December weather detective 🕵️♂️
Premium update #13
The last four, seven out of the last eight, and nine out of the last 11 Decembers have been warmer than average in the Hudson Valley.
Put another way, only December 2013 and 2017 have been cooler than average since 2011.
Join me on the hunt for clues to determine if December 2022 might buck the long-term warming trend! 🔎
Have you noticed a rise in Hudson Valley December temperatures over the years? Or a delay in the arrival of typical winter cold?
Here’s what the data says…
On Christmas 2020, the high temperature reached a record-breaking 65 degrees (at Poughkeepsie). In 2015, it was 72 on Christmas Eve, the equal-warmest December temperature on record.
December monthly average temperatures over the 30 years from 1991-2020 were about 3˚F warmer than those from 1959-1988 — 33.6˚F compared with 30.6˚F.
December temperature trends over the last 60 years are shown in the chart below 📈
In short, Decembers are warmer than they used to be.
❄️ This doesn’t mean that it can’t snow during December, but there is a correlation between colder temperatures and snow, obviously! Should this trend continue (it’s expected to), we might have fewer opportunities for snow during the first month of meteorological winter.
So how might December 2022 fit in the context of the trend? 🤔
To help answer this question, we look to the Barents Sea.
Yes, the Barents Sea 🌊
Big bonus credit to you if know where that is! It could be a Jeopardy! question under the geography category 😛
As part of the wider Arctic Sea, the Barents Sea sits north of Scandinavia and Russia.
For the geographically inclined, here’s a map of the Northern Hemisphere. The red star is centered on the Barents Sea, while the yellow star marks New York.
What does it look like there? 💭
Desolate is a word that comes to mind.
The image below is a high resolution satellite shot from above Severny Island, in the eastern part of the Barents Sea.
Do you remember the term that describes when a weather pattern in one part of the world influences the weather in another?
You can think of it like Mother Nature’s phone line 📞 — and the phone line between the Barents Sea and the United States is open for business! But as you’ll find out, the call will be re-routed around the world first…
Typically, the Barents Sea is a cold, stormy place, as it’s inside the Arctic Circle.
But not at the moment.
Right now, the opposite is happening: there’s a powerful ridge of high pressure, causing warmer temperatures, weaker winds, and more sunshine relative to average for the time of year.
A typical progression of this pattern involves high pressure spreading south and east across Russia and into eastern Asia. There, the interaction of the high pressure system with the Himalaya mountain range causes the jet stream (band of strong wind in the upper atmosphere) to speed up near China and Japan and spread eastward (called a jet extension), causing a trough of low pressure in the western Pacific Ocean. In response to this area of low pressure, a ridge of high pressure strengthens near Alaska.
The jet stream, in order to navigate around this strong ridge of high pressure (like an atmospheric stop sign 🛑), meanders farther north and weakens.
The now altered jet stream configuration can efficiently draw down air from the Arctic Circle into the lower 48! 🥶
In other words, the weather that the U.S. will experience is cold since the air mass has polar origins.
It’s all connected!
As you can see in the image below, one spoke of chilly air (🔵) will spread across the country on Wednesday-Thursday, reaching the Hudson Valley on Thursday morning. This initial cold spell will be short-lived, only lasting a day or two.
Another, possibly longer-duration, cold snap may arrive in the Hudson Valley during the week of December 5th, probably later on. In between the first and second wave, the “reservoir of cold” will get replenished over Canada.
⚔️ Importantly, the Mid-Atlantic and Northeast U.S. could sit near a “battle zone” of colder air to the west and north and milder air to the south.
This is called a temperature gradient. Storms develop upon temperature gradients 🌨️
The period from around December 6th into the mid-month looks like a window of increased storm chances for the Northeast.
So while it doesn’t look like a record cold December in the Hudson Valley, there’s enough happening on a hemispheric scale to keep things “interesting” and prevent a record warm month.
If we get our first snow or ice day in the weeks leading up to Christmas, you can thank the Barents Sea, a place you now won’t forget!
Thanks for reading and have a great weekend.