Forecasting when and where tornadoes form is a challenging research topic. Many previous studies have focused on tornado formation over the Great Plains, but relatively little research has been conducted on this topic over the southeastern US. In this region, land surface characteristics differ considerably from the Great Plains. These characteristics include, e.g., more variable terrain and larger and denser forested areas, which can impact the development, structure, and intensity of severe thunderstorms and tornadoes.
To improve scientific understanding of severe weather and tornadoes over the southeastern US, ATDD researchers are participating in the Verification of the Origins of Rotation in Tornadoes EXperiment-Southeast (VORTEX-SE) with collaborators from universities, the National Severe Storms Laboratory and other NOAA laboratories. VORTEX-SE was conducted between March and May 2016 in northern Alabama and included the deployment of a suite of in situ and remote sensing instruments. ATDD researchers played a vital role in the experiment, contributing a Doppler wind lidar and two 30 foot towers outfitted with a suite of instruments to measure temperature, humidity, wind, incoming and outgoing shortwave and longwave radiation, pressure, rainfall, and sensible and latent heat fluxes. In addition to these platforms, ATDD’s collaborators deployed state-of-the-art Doppler radars (polarimetric C-band and X-band); ground-based remote sensing instruments, including Doppler wind lidars, microwave radiometers, and an Atmospheric Emitted Radiance Interferometer to provide continuous profiles of atmospheric temperature, moisture, and wind; and networks of surface meteorological observing stations.
Whereas all of these platforms operated continuously throughout the experiment, during periods that were conducive to the development of severe weather, ATDD researchers launched weather balloons and performed flights with a small Unmanned Aerial System (sUAS) outfitted with a suite of instruments to sample temperature and moisture gradients over the lowest few hundred feet of the atmosphere. During these same periods, other participants in VORTEX-SE launched additional weather balloons and deployed mobile radars. A total of four intensive observation periods were conducted during the spring 2016 experiment.
Many of these measurement platforms deployed during the 2016 experiment have been redeployed in northern Alabama during the 2017 VORTEX-SE campaign which runs from early March through early May. During the 2017 campaign, ATDD is launching weather balloons from two different sites, is performing flights with two sUAS’s, and will deploy a tethered balloon that is outfitted with multiple temperature/relative humidity sensors to sample the evolution of finescale temperature and moisture gradients near the surface prior to severe weather. In addition, a NOAA P3 aircraft equipped with in situ meteorological instruments and Doppler radar will be flown on select days.
Observations from the 2016 and 2017 experiments are being used to characterize the state and evolution of the atmosphere prior to severe weather and to initialize high-resolution computer simulations of the atmosphere. ATDD researchers are using these simulations to investigate the role of small scale features in the atmosphere, particularly those caused or modified by differences in land surface characteristics, on the development and evolution of severe thunderstorms and tornadoes.
The knowledge obtained from VORTEX-SE research is being used to advance scientific understanding of the physical processes that cause the atmosphere to be more conducive for tornado formation. Obtaining this knowledge helps to improve representations of surface processes in weather forecast models. Improving the accuracy of these models is vital to improving the forecasts for severe weather used by the general public.
There is a Tech Memo titled Small Unmanned Aircraft System (sUAS) measurements during the 2016 Verifications of the Origins of Rotation in Tornadoes Experiment Southeast (VORTEX-SE) available here.
Tornado over Black Mountain, North Carolina
One of the 30 foot towers used by NOAA ATDD researchers during VORTEX-SE.
NOAA ATDD researchers perform a weather balloon launch during VORTEX-SE