Winter wonderland of forecasts is cloudy--but for promise of cold

November 01, 1990|By Luther Young

This much is certain: Winter in Maryland will feature some cold, some snow and lots of weather not predicted in brave and hopeful pre-season forecasts.

Yes, it's that season again. The National Weather Service issued a 90-day winter "outlook" this week. The almanacs are on the newsstands. And the woolly bear caterpillars have spoken in Hagerstown.

"Forecasts in the cold part of the year are better than any other season," said meteorologist Robert Livezey of the NWS's prediction branch, who nonetheless added that the long-range outlook "really isn't that useful, not like 24- or 48-hour forecasts."

While the 90-day winter outlooks average 65 percent accuracy for temperatures and 55 percent for precipitation, the short-term predictions can top 90 percent accuracy, he said. And the weather in some areas, such as the Southeast, is easier to forecast than in others.

Maryland falls in the middle of forecasting difficulty. For the months of November, December and January, the outlook for this area calls for a 60 percent to 65 percent chance of above normal temperatures.

But Dr. Livezey and his colleagues at the Climate Analysis Center in Camp Springs were unable to fathom any precipitation trends, giving equal chances for a dry or wet winter.

If that sounds like the 50-50 probability of a coin toss, you're right, and that uncertainty in long-range official forecasts gives almanacs their continued popularity.

"The universe is really very complex and chaotic and hard to deal with," Dr. Livezey said. "But some people like to think it's simple and orderly and predictable, and I guess that's what gives almanacs their appeal."

The Hagerstown Town and Country Almanack, published continuously for 194 years, carries "prognostications" made 18 months in advance by William O'Toole, a professor of mathematics and computer science at Mount St. Mary's College in Emmitsburg.

Dr. O'Toole predicts a local winter season of 126 days, from Nov. 27 to April 1, with two "very cold" months: December and February. Temperatures in November, January, March and April should be average or above average, he says.

A snowstorm on Dec. 23 and 24 will result in "a very nice white Christmas," the almanac predicts. Snowfall for the winter should be below normal.

The Hagerstown almanac claims 65 percent accuracy for its 12-month forecasts over the past 21 years, although last winter did nothing to boost that average.

For the six months from November 1989 through April 1990, prognostications for above or below normal temperatures and precipitation for each month were accurate only three times in the 12 categories.

As for the National Weather Service, it accurately forecast the mild January, February and March of 1990 and the minimal snowfalls during those months. Total snowfall for the season at Baltimore-Washington International Airport was 17.3 inches, 4 inches below normal.

But none of the predictions foresaw the brutal December in Maryland last year, more than 11 degrees colder than normal for the month. There were 14 days when daytime temperatures never climbed above freezing at the airport.

"We had absolutely no means to anticipate that," said Dr. Livezey. "No one did. It was just one of those events that was off the charts."

Tell that to the woolly bears, the caterpillars that become tiger moths after lending their fuzzy fur coats to the art of winter weather forecasting.

Last year, a thick head band and narrow tail band foretold the severe early winter and the mild remainder of the season, according to Gerald Spessard, business manager for the Hagerstown almanac, which has sponsored woolly bear contests for the past eight years.

This year? The markings indicate a winter "a little more severe dTC than normal" from mid-November to mid-January, then a warmer second half with "a lot of rain, not a lot of snow."

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