What Happened to Normal?
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First there was El Niño. From California to Texas to Florida, El Niño was blamed for the wet, wild winter of 1997-98. Then, right on its heels came La Niña, the sibling that's brought dry, mild weather to the Southwest and temperature ups and downs to the East. Isn't there such a thing as normal anymore? Hi, I'm Dave Thurlow for the Mount Washington Observatory and this is The Weather Notebook.

El Niño occurs when the surface waters warm above normal in the eastern Pacific Ocean, close to the equator. La Niña means that the same waters are running cooler than normal. But, in the long term, this part of the Pacific runs close to normal (there has to be a normal) about half the time. These neutral periods tend to be interspersed between El Niños and La Niñas, as if the ocean were taking a break.

Normal phases in Pacific temperatures tend to last about a year, although there have been particularly long normal phase of up to 5 years. Recently, the Pacific has been swinging quickly from one event to another. We went right from the record El Niño of 1997-98 to the current La Niña without a real break in between.

It's still not clear whether we'll go right to another El Niño this fall or enjoy a neutral period for a year or two. Spring is when computer models have the hardest time reading the Pacific's signals. Like us, they'll just have to hang in there a while longer to see what's going to happen.

Thanks to contributing writer Bob Henson. The Weather Notebook is underwritten by Subaru with major support provided by the National Science Foundation.