All posts by Jim Woodmencey

December 2022 Temperature Roller Coaster

Temperatures during the last month of 2022 took quite a roller coaster ride in the Town of Jackson, WY. More than once during the month we experienced temperature swings, both up and down, of over 50 degrees Fahrenheit.

Depending on the upper level flow direction at the time, which determined if temps were going up or going down, some of those changes occurred in a very short period of time.

The swinging pendulum began at the beginning of the month with a 50 degree change in temperature from a high of 33 degrees on the afternoon of December 1st (temps are recorded each morning at 9:00 am local time for the previous 24-hours). The low temp on December 3rd was minus 17 degrees. A 50 degree drop in just 2 days.

Two days after that, on December 5th, the high was back up to 30 degrees above zero, a 48 degree rise in temperature. Followed by a drop back down to 15 below zero on December 8th, a 45 degree change in the other direction.

The biggest plummet of temperatures though occurred on the Winter Solstice, December 21st to 22nd, 2022. That was followed just a few days later by a significant resurrection of temperatures. Here is how that story unfolded.

Cold Solstice

The Winter Solstice arrived with some gusto this year in Jackson Hole, with near blizzard conditions, followed immediately by a blast of Arctic air from the north that had temperatures dropping to 25 degrees below zero Fahrenheit.

The official high temperature at the Jackson Climate Station on December 21st, 2022 actually occurred in the morning, when it reached 31 degrees before 9:00 a.m. The low temperature the following morning, December 22nd, was 25 degrees below zero, a 56 degree drop in 24 hours.

Warm Christmas Weekend

It was also 25 below zero on December 23rd. Three days later, on the afternoon of December 26th, a southerly flow of air brought the high temperature all the way up to 44 degrees in the Town of Jackson. That’s a 69 degree rise in temperature in three days time.

Talk about a hard place to dress for!

Similar to 2016

Yes, those were unusual temperature swings. But we saw a similar roller coaster of  temperatures in December of 2016. There were 50 and 60 degree temperature swings in Jackson that December, as well.

Here is what that month looked like:

Record Cold in Casper, Wyoming

Perhaps the most impressive temperature drop I could find in Wyoming over the Winter Solstice this year was in Casper, WY. On the morning of December 21st, 2022, Casper’s airport thermometer went from 28 degrees above zero at 7:40 a.m. to 6 degrees below zero at 8:40 a.m. when the Arctic air arrived. That’s a temperature drop of 34 degrees in one hour.

Twenty-four hours later, on the morning of December 22nd, the low temperature in Casper was 42 degrees below zero. A precipitous cold plunge of 70 degrees from the previous morning’s reading of 28 degrees above zero.

That minus 42 degree reading broke Casper’s all-time cold temperature record. Prior to this December, the coldest temperature ever recorded in Casper was minus 41 degrees, on December 21st, 1990.

 

Posted by: meteorologist Jim Woodmencey

Coldest November Ever in Jackson, WY

November 2022 was the coldest November on record in Jackson, Wyoming. Let me repeat that, to let it sink in, this November was the coldest November Jackson has ever experienced. And that’s saying something, because it happened without breaking a single daily temperature record in November.

The month of November was just consistently cold, with 12 days reporting morning low temperatures that were below zero Fahrenheit. The average low temperature for November 2022 was 6.2 degrees, which is a full 10 degrees colder than Jackson’s long-term average monthly low temperature in November.

The average high temperature in November 2022 was 27.7 degrees, which is an amazing departure from the long-term average of 40 degrees in the month of November. That is a full 12 degrees colder than normal!

The coldest day of the month was on November 19th, 2022, with a low temp of 13 degrees below zero and a high temp of 11 degrees above zero.

Compared to one year ago, November, 2021 had no days with below zero temperatures and average high and low temperatures that were both several degrees above normal.

A Big Deal

The mean temperature for the month of November 2022 (the average of the average high and low temperatures for the month) was 17 degrees, which is 11 degrees below the long-term average mean temperature for the month of November.

All of this qualifies as the coldest November on record, going back through about 100 years of records. The previous coldest November in Jackson was 84 years ago, in 1938. The mean temperature that month was 18.8 degrees. No other month with complete records even comes close.

(Numbers in graphics are rounded up or down to whole numbers for simplicity).

This might very well be one of the largest differences between the long-term average temperatures and new record temperatures that I have seen in my 30 years of compiling and studying the weather stats here in Jackson.

Period of Record Stats

Long-term records refer to the entire period of record for a climate station. Jackson’s records date back to the early 1900’s. However, in analyzing monthly temperature averages like this, you have to throw out the years with incomplete records. Any month with more than 5 days of missing data is disqualified from this analysis.

The chart below shows all the years with complete data to calculate a monthly mean temperature in November, about 86 years that met the criteria.

By the way, if you think November was somehow a one-off, it was not. In recent times, October of 2019 was the coldest October on record, and 2019 was also the Coldest Year on Record in Jackson.

