Using Near-Ground Storm Relative Helicity in Supercell Tornado Forecasting

Coffer, Brice E.; Parker, Matthew D.; Thompson, Richard L.; Smith, Bryan T.; Jewell, Ryan E.

doi:10.1175/waf-d-19-0115.1

Cited by 70 publications

(65 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As shown in Fig. 6, the vertical velocity field is rather unsteady and is similar to that of the nontornadic simulation of Coffer and Parker (2017), with interspersed pockets of updraft and downdraft throughout the hook echo region [e.g., the downdraft near (1.5, 22) in Fig. 6c and the updraft pulse noted earlier].…”

Section: Observations: 2225-2245 Utcsupporting

confidence: 66%

“…The environment of the Prospect Valley storm possessed relatively little lowlevel streamwise vorticity (Table 2, Fig. 1), with only 40.3 m 2 s 22 of 0-500 m SRH, which is more similar to the median 0-500 m SRH in the nontornadic soundings examined by Coffer et al (2019) than that for the weakly tornadic (EF0-1) soundings (63.69 and 126.81 m 2 s 22 for the nontornadic and weakly tornadic soundings, respectively). This suggests that the disorganization of the low-level updraft and weakness of the low-level mesocyclone close to the center of rotation may be in part a result of the storm ingesting parcels with little streamwise vorticity at low levels.…”

Section: Low-level Trajectory Analysis a Motivationmentioning

confidence: 88%

“…These failure modes are summarized in Table 1. Perhaps most notable is Coffer and Parker (2017) and Coffer et al (2017), who found using an idealized model that small differences in the low-level wind profile in the near-inflow of a supercell have a large impact on whether or not tornadogenesis will occur. Specifically, excessive amounts of near-inflow crosswise vorticity and little near-inflow streamwise vorticity resulted in supercells with weaker and more disorganized low-level mesocyclones, which resulted in tornadogenesis failure.…”

Section: B Observations Of Tornadogenesis Failurementioning

confidence: 99%

“…Excessive negative buoyancy in the outflow (possibly owing to high LCLs) Markowski et al (2002), Shabbott and Markowski (2006), Grzych et al (2007), and Markowski and Richardson (2014) Disorganized low-level updraft owing to significant crosswise vorticity and insufficient streamwise vorticity in the low-level, near-storm environmental inflow Beck et al (2006), Coffer and Parker (2017), Coffer et al (2017), and Coffer and Parker 2018Short time period of favorable conditions Skinner et al 2014 Beck et al (2006) and Bowlan (2013) MAY 2020 M U R D Z E K E T A L .…”

Section: Mode Of Tornadogenesis Failure Referencesmentioning

confidence: 99%

“…The previous two sections have indicated that the Prospect Valley storm possessed a disorganized lowlevel vertical velocity field without a persistent low-level updraft and a weak low-level mesocyclone with relatively small circulation values close to the mesocyclone center. Recent modeling work has indicated that lowlevel updraft organization and low-level mesocyclone strength are related to the amount of near-storm environmental streamwise vorticity ingested by the supercell (e.g., Coffer and Parker 2017). The environment of the Prospect Valley storm possessed relatively little lowlevel streamwise vorticity (Table 2, Fig.…”

Section: Low-level Trajectory Analysis a Motivationmentioning

confidence: 99%

See 4 more Smart Citations

Processes Preventing the Development of a Significant Tornado in a Colorado Supercell on 26 May 2010

Murdzek

Markowski

Richardson

et al. 2020

Monthly Weather Review

View full text Add to dashboard Cite

A supercell produced a nearly tornadic vortex during an intercept by the Second Verification of the Origins of Rotation in Tornadoes Experiment on 26 May 2010. Using observations from two mobile radars performing dual-Doppler scans, a five-probe mobile mesonet, and a proximity sounding, factors that prevented this vortex from strengthening into a significant tornado are examined. Mobile mesonet observations indicate that portions of the supercell outflow possessed excessive negative buoyancy, likely owing in part to low boundary layer relative humidity, as indicated by a high environmental lifted condensation level. Comparisons to a tornadic supercell suggest that the Prospect Valley storm had enough far-field circulation to produce a significant tornado, but was unable to converge this circulation to a sufficiently small radius. Trajectories suggest that the weak convergence might be due to the low-level mesocyclone ingesting parcels with considerable crosswise vorticity from the near-storm environment, which has been found to contribute to less steady and weaker low-level updrafts in supercell simulations. Yet another factor that likely contributed to the weak low-level circulation was the inability of parcels rich in streamwise vorticity from the forward-flank precipitation region to reach the low-level mesocyclone, likely owing to an unfavorable pressure gradient force field. In light of these results, we suggest that future research should continue focusing on the role of internal, storm-scale processes in tornadogenesis, especially in marginal environments.

