New Forecasts Made on January 22:

In this week’s forecast, we are forecasting two new events:

 

STRAT_K1 (02/12-02/15)

We are forecasting a relatively weak and short-lived STRAT PULSE event to take place during the period 02/12-02/15 with its peak around 02/14 and we name it as STRAT_K1. The STRAT_J event, which is happening at this moment, will severely weaken the polar vortex. The weakened polar vortex will keep wobbling before it recovers its shape and returns back to the pole. As STRAT_K, STRAT_K1 is also associated with the back-and-forth wobbling of the polar vortex. STRAT_K1 is mainly associated with stronger wave activities of wave number 1, therefore, we expect STRAT_K1 will affect more on cold air surges over North America several days afterwards.

 

STRAT_L (02/19-02/26)

STRAT_L looks to be a strong and week-long event with its peak around 02/24. The peak of STRAT_L is mainly due to stronger wave activities of both wave number 1 and 2, resulting in several rounds of back-to-back cold air surges within the week after 02/22 or so over both North American and Eurasian continents

 

Follow up on Forecasts Made in Previous Weeks:

 

We are experiencing the cold air outbreaks associated with STRAT_J now. STRAT_J (01/21-01/27), first forecasts made on December 23, is going to take place perfectly within our forecasted time range. STRAT_J will have twin-peaks at 01/20 and 01/27, respectively. The second peak (01/27) is much larger, transporting more than 1.2 trillion tons of warm air into the polar stratosphere per day. The two peaks are expected to correspond well to the intensified cold air mass transported out the polar region near surface. The peak on 01/20, mainly driven by stronger wave number 2, corresponds to massive cold air outbreaks over both North America and Eurasian continents in the period 01/17-01/24; and the second peak on 01/27, driven by stronger activities of both wavenumber 1 and 2, is expected to cause another round of cold air outbreaks over both continents. The week-1 forecasts of GFS has confirmed the cold air outbreaks associated with the first peak of STRAT_J: a major eastern storm, Jonas, has been bringing brutal cold temperatures to the middle and eastern parts of North America and a “super cold air outbreak” has been hitting Eurasia, causing freezing temperatures, strong wind and heavy wintery precipitation.

 

STRAT_K (02/02-02/07), first forecasted on December 31, is expected to take place on time with its peaks achieved on 02/02 an 02/06. As we forecasted, STRAT_K is a moderate PULSE event. Therefore, it will result in mild cold air surges over both continents.