Science: Funny Winter

This winter the western half of the U.S. got its worst weather in history, and the eastern half some of its mildest. The U.S. Weather Bureau, looking on the dark (or cold) side, regards the 1948-49 winter as the hardest ever—worse in most respects than the winter of 1937. The records are not all in (spring does not come officially until March 21), but already the bureau has a fine collection of weather aberrations and never-befores.

In February, forsythia bloomed on Long Island, Maryland's spring peepers started to peep, and shirtsleeved New Yorkers lay on green grass in Central Park. In violent contrast, Southern Californians shoveled snow this winter for the first time in their lives, and the stiff bodies of frozen cattle broke the blades of rotary snowplows in blizzard-bound Montana.

In southern Louisiana, Spanish moss hanging from the live oaks stiffened into icicles for the first time in the memory of the oldest inhabitants. In Pasadena, the palms were loaded with four inches of white stuff which the residents recognized as snow. San Diego, one jump from the Mexican border, had a little snow too, the first since the earliest weather records (1850). Waco, Tex. had the coldest day (5° below zero) since 1899; Pocatello, Idaho, had the coldest day (31° below) ever recorded.

Great Blizzard. The cold in the west was not the bright, dry cold that westerners pretend to enjoy so much. It snowed & snowed & snowed. Bitter cold and roaring wind turned the snowstorms into blizzards. The great blizzard of early January was the worst that ever hit the high-plains states. In South Dakota the Black Hills region got 50 inches of snow; Deadwood got 77 inches. Total snowfall for January in western Nebraska averaged 70 inches.

What made the winter so odd? The Weather Bureau, which would like everyone to remember that it saw just such a winter shaping up as early as November, says that the same basic condition caused both the western cold and the eastern warmth. The villain, says William H. Klein of the bureau's Extended Forecast Section, was an "excess of [air] mass" in the subpolar regions of the Western Hemisphere and a "deficit of mass" in the subtropics. This unbalanced condition, favoring the southward movement of cold air, upset the whole air circulation of the U.S.

Weak Westerlies. The mid-latitude westerlies, which normally blow across the country toward New England, were comparatively feeble this year. Their weakness allowed cold air to sweep down unchecked from Canada, keeping warm winds away from the western states and bringing them abnormally cold and stormy weather.

The failure of the westerlies had the opposite effect in the east. A high-pressure area (the Bermuda High) was unusually strong and hung persistently off the coast. The wind circulating clockwise around it brought warm, moist air from over the Gulf Stream. Unchecked by the westerlies, it penetrated far into the interior, keeping the western cold away and giving the eastern U.S. a balmy "maritime" winter.