And May 24th brought a High Risk across the region as issued by the Storm Prediction Center. Flood/Flash Flood Safety, Special Programs The dashed black lines in (b) and (c) mark areas of weaker radial convergence leading to the second TVS. Storm Data The color-coded numbers are the maximum ΔV in the corresponding TVS. Range rings are every 5 km. I think that one of the things that has been overlooked in all of these discussions is; What was the "intent" of the author(s) (taking into consideration Dr. Fujita and the developers of the EF scale)? 2012; Bodine et al. We acknowledge the ongoing efforts of NSSL/CIMMS staff, including David Priegnitz and Pam Heinselman, in obtaining KOUN and MPAR data. In KTLX data (Fig. Notably, the TVSs wrap around each other in a helical manner (i.e., the TVSs are offset from one another in different directions at different heights; Figs. 2005) and, similarly, collocated or slightly offset from ZDR columns in supercells (e.g., Kumjian and Ryzhkov 2008; Snyder et al. 7d) collocated with this same portion of the ZDR column. Widespread EF-3, occasional EF-4 damage occurred between El Reno and Piedmont.

(2014) regarding the latter point are in error. 13c). The tornado developed at 5:03 PM CST (6:03 PM CDT) just northeast of the intersection of Heaston and Reuter roads. 13b).

This work was completed while the first author was a National Research Council Postdoctoral Research Fellow at the National Severe Storms Laboratory. Such a path also implies an overall leftward curve over the life cycle of any tornado. Just some thoughts here… I’m self taught, not trained or schooled in damage or rating, but I think this whole discussion shows how impossible it is to accurately and simply categorize something so varied and complex as tornadoes.

Why not just bypass it and go straight to the rating?

Office History. Satellite Imagery, Forecasts As a result of this uncertainty, an emphasis here is placed on qualitative height levels rather than exact heights. What We Do I think you could make the argument that a tornado with 70 mph winds is not going to do as much damage as one with 200+ mph winds given the same track/path. Most people in the path of a tornado want to know the damage it has the potential to cause, and wind speed is a good indicator of that. The main areas of enhanced ZDR are outlined by white circles. Two children were killed at this location. 8i), though given that the tornadoes are not resolved well, the brief period of time between the merger near the surface and aloft may not be meaningful. NWS

More Observations At right, completely obliterated vegetation and severe ground scouring following the 2011 El Reno tornado…

11a–d).

For the purposes of this study, and based on the results of 2D simulations of Rankine vortices (e.g., Waugh 1992), we define a tornado merger as occurring when two tornadoes interact such that neither persists individually after the interaction begins and the resulting tornado contains vertical vorticity from both original tornadoes. Later in the same storm, a tornado merger was observed by VORTEX teams near Allison, Texas (Grazulis 1997). Likewise, the evolution of the TVSs in this case do not follow the cyclic tornadogenesis process as it has been observed previously, where the original tornado moves rearward and to the left of storm motion while the second tornado forms farther south, in a location where vertical vorticity generation and convergence are often maximized in a RFGF “bulge” (e.g., Burgess et al. 11). Please try another search. The image in (a) is enhanced to better show the two distinct lowerings. (b) (bottom) A schematic of the locations of the two tornadoes (black and white circles) along the damage path. However, aloft the two TVSs rotate ~270° around each other while maintaining separate maxima in ΔV (Figs. Cyclonic (anticyclonic) isosurfaces are plotted in purple (orange) every 0.015 (−0.015) s−1 beginning at 0.02 (−0.02) s−1. Local

This seems overly complicated and is leading to what others are calling a contamination of the database of tornadoes. Data from KOUN and MPAR also are used to examine the supercell at midlevels (2–4 km ARL) during the formation of T2. This was on my mind because I had just finished reading your blog on the Jarrel, TX tornado. Section 2 provides a brief description of the data used in this study and section 3 presents data of TVS interaction and merger. 3d), there is only one TVS again, though it is now larger and contains stronger radial velocities than in the previous two volumes.

2014; Orf et al. In addition, the Edwards (2014) conceptual model proposes that satellite tornadoes usually form to the north of the main tornado as occurs in this case. Skywarn Storm Spotters CoCoRaHS, About Us The temporal evolution of T2 formation was best captured by the MPAR (Fig. 8a and 9a).

Monetary damage estimates were not available. In Dowell and Bluestein (2002b), the authors discuss the merger of two vorticity maxima in a supercell on 8 June 1995 during the Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX; Rasmussen et al. 8, but at 11.5° elevation angle. The images are centered at the same location. A definitive determination of why the storm evolves in this manner likely requires an inspection of high-resolution representations of the three-dimensional wind, pressure, and temperature fields, which are not available for this case.

