The National Weather Service will begin issuing yearlong nationwide weather forecasts in January, but don't expect the ultra long-range predictions to pinpoint the best day to get married or the prime time for vacation.
The first experimental 365-day forecast has just been completed by a small group of meteorologists and climatologists at the Climate Analysis Center in Camp Springs, Md., a Washington suburb.The group is headed by veteran long-range forecaster Huug van den Dool.
Experimental 365-day forecasts will continue for the remainder of the year and the first official prediction will be issued around New Year's, van den Dool said. Updates will be issued monthly.
The predictions will be very limited. They will say temperatures and precipitation will be above or below normal in each area of the country.
"We won't be able to predict a Midwest flood or a California drought," said Ronald McPherson, director of the National Meteorological Center. "But we think the forecasts will benefit farming, tourism, (electrical) power generation, transportation and other industries."
McPherson said state and city governments may use the forecasts to determine how much sand and salt they should purchase for use on icy and snowy roads. National Weather Service Director Elbert Friday said the year-long forecasts should help farmers determine what crops to plant.
"This is the beginning of a new era of weather forecasting," McPherson said. "It's one of the most exciting forecasting events I've ever seen."
Van den Dool said the new forecasts will be limited to areas where the year-long trend seems fairly clear.
"There will be lots of no-calls, lots of holes in areas that we're not sure of," he said.
The forecast is one of the benefits of a new Cray C-90 supercomputer unveiled Friday at the National Meteorological Center in Suitland, Md., a number cruncher that can make 15 billion calculations per second.
Using the new Cray and a four-year-old computer, the forecasters can easily handle an array of daily, weekly, monthly and seasonal weather forecasts and still have power to spare for the 365-dayer.
Friday said the supercomputer also will improve short- and medium-range forecasts by speedily analyzing thousands of worldwide weather observations.
"Our short-range forecasts will more accurately predict when precipitation will begin and end and how much precipitation likely will fall," he said.
The computer also will improve the monitoring of storm systems, air masses and jet streams, Friday said. As a result, medium-range forecasts will be expanded from the current 10-day span to 16 days.