What are the polar jet stream and arctic polar vortex?

A portion of the geographic United States, specifically the Southern Plains and Gulf Coast, were hit hard in late February with unusual life-threatening winter weather. The state of Texas became the epicenter of this winter event for several reasons. Widespread power outages, freezing water pipes and significant snowfall occurred, which, in some parts of Texas and the Gulf Coast is a rare happening. What was the cause — the Polar Jet Stream or the Arctic Polar Vortex?

First, let’s take a look at these two very different atmospheric realities. Each occurs in totally different layers of our atmosphere. Amy Butler, a stratosphere expert with the National Oceanic and Atmospheric Administration (NOAA) explains what each of these atmospheric happenings do: “The polar jet stream occurs in the troposphere, at altitudes between 5-9 miles above the surface. It marks the boundary between surface air masses, separating warmer, mid-latitude air and colder, polar air. It’s the polar jet stream that plays such a big role in our day-to-day winter weather in the mid-latitudes, not the polar vortex.”

The Polar Vortex is a cold air mass that is in constant motion over the Arctic at very high altitudes in the stratosphere and above the Polar Jet Stream. It’s generally stable, though disruptions do occur now and then. Butler further states, “We did have a sudden stratospheric warming in January. The polar vortex weakened. It got stretched out of shape and slid southward off the pole. Most of the time when this happens — and it happens on average about every other year in the Arctic — some part of the mid-latitudes will ultimately experience a cold air outbreak. The disruption of the vortex encouraged the polar jet stream to become wavier for several weeks, and in combination with other weather patterns, created favorable conditions for a severe cold air outbreak in the central U.S.” 

There were other factors involved with the massive, long-term power outages experienced in Texas. Those factors will have to be clarified and then addressed by people in official capacities, not atmospheric scientists.

Now that we are in Meteorological Spring as of the first of March, I’d like to share the results of Winter 2020-21 here. This data covers the months of December (2020), January and February (2021) and is gathered at my home weather station — your location may differ. The low temperature for the winter quarter was 11.2˚F on Febr.10. The high temperature was 53.6 on Feb.28, and the mean temperature for the winter quarter was 32.8. Total snowfall for the winter quarter was 16.0 inches, with a total precipitation, including melted snow, of 3.84 inches.

Now, let’s look at the weather data for the Month of February. The low temperature was 11.2˚F on the 10th, the high temperature was 53.6 on the 28th, and the mean was 31.9. The all-time low was -15 in 1950 and the all-time high was 61 in 1995. The all-time mean for the month is 32.5. The snowfall for the month was 4.2 inches, and the total precipitation was 0.43 inches. The all-time highest snowfall for the month was 17.1 inches in 1959. The all-time wettest February was 3.58 inches in 1940. The all-time mean for the month is 0.91 inches.

We seem to be getting clearer skies now. Some of you may want to venture out and view our night sky. Here is what our friends at EarthSky.com are sharing with us: “March 2021 features four bright planets! Mars is the only one to shine in the evening sky. Mercury, Jupiter and Saturn all appear in the east before sunrise. Venus — the brightest planet — hides behind the sun this month.” A full moon, called the Worm Moon and generally considered the last full Moon of winter, will be seen on March 28.