What we do: We are making sub-seasonal forecasts for time periods of high probability of cold air outbreaks in Eurasia and North America 30-40 days in advance. We issue such forecasts on a weekly basis and this website is updated around Thursday each week.
New Feature: Maps of probability of cold surface temperature anomalies over both North America and Eurasia continents in the vicinity of forecasted stratospheric PULSE events
New Forecast Made on December 17:
No new forecast is made this week.
Follow up on Forecast Made in the Previous Weeks:
STRAT_D (12/11 – 12/18), first forecasted on 11/20, and later revised on 12/03, is happening. The first peak of STRAT_D occurred on 12/11 with a net air mass transport into the polar stratosphere about 0.5 trillion tons per day, and the second peak, which is the main peak of STRAT_D originally forecasted on 11/20, is expected to occur on 12/16 with a 0.9 trillion ton per day of air mass transport. The impact of the first peak of STRAT_D was felt mainly over North America: a winter storm named as Caly swept through the continent, bringing heavy snow and imposing hazard conditions to people, causing nearly 80% area to plunge below normal temperatures. The main peak of STRAT_D on 12/16 will affect both continents: more than 80% of area over North America and 55% of area over Eurasia will plunge to cold temperature anomalies. Associated with the main peak of STRAT_D is a newly named winter storm, Decima, which is bringing extreme below-normal temperature to Western United States and heavy snow to the Northeastern United States.
STRAT_D1 (12/24 – 12/27), first forecasted on 11/25, and later revised on 12/03, is still expected to be a long-lasting, twin-peaked event. STRAT_D1 is expected to transport up to 0.7 trillion tons air mass per day into the polar stratosphere. Based on the map of probability of below-normal surface temperature, STRAT_D1 will mainly affect northern latitudes of the Eurasian continent and western half of North America, causing below normal temperature conditions up to 55% of area.
STRAT_E (01/08 – 01/13), first forecasted on 12/03, is still expected to occur between 01/8 and 01/13 with a peak on 01/10. We believe STRAT_E is going to be a strong event with a peak net mass transport into the polar stratosphere over 1.0 trillion tons per day. The map of probability of below-normal surface temperature shows high likelihood for strong cold air outbreaks to take place over the entire Eurasian continent, as well as the Western United States.
STRAT_F (01/23 – 01/28), first forecasted on 12/10 with a 45 days lead. STRAT_F is still expected to occur on time. It looks to be a twin-peaked, strong event with a peak net mass transport into the polar stratosphere about 1.0 trillion tons per day. We expect strong cold air intrusions over the North American continent, especially over Canada and west coast of the United States during the last week of January. The northern part of Eurasia (north of 45N) is also expected to experience below-normal temperatures (see map forecasts).
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