New Forecasts Made on December 3:

 

STRAT_G (12/25-12/29)

STRAT_G is expected to occur several days after STRAT_F. STRAT_G looks to be a large event. We expect associated cold air surges over both North American and Eurasian continent after Christmas.

 

STRAT_H (01/02-01/08)

In the first week of the year of 2016, a stratospheric PULSE event named as STRAT_H is expected to take place. STRAT_H is likely to cause cold weather in most areas of mid-latitudes.

 

Breakup of the stratospheric polar vortex (01/02-01/08, right after the STRAT_H event): The FOUR consecutive back-to-back STRAT events (E, F, G, and H) will lead to the first breakup of the stratospheric polar vortex in the winter of 2015-16, resulting in at least a minor stratospheric sudden warming event, if not a major one, near the end of the first week of January 2016. Associated with these STRAT events is the cold period for most mid-latitude regions over both continents. In particular, we expect several rounds of large-amplitude cold air outbreaks to take place over North America in the period from December 20 to January 8.

 

Follow up on Forecasts Made in Previous Weeks:

 

STRAT_D (11/30-12/05), firstly forecasted to occur between 12/02 and 12/08 on October 21. It turns out that STRAT_D has occurred a week earlier: Its main peaks have occurred on Nov. 28 and 30 with the peak intensity as large as 0.7 trillion tons per day (in the last week’s forecasts, we referred to them as the second peaks of STRAT_C). The main peaks were responsible for the twin peaks of the cold area index for North America, indicating below-normal temperature over up to 60% area of North America in the period between Nov. 25 and Dec. 1. There will be a secondary peak of STRAT_D, which will show up tomorrow (Dec. 4, 2015). Associated with the secondary peak are minor cold air surges mainly over Eurasia.

 

STRAT_E (12/11-12/16), first forecasted on November 12, is expected to be on time. Although we are downgrading the peak intensity of STRAT_E, it remains to be a potentially strong event because it will have multiple main peaks. We expect major cold air outbreaks over both continents in mid-latitudes, especially North America. According to GFS’s 2-week forecasts of surface air temperature, the below-normal temperature may first occur in the northwestern part of North America and then pervade along the North American trough. This could cause interruption of the 2015 pre-Christmas holiday travel.

 

STRAT_F (12/19-12/24), is also expected to be on time, which was first forecasted on November 12. STRAT_F is expected to be a long-lasting stratospheric pulse event, which could lead to major cold air outbreaks over both North American and Eurasian continents, which may affect the Christmas holiday travelers.