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of outbreak and isolated tornadoes . Wea. Forecasting , 33 , 1397 – 1412 , https://doi.org/10.1175/WAF-D-18-0057.1 . 10.1175/WAF-D-18-0057.1 Baerg , B. M. , and Coauthors , 2020 : Radar-based, storm-scale circulation and tornado-probability tendencies preceding tornadogenesis in Kansas and Nebraska . Electron. J. Severe Storms Meteor. , 15 ( 3 ), https://ejssm.org/ojs/index.php/ejssm/article/viewArticle/179 . Blair , S. F. , and J. W. Leighton , 2014 : Assessing real
of outbreak and isolated tornadoes . Wea. Forecasting , 33 , 1397 – 1412 , https://doi.org/10.1175/WAF-D-18-0057.1 . 10.1175/WAF-D-18-0057.1 Baerg , B. M. , and Coauthors , 2020 : Radar-based, storm-scale circulation and tornado-probability tendencies preceding tornadogenesis in Kansas and Nebraska . Electron. J. Severe Storms Meteor. , 15 ( 3 ), https://ejssm.org/ojs/index.php/ejssm/article/viewArticle/179 . Blair , S. F. , and J. W. Leighton , 2014 : Assessing real
Davies (2002) . Using surface-based parcels, SBCIN and SBLFC yielded similar results, with a large percentage (75%) of F1–F4 tornado cases having SBCIN less than or roughly equal to MLCIN. From a physical standpoint, an environment with large CIN and associated high LFC heights may inhibit low-level parcel ascent and stretching near the ground, reducing the likelihood of tornadoes. It is also possible that tornadogenesis may, in part, be related to rapid upward acceleration and stretching within
Davies (2002) . Using surface-based parcels, SBCIN and SBLFC yielded similar results, with a large percentage (75%) of F1–F4 tornado cases having SBCIN less than or roughly equal to MLCIN. From a physical standpoint, an environment with large CIN and associated high LFC heights may inhibit low-level parcel ascent and stretching near the ground, reducing the likelihood of tornadoes. It is also possible that tornadogenesis may, in part, be related to rapid upward acceleration and stretching within
conclusions about the association of DRCs with tornadoes. We have a much broader study in progress that utilizes dual-polarization radar and Weather Surveillance Radar-1988 (WSR-88D) data. The limited goal here is to establish, using radar data available to operational meteorologists, that some supercells produce DRCs prior to low-level mesocyclone and tornado formation; some supercells produce DRCs that are associated with low-level rotation intensification but not associated with tornadogenesis
conclusions about the association of DRCs with tornadoes. We have a much broader study in progress that utilizes dual-polarization radar and Weather Surveillance Radar-1988 (WSR-88D) data. The limited goal here is to establish, using radar data available to operational meteorologists, that some supercells produce DRCs prior to low-level mesocyclone and tornado formation; some supercells produce DRCs that are associated with low-level rotation intensification but not associated with tornadogenesis
–3-km SRH). Still, the roles of a wide variety of preexisting boundaries in convective initiation and tornadogenesis, including weakly convergent drylines, HCRs, confluence axes, and various reflectivity patterns not evident in surface and satellite data, warrant much additional attention. Observations suggested that subtle boundaries were important to the initiation and evolution of several tornadic supercells in the 3 May outbreak, and it remains crucial for forecasters to monitor high
–3-km SRH). Still, the roles of a wide variety of preexisting boundaries in convective initiation and tornadogenesis, including weakly convergent drylines, HCRs, confluence axes, and various reflectivity patterns not evident in surface and satellite data, warrant much additional attention. Observations suggested that subtle boundaries were important to the initiation and evolution of several tornadic supercells in the 3 May outbreak, and it remains crucial for forecasters to monitor high
northern storm, and an account of the control participants’ greater concern for tornadogenesis on the southern storm. Tornado warning–related decisions for the northern storm were made by control participant P2 and experimental participant P12 during the first 10 min of case 2, during which P2 received two 5-min PAR updates, and P12 received ten 1-min PAR updates. After P2 received her first scan at 2053 UTC, she reported seeing a “kidney bean shape” and midlevel rotation in the northern storm. These
northern storm, and an account of the control participants’ greater concern for tornadogenesis on the southern storm. Tornado warning–related decisions for the northern storm were made by control participant P2 and experimental participant P12 during the first 10 min of case 2, during which P2 received two 5-min PAR updates, and P12 received ten 1-min PAR updates. After P2 received her first scan at 2053 UTC, she reported seeing a “kidney bean shape” and midlevel rotation in the northern storm. These
