Wednesday, December 23, 2020

Blizzards - Notorious Winter Storms



With the impending blizzard that is part of a complicated storm system crossing the U.S. this Christmas Week, I thought it would be a good time to talk a little bit more about them. The image above was valid at 9:00AM Wednesday, December 23, 2020 and shows the states outlined in orange that were under Blizzard Warnings.

The animation below is from the U.S. GFS model showing the forecast track of the storm that is responsible for the blizzard conditions across the Northern Tier of the U.S.  

What Are They

BLIZZARD, that term evokes thoughts of whiteouts, extreme cold, getting stranded and lost outside. For anyone who has ever experienced one, it can be scary and certainly dangerous.  Most of you have an idea of what a blizzard is, but there is an actual definition for what it takes for conditions to be considered a blizzard. In the Glossary of Meteorology, a bible of sorts for weather terms, a blizzard is defined as:

-        sustained wind or frequent gusts of 16 m per second (30 kt or 35 mi per hour) or greater,
-        accompanied by falling and/or blowing snow,
-        frequently reducing visibility to less than 400 m (0.25 mi) for 3 hours or longer.

In a nutshell, they produce strong winds, very reduced visibility and lasts for at least 3 hours.  The timeframe is an important factor in the definition of a blizzard because often in snowstorms you can get a short period of those conditions but if they last long enough, they can strand people, livestock and anything else outside to make conditions life-threatening. Note, it doesn’t have to be snowing either.  The Northern Plains are notorious for “ground blizzards”, storms that whip up loose snow cover into the air to create those same conditions. I have been in ground blizzards before where at times you could look skyward and see clear conditions above the shallow storm.

Where Do They Occur

There are favored locations across the U.S. for blizzards. In fact, I have often referred to an area I call “Blizzard Alley”, a roughly 5 to 8 state region, from the Northern Plains and parts of the Central Plains and Upper Midwest.  The two most notorious states are North and South Dakota. Take a look again at the map below and compare that to the region where Blizzard Warnings are in effect for this week’s storm. That is why I consider this storm to be a textbook blizzard for location.

The total number of blizzards recorded by county during 41 winters 1959-60 to 1999-2000.

Blizzard Alley has specific features that are conducive to blizzards. The area is pretty flat, allowing for strong winds to blow unimpeded through the Alley. It is wide open to Canada, where some of the coldest air in the continent regularly spills down to the States.  The cold air assures that the snow, falling or on the ground is fluffy enough to be blown around to reduce visibility.  Finally, it is in a perfect location for two particular types of weather systems know to produce blizzards, Colorado Lows and Clippers.

Colorado Lows are storms that typically develop off the Rocky Mountains in the vicinity of Colorado. They intensify rapidly and move northeast toward the Great Lakes. They often will pull Gulf of Mexico moisture up with them.  To the north and west of their track they produce very strong winds and very heavy snowfall. Clippers are fast moving storms that typically form off the Canadian Rockies in places like the province of Alberta, and head east along the northern latitudes of the U.S.  These storms normally move faster than Colorado Lows, so they are of shorter duration. They also do not produce as much snow, they are considered moisture starved.  However, because they move so fast, they can catch people unprepared.  Below is a breakdown of the occurrence by state of these two types of storms in the vicinity of Blizzard Alley.  The storm this week is a hybrid of a Clipper System. It began off the Rockies in British Columbia and moved very rapidly eastward through the Northern Plains. After that, it’s Clipper characteristics change as it gets to the Great Lakes Region and morphs into a major winter system for the East.


Although blizzards are most common across Blizzard Alley, they occur across a large portion of the U.S. in any given winter. A study of the number of blizzards that have occurred in a 41-year timeframe from 1951-200 is shown below. As you can see, they have hit most of CONUS, with the exception of 5 states, mainly in the Southeast.

The total number of blizzards recorded by county during 41 winters 1959-60 to 1999-2000.

How Bad Can They Get

The dangers of being caught in a blizzard unprepared cannot be overstated.  With visibilities reduced to just a few yards at times, “whiteouts” on open roads can bring traffic to a standstill, you literally lose the road in front of your eyes. Often, the only way to proceed ahead is to watch the brake lights on the vehicle in front of you. Guess what, if the guy in front of you goes off the road, you will likely follow him. Once you are stuck, it is often difficult to get help because even emergency vehicles won’t risk going out in a storm like this to get stuck as well.  Below is a video of someone driving through a blizzard. Notice that the winds will also drift snow across roadways making them even more difficult to negotiate.  It’s gets pretty scary.

Historically there have been some terrible tragedies associated with these winter storms. Back in the 1888, long before there were accurate daily weather forecasts, the “Schoolhouse Blizzard”,  also known as “The Children’s Blizzard” hit very quickly after a warm and sunny day in mid-January across Blizzard Alley.  Many were caught outside completely unprepared for the extreme, and very rapid, change in the weather. As a result, over 200 people died in this storm, many of them children on the way to and from their schoolhouses, which were often several miles from their farms. 

More recently a massive blizzard back in October 2013 resulted in catastrophic consequences for ranchers and livestock.  The storm impacted thousands of ranches in western South Dakota.  Over 5 ft. of snow fell, winds gusted over 70 mph. As a result, livestock herds caught out in the open ranch land, were scattered for miles and resulted in the deaths of thousands of cattle due to exhaustion and hypothermia.

How To Prepare

The life-threatening conditions that accompany blizzards are why it is so important to have you and your car prepared for these conditions. Make certain you have a fully charged battery, always keep you gas tank filled, I like to say don’t let it get down below ½ a tank at any time.  Carry extra winter clothes including a hat, boots, gloves, a blanket, a cell phone charging block, and extra high energy food like protein bars. I also like to carry some extra water, although you need to make sure bottles do not crack if they freeze in your vehicle.

Finally, listen to the local forecasts for your area. It’s important to adjust any travel plans well ahead of time. The good thing about surviving a blizzard, if you prepare and hunker down until it has passed, you can escape most of its impacts. Understand that power outages often accompany them, so make sure your home is prepared as well, with flashlights, charged cell phones, and check with other family members to make sure you know where they will be.  Last but not least, in the event of a power outage, I always caution anyone who has a back-up generator to know the proper safety for using them. They MUST be put outdoors with adequate ventilation, away from a building, not under porches, nor in open garages, so that the deadly and odorless exhaust gas, carbon monoxide, does not overtake unsuspecting people.  There are many deaths every year from improper use of these systems.  

Being prepared and knowing the forecast will go a long way in living with these notorious winter storms.  In fact, once you and your family are safe at home, getting through the worst winter weather becomes much more manageable. Stay safe.  



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