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Spokane

More precise forecasts a click away

Wed., April 18, 2007, midnight

Say you are planning a hunting trip to North Idaho or a camping trip somewhere in the backcountry of the Pacific Northwest.

Getting an accurate weather forecast for your favored spot has long been difficult.

Now there is a tool to solve that problem.

The National Weather Service recently unveiled a fine-tuned computer system that gives detailed “point forecasts” for virtually every point on the U.S. map with the exception of Alaska. The forecasts are based on a map divided into 2.5-kilometer squares.

Anyone can access these forecasts on the National Weather Service’s Web sites at www.weather.gov/, or for the Inland Northwest at www.wrh.noaa.gov/otx/.

For users, it’s simple: Click your cursor at a point on the main map, and voila, you get a detailed seven-day forecast. You can fine-tune the location by moving the cursor and clicking again until you find the grid point that best matches your desired location. Each forecast gives location and elevation.

While rain might be predicted in Sandpoint, the forecast could be calling for snow in the nearby mountains depending on which grid point is selected.

“One little click away and you can change your rain to snow,” said Ron Miller, science operations officer for the Spokane office of the weather service.

The forecasts also give humidity, wind, air pressure, dew point, wind chill, chance of precipitation, sky cover, snow amounts and visibility.

For people who live on Mount Spokane, Browne Mountain or any rural location, the system provides greater accuracy than text-based forecasts.

One backcountry ski service in North Idaho found the point forecasts so useful they linked one mountain grid point to their Web page for a more accurate skiing forecast.

Anyone can do the same thing by finding the grid that best matches their home and saving it to their Web “favorites.”

The system took the weather service five years to develop and required a quantum change in how individual forecasters do their jobs.

“There was definitely a learning curve,” said Todd Carter, information technology officer for the weather service in Spokane.

Forecasters now have to visualize concepts across a full map rather than thinking in text boxes that give forecasts for wider areas, he said.

“I think it’s a good product,” he said. “I think it could be improved.”

Carter said that the system will get better as refinements are made in the computer models that form the basis for the forecasts. He also anticipates improvements in the way the data is presented to the public. For example, maps in the future will offer layers of information that can be added or subtracted.

The forecasts start with sophisticated computer models, and those are then automatically adjusted for elevation and local climate variations. Then, forecasters manipulate the maps to account for additional variations, such as the risk of fog in cold narrow valleys. Forecasters use their knowledge of the region for fine-tuning.

Each grid point does not get a unique forecast. Rather, specific input is applied at the weather office across broad groups of grid areas to improve forecasts for each point.

“We fully recognize it won’t cover every situation,” said Miller, adding the improvements, nonetheless, are dramatic and promise to get better.

“It’s definitely a marriage between us and the (computer) models,” Miller said.


 

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