I normally do not post detailed damage recaps, so this writeup is out of the ordinary for me. However, I did post my funnel cloud video for my followers on Facebook to see and I wanted to followup with a brief overview of what I believe caused the damage just a few blocks to my south. Was it a tornado? I don't believe so. I believe, based on my own damage assessment and a careful analysis of Doppler velocity data that the damage was caused by straight-line winds.
On the morning of Sunday, May 10, 2015, a bow echo moved into North Texas and across the DFW Metroplex. This bow echo formed well to the west, near Abilene, and propagated into western Tarrant County around 6 am. As it raced eastward across Tarrant County, a weak circulation formed near the Southlake/Grapevine border, north of Highway 114, around 6:30 am. At 6:35 am, I lost power and had peak winds of approximately 70 mph from the west (my observation was also included in the official NWS Local Storm Reports). At 6:36 am, I captured a very short video clip of a weakening funnel cloud just to the east-northeast of my location and just to the north of some wind damage that occurred within a couple of neighborhoods along Dove Road (east of Kimball Avenue).
After sunrise, I drove around to assess the damage and I found a couple of damaged roofs, several large trees uprooted, a large tree on a car, and numerous large branches that were snapped (larger than 3-inches in diameter). The following neighborhood streets east of Kimball Avenue along Dove Road were affected:
- Cripple Creek Trail
- Panhandle Drive
- Tumbleweed Trail
- Mesa Verde Trail
- Camelot Drive (north side of Dove across from Tumbleweed Trail)
Further east on Dove, I found some wooden fences blown over and some large tree limbs that had snapped. Finally, a few large trees were uprooted along Kimball Ave at East Highland Street, 4 blocks south of Dove.
Nearly all of the damage occurred on west-facing structures (fences, roofs, etc.) and all of the uprooted trees fell toward the east or northeast. This damage pattern is consistent with straight-line winds, most likely a downburst that occurred near Kimball Avenue. Although the funnel cloud was healthy, none of the damage that occurred suggest a tornado. In addition, the funnel cloud that I observed was located a few blocks north of the damage and north of the downburst path. Further down this page, I've also included the text of the damage survey conducted by the National Weather Service, and our findings are consistent.
Focused View of the Mesocyclone
Straight-line winds approaching Kimball Avenue in Grapevine at 6:32 am on Sunday May 10, 2015. Camera location (filming funnel cloud) is the blue square. Approximate funnel location at 6:35 am is marked with an X.
Apparent downburst with enhanced straight-line winds while crossing Kimball Avenue. This image is the next scan available (6:38 am) which clearly shows a core of straight-line winds. The funnel cloud is north of the damage path.
I Captured this Funnel Cloud at 6:35 am on Sunday 5/10/15
In the radar images above, I've indicated the most concentrated swath of wind damage. The pinks in the velocity data represent wind velocity away from the radar site (i.e., along the radial from southwest to northeast) ranging from 70 to 80 mph. This core of high winds continued northeastward into Lewisville where similar wind damage was reported. For brevity, I will not assess the damage in Lewisville, but the NWS covers it sufficiently in their damage survey (below).
The footage was taken at 6:35 am, approximately 3/4 mile to my east-northeast (see the map).
I had been forecasting and tracking a bow echo for well over 150 miles. My mind was not in "tornado" mode. I did see what appeared to be a broad circulation on radar to my west/southwest before I walked outside, but I didn't give it a second thought; circulations are quite common at the apex of bow echoes. It is for that reason that my video clip begins with me filming toward the west. As I panned to the right, I was surprised to see a funnel. It quickly dissipated (or became entirely obscured by rain), so I trimmed out that tiny segment of the footage.
As I watched the funnel cloud, I saw no evidence that it was making contact with the ground. Further, I've seen no other reports, photos, or videos indicating that this funnel touched down. In situations like these, we meteorologists have to rely solely on our knowledge of damage/debris-path patterns to determine the cause of the damage. In this case, the final determination made by both the National Weather Service and myself is the damage in Grapevine was caused by straight-line wind.