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with the observed increase in SREH seen from profiler data ( Thompson and Edwards 2000 ). Brooks et al. (1994a , b ) suggest that tornadogenesis is most likely when there is a balance between the mesocyclone circulation and the storm-relative winds; this can be estimated using model-generated BRNSHR values. Values of model-predicted BRNSHR between 40 and 100 m 2 s –2 appear to be most favorable for the development of low-level mesocyclogenesis ( Stensrud et al. 1997 ). At 0000 UTC 4 May, the
with the observed increase in SREH seen from profiler data ( Thompson and Edwards 2000 ). Brooks et al. (1994a , b ) suggest that tornadogenesis is most likely when there is a balance between the mesocyclone circulation and the storm-relative winds; this can be estimated using model-generated BRNSHR values. Values of model-predicted BRNSHR between 40 and 100 m 2 s –2 appear to be most favorable for the development of low-level mesocyclogenesis ( Stensrud et al. 1997 ). At 0000 UTC 4 May, the
computing divergence, vorticity, and their errors from three or more stations. Mon. Wea. Rev. , 121 , 713 – 725 . 10.1175/1520-0493(1993)121<0713:UFFCDV>2.0.CO;2 Dunn, L. B. , 1983 : Quantitative and spacial [sic] distribution of winter precipitation along Utah's Wasatch Front. NOAA Tech. Memo. NWS WR-181, 72 pp. [Available from NOAA/NWS Western Region Headquarters, 125 S. State St., Rm. 1311, Salt Lake City, UT 84138-1102.] . Dunn, L. B. , and Vasiloff S. V. , 2001 : Tornadogenesis and
computing divergence, vorticity, and their errors from three or more stations. Mon. Wea. Rev. , 121 , 713 – 725 . 10.1175/1520-0493(1993)121<0713:UFFCDV>2.0.CO;2 Dunn, L. B. , 1983 : Quantitative and spacial [sic] distribution of winter precipitation along Utah's Wasatch Front. NOAA Tech. Memo. NWS WR-181, 72 pp. [Available from NOAA/NWS Western Region Headquarters, 125 S. State St., Rm. 1311, Salt Lake City, UT 84138-1102.] . Dunn, L. B. , and Vasiloff S. V. , 2001 : Tornadogenesis and
. , and M. L. Ekster , 2010 : The association of the elevated mixed layer with significant severe weather events in the northeastern United States . Wea. Forecasting , 25 , 1082 – 1102 , doi: 10.1175/2010WAF2222363.1 . 10.1175/2010WAF2222363.1 Bosart , L. F. , A. Seimon , K. D. LaPenta , and M. J. Dickinson , 2006 : Supercell tornadogenesis over complex terrain: The great Barrington, Massachusetts, tornado on 29 May 1995 . Wea. Forecasting , 21 , 897 – 922 , doi: 10.1175/WAF957.1 . 10
. , and M. L. Ekster , 2010 : The association of the elevated mixed layer with significant severe weather events in the northeastern United States . Wea. Forecasting , 25 , 1082 – 1102 , doi: 10.1175/2010WAF2222363.1 . 10.1175/2010WAF2222363.1 Bosart , L. F. , A. Seimon , K. D. LaPenta , and M. J. Dickinson , 2006 : Supercell tornadogenesis over complex terrain: The great Barrington, Massachusetts, tornado on 29 May 1995 . Wea. Forecasting , 21 , 897 – 922 , doi: 10.1175/WAF957.1 . 10
: Dynamics of tornadic thunderstorms . Annu. Rev. Fluid Mech. , 19 , 369 – 402 , https://doi.org/10.1146/annurev.fl.19.010187.002101 . 10.1146/annurev.fl.19.010187.002101 Lemon , L. , and C. Doswell III , 1979 : Severe thunderstorm evolution and mesocyclone structure as related to tornadogenesis . Mon. Wea. Rev. , 107 , 1184 – 1197 , https://doi.org/10.1175/1520-0493(1979)107<1184:STEAMS>2.0.CO;2 . 10.1175/1520-0493(1979)107<1184:STEAMS>2.0.CO;2 Letkewicz , C. E. , A. J. French , and M. D
: Dynamics of tornadic thunderstorms . Annu. Rev. Fluid Mech. , 19 , 369 – 402 , https://doi.org/10.1146/annurev.fl.19.010187.002101 . 10.1146/annurev.fl.19.010187.002101 Lemon , L. , and C. Doswell III , 1979 : Severe thunderstorm evolution and mesocyclone structure as related to tornadogenesis . Mon. Wea. Rev. , 107 , 1184 – 1197 , https://doi.org/10.1175/1520-0493(1979)107<1184:STEAMS>2.0.CO;2 . 10.1175/1520-0493(1979)107<1184:STEAMS>2.0.CO;2 Letkewicz , C. E. , A. J. French , and M. D
also to occur closer to TC centers. TCTOR also contains National Hurricane Center “best track” data interpolated to the recorded time of each tornadogenesis, followed by derived azimuth and range information ( Edwards 2010 ). Accordingly, 2003–11 TCTOR data were mined for those whole-tornado entries corresponding to strictly nonsupercellular and supercellular modal-event segments herein, yielding polar plots of their distributions with respect to both true north and the estimated TC center at
also to occur closer to TC centers. TCTOR also contains National Hurricane Center “best track” data interpolated to the recorded time of each tornadogenesis, followed by derived azimuth and range information ( Edwards 2010 ). Accordingly, 2003–11 TCTOR data were mined for those whole-tornado entries corresponding to strictly nonsupercellular and supercellular modal-event segments herein, yielding polar plots of their distributions with respect to both true north and the estimated TC center at
