# Predicting a Snow Storm

## Atmospheric Scientists Make Snowfall Prediction More Accurate with Mathematical Formula

April 1, 2011

Atmospheric scientists developed a mathematical formula that uses the amount of water in snow to predict snowfall more accurately and with greater ease than traditional methods. The National Weather Service started using the new prediction model this year to help cities better prepare for winter weather conditions.

## Science Insider

ABOUT SNOWFLAKES: Snow is a form of precipitation. Rising warm air carries water vapor high into the sky, where it cools and condenses into water droplets. Some vapor freezes into tiny ice crystals, which can attract cooled water drops to form snowflakes. As snowflakes fall, they may meet warmer air and melt into raindrops, unless temperatures are below freezing close to the ground: then we get snow. A snow crystal is a single crystal of ice. It usually forms the shape of a hexagonal prism, but as the crystals grow, branches sprout from the corners, creating more complex shapes. Conditions such as temperature and humidity in the atmosphere can influence a snowflake's shape.

WHAT'S THE FORECAST: Weather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location. Humankind has attempted to predict the weather since ancient times. For millennia people have tried to forecast the weather. In 650 BC, the Babylonians predicted the weather from cloud patterns. In about 340 BC, Aristotle described weather patterns in Meteorologica. Chinese weather prediction lore extends at least as far back as 300 BC. Ancient weather forecasting methods usually relied observed patterns of events. For example, it might be observed that if the sunset was particularly red, the following day often brought fair weather. This experience accumulated over the generations to produce weather lore. Today, weather forecasts are made by collecting data about the current state of the atmosphere and using computer models of the atmospheric processes to project how the atmosphere will evolve.

The American Meteorological Society, the American Mathematical Society, the Mathematical Association of America, the American Statistical Association and the Society for Industrial and Applied Mathematics contributed to the information contained in the TV portion of this report.

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Jim Steenburgh
Atmospheric Sciences
University of Utah
jim.steenburgh@utah.edu

Mike Breen and Annette Emerson
American Mathematical Society,
paoffice@ams.org
1-800-321-4267

Steve Pierson
American Statistical Association,
pierson@amstat.org
703-302-1841

American Meteorological Society
617-227-2425

Ivars Peterson
Mathematical Association of America,
ipeterson@maa.org
1-800-741-9415

Karthika Muthukumaraswamy
Society for Industrial and Applied Mathematics
karthika@siam.org
267-350-6383