The October 26-27 2010 Significant Extratropical Cyclone

Welcome to the NWS Duluth web page on the North American Extratropical Cyclone of October 26-27, 2010.

If you have pictures of the impacts of this storm (rain, flooding, snow, wind, waves, etc.) and would not mind them being included on our web story about the storm, please email them to w-dlh.webmaster@noaa.gov. Make sure to indicate that we have permission to use the photographs.

An extratropical cyclone of rare intensity impacted parts of Northeast Minnesota and Northwest Wisconsin on October 26-27, 2010. While the storm traveled directly across the Northland, it impacted the weather conditions across a large portion of North America. In the left hand image below, you can see that the low, while centered in northern Minnesota, was powerful and large enough to affect the wind field from Hudson Bay south to the Gulf Coast, and from the Rocky Mountains east to the Atlantic Coast. Wind barbs are in light blue, and sea level pressure contours are in black.

The image above and to the right is a satellite image from NOAA-NASA GOES Project at 4:32 PM CDT on October 26. The MODIS true-color images from NASA's "Blue Marble" global map are used as a background, projected as though viewed from the GOES satellite location. Semi-transparent layers of GOES infrared and visible images are enhanced and layered on top of that color background.

The cyclone reached its peak intensity (as discerned by pressure readings) over the NWS Duluth county warning area. The automated weather observing system at Bigfork, Minnesota (KFOZ) reached a 955.2 millibar (28.21 inches of mercury) sea level pressure at 5:13 pm CDT on October 26, 2010. This established a new low pressure record for the state of Minnesota.

In the Northland area, this storm had a wide variety of impacts. A lot of precipitation fell across the region, and in our area the highest total through the morning of October 27th was 5.50" of liquid precipitation 7 miles northwest of Two Harbors, MN (Lake County). Some of that precipitation changed over to snow on the evening of October 26th, and a band of generally 2 to 6 inches of snow developed from Fort Ripley, through the Brainerd area, up towards southern St. Louis County, and along the north shore of Lake Superior to near Tofte. Isolated totals of up to 9 inches were reported just northwest of Duluth.

The winds to the south of the low were extremely strong, and in places gusted to over 50 mph. The highest gust that we had in our area was 65 mph on the Blatnik Bridge that connects Superior and Duluth. Some of the winds caused damage around the area, mainly by knocking down trees and power lines. The winds were also strong out over the lake. A ship reported 61 mph winds in the open waters of western Lake Superior. Just east of Grand Portage, the Rock of Ages observation on Isle Royale, Michigan recorded a sustained 68 mph wind at 3 AM October 27th, with gusts to 78 mph. The very strong winds over the lake helped to generate large waves. The western mid-lake buoy on Lake Superior reported significant wave heights up to 18.7 feet. The significant wave heights in the far northern part of the lake (out of our area) were 26.6 feet at the Canadian NOMAD buoy.

Regional and National Scale Impacts

Above: a regional impacts graphic from the storm on October 26-27, 2010. Smoothing and estimation used in the creation of certain parts of the graphic.

Winds are created by differences in atmospheric pressure. As a low rapidly intensifies, the pressure gradient around that low will often increase - and thus the difference in pressure between the center of the low and a given point some distance away will increase. Such was the case on October 26th as a low deepened over the state of Minnesota. The pressure gradient became quite strong from the northern High Plains into the central Great Lakes. Plotted in the map above in red are peak non-thunderstorm wind gusts from this storm. The highest wind gust that we could locate was a 79 mph wind gust in Sherwood, Wisconsin - near Lake Winnebago.

Due to the low pressure system, wind gusts of at least 58 mph (equivalent to a severe thunderstorm) were observed from far northeast Montana, through the Dakotas, into the Upper Mississippi River Valley, and then into both peninsulas of Michigan. These gusty winds caused damage across the region - primarily by blowing down trees, power lines, and a few power poles. In some isolated instances, there was some structural damage with roofs damaged and small towers toppled. On some highways, semi-trailers and other high profile vehicles were blown off the road. Power outages were reported across parts of the region mentioned above.

The winds whipped up some very large waves on the Great Lakes, with buoys reporting at least 10 foot waves on most of Lake Huron, Lake Superior, and Lake Michigan at some point during the event. The highest observed significant wave heights were 27 feet in the northern part of Lake Superior. To put it in perspective, this would be roughly the height of a two story house, give or take a few feet.

Further south, widespread thunderstorm activity resulted in severe weather. The first round was with a squall line that started to take shape from far southeast Kansas into northeast Oklahoma around 11 PM on October 25th. The squall line eventually expanded north, and raced east, and produced widespread wind damage from southern and eastern Missouri to the Appalachian Mountains of western Pennsylvania and West Virginia. Later in the day, additional thunderstorms developed even further to the south along the cold front and produced severe weather as far south as central Mississippi and central Alabama. In total, 557 preliminary severe weather reports were logged on the Storm Prediction Center website with the thunderstorms that occurred along the cold front associated with this low pressure system (Oct 25-27).

There was a band of accumulating snow that developed from eastern Montana, into North Dakota, and into parts of central and northeast Minnesota. The orientation of the accumulating snow was a bit unusual in that it occurred generally to the south and even southeast of the low. For most winter storms, the accumulating snow will fall "to the left" of the low track or generally to the north or northwest. This low was powerful enough to pull warmer air around the north and northwest sides of the low, and cold air around the south side of the low. Snow amounts were largely under 6 inches, and measuring was difficult in many areas with strong winds. The areas of heaviest snow (6 to 9 inches), excluding the Rocky Mountains, were northwest of Duluth near Twig and in parts of northern North Dakota. Parts of North Dakota were also under Blizzard Warnings during this storm.

Finally, there was a large amount of liquid precipitation that fell as a result of this storm. Liquid equivalent precipitation of nearly 5 inches occurred in parts of Northeast Minnesota, as quite a bit of rain preceded the snow band that developed later. Rain gauge adjusted radar estimates (courtesy NMQ site: National Mosaic and Multisensor QPE) of precipitation in the 72 hours between 7am CDT October 25 and 7am CDT October 27 are available in this graphic. Much of the country east of the Mississippi River received at least 1/2" of rain. The heaviest totals were from eastern North Dakota into northern Minnesota and parts of Wisconsin and Michigan where heavy rain persisted the longest. Also, there was a secondary area of heavy rain from southern Arkansas into eastern Tennessee where training thunderstorms developed for a time.