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observations of a splitting storm were correlated with Doppler radar data. [Prior to this storm, Achetemier (1969) had correlated his visual observations of a splitting storm in Iowa in 1965 with conventional radar images.] A summary of radar observations combined with visual and other observations by Lemon and Doswell (1979) , for storms studied in the early and mid-1970s, indicated the coincidence of supercell tornadogenesis with the rear flank downdraft and its visual manifestation, the “clear slot
observations of a splitting storm were correlated with Doppler radar data. [Prior to this storm, Achetemier (1969) had correlated his visual observations of a splitting storm in Iowa in 1965 with conventional radar images.] A summary of radar observations combined with visual and other observations by Lemon and Doswell (1979) , for storms studied in the early and mid-1970s, indicated the coincidence of supercell tornadogenesis with the rear flank downdraft and its visual manifestation, the “clear slot
November 2012, and was responsible for one death and estimated damage of 60 million euros ( Miglietta and Rotunno 2016 , hereafter MR16 ). A numerical simulation of the meteorological causes for the severe weather in this case using the Weather Research and Forecasting (WRF) Model is the subject of the present study. Most studies of tornadogenesis in the Mediterranean have focused on mesoscale and synoptic-scale observations. Bech et al. (2007) found that a mesoscale convergence line in a highly
November 2012, and was responsible for one death and estimated damage of 60 million euros ( Miglietta and Rotunno 2016 , hereafter MR16 ). A numerical simulation of the meteorological causes for the severe weather in this case using the Weather Research and Forecasting (WRF) Model is the subject of the present study. Most studies of tornadogenesis in the Mediterranean have focused on mesoscale and synoptic-scale observations. Bech et al. (2007) found that a mesoscale convergence line in a highly
were difficult to categorize or probably nonmesocyclone in nature. It should also be highlighted that the distinction between mesocyclone and nonmesocyclone processes can be unclear and confusing in tornado cases that involve supercell thunderstorms but tornadogenesis processes that may be nonmesocyclone in nature, as in Wakimoto and Atkins (1996) . Due in part to an emphasis on supercell storms in the initial database from D04 , it can be noted that roughly 80% of the profiles were associated
were difficult to categorize or probably nonmesocyclone in nature. It should also be highlighted that the distinction between mesocyclone and nonmesocyclone processes can be unclear and confusing in tornado cases that involve supercell thunderstorms but tornadogenesis processes that may be nonmesocyclone in nature, as in Wakimoto and Atkins (1996) . Due in part to an emphasis on supercell storms in the initial database from D04 , it can be noted that roughly 80% of the profiles were associated
rated EF0 by the National Weather Service and minor damage was documented by researchers in Amity. Tick marks are at 1-km intervals, and 1-km scale is indicated. North is up. b. Multiple tornadoes under different broad circulations/mesocyclones The process of cyclic tornadogenesis frequently is observed to occur with the formation of a new or extended hook echo and a new distinct near-surface circulation, or as the old tornado moves away from the inflow region and is replaced by a new tornado, as
rated EF0 by the National Weather Service and minor damage was documented by researchers in Amity. Tick marks are at 1-km intervals, and 1-km scale is indicated. North is up. b. Multiple tornadoes under different broad circulations/mesocyclones The process of cyclic tornadogenesis frequently is observed to occur with the formation of a new or extended hook echo and a new distinct near-surface circulation, or as the old tornado moves away from the inflow region and is replaced by a new tornado, as
important for significant tornadogenesis were examined ( Table 2 ). Two nonparametric (no probability distribution assumed) statistical significance tests are used to identify differences between the parameter distributions obtained using different proximity criteria. A permutation test ( Efron and Tibshirani 1993 ) is used to identify significant differences between the distribution means, and a Kolmogorov–Smirnov (K–S) test ( Conover 1999 ) is used to assess differences between the empirical
important for significant tornadogenesis were examined ( Table 2 ). Two nonparametric (no probability distribution assumed) statistical significance tests are used to identify differences between the parameter distributions obtained using different proximity criteria. A permutation test ( Efron and Tibshirani 1993 ) is used to identify significant differences between the distribution means, and a Kolmogorov–Smirnov (K–S) test ( Conover 1999 ) is used to assess differences between the empirical
