What we do: We are making sub-seasonal forecasts for time periods of high probability of cold air outbreaks in Eurasia and North America 30-40 days in advance. We issue such forecasts on a weekly basis and this website is updated around Thursday each week.
The 2016-2017 Forecast Season has begun!
New Forecast Made on November 25:
STRAT_D1 (12/24 – 12/27)
We are forecasting a new event following STRAT_D1. STRAT_D1 looks to be a relatively weak event with a peak net mass transport into the polar stratosphere up to 0.7 trillion tons per day. We expect modest cold air incursions over mid-latitude regions of both North American and Eurasian continents, which will slightly affect Christmas holiday travel.
We continue to forecast mild winter conditions over both continents in the 2-3 weeks after STRAT_C is over till STRAT_D when the new rounds of cold air outbreaks begin.
Follow up on Forecast Made in the Previous Weeks:
STRAT_B2 (11/15 – 11/21), which is forecasted on 10/21, has peaked on 11/16, transported over 0.8 trillion-ton each day. It affected more than 60% of the mid-latitudes of both the Eurasia and the North America continents causing cold temperatures and wintery precipitation there, especially the United States, Eastern China, and Europe.
STRAT_C (11/25 – 11/30), first forecasted on 10/14 at a lead time of 40 days, is happening right now. According to the latest forecasts, STRAT_C turns out to have twin peaks, one has already taken place on 11/23 when it transported about 0.9 trillion-ton air mass per day into the polar stratosphere. The second peak of STRAT_C is going to occur on 11/30 with peak intensity of 0.6 trillion tons per day. Though the second peak is not very strong, but it is also coupled with stronger cold air transport out of the polar region near surface, which will bring cold surges to mid-latitudes of both continents during the week after Thanksgiving.
STRAT_D (12/17 – 12/21), first forecasted on 11/20, is still expected to occur within the forecasted range. STRAT_D looks to be a moderate event with a peak net mass transport into the polar stratosphere about 0.9 trillion tons per day. We expect surface cold air temperatures over the mid-latitude regions of Eurasia, while a round of polar cold air is expected to intrude southward across the whole continent.
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