The science behind the snowstorm and how it compares to other April storms

BISMARCK, ND (KFYR) – Let’s dive into some of the great weather forecasts behind this historic springtime snowstorm and rank it with all the snowstorms in North Dakota this past April.

Because the atmosphere is tens of thousands of feet thick and consists of many layers, meteorologists often evaluate the atmosphere from top to bottom to demonstrate how the system formed and strengthened. So let’s start with the upper levels of the atmosphere at about 30,000 to 35,000 feet from the ground, where planes usually fly. This is where the jet stream is located, which plays a major role in driving our weather patterns.

On Monday, there was a significant drop in the jet stream over the western United States, as shown in the map below. This is called a small basin, and storms usually form on the eastern sides of these basins. Since this was a very large drop in the jet stream, a lot of energy was concentrated on the eastern side of the trough and this is a favorable area for upward movement, leading to the development of low pressure systems.

In addition, the regions of faster moving air in the jet stream shown below (yellow and orange colors) are called jet lines. Certain areas of these jet lines (both front and back) could allow for stronger upward movement and favorable development of strong storm systems. This was the case in the Northern Plains/Upper Midwest on Tuesday allowing the development and strengthening of the Colorado Depression.

jet stream tuesday(kefir)

Now lowering in the atmosphere a little to about 20,000 feet above the Earth’s surface, we see what’s called a ‘closed bottom’. This means that the region of low pressure at this level of the atmosphere is closed (note the closed circuit where the low is placed) and separated from the mean west-to-east flow across the country. This usually causes the system to stall over the area because the guidance winds in the atmosphere can’t push it east as fast as they usually can, which is certainly the case with our low pressure area resulting in a long snowstorm.

Wednesday top level pattern
Wednesday top level pattern(kefir)

A “closed low” at 20,000 feet in the atmosphere translates to the surface as well, as our region of low pressure over eastern North Dakota has been disrupted in the past 24 hours (it even retreated slightly to the west at one point). This resulted in the strong winds we saw and snow wrapped around it through Thursday. You will also notice below that this system is now “closed”. The purple line is a clogged interface. This means that the system is so mature and late in its “life cycle” that it has become strong and stalled with another region of low pressure developing over the Great Lakes, in an attempt to pull the entire system east.

Radar and isobars (isobar lines) at 4 p.m. Wednesday
Radar and isobars (isobar lines) at 4 p.m. Wednesday(kefir)

Since the atmosphere is now closed off with our low-pressure parked zone over North Dakota, a high-pressure zone has already formed over western Montana. This just tightened our pressure gradient above the first warning display area even more. Notice in the image below how tightly the isobaric streaks (isobaric streaks) beam, which results in very strong northerly winds (we saw gusts of 50 to 60 mph in some places).

Radar and isobars (isobar lines) Wednesday at 4 pm
Radar and isobars (isobar lines) Wednesday at 4 pm(kefir)

Another interesting component of our historical snowstorm is how severe snowfall rates are at times. One time in particular stood out when this system was moving to our area on Tuesday. A heavy pack of snow moved at a rate of 2-3″ per hour of snowfall from south to north across the state. This is referred to as a medium sized snow bar. The term mesoscale refers to small scale weather phenomena, while in meteorology the term comprehensive scale refers to large scale phenomena (such as entire storm systems).

Strong uplift (or upward movement) in the atmosphere led to this medium-sized icy band, prompted by a term called “front formation”. The genesis of the forehead is the generation or intensification of the forehead. It occurs when warm air converges with cooler air, and the temperature gradient amplifies. In our case on Tuesday, warm air was directed into the region from the south resulting in this strong convergence zone, thus raising it, creating more clouds and snow and, as a result, heavy snowfall rates.

Skytracker Radar during Tuesday morning when a heavy mass of snow was heading north
Skytracker Radar during Tuesday morning when a heavy mass of snow was heading north(kefir)

Finally, how does the blizzard of April 2022 compare to those in the past? We’ve definitely seen some big and historic April snow storms before, as featured in this list below. Bismarck is used in the list below because the snowfall records are as far back as here, dating back to 1875. As of 7 a.m. Thursday, Bismarck’s snow total from this blizzard is officially 17.5″ at the airport, putting it in a tie For the second time with the April 1997 snow storm that occurred 25 years ago, as we looked back last week. But the April 2022 blizzard will definitely be one we will remember for a long time to come.

Snowstorms last April in Bismarck
Snowstorms last April in Bismarck(kefir)

Copyright 2022 KFYR. All rights reserved.

Leave a Comment