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🔴 Warm start to November... then? 🔵
Premium update #8
👋 Greetings Hudson Valley weather watcher!
Over a 70 year period in Poughkeepsie, November featured the first inch of snow 29 times (41% of the time), most recently in 2018.
❄️ Point being, it can snow in November. So will it snow this November? Join me for a bit of crystal ball gazing 🔮
If you read my winter outlook or earlier premium post on when the first snow typically falls in the Hudson Valley (of course you did 😉), you would have learned that the region typically receives its first inch of snow sometime between November 23rd and December 16th with the median date being December 4th.
If you read my November climate clues post, you would have learned that I was on the lookout for an interesting weather pattern.
A few weeks later and things are still looking interesting! Because this November might just have a little something for everyone 🎢
The first two weeks generally look much warmer than average. The antithesis of snow!
☀️ We’re talking temperatures well into the 60s and maybe even some 70s at times! An amazing stretch for outdoor activities and a bit out of character for the time of year.
🐍 You can thank the Pacific jet stream. This speedy serpent of air over 30,000 feet above Earth’s surface is following a path that leads it to “dip down” along the U.S West Coast. Where the jet stream dips, the storms track. The Intermountain West will be in for a fast start to ski season because of it! 🎿
Mother Nature likes balance, so what goes down must come up.
The jet stream will commonly follow a pathway up and over the eastern U.S. during the first two weeks of the month, creating a ridge of high pressure.
This pattern of a jet stream dip in the west and ridge in the east is called the negative phase of the Pacific / North American Pattern (PNA). The PNA is a useful indicator of week-to-week weather variability across North America, especially during winter.
What happens when the PNA goes positive?
…the opposite pattern, of course!
The positive phase of the PNA is associated with a ridge of high pressure over the western U.S. and Canada, forcing the jet stream to change its path. Now flowing further east, it can more effectively usher cold, Canadian air masses into the central and eastern states — including the Hudson Valley.
So will the PNA flip from its current negative phase to positive this month?
The (partial) answer to that question lies some 10,000 miles away in a place called the Maritime Continent — a cauldron of meteorological ferment located north of Australia. Weather that happens here has the ability to affect conditions in far off places. The technical term is teleconnection.
The teleconnection involved is an eastward moving pulse of rain and cloud in the tropics called the Madden-Julian Oscillation (MJO) that circles the planet every 30-60 days on average. The influence the MJO has on the weather depends on where it is and the time of year.
When the MJO becomes active in the Maritime Continent during November, the jet stream over eastern Asia changes. This has ripple effects on the pattern across the Pacific Ocean, typically culminating in a weaker jet stream flow near the west coast of North America and the development of a ridge of high pressure there.
Remember, what goes up, must come down! It’s usually the East Coast where things go down in this situation, temperature wise 📉
The MJO is due to reach the Maritime Continent during the 3rd and 4th week of November. That doesn’t guarantee the 3rd and 4th week of November will be ultra cold in our neck of the woods, but it does increase the odds for the arrival of some chillier than normal conditions ❄️
In the meantime, enjoy the warm weather. Snowy days aren’t far off now ⏳
Programming note: This email is coming to you from Sydney, Australia! I’m on vacation this week and the weather in the Hudson Valley is well behaved. Two good things! I’ll be skipping my Sunday weather bulletin this week and resuming on Sunday November 6th.