Winter Weather Research at the National Severe Storms Laboratory
Improving understanding and forecasts of hazardous winter storms
NSSL is about more than just tornadoes and thunderstorms--we are also a focal point for National Oceanic and Atmospheric Administration (NOAA) research on hazardous winter weather. In addition to conducting research on convective storms, NSSL scientists study blizzards, freezing precipitation, and heavy snow. Radar research and development efforts also are being conducted to improve the discrimination of rain from snow, the quantitative measurements of snowfall, and the small-scale structure of winter-weather systems.
The Wasatch Mountains of northern Utah served as a backdrop for IPEX.
Radar cross section of a snowstorm that produced over 4 feet of snow in the Wasatch Mountains in northern Utah. (larger view)
Freezing drizzle is most likely to occur in central North America. (larger view)
Numerical models are used at NSSL to improve precipitation-type forecasts. (larger view)
The OU Doppler-on-Wheels and the NSSL Mobile Laboratory take measurements of electrified snowstorms in Idaho during the Intermountain Precipitation EXperiment. (larger view)
NSSL explores new techniques for the numerical modeling of winter storms. (larger view)
A Salt Lake City NWS hydrologist and NSSL meteorologist check remote weather data collection instruments.
The
Intermountain Precipitation Experiment (IPEX)
IPEX is a research program designed to improve the understanding, analysis,
and prediction of precipitation and precipitation processes in the mountains
of the western United States. Over 30 scientists from NOAA and the Universities
of Utah, Oklahoma, and Nevada collected data in February 2000 using research
aircraft, mobile radars, and weather balloons. Analysis and interpretation
of this data will allow project scientists to examine the factors controlling
the distribution and intensity of snow across narrow, steeply sloped mountain
ranges like the Wasatch Mountains.
PAYOFF: The knowledge gained through analysis of IPEX datasets conducted by NSSL scientists will lead to better forecasts of deadly winter storms in the western United States
MORE INFORMATION:
http://www.nssl.noaa.gov/teams/ipex/
Precipitation
Type
Predicting the type of precipitation (rain, snow, freezing rain, or sleet)
can be a difficult forecast challenge. A first step in such predictions
is understanding the climatological distribution of precipitation type.
NSSL scientists are working with collaborators at the National Center
for Atmospheric Research, Environment Canada, and the University of Oklahoma
to compile such information for North America. The next step to improve
forecasts is to develop algorithms for the prediction of precipitation
type. The goal of the Precipitation-Type Algorithm Experiment (PTAX) is
to determine the quality of existing algorithms and investigate ways to
display the results using probabilities. Other research at NSSL showed
the importance of falling snow melting aloft to changing the precipitation
type observed at the surface.
PAYOFF: Better information will help forecasters provide more accurate warnings for freezing rain, sleet, and snow.
MORE INFORMATION: http://www.cimms.ou.edu/~cortinas/preprints/avi09/9aviation.html
http://www.spc.noaa.gov/exper/ptax/
Winter
Lightning
Lightning is not restricted to summertime thunderstorms--sometimes snowstorms
can produce lightning as well. NSSL scientists have produced maps of wintertime
thunderstorms across the United States that show these storms occur most
frequently in the Great Plains. Another study provides guidance for forecasters
in Buffalo and Salt Lake City for determining the occurrence of lightning
associated with lake-effect snowstorms in their localities. Finally, during
IPEX, NSSL scientists and their collaborators obtained the first measurements
of the electric field inside winter storms over the United States.
PAYOFF: This research will improve the fundamental understanding of conditions that cause wintertime lightning.
MORE INFORMATION:
http://www.nssl.noaa.gov/mag/network.shtml
Banded
Precipitation Studies
When precipitation appears as organized bands on radar, accumulation at
the surface can be extreme. Researchers are looking at conditional symmetric
instability and frontogenesis as predictors of banded precipitation. Other
studies have shown that small-scale circulations in winter precipitation
can sometimes be similar to supercell thunderstorms.
PAYOFF: Studies of banded precipitation ultimately result in better mesoscale forecasts, traveler's advisories, and other detailed forecast products used by schools, businesses, transportation systems and local governments.
MORE INFORMATION:
http://www.nssl.noaa.gov/csi/
Improving
WSR-88D Snowfall Estimates
Data from IPEX and previous winter storm studies in the mountains of northern
Utah are being used to calibrate the nearby WSR-88D. A special network
of snow gauges provides snow water equivalent measurements that are used
to determine correction factors for remote radar precipitation estimates.
PAYOFF: More accurate radar precipitation estimates provide forecasters with better real-time water-equivalent snowfall rates. In addition, hydrologists and water managers (e.g., reservoir operators) have more accurate knowledge of potential snow melt run-off.
