Tornadogenesis and early tornado evolution in the El Reno, Oklahoma, supercell on 31 May 2013

Details

• Journal Title:
  Monthly Weather Review
• Personal Author:
  Bluestein, Howard B. ; Thiem, Kyle J. ; Snyder, Jeffrey C. ; Houser, Jana B.
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; NSSL (National Severe Storms Laboratory) ; NWS (National Weather Service)
• Description:
  This study documents the formation and part of the early evolution of a large, violent tornado near El Reno, Oklahoma, based on data from a mobile, polarimetric, rapid scan, X-band, Doppler radar. The main circulation associated with the tornado formed near the ground initially, ~90 s prior to the development of the vertically coherent vortex, which built upward through a vertical column of at least 3.5 km in less than 20 s, the update time of the Doppler radar data. Strong but broad rotation from 500 m to 1.5 km AGL also preceded the formation of the tornado at the surface by several minutes. A precipitation-loaded downdraft was observed in the right-forward flank of the storm, which could have enhanced evaporative cooling and allowed for a faster rate of baroclinic generation of low-level horizontal vorticity, while descending reflectivity cores in the right-rear quadrant might have enhanced low-level convergence to the rear of or along the leading edge of the rear-flank gust front. The intensification of the tornado occurred in spurts, not steadily, perhaps owing to surges in momentum at the surface associated with the precipitation-laden downdrafts. The tornado was highly tilted even when it was intensifying, calling into question the importance of a vertical juxtaposition of the mesocyclone aloft and the tornado at the surface. In this case study, while the development of a weak-echo hole was evidence of rotation, the absence of one did not mean that there was not a strong vortex, owing to the lofting of debris.
• Keywords:
  Mesocyclones Severe Storms Supercells Tornadoes Severe Storms
• Source:
  Monthly Weather Review, 147(6), 2045-2066
• DOI:
  https://doi.org/10.1175/MWR-D-18-0338.1
• Document Type:
  Journal Article
• Rights Information:
  Other
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha256:1256d810eaef0776d847c5c54aeeaded374da6a2f082fba2c57324e8c77236fe
• Download URL:
  https://repository.library.noaa.gov/view/noaa/32207/noaa_32207_DS1.pdf
• File Type:
  [PDF - 8.14 MB ]