One photograph in the aforementioned short series shows a near-surface gap between two condensation funnels (Fig. 8a–e). 3c), there are two TVSs; the second one develops in the area of radial convergence present in the previous volume.

Finally, the tornado dissipated northeast of Guthrie with some minor tree damage. Roger Edwards also provided photographs of the event. Similarities between the merger observed in this case and in previous cases also are discussed. Graphical Forecasts As in Fig. There is considerably more evidence to support the merger of the Hesston and Goessel tornadoes. (b) (top) Part of the damage path of the Midway tornado, including at the time of the picture in (a). 5c).

There, the tornado abruptly turned to the north, while also accelerating to greater than 50 mph. Given the difficulty of separating this damage from tornadic damage, the OU RaXPol radar was used to help determine the width. The authors thank Curtis Alexander, Corey Potvin, Alex Schenkman, and Jeffrey Snyder for useful data and discussions regarding this research topic.

For this case, better visual observations or radar observations with greater spatial resolution in addition to vorticity trajectories would be necessary to state definitively that the tornadoes merged.

The dotted black line in (a) is an area of weak radial convergence north of the rear-flank gust front and the blue rectangle in (b) is an area of radial convergence. Cars were thrown thousands of feet off the roadways. The merger aloft is completed within three scans (32 s) of that in data near the surface (Fig. Submit a Spot Forecast, Warnings and Other Products A simple 1–2–1 filter was used to smooth the ΔV values. On 24 May 2011, a series of supercells produced at least 12 tornadoes in central Oklahoma, including an enhanced Fujita scale (EF5) tornado having a pathlength of 101 km near El Reno and Piedmont, Oklahoma, among other locations, over a 105-min span [hereafter the El Reno–Piedmont tornado (ERPT); Pazmany et al.

NWS The photographs were taken ~1 mile south of OK-3 on Cimarron Rd., looking southwest toward El Reno at (a) 2133, (b) 2134, and (c) 2137 UTC 24 May 2011. Nationwide Flood Warnings It’s never a good day when tornadoes happen so close to the Oklahoma City metro area and today was one of those days.

The images are centered at the same location. In one of the instances of simultaneous tornadoes in the El Reno–Piedmont supercell, the tornadic vortex signature1 (TVS; Brown et al. If a complete vortex merger occurs, the core circulation of the merged vortex is likewise greater than that of either of the original two vortices. To investigate further the formation of T2, KOUN radial velocity and polarimetric data were compared to the location of the surveyed damage path at ~900 m above radar level (ARL; Fig. 22–24 and 46–47 in Fujita et al. We prefer to chase storms over open country and never like chasing close to Oklahoma City. The tornado continued to expand in size just southwest of the El Reno Municipal Air Park, where its speed increased to 30 to 40 mph. In addition, calculating the number of gates with radial velocity magnitudes of 50 m s−1 or greater and lying within a 500 m × 500 m box centered on the strongest positive and negative radial velocity magnitudes in the TVS yielded similar trends in TVS size (Fig.

Reading through this thread, I'm struck by just how problematic the F/EF Scale really is. About Our Office

For example, in recent high spatial resolution simulations of a supercell (C. Potvin 2014, personal communication), a merger of two relativity strong small-scale vorticity maxima (each with ζ ≥ 0.7 s−1) results in an increase in the circulation of the merged vortex by as much as 40% compared to the two individual vorticity maxima. 9).

(2014), but in an idealized framework, and the formation of T2 or a tornado merger was not captured. 5). At center left, impact marks and partial ground scouring after the 2011 Smithville tornado.

Part II: Cyclic tornado formation, maintenance, and dissipation, Quantification of the inelastic interaction of unequal vortices in two-dimensional vortex dynamics, Reexamining the vertical development of tornadic vortex signature in supercells, Mobile, phased-array, Doppler radar observations of tornadoes at X band, Short note on the behavior of two vortices, Rapid-scan, polarimetric, Doppler radar observations of tornadogenesis and tornado dissipation in a tornadic supercell: The “El Reno, Oklahoma” storm of 24 May 2011, Polarization radar studies of precipitation development in convective storms, Polarimetric signatures in supercell thunderstorms, The numerical simulation of non-supercell tornadogenesis.

In MWR-05XP data shown in French et al. By 2135:43 (Fig.

At 5:19 PM CST the tornado crossed U.S. Highway 81 near Reno Road as it continued to expand in size. National Weather Service (2013)]. 3. Local Climate Data 2014). After T2 forms, the distance between the two TVSs decreases as they rotate around each other and then merge in a helical manner.

Surface Maps The radar’s volumetric update time of 11 s and its distance to the two TVSs (<15 km) allows for the interaction of the two TVSs to be documented in the 2 min leading up to and through the merger (Figs.