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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!

























Forecasts Revised on December 3:

STRAT_D (12/11 – 12/16), first forecasted on 11/20, appears to occur a couple of days earlier according to the updated forecasts. We revise the time window of STRAT_D to 12/11-12/16 with a peak on 12/15. STRAT_D will be a moderate event with a peak net mass transport into the polar stratosphere about 0.9 trillion tons per day. It will mainly impact North America with more 70% area plunging below normal temperatures. Nevertheless, it would also cause 50% of the area over the mid-latitude regions of Eurasia suffering from below normal temperatures in the second half period of the STRAT_D event.

STRAT_D1 (12/24 – 12/27), first forecasted on 11/25, appears to be a long-lasting, twin-peaked, but relatively weak event. We this week extend the time window of the STRAT_D1 to 12/24 – 12/31 with peaks on 12/25 and 12/29. STRAT_D1 is expected to transport up to 0.7 trillion tons air mass per day into the polar stratosphere, and bring cool weather to mid-latitude regions of both North American and Eurasian continents. STRAT_D1 may affect Christmas holiday travel.

New Forecast Made on December 3:

STRAT_E (01/08 – 01/13)

We are forecasting this week a new event, STRAT_E, to occur between 01/8 and 01/13 with a peak on 01/10. STRAT_E is expected to be a very strong event with a peak net mass transport into the polar stratosphere over 1 trillion tons per day. We expect strong cold air outbreaks over both North American and Eurasian continents.

Follow up on Forecast Made in the Previous Weeks:

STRAT_C (11/25 – 11/30), first forecasted on 10/14, has been materialized. STRAT_C turns out to have multiple peaks. The 1st peak was on 11/23 when about 0.9 trillion-ton air mass was transported into the polar stratosphere per day. The 2nd peak was on 11/27 transported over 0.6 trillion tons per day, and the 3rd peak on 11/30 has an intensity of 0.5 trillion tons per day. Associated with STRAT_C, winter storm Blanche was named on 11/27. It swept across most regions of the United States, brought heavy snow and rainfall, and disrupted holiday travel after Thanksgiving heavily. Winter Storm Blanche is still bringing heavy snow in New England. In the meantime, Europe and southeastern China experienced below-normal temperatures. Thus, overall, the timing, intensity, and impact area of STRAT_C was well captured at a forecast lead time of 40 days.

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