Newspaper article The Christian Science Monitor

Unlocking the Storm Code ; Figuring out Atmospheric Triggers for Warm-Weather Storms Could Improve Forecasts and Help Prevent Billions in Damage Annually

Newspaper article The Christian Science Monitor

Unlocking the Storm Code ; Figuring out Atmospheric Triggers for Warm-Weather Storms Could Improve Forecasts and Help Prevent Billions in Damage Annually

Article excerpt

On a warm July morning over the Great Plains, the sky is a meteorological nursery dotted with bundles of infant clouds.

Nourished with warmth and water vapor, some of these infants will grow into towering giants that can unleash hail or heavy rain, or spawn tornadoes and flash floods. Yet estimating when and where such warm-weather storms will appear and the type and intensity of what they drop is one of the toughest challenges in weather forecasting.

Now, however, an international team of atmospheric scientists is poring over data that could help uncover atmospheric triggers for warm-weather storms and determine which high-tech tools would be most

effective in detecting them.

The hope is that by improving forecasts for these storms, the nation can reduce the deaths and wreckage from events such as flash floods, which inflict more than $5 billion a year in damage and kill more people than hurricanes, tornadoes,7 windstorms, or lightning.

Where today's flash-flood forecasts have a lead time of less than an hour, for example, the team hopes its results will help extend that to at least several hours.

The research effort, known as the International H2O Project (IHOP 2002), is part of a national program aimed at improving precipitation forecasts.

Over the years, these efforts have led to more-accurate forecasts of snowfall amounts and rainfall estimates from storms along broad weather fronts. But the capability to forecast clearly the location, amount, and intensity of rain or hail from warm-weather storms that seem to pop up out of nowhere lags far behind.

"It's really miserable. We are failing," laments Steven Koch, an atmospheric scientist at the National Oceanic and Atmospheric Administration's Forecast Systems Laboratory in Boulder, Colo.

The reasons are many, researchers say. For example, the conditions that trigger warm-weather, or convective, storms can occur in volumes of the atmosphere too small to be picked up by computerized forecasting models. Moreover, while researchers can cite a number of conditions necessary for triggering warm-weather storms, they are less certain about which condition or combination of conditions are the most important to spot and track.

But at the most fundamental level, researchers still have a difficult time measuring and tracking changes in the amount of water vapor in the atmosphere - the vapor the fuels these storms.

From mid-May to the end of June, some 100 researchers and technicians from the US, Canada, France, and Germany marshaled a small squadron of research aircraft, mobile radars, radar-like laser detection systems known as lidar, and instrument-laden cars and vans in an attempt to fill this scientific void.

In the past, scientists have chased roiling masses of clouds to study the formation and evolution of storms. For IHOP 2002, however, the scientists opted to chase the invisible.

They focused "on the moisture content in preconvective situations, when there's nothing out there" in terms of storms, explains Tammy Weckwerth, an atmospheric scientist at the National Center for Atmospheric Research (NCAR) in Boulder, Colo., and one of the project's leaders.

Although it will take several years for the scientists to digest the data the $7 million research project has gathered, they note that the field measurements already have yielded intriguing observations.

For example, researchers had held that convection typically begins on the boundaries between contrasting air masses. …

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