The 1991 Halloween blizzard was a powerful storm that caused a period of heavy

snowfall Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water throughout ...

and ice accumulation, which affected parts of the

Upper Midwest The Upper Midwest is a region in the northern portion of the U.S. Census Bureau's Midwestern United States. It is largely a sub-region of the Midwest. Although the exact boundaries are not uniformly agreed-upon, the region is defined as referring ...

of the United States, from October 31 to November 3, 1991. Over the last week of October 1991, a large storm system over the Atlantic Ocean ( 1991 Perfect Storm) blocked most of the weather patterns over the eastern half of the United States, and in turn, moisture from the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United ...

was funneled straight northward over the affected region. By the time the precipitation stopped falling, many cities in the eastern half of

Minnesota Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over t ...

and northwestern

Wisconsin Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake M ...

had witnessed record early-season snowfall accumulations, while parts of southern Minnesota and northern

Iowa Iowa () is a U.S. state, state in the Midwestern United States, Midwestern region of the United States, bordered by the Mississippi River to the east and the Missouri River and Big Sioux River to the west. It is bordered by six states: Wiscon ...

were crippled by a large ice storm.

Arctic The Arctic ( or ) is a polar regions of Earth, polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenla ...

air that was pulled southward behind the storm had combined with the heavy snow pack to produce many record low temperatures. Between the blizzard and the ice storm, 22 people were killed and over 100 were injured.

Meteorological synopsis

Surface map of the United States October 30 1991

The 1991 Halloween Blizzard developed from a strong arctic cold front that pushed south and east through the central United States several days prior. On October 28, temperatures to the east of the cold front were above normal. High temperatures reached into the 70s from the middle Mississippi River Valley south into northern Texas, and into the 80s across much of central and southern Texas. Meanwhile, high temperatures remained below 20 degrees

Fahrenheit The Fahrenheit scale () is a temperature scale based on one proposed in 1724 by the physicist Daniel Gabriel Fahrenheit (1686–1736). It uses the degree Fahrenheit (symbol: °F) as the unit. Several accounts of how he originally defined hi ...

across most of

Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columb ...

and

Wyoming Wyoming () is a state in the Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the southwest, and Colorado to t ...

. The contrast between the two air masses was stark, and by the morning of October 29 the cold front was about halfway through Texas. At 6 am CST, the temperature in the western Texas city of

Amarillo Amarillo ( ; Spanish for " yellow") is a city in the U.S. state of Texas and the seat of Potter County. It is the 14th-most populous city in Texas and the largest city in the Texas Panhandle. A portion of the city extends into Randall Cou ...

had dropped to 22 degrees with a strong northerly breeze. Farther east in Texas, the temperature was 64 in Dallas – a 42-degree temperature difference over about . In the northern United States, morning lows were much colder. Temperatures were in the single digits across Montana and Wyoming and in the teens in

North Dakota North Dakota () is a U.S. state in the Upper Midwest, named after the indigenous Dakota Sioux. North Dakota is bordered by the Canadian provinces of Saskatchewan and Manitoba to the north and by the U.S. states of Minnesota to the east, ...

and

South Dakota South Dakota (; Sioux: , ) is a U.S. state in the North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota and Dakota Sioux Native American tribes, who comprise a large po ...

By October 30, the cold front had pushed east to the Texas shoreline with the

, and stalled in that location. As an upper-level

shortwave trough A shortwave or shortwave trough is an embedded kink in the trough / ridge pattern. Its length scale is much smaller than that of and is embedded within longwaves, which are responsible for the largest scale (synoptic scale) weather systems. Sho ...

approached the Southern Plains, it aided the development of an area of surface low pressure along the sharp temperature gradient near the

Texas Gulf Coast Texas Gulf Coast is an intertidal zone which borders the coastal region of South Texas, Southeast Texas, and the Texas Coastal Bend. The Texas coastal geography boundaries the Gulf of Mexico encompassing a geographical distance relative be ...

