Miguel Pierre

The PDO, MJO and Their Potential Influence In This Upcoming El Nino Winter

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When a forecaster makes a seasonal outlook or forecast, he/she must consider all possible climate drivers and variables with teleconnections. Previous articles such as Monitoring the Stratosphere and The Importance of High Latitude Blocking in Upcoming Winter discussed the variables that were considered for our winter forecast, and how much weight was put into each. Now it’s time to look at some other climate patterns in Pacific.  For example, this year’s strong El Nino is something you probably have heard the most about.

There is little doubt that a strong El Nino has a large influence over the atmospheric pattern in the Pacific Basin. Some have used the term “Godzilla El Nino” to describe this year’s phenomenon; which, while catchy, could perhaps be unneeded sensationalism. Another common thought is that after 1997-98 — the last “Super” El Nino, which was an extremely warm and snowless winter — that this winter will also be very warm and snowless in the Northeast. However, there are other climate patterns in the Pacific that can still have influence, even in the midst of such a strong El Nino, which makes such strongly-worded conclusions about this winter not justified.

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Miguel Pierre

An Early Look at the Pattern for Thanksgiving Week

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The days before Thanksgiving are some of the busiest travel days of the year, meaning that the weather has an even larger impact than usual. Accordingly, we have already been keeping an eye on model guidance for this period. While it’s still too far out to forecast with confidence, our November outlook did show some cooling to near average later this month, with an overall warm month in the means. Not coincidentally, there does appear to be some kind of pattern change on the model guidance that has piqued our interest.

Forecast models and their ensembles have consistently showed above normal 500mb heights developing early next week over the Northeast Pacific. These heights extend up to Alaska, which causes the Eastern Pacific Oscillation (EPO) to go into its negative phase. Another ridge initially over the eastern US this will be forced to build into the Davis Strait and Greenland — temporarily bringing the North Atlantic Oscillation (NAO) down into its negative phase as well. This pattern will bring one or two cold shots into the Western and Central US on Thanksgiving week. The main questions are: a) will this airmass make it into the Eastern US, b) if so, how much (if any) modification will there be, and c) how long will this colder regime last?

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