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.
New Feature: Maps of probability of cold surface temperature anomalies over both North America and Eurasia continents in the vicinity of forecasted stratospheric PULSE events
New Forecast Made on March 3:
No new forecast is made this week.
Major Stratospheric Warming Event (02/23 – 03/01)
The stratospheric warming event ended in 03/01 was a major SSW event, stronger than what we forecasted on 02/18 as a minor SSW event. As we just had two back-to-back major SSW events and we are already in March, we believe that the polar vortex will not gain strength before the final warming. As a result, we are not expecting major continental scale cold air outbreaks before the final warming and therefore we declare the winter of 2016-17 is over. We would not be making new forecasts for 2016-17 winter unless we see a strong PULSE event.
Follow up on Forecast Made in the Previous Weeks:
STRAT_H (02/23 – 02/28), first forecasted on 01/21 to take place between 02/23 and 02/28 has been materialized. STRAT_H peaked on 02/26 with a net mass transport into the polar stratosphere about 0.8 trillion tons per day. Associated with STRAT_H, up to 55% of area in the United States suffered from below-normal temperature, especially mid-west, where heavy snow, low temperatures and extreme weather were seen; while in China, regions below 45°N had abnormally cold weather, and snow were reported in some areas where snow is not common.
STRAT_I (03/08 – 03/12), first forecasted on 02/11, is expected to take place on time. We believe STRAT_I is a moderate “aftermath” event after the major stratospheric warming event, with a peak intensity of 0.6 – 0.7 trillion tons per day. Associated with STRAT_I, the majority of the area above 45°N in both North American and Eurasian continents will experience below-normal temperatures.
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