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    Brett Anderson

    An Exciting New Tool for Seasonal Forecasting

    11/14/2012, 9:53:55 AM

    While I was out in Colorado last month for the Climate Prediction Center's (CPC) annual conference, I was introduced to their relatively new and experimental U.S. National Multi-Model Ensemble forecast system, otherwise known as the NMME.

    Phase 1 of this multi-model ensemble was developed in 2011.

    According to the CPC, the multi-model NMME, while only a year old, has proven to produce better long-term (months/seasons) prediction quality on average than any single model ensemble. This makes a lot of sense when you think about it.

    The NMME factors in the known strengths and weaknesses of several U.S. forecast models, including one from Canada, then it applies a particular weight to each model and averages it into what becomes the NMME.

    There is also an International Multi-Model Ensemble forecast system, which combines several international models such as those from the UK and France. By the way, the ECMWF is one of those models which is factored into the IMME, but not the NMME.

    By the way, the NMME and IMME update once a month.

    Below is the latest NMME and IMME North American monthly average temperature anomaly forecasts for December, January, February and March. Keep in mind this is an experimental multi-model ensemble forecast and not an official forecast from AccuWeather.com or NOAA.

    Images courtesy of the Climate Prediction Center.








    We will look at the precipitation anomalies later this week.


    El Nino or not?

    Below is the latest multi-model ensemble forecast for El Nino Southern Oscillation (ENSO). Basically, an El Nino is a several-month period where the index is at +0.5 or higher, while a La Nina is -0.5 or lower.


    As you can see, the ensemble average projects very little change in the ENSO through spring with near-neutral or just shy of weak El Nino conditions.

    The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com


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