 

All data is from the Jackson Climate Station, which is located on North Cache Street in Jackson, WY.

Posted by meteorologist Jim Woodmencey of MountainWeather.com

December 5th, 2022

A Long Indian Summer this October

According to the Glossary of Weather and Climate, Indian Summer is defined as:
A time interval in mid or late autumn, of unseasonably warm weather, generally clear skies, sunny but hazy days, and cool nights. At least one killing frost and preferably a substantial period of normally cool weather must precede this warm spell in order for it to be considered a true “Indian Summer”.  It does not occur every year; and in some years two or three Indian Summers may occur.

The weather in Jackson Hole and across much of the West and Rockies during the first 3 weeks of October 2022,  fit that bill, for the most part. At least most everyone I’ve spoken with has referred to it as “Indian Summer” weather. Which has been welcomed by most and loathed by a few. There are those among us who might prefer to see Mother Nature bring on the snow by mid-October. I am not one of them.

What Caused it?

This year’s spectacular October weather was courtesy of a big, warm ridge of high-pressure that developed over the western United States. That ridge has remained sandwiched in-between two large and cold troughs of low-pressure.

One of those low-pressure centers has been parked over the eastern United States causing colder than normal temperatures, cloudy skies, and rain. Some areas around the Great Lakes have also seen snow. The other low-pressure area is to the west of us, in the Pacific. That low has been circulating around out there bringing rain and snow to south-central and southeastern Alaska.

This is a classic blocking pattern in the atmosphere, one that occurs periodically. It is nothing unusual and it looks like it will be breaking down very soon.

Short Memories

I have always maintained that we have very short memories when it comes to the weather. For instance, could you tell me what last October was like in Jackson, WY? Or perhaps the last three Octobers? Were they warm and dry, cold and wet?

To be honest, if I don’t go back and look it up, I can’t always instantly recall what the weather was doing here from one year to the next. Unless there was something I did that was memorable, like backpacking in the Wind River Range at 11,000-feet in mid-October, about 10 years ago? Or skiing on Teton Pass by Halloween, in whatever year that was? See what I mean.

To refresh our memories, here is a rundown of what the weather was like in Jackson the last few Octobers, as they were all quite different.

October of 2021

Last October began with high temperatures in the mid to upper 60’s during the first week, with two days in there with highs of 71-degrees. Through the first two weeks of this October, we had a spate of days with highs in the mid 60’s, the warmest high temperature in town through mid-month was 68-degrees on October 9th, 2022.

The second week of October 2021, temperatures cooled, and we got some rain. At the end of that second week, Jackson had several days with high temperatures only in the 30’s and 40’s, with a little bit of snow in town, near a half-inch, on October 13th, 2021.

Overnight low temperatures in the first half of October 2021 got down into the teens several times. This October, the coldest morning was 21 degrees on October 10th, 2022.

October of 2020

Two years ago, October 2020 also started out warm and dry, much warmer than this October, with high temperatures over 70 degrees in town every day for the first 10 days of the month! The warmest day was October 7th, 2020, with a high temperature of 75 degrees in town. Another October that had a great Indian Summer.

By the end of the second week of October, however, it snowed about 2 inches in town. At the very end of the month there was record breaking cold, with a high temperature of only 18 degrees and a low temperature of minus 9 degrees on October 26th, 2020. Those are the coldest high and low temperatures ever recorded in Jackson during the month of October. That was just two Octobers ago, mind you.

October of 2019

Three years ago, October 2019 started out cooler than normal, with our first measurable snow in town on October 1st. High temperatures fluctuated wildly throughout the first two weeks or so of the month, ranging from 30 degrees to 66 degrees in town. Overnight low temperatures had already dipped into the single digits by October 11th, 2019, with a low of 8 degrees.

October 2019 established new record low temperatures for the month of October, with a high temperature of 20 degrees and a low of minus 6 degrees on October 29th, 2019. Both of those monthly records were broken the following year, in October 2020, as noted above.

Overall, October 2019 remains the coldest October ever recorded in Jackson, for both average high and average low temperatures. No Indian Summer here that October.

The Ups and Downs

Whether we get an Indian Summer or not, depends on the weather pattern. Sometimes we are under a high-pressure ridge, sometimes we are under a low-pressure trough. When either of those features persists overhead, we either get long stretches of warm and dry, or cold and wet weather. Sometimes we are in-between or the weather pattern is more transitory, and thus variable.

The weather pattern this October kept high pressure parked over us and allowed a long stretch of Indian Summer weather. Personally, I’ve enjoyed it, winter is already long enough, without adding autumn to that schedule.

NOTE: To learn more about the origins and history of the term Indian Summer, check  out this article published on the Old Farmer’s Almanac website. Or this one from the Farmers’ Almanac.

 

Jim is the chief meteorologist at mountainweather.com and has provided a weather forecast for Jackson Hole and the Teton Range for the over 30 years