Where is Blizzard Alley?
New data has shined a light on areas most susceptible to blizzards, an occurrence five times more deadly than tornadoes in the United States.
While Tornado Alley may be the most well-known corridor for severe weather across the country, there remains a vast area that is impacted by other damaging weather events. Analysis by AccuWeather’s data science team provided a clearer picture of where these other deadly weather events commonly unfold — in particular, those most susceptible to blizzards.
Blizzards aren't necessarily defined by high snow amounts, but rather by the dangers of wind and reduced visibility combined with the snow. A blizzard warning is issued when sustained winds or frequent gusts to 35 miles per hour or greater and considerable amounts of falling or blowing snow are expected to prevail for three or more hours, reducing visibility to less than a quarter mile.
At about 400 deaths a year, blizzards are five times more deadly than tornadoes. On average, tornadoes are responsible for about 80 deaths a year, according to the National Weather Service.
There are three defined Blizzard Alleys inside the United States -- in the Central region, in Colorado and in the Northeast. All these areas have unique characteristics that make them prone to experiencing blizzard events.
The center of Blizzard Alley
Tim Jones plows the road to his residence between Fargo and Wild Rice, North Dakota, after the National Weather Service issued a blizzard warning on Feb. 13, 2014. (AP Photo/Dave Kolpack)
Since 2000, nearly 400 counties across the Lower 48 have recorded at least 10 blizzard warnings. Of those, 36 have recorded at least 40 and just seven have recorded at least 50. These counties are mostly centered around the Northern Plains, including North Dakota, Minnesota and South Dakota.
Some counties in Wyoming and South Dakota also topped the list with at least 50 blizzard warnings over the 22-year span. More regionally, the data compiled shows Blizzard Alley centers around northeastern North Dakota around Grand Forks and expands north and south, encompassing much of eastern North Dakota, extreme northwestern Minnesota and northeastern South Dakota.
Fargo, North Dakota; Watertown, South Dakota; and Fergus Falls, Minnesota, are all in the center of Blizzard Alley. The less frequent part of Blizzard Alley extends into the entirety of North Dakota, most of South Dakota, and areas along central and northwestern Iowa, including Sioux City. To the south, the swath of warnings extended into a large portion of Nebraska and western Wyoming, including Cheyenne.
The geography of the northern Plains is critical to the area being such a hotspot for blizzards. The region is in close enough proximity to the Gulf of Mexico for moisture to flow freely northwest and is a zone where storms tend to intensify east of the Rockies.
"Usually when blizzards happen, a very potent storm strengthens over the Midwest and winds become strong on the northern side of the storm where cold air and moisture from the Gulf of Mexico collide," said AccuWeather meteorologist Nicole LoBiondo.
The counterclockwise rotation around low pressure in the northern hemisphere allows moist air from the Gulf of Mexico to be ushered north into the plains. This moisture is key for intense snowfall in blizzard scenarios.
Cold air is another key ingredient for blizzard conditions, which can easily dip from Canada into the northern plains. The mountains also play a vital role in Blizzard Alley.
"The lack of mountains allows for no physical barriers to disrupt the rapid strengthening of storms in this part of the country to rapidly intensify. This rapid intensification is how the winds become so gusty for so long in order to have whiteout conditions," said LoBiondo.
Walsh County, North Dakota, tops the list for blizzard warnings since 2000 with a stunning 84 recorded since 2000. Following behind are Polk County, Minnesota, and Elbert County, Colorado, which both recorded at least 60 warnings.
Colorado Blizzard Alley
Two women, with coffee in hand, negotiate the parking lot in front of King Soopers at University Hills during a major spring snow storm in Denver. (Photo By Andy Cross/The Denver Post via Getty Images)
As the northern plains portion of Blizzard Alley extends southward, another peak of warnings can be found in Colorado.
Nearly every county in the eastern plains of the state has at least 20 blizzard warnings since 2000, with higher amounts towards the Kansas and Nebraska border.
But the most blizzard warnings in the state aren't found here, nor in the mountains. The most warnings can be found in Elbert County, located just northeast of Colorado Springs. Over the past 22 years, Elbert has recorded 60 blizzard warnings.
To the southeast of Elbert County is the second highest total in the state -- Lincoln County. These portions of Blizzard Alley are made possible because of how storm energy moves over the Colorado Rocky Mountains.
Rush hour traffic heads south into Denver from the I-25 and Colorado 7 intersection during a snowstorm in Thornton, Colorado, Jan. 5, 2007. (AP Photo/Will Powers)
When storms move over the mountains, surface energy gets disrupted and often ripped apart, but upper-level energy remains. As the storm moves over the mountains, it can resurge when it's east of the Rocky Mountains.
"Surface love pressure has the opportunity to develop and often strengthen since there are no mountains to rip it apart in the plains," said LoBiondo.
This is why counties directly east of the Rocky Mountains such as Douglas, Jefferson and Adams, all have at least 20 warnings over the past 22 years, while counties along the Rocky Mountains, such as Jefferson and Denver, have none.