tornadoes that occur in the middle or at the end of an event. There are a number of reasons that could explain this difference in warning performance. One reason is that forecasters may be unsure whether atmospheric conditions are currently conducive for tornadogenesis. This is consistent with our finding that only 25.7% of false alarms issued during tornadic events occurred prior to the first tornado of the day. After a tornado occurs, forecasters are likely more confident that the environment is
tornadoes that occur in the middle or at the end of an event. There are a number of reasons that could explain this difference in warning performance. One reason is that forecasters may be unsure whether atmospheric conditions are currently conducive for tornadogenesis. This is consistent with our finding that only 25.7% of false alarms issued during tornadic events occurred prior to the first tornado of the day. After a tornado occurs, forecasters are likely more confident that the environment is
:12, not shown). This process differs from cited studies/sources by 1) removing the strict dependency of ρ hv criteria and 2) acknowledging that tornadogenesis can occur with certain storm modes and environments, which results in shallow or compact circulations (such as QLCSs) that can prove challenging for radar operators to resolve, necessitating the inclusion of convergence zones in the V r analysis. It is a scalable technique that identifies the physical debris-lofting processes taking place
:12, not shown). This process differs from cited studies/sources by 1) removing the strict dependency of ρ hv criteria and 2) acknowledging that tornadogenesis can occur with certain storm modes and environments, which results in shallow or compact circulations (such as QLCSs) that can prove challenging for radar operators to resolve, necessitating the inclusion of convergence zones in the V r analysis. It is a scalable technique that identifies the physical debris-lofting processes taking place
July 1996 . Mon. Wea. Rev. , 128 , 795 – 809 , doi: 10.1175/1520-0493(2000)128<0795:ATSOEC>2.0.CO;2 . Bosart, L. F. , Seimon A. , LaPenta K. D. , and Dickinson M. J. , 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 . Canham, C. D. , Papaik M. J. , and Latty E. F. , 2001 : Interspecific variation in susceptibility to windthrow as a function of tree size
July 1996 . Mon. Wea. Rev. , 128 , 795 – 809 , doi: 10.1175/1520-0493(2000)128<0795:ATSOEC>2.0.CO;2 . Bosart, L. F. , Seimon A. , LaPenta K. D. , and Dickinson M. J. , 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 . Canham, C. D. , Papaik M. J. , and Latty E. F. , 2001 : Interspecific variation in susceptibility to windthrow as a function of tree size
between a squall line and an isolated supercell coincided with the development of a tornado rated F4 on the Fujita scale that struck Huntsville, Alabama. Using regional composite radar data, observations from a nearby surface mesonet, and visual observations of the storm, the authors demonstrated that tornadogenesis appeared to coincide with an interaction between the supercell and the gust front associated with the squall line’s cold pool. Furthermore, these observations also showed a “distortion” of
between a squall line and an isolated supercell coincided with the development of a tornado rated F4 on the Fujita scale that struck Huntsville, Alabama. Using regional composite radar data, observations from a nearby surface mesonet, and visual observations of the storm, the authors demonstrated that tornadogenesis appeared to coincide with an interaction between the supercell and the gust front associated with the squall line’s cold pool. Furthermore, these observations also showed a “distortion” of
and tornadogenesis downstream of prominent terrain features are often attributed to leeside vortex stretching ( Keighton et al. 2004 ; Lyza and Knupp 2014 ), but not all supercells experience leeside intensification ( Prociv 2012 ). Numerical simulations of supercells interacting with complex terrain have indicated that terrain slope, peak altitude, and orientation relative to the low-level environmental flow can modulate storm intensity by altering the instability and vertical shear in the
and tornadogenesis downstream of prominent terrain features are often attributed to leeside vortex stretching ( Keighton et al. 2004 ; Lyza and Knupp 2014 ), but not all supercells experience leeside intensification ( Prociv 2012 ). Numerical simulations of supercells interacting with complex terrain have indicated that terrain slope, peak altitude, and orientation relative to the low-level environmental flow can modulate storm intensity by altering the instability and vertical shear in the
