New Forecasts Made on December 31：
In this week’s forecast, we are forecasting a new event, named as STRAT_K, to occur during the period of 02/02-02/07. STRAT_K appears to be a major aftermath PULSE event right after the major breakup of the stratospheric polar vortex. The associated cold air outbreaks will occur over both North American and Eurasian continents.
The stratospheric polar vortex may break completely following STRAT_J (in the last week of January, 2016).
We are continuing to forecast that the stratospheric polar vortex will be weakened significantly twice in the month of January of 2016, one after STRAT_H and the other after STRAT_J. The latest forecasts indicate that STRAT_H will be mainly driven by stronger wave activities of wave number 2. The warm air transported by wave number 2 will not only fill in the polar stratosphere with anomalously large amount of warm air but also split the stratospheric polar vortex into two.
STRAT_J is also a strong PULSE event due to stronger wave activities of wave number 1 and 2. STRAT_J will give the already weakened vortex another powerful punch, leading to a breakup of polar vortex in the period 01/27-02/03. As forecasted above, there will be a major PLUSE event right after the breakup of the polar vortex. As a result, the polar vortex may not be rebuilt till middle of February. Associated with STRAT_H, J, and K are continental-scale cold air outbreaks over both continents.
Follow up on Forecasts Made in Previous Weeks:
STRAT_G (12/25-12/29), peaked on 12/29, within the time window that we first forecasted on December 3. Coupled with STRAT_G is a stronger event of cold air mass transported into the mid-latitudes near surface, resulting in cold air outbreaks into North America in the week after the Christmas.
Right after STRAT_G, STRAT_H (01/02-01/08) is coming within the time window that we first forecasted to occur on December 3. STRAT_H is expected to be the strongest stratospheric PULSE event since 2015 September, transporting up to 1 trillion tons per day warm air mass into the polar stratosphere. Therefore, we are continuing to forecast cold weather over both continents in the first week of 2016.
STRAT_I (01/13-01/19), first forecasted on December 11, is expected to occur on time. As we forecasted last week, the intensity of STRAT_I is probably moderate, but the associated cold air surges help refuel the cold air mass in the mid-latitudes, especially North America.
STRAT_J (01/21-01/27) is expected to occur within the same time window as first forecasted on December 23. In this week’s forecasts, we are upgrading the intensity of STRAT_J to be at least as strong as STRAT_H. Associated with STRAT_J are continental-scale cold air outbreaks over both North American and Eurasian continents.