But the mountains aren't completely left out of blizzard conditions as these high peaks do not stop the winds. The highest peaks usually experience blizzard conditions, but the more populated valley locations are shielded from the worst of the winds and blizzard conditions.
Northeast Blizzard Alley
Tornado alley isn't the only corridor to have a secondary area. But unlike tornado alley's southern secondary corridor, Blizzard Alley claims the northeast. The secondary Blizzard Alley appears along the east coast of New England from New Jersey to Maine.
What makes the northeast a secondary Blizzard Alley is many of the same ingredients that make the northern plains the primary alley.
"There is a lack of mountains outside of the Catskills, Adirondacks, Berkshires and Appalachians. The lack of physical barriers helps storms strengthen, and moisture from the Atlantic allows for intense precipitation to occur," explained LoBiondo.
This type of storm in the northeast is classified as a nor'easter because they track over the Atlantic Ocean right off the Northeast coast. Nor'easters are notorious for being strong in several aspects.
People walk through New York's Times Square during a snow storm, Saturday, Jan. 29, 2022. (AP Photo/Mary Altaffer)
"One in particular is the wind gusts are strong with Nor'easters as low pressure is able to intensify rapidly over the ocean since there are no mountains or physical barriers to interrupt rapid intensification," explained LoBiondo.
In addition to intensifying low pressure, nor'easters also draw in cold air from Canada to the northwest. This cold air collides with the Atlantic moisture and creates a perfect setup for blizzard conditions.
Nor'easters can intensify dramatically enough that it becomes a bomb cyclone, which occurs when a storm strengthens so fast that the central barometric pressure falls by 0.71 of an inch of mercury (24 millibars) within 24 hours.
The stronger nor'easters on record have been given nicknames such as "The Storm of the Century" and "The Perfect Storm."
The six states without a blizzard warning
A local motorist ties up traffic after becoming stuck in a snowdrift on Dec. 27, 2015, in Lubbock, Texas. (Photo by John Weast/Getty Images)
Overall, nearly every state has been issued at least one blizzard warning since 2005. The only exceptions are six states, all located in the southeast, and Puerto Rico.
Until 2009, a blizzard warning had never been issued in Texas south of Interstate 20, according to CHRON. Interstate 20 routes along northern Texas and runs through cities such as Odessa, Midland, Abilene, Dallas and Longview.
A rare blizzard on Christmas Eve 2009 brought blizzard conditions to areas west and northwest of the Dallas-Fort Worth metroplex, prompting some of the southernmost blizzard warnings on record. Warnings were issued in areas such as Callahan County, which is located about 65 miles northeast of San Angelo.
While Texas has experienced some blizzards over the years, bordering Louisiana has zero recorded blizzard warnings since at least 2000. A majority of the southeast joins the list of states to not record a blizzard warning this century so far, such as Mississippi, Alabama, Georgia, South Carolina and Florida. When expanding to major U.S. territories, Puerto Rico and Guam also join the list.
Seven blizzard warnings have been issued in Hawaii since 2000, all on Big Island Summit. The most recent warning for the state was issued on Dec. 4, 2021, with the three prior warnings coming during the month of March.
What about Alaska?
In this Feb. 21, 2019, photo, the entrance to Norton Sound Regional Hospital is seen through a snow storm in Nome, Alaska. The hospital serves Nome and surrounding villages of the Bering Strait region. (AP Photo/Wong Maye-E)
When including Alaska, the state accounts for the top seven spots for blizzard warnings over the past 22 years. Every corner of the state has been under a blizzard warning, but it isn't just the northern location of Alaska that makes it so prone to blizzards.
The Alaska mountain range between Fairbanks and Anchorage helps drive storms to the less mountainous parts of the state. Winter storms coming from the west into Alaska either travel north or south of the Alaska range because the tallest mountain in the United States -- Mt. Denali -- is located in the range.
"That big and tall mountain is not moving, but air and the atmosphere moves around it," explained LoBiondo.
When a storm tracks north of the Alaska range, there are no longer the physical barriers of mountains to prevent the storm from strengthening. This allows a system to build in intensity and winds.
"There is plenty of cold air available too to allow for snow and moisture from the Beaufort Sea," said Lobiondo.
The Beaufort Sea Coast tops the entire list for most blizzard warnings since 2000, with the region recording an astonishing 201 warnings over that time period. This is made possible by massive Bering Sea lows, which are caused by cold air in Russia that create a gradient with the warmer Bering Sea.
"Storms like to develop and strengthen rapidly over the sea, then 40-70 mph winds are typical and if there’s snow, you can easily get 1/4 mile visibility for 3 hours, especially if there’s an arctic high ushering in cold air into Alaska and along the coast," National Weather Service Fairbanks Meteorologist Bobby Bianco told AccuWeather.
The Prince William Sound region, located about 70 miles southeast of Anchorage, came second on the list with 189 warnings. Other regions in Alaska making the top five include; St. Lawrence Island, including Bering Strait Coast, Kuskokwim Delta, Pribilof Islands and the Arctic Coast.
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