. The development of low-pressure systems along coastal fronts in this fashion is relatively common in the cool season along the Texas Gulf Coast and along the Atlantic Seaboard near the

Gulf Stream The Gulf Stream, together with its northern extension the North Atlantic Drift, is a warm and swift Atlantic ocean current that originates in the Gulf of Mexico and flows through the Straits of Florida and up the eastern coastline of the Unit ...

current. From October 30 – 31, this low-pressure system slowly became better organized over Texas, before it ejected north over the Mississippi River Valley. This meridional trajectory of a low pressure track (almost due north from the western Gulf) is climatologically favorable to produce very heavy snowfall in the winter months because it allows copious amounts of moisture to flow north where it can interact with colder air. Cooler readings lingered at the very end of October across the

, and a re-enforcing pool of Arctic air was just beginning to push southeast through the western

Canadian Provinces Within the geographical areas of Canada, the ten provinces and three territories are sub-national administrative divisions under the jurisdiction of the Canadian Constitution. In the 1867 Canadian Confederation, three provinces of British Nort ...

. On November 1, the low-pressure system moved north from western

Illinois Illinois ( ) is a state in the Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolitan areas include, Peoria and Rock ...

into the

Upper Peninsula of Michigan The Upper Peninsula of Michigan – also known as Upper Michigan or colloquially the U.P. – is the northern and more elevated of the two major landmasses that make up the U.S. state of Michigan; it is separated from the Lower Peninsula by ...

and the minimum pressure fell about 24

millibars The bar is a metric unit of pressure, but not part of the International System of Units (SI). It is defined as exactly equal to 100,000 Pa (100 kPa), or slightly less than the current average atmospheric pressure on Earth at sea lev ...

in 24 hours, indicative of rapid deepening and strengthening of the cyclone. The low pressure eventually became occluded, weakened, and then continued to dissipate as it pushed east across northern

Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...

in subsequent days.

Precipitation

The precipitation from this system began falling as snow in Iowa late on October 30, and by the morning of October 31, it had changed over to ice and spread northward across southeast Minnesota. During

Halloween Halloween or Hallowe'en (less commonly known as Allhalloween, All Hallows' Eve, or All Saints' Eve) is a celebration observed in many countries on 31 October, the eve of the Western Christian feast of All Saints' Day. It begins the observan ...

day, the precipitation spread to the north, where it fell mostly as rapidly accumulating snow. The snow continued to develop northward, eventually spreading into the Minnesota Arrowhead. Eventually all of the precipitation changed over to snow, and in some areas it would continue falling until November 3.

Snow

The heavy snow began falling across east central Minnesota and northwest Wisconsin during the late afternoon hours of October 31. By midnight, the

Twin Cities Twin cities are a special case of two neighboring cities or urban centres that grow into a single conurbation – or narrowly separated urban areas – over time. There are no formal criteria, but twin cities are generally comparable in sta ...

had already recorded 8.2 in (20.8 cm) of snow. This not only set a record for the largest amount of snow on that date, but also for the most snow ever recorded in the Twin Cities during the month of October. As the storm system pushed its way northward, more communities in eastern Minnesota and northwestern Wisconsin began to experience similar conditions; and

thundersnow Thundersnow, also known as a winter thunderstorm or a thundersnowstorm, is a kind of thunderstorm with snow falling as the primary precipitation instead of rain. It is considered a rare and unusual phenomenon. It typically falls in regions of s ...

occurred as far north as

Duluth , settlement_type = City , nicknames = Twin Ports (with Superior), Zenith City , motto = , image_skyline = , image_caption = Clockwise from top: urban Duluth skyline; Minnesota ...

. Over the next two days the snow continued to fall, leading to additional snowfall of one to two feet (30 cm to 60 cm). By the time the snowfall ended on November 3, the storm had dropped 36.9 in (93.7 cm) on Duluth, the largest single snow storm total in Minnesota history at that time. The

received 28.4 in (72.1 cm), setting a single-storm record for the metropolitan area. In all, at least one foot (30 cm) of snow fell in a swath approximately 100 mi (160 km) wide from south central Minnesota, northeastward into northwestern Wisconsin and into the Minnesota Arrowhead. A more narrow band of 2+ ft (60+ cm) of snow fell from the Twin Cities to Duluth and northward.