velocity across adjacent beams at the lowest scanning elevation angle from the WSR-88D (around 0.5°). This guidance comes from several studies that indicate enhanced differential velocities are present near cloud base at the onset of tornadogenesis, particularly for storms closer to the radar ( Brown et al. 1978 ; Trapp and Davies-Jones 1997 ; Trapp et al. 1999 ). Two common metrics employed to quantify these lowest angle velocities are low-level delta velocity (LLDV) and low-level rotational
velocity across adjacent beams at the lowest scanning elevation angle from the WSR-88D (around 0.5°). This guidance comes from several studies that indicate enhanced differential velocities are present near cloud base at the onset of tornadogenesis, particularly for storms closer to the radar ( Brown et al. 1978 ; Trapp and Davies-Jones 1997 ; Trapp et al. 1999 ). Two common metrics employed to quantify these lowest angle velocities are low-level delta velocity (LLDV) and low-level rotational
windstorms but rather with regard to their effects on such phenomena as rain shadows ( Brady and Waldstreicher 2001 ) and tornadogenesis ( Bosart et al. 2006 ). Therefore, it was quite unexpected to forecasters and climatologists alike when the New Jersey Weather and Climate Network ( Robinson 2005 ) observed a localized high wind event near High Point, New Jersey, on 4 January 2009. This study uses theory, observations, and modeling to show that the high-wind event near High Point was a consequence of
windstorms but rather with regard to their effects on such phenomena as rain shadows ( Brady and Waldstreicher 2001 ) and tornadogenesis ( Bosart et al. 2006 ). Therefore, it was quite unexpected to forecasters and climatologists alike when the New Jersey Weather and Climate Network ( Robinson 2005 ) observed a localized high wind event near High Point, New Jersey, on 4 January 2009. This study uses theory, observations, and modeling to show that the high-wind event near High Point was a consequence of
seeding and accretion that are enhanced by the large volume of hydrometers among the merged cells. In addition to the enhanced precipitation production, it has also been suggested in the literature that cell mergers can be precursors to tornadogenesis ( Lemon 1976 ; Finley et al. 2001 ; Lee et al. 2006 ). In observational studies by Lemon (1976) and Finley et al. (2001) , and numerical studies by Kulie and Lin (1998) , updraft strength and midlevel rotation increased after a cell merger
seeding and accretion that are enhanced by the large volume of hydrometers among the merged cells. In addition to the enhanced precipitation production, it has also been suggested in the literature that cell mergers can be precursors to tornadogenesis ( Lemon 1976 ; Finley et al. 2001 ; Lee et al. 2006 ). In observational studies by Lemon (1976) and Finley et al. (2001) , and numerical studies by Kulie and Lin (1998) , updraft strength and midlevel rotation increased after a cell merger
the corrected shear field produced by both range-correction methods proved to be a better indicator of tornadogenesis in comparison to the original LLSD shear field. However, the corrected shear trend was not evident for some tornadoes at far ranges, even for the ANN method, which was likely a consequence of the range restrictions imposed on the range-correction algorithm. In addition, the increasing height and width of the radar beam was likely partially responsible for the poor performance of
the corrected shear field produced by both range-correction methods proved to be a better indicator of tornadogenesis in comparison to the original LLSD shear field. However, the corrected shear trend was not evident for some tornadoes at far ranges, even for the ANN method, which was likely a consequence of the range restrictions imposed on the range-correction algorithm. In addition, the increasing height and width of the radar beam was likely partially responsible for the poor performance of
focus primarily on Z DR columns relative to severe and nonsevere storms since the differences in the distributions are more robust ( section 3c ) and there is more research linking Z DR columns with updrafts and severe hail (e.g., Kumjian and Ryzhkov 2008 ; Picca et al. 2010 ; Kumjian et al. 2014 ; Kuster et al. 2019 ) than there is linking Z DR columns to tornadogenesis. Table 2. Statistical significance using a bootstrapping method with replacement and K–S test p values for various
focus primarily on Z DR columns relative to severe and nonsevere storms since the differences in the distributions are more robust ( section 3c ) and there is more research linking Z DR columns with updrafts and severe hail (e.g., Kumjian and Ryzhkov 2008 ; Picca et al. 2010 ; Kumjian et al. 2014 ; Kuster et al. 2019 ) than there is linking Z DR columns to tornadogenesis. Table 2. Statistical significance using a bootstrapping method with replacement and K–S test p values for various
