What technology does NOAA use to forecast and warn for winter storms?


NOAA National Weather Service meteorologists rely on a number of tools to make the best winter weather forecasts and warnings possible. Forecasts are largely based on information from numerical weather prediction models, while warnings also incorporate information from observations. Small variations in near surface temperature – even tenths of a degree – can determine whether precipitation will fall as snow, sleet or freezing rain, and this sensitivity makes forecasting these events a challenge.

Surface Observations
NOAA has weather stations around the U.S. constantly taking measurements of temperature, humidity, wind and pressure. Forecasters use this data to predict the development or track the movement of a storm and to predict what type of precipitation will fall.

Upper Air Observations
Weather balloons launched by National Weather Service forecast offices every 12 hours, measure the conditions in the atmosphere as they rise. The data is beamed to the ground to be analyzed and fed into numerical forecast models, so forecasters learn how the storm will behave, including where snow, sleet or freezing rain might fall.

Numerical Weather Prediction Models
On a daily basis, NOAA runs several numerical weather prediction models to provide forecast guidance out to 14 days for the United States. These forecasts provide information on the expected temperature, precipitation type/amount, and winds, which human forecasters use to make forecast and warning decisions. 

Meteorologists study the images from NOAA satellites to understand the big picture. They look for features that signal winter storms, such as a large distinct comma-shaped cloud mass that can encompass several states. They watch how these features move over time to help forecast where the storm is heading next and when it will arrive.

Radar gives clues about whether rain, sleet or snow is falling. Sleet shows up well on radar because it is a solid pellet of ice. Sometimes it can be mistaken for heavy snow on radar, so forecasters use both surface observations and radar to make accurate forecasts and warnings.

Scientists at NOAA's National Severe Storms Laboratory develop new weather radar techniques to help forecasters detect different types of winter precipitation. NSSL researchers make it easier for forecasters to handle the vast amount of data available to them, especially during hazardous weather.  Both NSSL and NOAA’s Earth System Laboratory work to refine and improve computer predictions of the weather. ESRL also studies how icing can form in clouds, and how these conditions can be detected to assist pilots in avoiding hazardous air space.

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This month’s expert:  Dave Stensrud, NOAA National Severe Storms Laboratory.

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