relation to moderate hurricane churning through the Atlantic or Gulf of Mexico. Wind gusts over 60 mph were recorded in Wausau and Rhinelander, and over 70 mph in Sherwood (Calumet Co.). This lead to many reports of downed trees and power outages in the state. There was also an EF1 confirmed tornado that ripped through Racine with the cold front as it passed through SE Wisconsin around 8am on October 26th. On a more national scale, this storm system produced approximately 56 tornado sightings from the Plains into the Tennessee River Valley, and over 300 wind damage reports. Next is the precipitation. Nearly an inch of rain fell in Wausau as this storm was approaching, with many other spots locally picking up anywhere from .50 to 1.25". On the back end of this storm, snow piled up with 5-10" in the arrowhead of Minnesota, which at times lead to white out conditions with the brisk winds blowing it around.
How is it possible then that the lowest pressure ever recorded in Wausau wasn't eclipsed? Well for one, the center of the low wasn't right over us, but instead in northern Minnesota. Meantime, the storm on April 3, 1982 (which still stands in Wausau at 28.57") was the previous mark of the lowest Wisconsin pressure measured in Green Bay at 28.45". That storm was also remembered for causing strong winds, heavy rainfall and some snow. Locally in Central Wisconsin, 1-4" of snow fell as temperatures dived in Wausau from the mid 40s in the morning to the upper single digits by 8pm. Rain switched over to snow and even though only an inch of snow fell in Wausau, white out conditions (with visibilities under 1/4 mile) we observed for 6 hours straight thanks to 20-30 mph winds and gusts up to 46 mph. This storm also caused the Brewers home opener in Milwaukee to be postponed, due to 9" of snow and intense winds.
We have had some historic weather over the past 5 years. The most tornadoes in a year in Wisconsin (2005), the second largest hail stone to fall in Wisconsin (Port Edwards, 2007), the highest amount of snow in Wausau for December (2008), and one of the wettest summers this past season. What else is on tap for the months and years ahead? Stay tuned to find out.
In the meantime, the strong winds mean lots of energy being produced by the Wausau East High School Wind Turbine. Check it out the data in real-time.
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