1 / 27

A Study of Cool Season Tornadoes in the Southeast United States

A Study of Cool Season Tornadoes in the Southeast United States. Alicia C. Wasula and Lance F. Bosart University at Albany/SUNY and Russell Schneider, Steven J. Weiss, and Robert H. Johns Storm Prediction Center. Motivation.

candid
Télécharger la présentation

A Study of Cool Season Tornadoes in the Southeast United States

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. A Study of Cool Season Tornadoes in the Southeast United States • Alicia C. Wasula and Lance F. Bosart • University at Albany/SUNY • and • Russell Schneider, Steven J. Weiss, and Robert H. Johns • Storm Prediction Center

  2. Motivation • Understand physical mechanisms behind cool season (November – March) tornado occurrence in the Southeast U.S. • Understand role of mesoscale features in modifying large-scale environment to enhance or inhibit tornado development

  3. Number >=F2 Tornadoes Number Cool Season >=F2 Tornadoes FL 228 115 CO 396 210 AP 976 460 MR 1071 560 OZ 250 142 Cool Season = November-March

  4. Percent Tornadoes (>=F2) by Month Percent Tornadoes (>=F2) by Hour (UTC)

  5. COMPOSITE TORNADO EVENT 0000-0600 UTC (n=393, Tornado point = 32 N, 90 W) 500 hPa heights (solid, dam), vorticity (dashed, x 10-5 s-1), vort. advection (shaded, x 10-10 s-2) 200 hPa heights (solid, dam), isotachs (shaded, m s-1)

  6. COMPOSITE TORNADO EVENT 0000-0600 UTC (n=393, Tornado point = 32 N, 90 W) 850 hPa heights (solid, m), temperature (dashed, °C), temp. advection (shaded, x 10-5°C s-1) 1000 hPa heights (solid, m), 1000-500 hPa thck (dashed, dam), 700 hPa relative humidity (%)

  7. COMPOSITE TORNADO EVENT 0000-0600 UTC (n=393, Tornado point = 32 N, 90 W) 700 hPa heights (solid, m), vertical motion (dashed and shaded, x 10-3 hPa s-1), 850-500 hPa lapse rate (dashed°C), 850 hPa e (shaded, K), 850 hPa winds

  8. SEVERE WEATHER REPORTS: 22-23 February 1998 7 Tornadoes 3 F3 42 Fatalities 260 Injuries Blue = Wind > 25.7 m s-1 Green = Hail > 1.91 cm Red = Tornado

  9. 22 February 1998 0000 UTC AVN Analysis SFC 500 hPa 200 hPa 850 hPa

  10. 22 February 1998 1200 UTC AVN Analysis SFC 500 hPa 200 hPa 850 hPa

  11. 23 February 1998 0000 UTC AVN Analysis SFC 500 hPa 200 hPa 850 hPa

  12. Tampa Bay (TBW) Sounding and Hodograph 23 February 1998 0000 UTC CAPE = 2891 J/kg LI = -9 C LCL = 962 hPa V (m s-1) U (m s-1)

  13. 22/1815 UTC IR Satellite

  14. 22/2115 UTC IR Satellite 23/0015 UTC IR Satellite 22/2345 UTC IR Satellite

  15. 23/0100 UTC BREF Mosaic Surface Temp. (°C) and contours 23/0015 UTC 22/2255 UTC

  16. 23/0200 UTC BREF Mosaic Surface Temp. (°C) and contours 23/0315 UTC 23/0145 UTC

  17. 23/0300 UTC BREF Mosaic Surface Temp. (°C) and contours 23/0530 UTC

  18. 23/0400 UTC BREF Mosaic Surface Temp. (°C) and contours

  19. 23/0500 UTC BREF Mosaic Surface Temp. (°C) and contours

  20. 23/0600 UTC BREF Mosaic Surface Temp. (°C) and contours

  21. SST’ > 0 SST’<0 LAND

  22. Surface Frontogenesis (°C 100 km-1 3 h-1) 23/ 0000 UTC 23/ 0200 UTC 23/ 0400 UTC 23/ 0600 UTC

  23. Surface Trajectories Ending 23/0400 UTC End point north of boundary End point south of boundary

  24. Surface Vorticity (x 10-5 s-1) 23/ 0000 UTC 23/ 0200 UTC 23/ 0600 UTC 23/ 0400 UTC

  25. Conclusions • Case study fits with composite results on synoptic scale • Convection reorganized into line of tornadic supercells after landfall • Intensity of squall line related to Gulf SST anomalies • Strong frontogenesis maintained east-west baroclinic zone and enhance upward motion in warm air across central Florida • Baroclinic zone maintained strength as surface air traversed over anomalously warm (cold) SST anomalies to south (north) • Increase in ambient surface absolute vorticity on FL peninsula is associated with evolution of line into supercells

More Related