Severe Weather 101
Currently, cloud-to-ground and intra-cloud lightning flashes are detected by more than 100 remote, ground-based sensing stations located across the entire U.S. and mapped in real-time by the National Lightning Detection Network (NLDN), a system owned and operated by Vaisala Inc.
These remote sensors send the raw data via a satellite-based communications network to Vaisala’s Data Center in Colorado. Within seconds of a lightning strike, the Data Center processes information on the location, time, polarity, and amplitude of each strike. The lightning information is then communicated to users across the country.
Lightning data collected by the NLDN is available for use in two different categories, real-time and archive. Real-time data subscribers receive live, second-by-second data on lightning activity within their own designated area of application, up to and including the 48 contiguous states. The NLDN’s vast archive data library contains over 2.5 billion lightning strokes and cloud pulses from 1989 to the present (2019), and grows by around 200 million events per year.
What we do: NSSL purchases and uses these detailed 3-D maps from the NLDN to learn how storms produce these flashes and how each flash type is related to other storm hazards. Scientists also use trends in the flash rate and location of each type of lightning to help identify the development of thunderstorms, the growth of updrafts, and the formation of precipitation and downdrafts.
Lightning Mapping Arrays provide three-dimensional mapping of lightning channel segments over the array. Up to thousands of points can be mapped for an individual lightning flash to reveal its location and the development of its structure. Research LMA's exist in Oklahoma, the Texas Panhandle. northern Alabama, Washington D.C., and Kennedy Space Center in Florida.
What we do: NSSL uses the LMA to investigate how lightning characteristics relate to updrafts, precipitation, and severe storm processes. Scientists also use the LMA to investigate using lightning data in weather forecast models.
The Geostationary Lightning Mapper (GLM) is an instrument to be installed on the next generation of weather satellites that maps total lightning (in-cloud and cloud-to-ground) activity continuously day and night over the Americas and adjacent ocean regions. The GLM will provide early indication of storm intensification and severe weather events.
It is anticipated that GLM data will have immediate applications to aviation weather services, climatological studies, and severe thunderstorm forecasts and warnings. The GLM will provide information to identify growing, active, and potentially destructive thunderstorms over land as well as ocean areas.
What we do: NSSL and partners are working on applications and products that will use the GLM.
Flashes have also been detected from space during the past few years by an optical sensor. This experimental satellite covers the earth twice a day in tropical regions. The satellite also detects flashes that do not strike the ground, but cannot tell the difference between ground strikes and cloud flashes.
Newer lightning mapping techniques show that some supercell thunderstorms have “lightning holes” where updrafts are located and precipitation is scarce. If these holes form, as suspected, just before a storm becomes severe, this information could alert forecasters to developing severe conditions.