Ice

Areas of southern Minnesota and Iowa along and south of the

I-90 Interstate 90 (I-90) is an east–west transcontinental freeway and the longest Interstate Highway in the United States at . It begins in Seattle, Washington, and travels through the Pacific Northwest, Mountain West, Great Plains, Midwest, an ...

corridor did not see as much snow, but instead saw a major

ice storm An ice storm, also known as a glaze event or a silver storm is a type of winter storm characterized by freezing rain. The U.S. National Weather Service defines an ice storm as a storm which results in the accumulation of at least of ice on ...

. Though the precipitation started out as snow in these areas, it changed over to ice during the day on October 31 and continued falling over the next day. Ice accumulations as high as 2–3 in (6 cm–9 cm) were recorded in these areas before the precipitation changed to snow. Up to 10 in (25.4 cm) of snow proceeded to fall on top of ice accumulations from the previous day, making travel even more treacherous. Up to 1 inch of ice accumulation was reported as far south as

Omaha, Nebraska Omaha ( ) is the largest city in the U.S. state of Nebraska and the county seat of Douglas County. Omaha is in the Midwestern United States on the Missouri River, about north of the mouth of the Platte River. The nation's 39th-largest ...

Impact

Most of Minnesota, western Wisconsin and northern Iowa were heavily impacted by the storm. $63+ million in damages was reported from fallen power lines, and $5 million in crop damages were reported in Iowa. Eleven counties in southern Minnesota were declared federal disaster areas, and 52 counties in Iowa were declared disaster areas. At least 100,000 people lost power because of the weight of the ice downing power lines, and in some cases it took up to a week for the power to be restored. Many roads were closed both from the snow and ice, including long stretches of I-90, I-35 and I-29 in Iowa, Minnesota and South Dakota. Highway snow removal was hindered by record cold temperatures that followed the storm and transportation was hampered for many days. Nine hundred schools and business were closed in Minnesota alone. The storm occurred on a Thursday night. Schools in Minong, Wisconsin (40 miles southeast of Superior) were closed even the Monday following the storm. Twenty-two people died in this storm, twenty in Minnesota and two on the Mississippi River near La Crosse.

Records

In eastern Minnesota, the Halloween Blizzard shattered many of the previous October snowfall records. The 8 inches that fell in the Twin Cities on October 31 was more snow than had ever been recorded in any October in its recorded history. November 1 saw similar daily records fall, but with a more wide reaching area from most of central Minnesota eastward to

La Crosse La Crosse is a city in the U.S. state of Wisconsin and the county seat of La Crosse County. Positioned alongside the Mississippi River, La Crosse is the largest city on Wisconsin's western border. La Crosse's population as of the 2020 census ...

and

Eau Claire, Wisconsin Eau Claire (; ) (French for "clear water") is a city mostly located in Eau Claire County, Wisconsin, of which it is the county seat, and with a small portion in Chippewa County, Wisconsin. It had a population of 69,421 in 2020, making it the stat ...

. Following the storm Arctic air poured southward from Canada to produce many record low temperatures in these same areas.

Bismarck, North Dakota Bismarck () is the capital of the U.S. state of North Dakota and the county seat of Burleigh County. It is the state's second-most populous city, after Fargo. The city's population was 73,622 in the 2020 census, while its metropolitan popul ...

, sank to −10 °F on October 31, breaking their previous record low of by 16 degrees. Record snow and cold was recorded as far south as Nebraska and Colorado.http://www.crh.noaa.gov/oax/?n=Halloween
/ref> The Arctic air also spread over Chicago, recording a low of 11 on November 4.http://www.crh.noaa.gov/dtx/climate/fnt_summary_2003.php
/ref> Four weeks later on November 29 – 30, another large storm system dropped as much as 18 inches of snow over these same areas. These two storms combined to set a single-month record for most snowfall in the Twin Cities and Duluth.

References

External links

Minnesota Public Radio – Jet Streaming for Wednesday, October 31, 2007 (MP3)
{{United States winter storms 1991-10 Halloween blizzard Halloween blizzard Halloween blizzard Halloween Halloween in the United States Halloween blizzard Halloween blizzard Halloween blizzard Halloween blizzard Halloween blizzard Halloween blizzard Halloween blizzard Halloween blizzard October 1991 events in the United States November 1991 events in the United States