Glossary Of Climate Forecasting Terms

Hello everyone!

While I usually stay away from long term climate type forecasts, I do usually post winter forecasts in the fall that use some special terminology. Also included here are the teleconnections sometimes used midwinter to sniff out which weeks are more likely to see storms.


AO: Arctic Oscillation. A swinging pendulum of sorts in the Arctic that determines how deep our supply of cold air is. A negative AO opens the spicket in terms of the cold air and a positive AO will shut the supply right off. This is one of the main teleconnections and forecasts for it can be found on the CPC site.

ENSO: El-Nino Southern Oscillation. Basically describes the location and strength of a pool of warm water that sloshes back and forth across the equatorial Pacific. Can have significant impacts on our weather as well as the weather across the globe.

MJO: Madden Julian Oscillation. The MJO is basically a measure of how intense tropical rainfall is. Believe it or not, this has significant ramifications for our weather here in Maine.

NAO: North Atlantic Oscillation. One of the main teleconnections, the NAO can have significant impacts on the weather here in New England.  The NAO represents a north/south swing in pressure across the Atlantic. When the NAO is in a positive phase, upper level ridging takes over Eastern North America and brings warmer temperatures. The opposite happens when the NAO is negative. While the NAO can have big impacts on our weather, other teleconnections can negate the effects of the NAO.

PNA: Pacific North American teleconnection. An index derived from several SST readings and surface pressure readings across North America and the North Pacific. A positive PNA is conducive for cold and snow in Maine.

SST’s: Sea Surface Temperatures. Pretty self explanatory, the temperature at the surface of the ocean. These can be critical in both climate forecasting as well as forecasting coastal weather where the ocean plays a big part in precip type and temps.


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Reliably hype-free weather info for Western Maine and New Hampshire from amateur forecaster Jack Sillin

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