Polar Vortex Shake-Up Won’t Bring Arctic Cold to the U.S. This Month
Although the polar vortex is on the move, Americans should be safe from the surge of Arctic air that typically accompanies this movement. Read on for why meteorologists believe that the U.S. will be spared from frigid air outbreaks in November.
Polar Vortex is Weakening But Not Likely to Translate to Cold Air Invasion in the U.S.
October wrapped up on an unseasonably warm note for much of the northern half of the U.S. With the exception of Florida and the Gulf Coast, most of the East also enjoyed abnormally dry conditions for much of the month. What does November have in store? While average weather patterns would suggest that cold weather is in the immediate future, November is setting up to usher in moderate temperatures when compared to the norm this time around.
What is happening on schedule is the normal shift in the polar vortex that happens this time of year. The polar vortex is the region of strong winds that circulate near the Earth's pole. A strong polar vortex keeps the coldest air locked up over the Arctic Circle. However, the frigid air is able to escape and seep down into Canada and the U.S. when this vortex starts to weaken heading into November.
The jet stream is forecast to develop some pronounced buckles across the Northern Hemisphere over the next few weeks. This would normally allow the cold air locked up at the pole to dive to the south.
However, the air that is currently anchored over northern Canada is not as cold as it usually is by this time of the fall season. This means that there simply is not enough cold air to migrate over the border into the U.S., even if the polar vortex does show signs of weakening. Any air that does make it down from the far reaches of Canada will be mild enough to mitigate the threat of bitterly cold weather.
What Does This Mean on a Local Level Across the U.S.
Temperatures are forecast to be on a downward trajectory across most of the U.S. during the first two weeks of November. But the cooler air is not the result of a breakdown in the polar vortex. Instead, the cooler temperatures will come as a result of changes in the jet stream. While the mercury is heading downward, it will still be warmer than usual for a large swath of the northern U.S.
What also makes this November different already is that the greatest departure from normal readings will be across the Southwest and the south-central U.S. The northern tier of the country will dodge the coldest weather due to the position of the jet stream. Cities such as San Francisco, Portland, Seattle, Minneapolis, Chicago, Detroit, Buffalo, Pittsburgh, New York City, and Boston will all trend above normal for the month. This warmth will extend down the Atlantic coastline and into Florida.
In addition, the dry weather that has been a mainstay over the eastern half of the country is on its last days. Widespread rain is likely for much of the East in the days and weeks ahead. Similarly, the wet weather pattern will persist across the Southwest, the Four Corners region, and the south-central U.S.
This blocking pattern in the jet stream is likely to ease by the back half of November. This development would allow cooler air to come down from Canada and into the northern U.S. Despite slightly cooler temperatures making their way from the north, it is not likely to be enough to give ski resorts in the East a much-needed boost.
Stay with us as we monitor the changes in this weather pattern as fall gradually gives way to winter.
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