New Forecasts Made on November 12：
The first new event we are forecasting this week is named as STRAT_E, which is expected to occur between 12/11 and 12/16. STRAT_E looks to be a major stratospheric pulse event with the peak net mass transport into the polar stratosphere exceeding 0.8 trillion tons per day. We expect major cold air outbreaks mainly over the North American continent. Associated with STRAT_E, the Eurasian continent may also suffer from cold air outbreaks, although not as severely as those over North America.
The second new event we are forecasting this week is named as STRAT_F, to occur between 12/19 and 12/24. STRAT_F is a potentially major stratospheric pulse event with the peak net mass transport into the polar stratosphere as large as 1 trillion ton per day. We expect another round of major cold air outbreaks circulating along the mid-latitudes, especially North America, because statistically speaking, cold air outbreaks associated with a stronger PULSE event prefer to impact the North American continent more strongly. Thus, the 2015-16 STRAT_F event would exert a great impact on the Christmas holiday travelers globally.
Since STRAT_E and STRAT_F are back-to-back strong stratospheric PULSE events, we expect a large portion (exceeding 60%) of the two continents to experience below-normal temperature since the end of the second week of December. Also, the back-to-back strong stratospheric PULSE events would lead to a substantial weakening of the stratospheric polar vortex.
Follow up on Forecast Made in Previous Week:
STRAT_B1 (11/10-11/15), first forecasted on October 15 to occur during 11/10-11/15, has been materialized. As we forecasted, the intensity of STRAT_B1 is relatively weak, transporting 0.45 trillion tons air mass transported into the polar stratosphere per day. Despite of the weak intensity, it has multiple peaks and may last a week. As a result, North America and the northern part of Eurasia will suffer a new round of cold air surges from the second week of November to the beginning of the third week of November, coinciding with the week-1 forecasts of surface air temperature from the GFS model.
STRAT_C (11/25-11/29), which was first forecasted on October 7, appears to occur a couple days later than orginially anticipated. Therefore, we have revised the forecasts for the peak time of STRAT_C for the second time (first on 10/14): STRAT_C will peak around 11/27. Nevertheless, STRAT_C still remains to be a week-long and relatively strong event and is likely to bring cold air temperatures into the mid-latitudes, particularly North America. The week-2 forecasts of surface air temperature from the GFS model also consistently suggest below-normal temperature anomalies prevailing over the entire mid-latitude North America, especially the eastern half of the continent, a few days both before and after the peak day of STRAT_C, and over East Asia mainly before the peak day. Therefore, STRAT_C is very likely to cause interruption of the 2015 Thanksgiving travel.
STRAT_D (12/02-12/08), is expected to be on time as we originally forecasted to occur between 12/02 and 12/08 on October 21. Within a few days after the peak dates of STRAT_D, we expect an increase in the areas occupied by below-normal temperatures for both North American and Eurasian continents.