The 2015-2016 Forecast Season has begun!
New Forecasts Made on March 3：
New Forecasts Made on March 3：
No new forecast is made in this week.
The 2nd complete breakup event of polar vortex is going to take place after STRAT_N, which appears to be the final stratospheric warming event in the 2015-16 winter:
The strong event of STRAT_L, which took place during the period from 02/18 to 02/27, with the peak intensity of 1.9 trillion tons per day of warm air mass transport into the polar vortex in the stratosphere, has already weakened the stratospheric polar jet. As shown in the NCEP CPC’s stratosphere-troposphere monitoring website, the polar jet is less than 15 m/s today. The next stratospheric PULSE event, namely STRAT_M, will occur in the period of 03/03-03/08. But since the STRAT_M looks to be a very weak PUKSE event, it would not further weaken the stratospheric polar vortex very greatly. The next stratospheric PULSE event, namely STRAT_N, appears to be a very strong event with peak intensity of 1.2 trillion tons per day. It is almost certain that the polar vortex will go through a complete breakup during the STRAT_N event. Therefore, we will witness the 4th stratospheric polar warming event in the winter of 2015-16 within a week, which is the 2nd complete breakup event of stratospheric polar vortex in this winter. We still forecast this will be the final stratospheric warming event in the winter of 2015-16.
Follow up on Forecasts Made in Previous Weeks:
The second peak of STRAT_L, first forecasted on January 22 to occur around 02/27, has been materialized. It was indeed the strongest event in the 2015-2016 winter, with the intensity of 1.9 trillion tons per day. The second peak of STRAT_L brought a round of cold air outbreaks over both continents, particularly over the mid-eastern regions of North America during 02/26-02/29.
STRAT_M (03/03-03/08) is going to take place in the same time period as we first forecasted on February 4. STRAT_M will have twin peaks, one on 03/03 and the other one on 03/06. According to the updated forecast data, STRAT_M is expected to be very weak and the second peak is almost merged into STRAT_N. Despite of the weak intensity, STRAT_M still relates with a stronger equatorward air branch of mass circulation in the troposphere, which will cause cold air surges over North America during the forecasted time period.
STRAT_N (03/09-03/13), first forecasted on 02/18 to occur during 03/14-03/18, is going to take place 5 days earlier than we forecasted, with its peak to occur around 03/11. We are upgrading the intensity the STRAT_N this week to have peak intensity as large as 1.2 trillion tons per day. As we mentioned above, STRAT_N will deliver the final punch to the polar vortex, leading to a complete breakup of the polar vortex. Associated with STRAT_N are continental wide below-normal temperatures over mid-latitude region. In addition, STRAT_N will be driven mainly by stronger wave activities of wavenumber 1 with minor contributions from wavenumber 2. Therefore we expect that cold temperature anomalies will be more pronounced over North America than Eurasia.