Friday December 30

Light snow to end the year

School Forecast for:
the rest of 2017
Last Updated: 9AM Friday December 30, 2017
Delay No School Early Dismissal
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9AM Friday

A few clouds beginning to filter in before a shot at some snow tomorrow. The forecast for up to an inch of snow tomorrow morning remains valid.
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6PM Thursday

There is the potential for light snow on Saturday. With temperatures in the teens, however, even very light accumulations could result in road impacts.

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December Pattern Change
Updated: December 1, 2017

~ Calm November ~

The past several weeks have featured a rather calm weather pattern. This pattern has affected our local temperatures by causing them to be fairly steady, that is, some days have been a few degrees above average and others have been a few degrees below average, but overall they have not been too extreme in either direction. The pattern has also affected our local precipitation by decreasing both the number and intensity of storms that we have experienced — November typically averages about 3.47 inches of rain; this November we recorded 0.82 inches.
So what's up?

~ When the jet is flat, we'll stay where we're at ~

The culprit for November's calm weather has been a zonal jet stream ("zonal" is the official meteorological term for "flat"). The jet stream is a layer of strong winds that circulates around the globe in the upper layers of the atmosphere. This "river of wind", typically delineates the boundary between cooler arctic air and warmer air to the south. The wavy-ness of the jet stream constantly fluctuates. When the jet stream is flat with small and few kinks in it, the pools of warm and cold air generally remain stationary. This means that most areas experience very little temperature variation. Additionally, under these conditions it is very difficult for strong storms to develop since the mixing of warm and cold air is a key step in the development of many storms in our part of the world.

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Image caption: The last few weeks of November featured a flat, or zonal, jet stream. A zonal jet stream has very small kinks. This lack of waves generally keeps cold air confined to the north and warm air to the south, and makes for very little variation in the weather.

~ A kinky jet stream makes the weather extreme ~

As we transition into December, it is becoming increasingly likely that we will see a return of the wavy jet stream (it was this pattern that produced brief record cold the first week of November). When the height, or amplitude, of the waves in the jet stream increases it allows warm and cold air to migrate. In some areas warm air surges northward, and in other areas cold air seeps southward - in either case, temperatures become more extreme. The currently emerging pattern should favor warm weather across the west coast with a cooler weather in our part of the country. Additionally, because there is a greater mixing of warm and cold air, and due to the way winds behave as they navigate the twists and turns of the jet stream, there tends to be an increased probability of storms during these patterns. As for whether or not any potential storms directly affect us, this remains a question for the future.

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Image caption: It is becoming increasingly likely that the first half of December will feature a return of the wavy jet stream. This pattern allows cold air to seep south and warm air to flow north resulting in greater weather extremes.

Kingstonsnows ♦ Kingston, NY
Since January 2009
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