Jared Rennie Student Meteorologist: Plymouth State University Mentor: David Andra (SOO)

1. Analyzing Conventional and Emerging Radar Technologies for the May 8th, 2007 Central Oklahoma Tornado Case Jared Rennie Student Meteorologist: Plymouth State University Mentor: David Andra (SOO) NWS Norman, Oklahoma

2. Outline • Introduction / Objectives • Background / Methodology • Results / Conclusions • Summary • Acknowledgements / Questions

3. Introduction / Objectives • Since the WSR-88D, forecasters have been able to improve detection of severe weather. • However, over the past few years, new Radar technologies have been developed to better help predict mesoscale / microscale phenomena within these storms. Which radar proves to be the most effective when “seeing the storm” at not only a clearer resolution, but also an earlier time frame?

4. Background • 4 types of Radars in Central Oklahoma

5. WSR-88D • 158 network Radars • Wavelength: 10 cm • Maximum Range: 230 km • Volume Scan Updates: ~ 213 seconds • KTLX in Cleveland County, OK

6. TDWR • Terminal Doppler Weather Radar • 44 radars operated by the FAA • Wavelength: 5 cm • Maximum Range: 90 km • Volume Scan Updates: ~60 seconds

7. Phased Array Radar (MPAR) • Operated by NSSL • National Weather Radar Testbed (NWRT) • Flat panel antenna • Wavelength: 9.4 cm • Maximum Range: 230 km • Volume Scan Updates: ~29 seconds

8. CASA Radars • Low powered radars that can see the lowest levels of the atmosphere • Wavelength: 3 cm • Maximum Range: 30 km • Volume Scan Updates: ~60 seconds • Four radars in Oklahoma • Chickasha, Cyril, Lawton, and Rush Springs

10. Case: May 8th, 2007 • Mesoscale Convective Vortex (MCV) • 23Z (6pm) – 07Z (2am) • Propagated northeastward • Thermodynamics • CAPE Values over 2000 J/Kg • Lifted Index: -6° C • Low Level Wind Shear • Two tornadoes officially entered as LSR

11. Methodology • Warning Decision Support System: Integrated Information (WDSS – II) • NOAA’s Hazardous Weather Test Bed

12. Methodology (cont.) • 0.5° velocity scans of KTLX, TDWR, MPAR and the 2° scans of CASA • Pinpoint circulations that were depicted by at least two of the four radars. • Calculate Shear Shear = | Inbound (ms-1) | + | Outbound (ms-1) | Diameter (m)

13. Expectations • Shear values for the Phased Array and CASA radars should to be higher than those from KTLX and TDWR. • Higher resolution. • Due to faster updates, TDWR, Phased Array, and CASA should detect phenomena that KTLX would not.

14. Results • Eight circulations during time period • KTLX / TDWR saw all eight • MPAR saw six • Three in CASA Network • Four out of the eight circulations • Vortex one, three, four, five.

15. Vortex One • 1:00 – 2:35 UTC • Tornado reported at 1:15 UTC in Comanche County • In all four radars • TDWR did not pick up until ~ 2Z • Not in range

16. TVS

18. Vortex Three • 3:10 – 3:45 UTC • MPAR not on • In the CASA Network

19. Area of Pure Convergence

20. TDWR KTLX ? CASA

21. Vortex Four • 4:22 – 4:28 UTC • Outside of CASA Network • Possible F0, but not entered as local storm report

23. Vortex Five • 4:40 – 4:59 UTC • Outside of CASA Network • Tornado reported at 4:45 UTC in Canadian County

27. Conclusions • No radar is perfect. • Advantages and disadvantages

28. Conclusions (KTLX) • Advantages • Large network across the lower 48 • Rarely any downtime • Was able to see all vortices in case • Disadvantages • Relatively coarse resolution • Updates only every 4 – 5 minutes

29. Conclusions (TDWR) • Advantages • Calculated low level wind shear well at a clear resolution • Updates every 60 seconds • Able to see all vortices in case • Disadvantages • Radius only 90 km

30. Conclusions (MPAR) • Advantages • Calculated wind shear well • Updates every 29 seconds • Disadvantages • Only one flat panel antenna • Maintenance issues when turned on

31. Conclusions (CASA) • Advantages • Very high resolution • Had highest shear values • Other small scale circulations that other radars did not pick up on • Disadvantages • Attenuation • Circulation versus noise • Issues displaying high velocity values

32. Summary • Four conventional and emerging radar technologies used by NOAA for forecasting and research • May 8th 2007 gave researchers an MCV that was in all four radars • After analysis, each radar has its advantages and disadvantages. • More research needs to be done

33. Acknowledgments • Heinselman, Pamela L., 2007: Comparison of storm evolution characteristics: The NWRT and WSR-88D. 87th Annual AMS Meeting, San Antonio, TX, Amer. Meteor. Soc. • HPC, cited 2007: Surface Analysis Archive [available online at http://www.hpc.ncep.noaa.gov/html/sfc_archive.shtml] • PSU Vortex, cited 2007: Product Generator for Archived Data [available online at http://vortex.plymouth.edu/u-make.html] • SPC, cited 2007: Severe Thunderstorm Events [available online at http://w1.spc.woc.noaa.gov/exper/archive/events/] • Vasiloff , Steven V., 2001: Improving Tornado Warnings with the Federal Aviation Administration’s Terminal Doppler Weather Radar. Bulletin of the American Meteorological Society. 5, 861-174. This research was performed under appointment to the NOAA Ernest F. Hollings Undergraduate Scholarship Program administered by Oak Ridge Institute for Science and Education for The U.S. Department of Commerce.

34. Questions?