Weekly Highlights

• The STRAT_C event will peak on November 11, within the window period that we forecasted on October 6.  The STRAT_C event is responsible for the cold air outbreaks in this weekend and the first half of the coming week.

 

• Cold air outbreaks are forecasted around the week of November 18, following the new stratospheric event, STRAT_C1, which is anticipated to peak around 11/18 (this is the first time we forecast this STRAT event).

 

• Due to the back-to-back week long STRAT events (C and C1), we expect this November is going to be a below-normal cold November. 

 

• We have downgraded the duration of the STRAT_D event that was first forecasted on October 28.  Now we forecast the STRAT_D is only a week-long event with a peak around December 2.  We still anticipate a series of waves of cold air circulating mid-latitudes between the last week of November and the first week of December.

 

• We tentatively forecast the STRAT_E event to take place in the week around of Christmas.

 

• Due to the short duration of the STRAT_D event, and lack of a major stratospheric event after STRAT_D till in the week around of Christmas, our new forecast calls for below-normal temperatures in the first week and the last week of December and mild winter in the middle two weeks.

 

Forecasts made on November 6, 2014

• The STRAT_C event is expected to peak on 11/11 at a rate of over 500 billion tons per day.  As more air mass is transported into the polar stratosphere, the cold air branch starts strengthening with a peak mass transport out of the polar circle around 11/13 at a rate of 8-11 trillion tons per day, nearly twice as strong as the climatology.  Therefore, this event is expected to be a monster event and will lead massive cold air outbreaks in both continents. This event was first forecasted on 10/06/14, giving us a lead-time of more than 30 days.

 

• There is a new STRAT event before the STRAT_D. The new event is named as STRAT_C1, and is expected to be a prolonged event (from Nov. 18 to Nov. 23) with peak mass transport into the polar stratosphere at a rate over 500 billion tons per day.  However, we expect this event would not cause major cold air outbreaks over the two continents since the cold air branch does not appear to be intensified greatly.

 

• Due to the back-to-back week long STRAT events (C and C1), we expect this November is going to be a below-normal cold November.  

 

• On Oct. 28, we predicted the STRAT_D event to take place in the last week of November and first two weeks of December.  We now no longer forecast it as a prolonged event consisting several peaks of strong mass transport into the polar stratosphere.  Based on the latest forecasts, we expect the STRAT_D to be a week long event which will peak around 12/2/14 at a rate of about 500 billion tons per day.  Although we have downgraded our forecasts for the STRAT_D event (a week long instead of three weeks), we still anticipate a series of waves of cold air circulating mid-latitudes between the last week of November and the first week of December.

 

• After the STRAT_D event, there seems no other major STRAT event till the second half of December.  Therefore, we expect that second week of December is going to be mild, which could extend to the third week of December.  At this moment, we are not ready to formally predict when the STRAT_E event is going to take place. But we tentatively predict it will take place in the week around Christmas time.

 

• Due to the short duration of the STRAT_D event, and lack of a major stratospheric event after STRAT_D till in the week around of Christmas, our new forecast calls for below-normal temperatures in the first week and the last week of December and mild winter in the middle two weeks.