Several Wyoming communities are on track to reach record-high temperatures this week, while the eastern half of the United States got smothered under a blanket of snow.
Temperatures in Wyoming have been in the high 50s so far this November and could reach the high 60s or low 70s on Thursday and Friday. Meanwhile, on Tuesday, it was warmer in Anchorage, Alaska, than in Orlando, Florida.
“Nashville, Tennessee, had snow before Denver, Colorado, had snow,” said Cowboy State Daily meteorologist Don Day. “That's what it's been like this week."
What in the world is going on? Nothing too unusual, according to Day and other Wyoming meteorologists.
This week can be considered “the last hurrah.” Big changes are already on the horizon, and this time, they'll set a wintry precedent for the next several months.
“The first half of November has been warm, but things are changing,” Day said. “We will have this warmth and dryness for another three days or so, but we’re going to see quite a turn. Starting this weekend, our fortunes are going to reverse. Our luck is running out.”
Ridged For Your Weather
The disparity in weather between the western and eastern halves of the United States is due to a high-pressure ridge in the upper atmosphere. The ridge is so strong that it’s insulated Wyoming from the wintry weather elsewhere.
“High pressure suppresses any kind of showers and precipitation,” said Molly Gerhard, a meteorologist with the National Weather Service (NWS) office in Riverton. “That’s kept us largely dry, and in turn keeps temperatures warmer.”
According to Gerhard, the NWS forecast is calling for a high of 66 degrees in Buffalo and Worland on Thursday. That’s within striking distance of the record high for Nov. 13 of 70 degrees, recorded in both communities in 1999.
Casper’s anticipated high for Friday is 67 degrees. That’s only one degree off its Nov. 14 record of 68 degrees set in 1939.
Earlier this week, Wyoming’s weather was balmy while many southern states were placed under freeze warnings, shattering many record-low temperatures in Alabama, Florida, and Georgia. At the same time, the Great Lakes region got several inches of snow.
“If you look at the extremes, there were parts of Florida that were 30 degrees colder than the 30-year average on Tuesday morning,” Day said. “When you look at Wyoming and the Intermountain West, we were areas that were 30 degrees warmer than the 30-year average during the same period.”
That’s a natural consequence of the high-pressure ridge over Wyoming and national weather trends overall. There’s always an equal and opposite reaction when it comes to these seasonal shifts.
Day noted that Earth’s atmosphere always seeks equilibrium. When you account for the 30-degree lows in the South and 30-degree highs in the West, you reach zero.
“The general weather pattern in winter is that when it's warm in the western United States, it's cold in the eastern United States,” he said. “When you have a big outbreak of cold somewhere, you're going to have the opposite somewhere else. That’s how the jet stream configures itself during these cold and warm snaps.”
Day noted that the wintry weather in the eastern half of the U.S. was caused by a pocket of cold air that drifted southward out of Hudson Bay in Canada. The high-pressure ridge over the western U.S. forced that cold air east and south, while keeping Wyoming warm and dry.
“People in Florida and Tennessee are saying it’s too cold, while Wyomingites are saying it’s too warm and dry,” he said. “They say it’s not normal, or that something is not right, but that’s how our weather works. When you have one extreme, you're going to have the other somewhere else.”
Gerhard said this isn't unheard of in early November, but it's "typically not how things work." Nevertheless, this is exactly how weather patterns shift when a stubborn high-pressure ridge forms.
"It's like a wave," she said. "If there's a ridge out west, there can be a trough indicating a more active, cooler pattern out east. I wouldn't say it's anything to be concerned about."
Here Comes The Cold
Day has been warning that the latter half of November will feel very different than the former. Now, short and long-range forecasts are validating his warnings.
“Starting next week, we're going to see the weather turn quite a bit,” he said. “We’re seeing masses of cold air building up in the higher latitudes, and those weather patterns aren't going to be able to be held up anymore. Eventually, they’ll cut loose and force a seasonal change."
Gerhard corroborated Day’s assessment, saying the NWS is monitoring an “active pattern” that will fully swoop into Wyoming early next week. Its harbinger will be colder temperatures and even some snow over the weekend.
“The higher elevations could be looking at snow by Friday night,” she said. “There’s nothing too impressive in the valleys and lower elevations for a while, but that’s a distinct turn from what we’ll experience on Thursday and Friday.”
The three- to four-week outlooks from the NWS Climate Prediction Center show slightly favorable chances for below-normal temperatures and similarly above-normal precipitation for the end of November and beginning of December. Gerhard expects that it will look like winter in Wyoming.
“It’s too early to tell, but we’re probably looking at some snow and more wintry weather before December,” she said. “The first part of November has trended a bit warmer and drier than normal, but if we get a few more active periods next week and into the late part of the month, that could all change.”
Descending Into Winter
Day compared the upcoming weather patterns to a ladder that Wyoming will descend over the next few weeks. Except this time, we won’t be going back up.
“This weekend, we go down a couple of steps,” he said. “Late next week, we’ll go down a few more. By the time we go down a couple more steps, you’ll realize the season has changed on you. We won’t wake up one morning to find that it's five below zero with 15 inches of snow, but we’ll start stepping down. And as we go down, we'll stay there.”
If Wyoming “rebounds” in terms of temperature, it won’t be back into the high 60s. According to Day, the momentum has firmly shifted towards winter.
“We have some stratospheric events in Siberia and northeast Asia that will enhance these structural changes,” he said. “Confidence is pretty high that our weather is going to change pretty significantly starting this weekend and going into the rest of November.”
Anyone traveling for Thanksgiving should take heed. Winter weather means flight cancellations, black ice on pavement, and possible road closures due to snow or multi-vehicle accidents.
As for the first snow, both Day and Gerhard said it’s too early to say when it’ll happen. However, neither would be surprised if Wyoming were covered in snow before the end of November.
“I really see us in the thick of it by Thanksgiving week and into the first week of December,” Day said. “After Friday, our weather is going to turn quite a bit.”
Andrew Rossi can be reached at arossi@cowboystatedaily.com.
