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Diagnosing Model Errors for the 20 May 2019 Oklahoma Tornado Outbreak



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  • Journal Title:
    Journal of Operational Meteorology
  • Personal Author:
  • NOAA Program & Office:
  • Description:
    During the afternoon of 20 May 2019 through the early morning hours the next day, 42 tornadoes occurred in Oklahoma with four rated EF2 on the Enhanced Fujita scale. This event was notable because forecast environmental parameters for tornadoes were so exceptionally extreme and several sources of convection-allowing model guidance depicted up to nine supercells in the warm sector moving across central Oklahoma during the afternoon and evening suggesting an historic tornado outbreak. While the tornado report coverage, intensities, and cumulative path lengths justified the “High Risk” issued by the Storm Prediction Center, the warm sector supercells did not occur as expected and thus the magnitude and severity of the event did not reach historic levels. This study presents an analysis of this event and diagnosis of the factors that led to the most impactful forecast errors in the operational High-Resolution Rapid Refresh (HRRR) model. Errors in the HRRR model could be traced to westward-displacement errors of 700 hPa mesoscale vorticity disturbances over western Texas, which contributed overestimates of warm sector areal coverage, insolation, instability, moisture, and sustained mesoscale ascent in west-central Oklahoma during the afternoon compared to observations. The position errors in the vorticity disturbances were linked to the separate development in the HRRR forecasts of a large mesoscale convective vortex with a mesoscale convective system in the Oklahoma Panhandle and southern Kansas. More generally, this study highlights the importance of mesoscale vorticity disturbances that influence downstream convective initiation by modulating the mesoscale environment embedded in an otherwise favorable synoptic-scale severe weather environment.
  • Source:
    Journal of Operational Meteorology (2026)
  • DOI:
  • ISSN:
    2325-6184 ; 2325-6184
  • Format:
    PDF
  • Publisher:
    National Weather Association
  • Document Type:
    Journal Article
  • Rights Information:
    Other
  • Compliance:
    Submitted
  • Main Document Checksum:
    urn:sha-512:e6fa98fcf0bf2c72a974a1ba70190fc2d4abdda7dfe0633e8b710956ac49ede1df44472b1139c13d38e7241938a1d8b379d5ccbe7a6e620b7282c0e9fa146ac9
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  • File Type:
    Filetype[PDF - 22.89 MB ]
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