New Forecasts Made on January 14：
No new event is forecasted in this week’s forecasts.
The stratospheric polar vortex may NOT break completely until a much later time.
As we forecasted last week, the stratospheric polar vortex will not break up completely after STRAT_J, though it will be weakened by the anomalously strong mass transport of the STRAT_J PULSE. It is noteworthy to mention that after the winter solstice, the polar vortex starts to be gradually weakened as sunlight comes back to the Arctic. Therefore, in the later winter month, the polar vortex is more vulnerable to stratospheric PULSE events. We will keep an eye on the intensity variations of polar vortex in the stratosphere in the next week to see if the polar vortex can be broken up by STRAT_J and recovered afterwards before the final stratospheric warming.
Follow up on Forecasts Made in Previous Weeks:
STRAT_I (01/13-01/19), first forecasted on December 11, has taken place 3 days earlier, from 01/10 to 01/15. It peaked on 01/14, transporting about 0.7 tons per day of warm air into the polar stratosphere at its peak time. Associated with STRAT_I, up to 75% of the area over North America has been experiencing below-normal temperatures in the period 01/10-01/15.
STRAT_J (01/21-01/27), is going to take place perfectly within our forecasted time range since the first forecasts made on December 23. STRAT_J looks to be indeed a strong event with its peak intensity of 1.2 trillion tons per day. As we forecasted, STRAT_J will be a week-long lasting event. STRAT_J appears to be responsible for more than 70% area of both North America and Eurasian continents going back to below-normal temperatures in the last 10 days of January.
STRAT_K (02/02-02/07), first forecasted on December 31, is expected to take place on time. We are continuing to forecast STRAT_K as a moderate PULSE event, which will result in cold air surges over both continents, particularly for North America.