16 October 2014

The Winter Forecast Is Out, and It’s Probably Wrong!

Posted by Dan Satterfield

From NOAA's Climatre Prediction Center

From NOAA’s Climatre Prediction Center


NOAA Released the 2014/2015 winter forecast today and it is probably wrong. I’m not taking a slam at NOAA here, they will also admit to you that the odds are that this forecast will not be correct. The truth is, that any forecast beyond 5-7 days has very low skill. That said, we cannot learn to make long-range forecasts unless we try, and that’s how science works: we make predictions based on theory and observations, and test them!

A "Modoki El Nino" will not bring relief to the California drought. It's possible we could see this type of El Nino this winter.

This image from the Japanese Metr. Agency shows that Modoki El Nino events (on average) bring very dry weather to California. It’s possible we could see this type of El Nino this winter.

Most meteorologists feel that these winter forecasts are not really good enough for prime time, and it’s good to remember that last year’s forecast was badly wrong. The factors we are looking at this year are a possible El Nino, but the strength of the El Nino looks weak as of now, and there is high uncertainty in just how it will end up impacting our winter weather. There is also the possibility of a rarer type of El Nino called an El Nino Modoki which brings rather different conditions (especially to California). Modoki means same but different in Japanese, and this type of El Nino is characterized by warming waters in the Central Pacific more-so than along the Equator off Peru.

This forecast from NOAA is based on having a weak regular type El Nino, and it’s also based on ocean temperatures in the Pacific and Atlantic. Looking at patterns of ocean temperature anomalies, and comparing them to similar ones in past winters is also valuable, and the forecast is also based on this as well (especially so for Alaska). Another technique is to look at October snowfall in Siberia, because heavy snow in October there can lead to a cold and snowy winter in the Eastern U.S. So far this has been a snowy October in NW Russia, and this signal partially conflicts with the prediction based on an El Nino!

All of this means high uncertainty in what the winter will bring, so take this forecast as an educated guess at best!

PS: Seth Borenstein the AP’s excellent science reporter has a good piece on this as well today. It’s well worth a read.