TORUS: Finding New Ways to Study Supercells

TORUS: Finding New Ways to Study Supercells

June 1, 2019 Off By ThielWx

This summer, I had the opportunity to work for three weeks on the Targeted Observation by Radars and UAS of Supercells (TORUS) field project, so I figured a blog post about it was in order to describe the project and its importance to the meteorological community.

Supercells, which are thunderstorms that have a deep and persistently rotating updraft, are one of the smallest factions of storm types yet produce a disproportionate amount of large hail, damaging winds, and tornado events. Our understanding of the environmental factors, internal dynamics, and conceptual evolution of supercells has dramatically increased over the last 30 years, with the aid of in-situ (in-field) measurements around and in these storms. Forecasters have been able to use this knowledge to further protect life and property.

A diagram of a supercell and some of its main components. These types of thunderstorms are formed by strong changes in wind direction and speed with height, which allow the updraft to spin and create well-defined inflow, updraft, and downdraft regions. Studying the low-level characteristics of these storms will provide more insight into supercell development, maintenance, and tornado potential.
Imagine this as viewing the previous diagram from due east (near the legend), this is what an idealized supercell would look like. (Hint: It never does) Source

TORUS is the next step in creating more spatially complete kinematic and thermodynamic datasets around supercells, to fuel future research, education, and outreach for a number of scientific objectives. Many of which involve collecting data near or in the the rear flank downdraft, forward flank downdraft, and the inflow regions of the storm. So how exactly will TORUS collect of this data? The answer to that lies in an armada of vehicles with mobile mesonets (weather stations), mobile radars, lidar, sounding teams, unmanned aircraft systems (UAS), and the NOAA P-3 hurricane hunter aircraft. By coordinating all of these instruments around supercells in certain regions, critical data at the lowest levels of the atmosphere can be used to ‘fill in the gaps’ for what we know about supercells and tornado formation.

TORUS aims to use the data collected to improve the conceptual model of supercell thunderstorms (the parent storms of the most destructive tornadoes) by exposing how small-scale structures within these storms might lead to tornado formation.

UCAR-EOL

TORUS by the Numbers

  • 9: Mobile mesonets
  • 4: Unmanned aircraft systems
  • 3: Mobile radars
  • 2: Radiosonde Swarms
  • 1: Mobile sounding systems
  • 1: Mobile lidar unit
  • 1: NOAA P-3 Hurricane Hunter Aircraft
One of the drones used in TORUS, from the University of Colorado-Boulder IRISS team.

My Mission-NOXP Scout

As mentioned above (and in the project title), mobile radars are critical for scanning the lowest levels of the atmosphere and ‘seeing into’ the storms at greater resolutions than the radars used by the National Weather Service (NWS). My job was to aid the NOAA X-POL (NOXP) radar by finding deployment locations to improve data quality. NOXP, owned by the National Severe Storms Lab, is a dual-pol mobile radar with a 3 cm wavelength. NWS radars are also dual-pol but have a 10 cm wavelength, meaning they can ‘see’ farther, but with a lower resolution than NOXP.

NOXP deployed on a storm near Magnum, OK on May 20th, 2019.

The first thing you might realize about NOXP is that it’s BIG (27 feet long, 14 feet tall, and over one ton), making it more difficult to navigate to get to the storm. That’s where the NOXP Scout comes in. While it’s just a rental car (Ford Focus this year), finding deployment locations for a radar can be quite the challenge. Finding hills, open spaces, gravel lots and farm-field access points, along with avoiding trees, wind farms, dirt roads, low bridges, and narrow roads are critical for allowing NOXP to collect good data. While all of this is happening, it’s also important to keep in mind supercell motion, as we of course want to stay safe and NOXP takes time to undeploy.

For those wondering, yes we saw tornadoes! The NOXP crew ended up seeing two supercells that produced tornadoes. The storm pictured produced multiple tornadoes, which was viewed from over 10 miles away!

No two years are created equal with severe weather, and in the first three weeks TORUS took advantage of a very active pattern of severe weather, and a rare high risk day! After three weeks for the first shift, TORUS had traveled 6,000 miles across 5 states, deploying on 12 supercells (6 of which were tornadic) over 10 days of deployments. The datasets we collect this year and next year will help to further our understanding of these impactful storms, leading to better forecasts and warnings.

OU, NSSL, and CIMMS members from the first deployment of TORUS. Vehicles from left to right: Mobile mesonet, P3 Hurricane Hunter, and NOXP.
All of the institutions involved in the TORUS field campaign.

Looking for more info on TORUS? Check out the links below!