shown), where Z HH is between 20 and 25 dB Z ( Figs. 9a,b ). While lower ρ HV could result from a lower signal-to-noise ratio (SNR), much higher ρ HV values (0.97–0.98) are observed at 20–25 dB Z within the hook echo (in regions with small drops). So, the lower ρ HV values within the TVS could indicate some light debris being lofted at the onset of tornadogenesis. Fig . 9. As in Fig. 6 , but for the Goldsby EF4 tornado. NT indicates that a tornado was not observed. The tornado produces EF
shown), where Z HH is between 20 and 25 dB Z ( Figs. 9a,b ). While lower ρ HV could result from a lower signal-to-noise ratio (SNR), much higher ρ HV values (0.97–0.98) are observed at 20–25 dB Z within the hook echo (in regions with small drops). So, the lower ρ HV values within the TVS could indicate some light debris being lofted at the onset of tornadogenesis. Fig . 9. As in Fig. 6 , but for the Goldsby EF4 tornado. NT indicates that a tornado was not observed. The tornado produces EF
instigate tornadogenesis barotropically? J. Atmos. Sci. , 65 , 2469 – 2497 . Dobur, J. C. , 2005 : A comparison of severe thunderstorm warning verification statistics and population density within the NWS Atlanta county warning area. Preprints, Fourth Annual Southeast Severe Storms Symp., Starkville, MS, East Mississippi Chapter National Weather Association/Amer. Meteor. Soc., D2–6 . Fujita, T. T. , 1989 : The Teton–Yellowstone tornado of 21 July 1987 . Mon. Wea. Rev. , 117 , 1913 – 1940
instigate tornadogenesis barotropically? J. Atmos. Sci. , 65 , 2469 – 2497 . Dobur, J. C. , 2005 : A comparison of severe thunderstorm warning verification statistics and population density within the NWS Atlanta county warning area. Preprints, Fourth Annual Southeast Severe Storms Symp., Starkville, MS, East Mississippi Chapter National Weather Association/Amer. Meteor. Soc., D2–6 . Fujita, T. T. , 1989 : The Teton–Yellowstone tornado of 21 July 1987 . Mon. Wea. Rev. , 117 , 1913 – 1940
. IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens. , 5 , 652 – 662 . Lemon, L. R. , and Doswell C. A. III , 1979 : Severe thunderstorm evolution and mesocyclone structure as related to tornadogenesis . Mon. Wea. Rev. , 107 , 1184 – 1197 . Liu, D. C. , and Nocedal J. , 1989 : On the limited-memory BFGS method for large-scale optimization . Math. Programm. , 45 , 503 – 528 . Lorenc, A. C. , 1992 : Iterative analysis using covariance functions and filters . Quart. J. Roy. Meteor
. IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens. , 5 , 652 – 662 . Lemon, L. R. , and Doswell C. A. III , 1979 : Severe thunderstorm evolution and mesocyclone structure as related to tornadogenesis . Mon. Wea. Rev. , 107 , 1184 – 1197 . Liu, D. C. , and Nocedal J. , 1989 : On the limited-memory BFGS method for large-scale optimization . Math. Programm. , 45 , 503 – 528 . Lorenc, A. C. , 1992 : Iterative analysis using covariance functions and filters . Quart. J. Roy. Meteor
important when considering how the sources influence warning outcomes. Most tornadoes are short lived, the appearance of a TDS in radar data can be delayed (~2–3 min after tornadogenesis, on average, if sufficient debris is present to be lofted), and the time required to issue a tornado warning can result in both a missed event and a false alarm. Figures 14 and 15 show the expected FAR if a tornado warning were issued for all missed events with a TDS from 2016 to 2018. These were grouped in 1-min
important when considering how the sources influence warning outcomes. Most tornadoes are short lived, the appearance of a TDS in radar data can be delayed (~2–3 min after tornadogenesis, on average, if sufficient debris is present to be lofted), and the time required to issue a tornado warning can result in both a missed event and a false alarm. Figures 14 and 15 show the expected FAR if a tornado warning were issued for all missed events with a TDS from 2016 to 2018. These were grouped in 1-min
have substantial societal impact ( Ashley et al. 2008 ), are difficult to forecast and warn ( Brotzge et al. 2013 ; Anderson-Frey et al. 2016 ), and often appear to occur in environments with ingredients not typically considered favorable for significant tornadogenesis ( Kis and Straka 2010 ). Though tornado counts with both QLCSs and non-QLCSs reach a minimum during the overnight, the proportion that are due to QLCSs rapidly increases from less than 15% during the afternoon/evening hours to over
have substantial societal impact ( Ashley et al. 2008 ), are difficult to forecast and warn ( Brotzge et al. 2013 ; Anderson-Frey et al. 2016 ), and often appear to occur in environments with ingredients not typically considered favorable for significant tornadogenesis ( Kis and Straka 2010 ). Though tornado counts with both QLCSs and non-QLCSs reach a minimum during the overnight, the proportion that are due to QLCSs rapidly increases from less than 15% during the afternoon/evening hours to over
