New Forecasts Made on October 8：
The two new events of stronger stratospheric mass transport into the polar stratosphere mentioned in the last week’s in October 1 continue to show up in this week’s forecasts. Therefore, we officially name the two events as STRAT_B and STRAT_C in this week’s forecasts:
STRAT_B (11/01-11/06): STRAT_B is expected to peak in the first week of November. Its impact will be limited because STRAT_B is a minor stratospheric PULSE event. As a result, we expect the cold air surge associated with STRAT_B will only affect northern latitudes of North America and Eurasia.
Two weeks after STRAT_B, a new round of cold surges are expected on their way, due to a major peak event of stronger stratospheric mass transport into the polar stratosphere, which is named as STRAT_C and is expected to occur in the third week of November. Near the end of the third week and beginning of the four week of November, we expect a major cold air outbreak event to circulate much of the area of mid-latitudes, particularly over North America. Therefore, STRAT_C may affect pre-Thanksgiving holiday travel.
Follow up on Forecast Made in Previous Week:
STRAT_A (10/22-10/25), first forecasted on September 25 to occur during the time range from October 21 to 28 and such range was narrowed down to October 25-28 in last week’s forecasts, is shifted toward the earlier half of the original time range, namely 10/22-10/25. Within a few days after the peak date of STRAT_A, we expect cold surges to take place, resulting in below-normal temperature mainly over the northeastern region of North America and the Siberian region of Asia. Since the STRAT_A is going take place earlier, the Halloween weekend may come back to the mild and warm period after the cold surge event associated with STRAT_A.