show abstract

Section: Observations: 2225-2245 Utcsupporting

confidence: 66%

Section: Low-level Trajectory Analysis a Motivationmentioning

confidence: 88%

Section: B Observations Of Tornadogenesis Failurementioning

confidence: 99%

Section: Mode Of Tornadogenesis Failure Referencesmentioning

confidence: 99%

Section: Low-level Trajectory Analysis a Motivationmentioning

confidence: 99%

See 3 more Smart Citations

Processes Preventing the Development of a Significant Tornado in a Colorado Supercell on 26 May 2010

Murdzek

Markowski

Richardson

et al. 2020

Monthly Weather Review

View full text Add to dashboard Cite

show abstract

Tornadic environments in the Iberian Peninsula and the Balearic Islands based on ERA5 reanalysis

Rodríguez

Bech

2020

Intl Journal of Climatology

View full text Add to dashboard Cite

A dataset of 907 tornado and waterspout events recorded from 1980 to 2018 was built to study convective environments in the Iberian Peninsula and Balearic Islands (western Mediterranean). The events were grouped into different categories, distinguishing waterspouts and tornadoes that were stratified by intensity according to the Fujita (F) scale and the Enhanced Fujita (EF) scale. The analysis separated the northeast (NE) and southwest (SW) subareas in the region of study, which present different seasonal cycles. For each event, atmospheric profiles from the ERA5 reanalysis data were used to determine convective available potential energy (CAPE), storm-relative helicity (SRH), vertical wind-shear (WS), the Universal Tornadic Index (UTI), and the product of wind-shear and the square root of two times CAPE (WMAXSHEAR). Results showed that the NE events are mostly associated with higher CAPE and lower helicity and wind-shear than the SW events. Thus, a significant number of SW tornadoes are associated with high-shear, low-CAPE environments. Moreover, the low-shear, high-LCL tornado environment, which is common inland during warm-season, is more usual in the NE subarea. Composite parameters such as the UTI and WMAXSHEAR 06 are good discriminators between significant and weak tornado events, although WMAXSHEAR 06 presents some limitations for the SW events due to low CAPE and weak differences in the WS (0-6 km) between the (E)F1 and (E)F2+ events. This weakness was resolved by using the 0-3 km WS instead of the 0-6 km WS when calculating the WMAXSHEAR. A new threshold for WMAXSHEAR 03 is proposed (500 m 2 Ás −2) to distinguish between significant and non-significant tornado environments. Finally, the Szilagyi Waterspout Nomogram, originally developed for the Great Lakes of North America, was successfully tested in the forecasting of waterspout formation for the first time in the western Mediterranean area, although the technique should be adapted to correctly detect coolseason mid-latitude waterspouts.

show abstract

Differences in tornado activities and key tornadic environments between China and the United States

Zhou

Meng

Bai

2021

Intl Journal of Climatology

View full text Add to dashboard Cite

The yearly tornado occurrence in China is approximately 5–10% of that in the United States, and the peak month of tornado occurrence in China is July, while that in the United States is May. However, the two countries have nearly the same land area and similar latitudinal location. This study attempts to disclose the differences in the key tornadic environments that are most possibly responsible for the large discrepancy of tornado occurrences observed between the two countries. The region with the highest tornado density in China (JS) is compared with three similarly sized regions in the United States, including two tornado‐prone regions (UC and USE1) and one region similar to JS (USE2). The results show that JS has a much lower tornado frequency than UC and USE1, mainly due to JS's much lower likelihood of multiple tornadoes occurring in a short period during its tornado season. Compared with UC and USE1, JS features relatively low mean values of the significant tornado parameter (STP) during their respective tornado seasons. The STP, incorporating several tornado‐related variables, was found to show a monotonic relationship with the total tornado count at a seasonal scale and perform well to explain monthly variations in tornado frequencies. Compared with the target regions in the United States, JS has a similar magnitude and decreasing trend of the 0–6‐km vertical wind shear from spring to summer, but a later increase in instability. Resulting from a balance between the decreasing vertical shear and the increasing thermodynamic instability, JS features a delayed monthly peak of STP and thus a delayed tornado season, which makes JS having a worse kinematic environment for tornadogenesis with far lower low‐level vertical wind shear during its tornado season than that of the United States.

show abstract

Using Near-Ground Storm Relative Helicity in Supercell Tornado Forecasting

Cited by 70 publications

References 47 publications

Processes Preventing the Development of a Significant Tornado in a Colorado Supercell on 26 May 2010

Processes Preventing the Development of a Significant Tornado in a Colorado Supercell on 26 May 2010

Tornadic environments in the Iberian Peninsula and the Balearic Islands based on ERA5 reanalysis

Differences in tornado activities and key tornadic environments between China and the United States

Contact Info

Product

Resources

About