4/21/07 REPORTS: TX / KS / NE / CO

[Reed Timmer]

Here are some video frame captures of the nighttime tornado we saw from SR 285 between Happy and Wayside, TX as it moved through the Palo Duro, Canyon. After observing the tornado, we ran into the damage path on SR 285 a few miles down the road. Telephone poles were knocked over, blocking the road, and cows were wandering outside their fence. This tornado looked very strong.

 

[Scott Olson]

The decision this day was between southern South Dakota and the Texas Panhandle. I had thought Texas looked like a slam dunk all week, namely because of the GFS and ECMWF agreement on nice directional shear (towards the base of the trough) and a more approtiate intiating boundary (dryline). However, I had already made many trips down south this year to limited success and was encouraged at the presence of a warm front across south-central South Dakota and into east central South Dakota. This area had comparable levels of instability and slightly higher dewpoints (lower LCL’s). The directional shear wasn’t so great but the speed shear still made for effective bulk shear supportive of supercells (45-55kts). Enhancement along the boundary looked to provide a favorable environment for at least landspouts. So let the first home territory chase of 2007 begin.

I pulled into Pierre around noon. Originally I had favored more of a Kennebec location but I was relying more on the assumption of the northward moving boundary intiating. After two more hours of looking at data, I decided that storm intiation was more likely to the south and that a weak low pressure system (that was well present in the early afternoon) could provide much needed localized enhancement for tornadoes. I went south of Presho and started noticing some weak dis-organized storms going up near North Platte. I didn’t want to get pulled in to quickly, the warm front was just starting to pull north of I90 and may still intiate. However, my main concern with the front was that boundary orientation would provide a feeding ground of rain-cooled air for other storms. This was because the boundary was oriented to the shear vector and only spotty development and strong deviant motion could have brought in a good tornado risk. Nonetheless, as I checked the radar I noticed that those weak showers had formed into a single decent looking cell. That was good enough for me and I blasted south of Presho for an intercept. The storm quickly strengthend and obtained several areas of radar indicated rotation. However as I neared about 20 miles north of the Nebraska border the cell began to fall apart. As this occured the cell southwest of it took to the throne and quickly became supercellular, obtaining several areas of rotation. I headed south, planning to intercept near Springview. Watching the evolution on radar, the cell went from a more classic appearance to HP and then to various degrees of health and undercutting. I arrived in Springview and headed a bit west as a tornado warning was issued to my SW.

I setup the tripod, than the winds kicked in with a vengence. Noticing with interest, the winds weren’t blowing away from the cell or even from the south, they were blowing from the east and with impressive ferocity that made use of the tripod impossible (and wearing a hat). Quickly back north and through Springview, I then headed east on Highway 12. I quickly noticed that the beginning of the stronger low level winds that was responsible for the high wind advisories/warnings for the area. Surface winds started coming out of the south at 25-30kts. After only a couple miles I looked south and saw the dirt being torn from the ground and a small concentrated spin-up present. Well if it isn’t a gustnado! Not so much of a surprise given the strong winds from the environment and storm that were converging right there.

Further east I stopped again and was treated to even better structure.

I headed further east and pulled north onto highway 137. It was then that I saw what clearly appeared to be a tube shape structure with the classic definition that I’ve come to expect. I stopped and took some video of it. I just couldn’t see any rotation and I was less than a 1/2 mile away so certainly it was not for lack of a diffenitive vantage point. After making the decision to continue I took one look at the radar and road options, it was clear decisions were limited. One highway went only east for a long ways, the other went north. The storms were moving northeast and would soon cross the Missouri River. I headed north to give a little more chance to this storm. Near Burke, it was beginning to move away but a nice updraft and meso were still keeping it together.

I stood outside of the car and gave it my farewell and I also declared my intention that we would meet again on the other side of the Missouri River.

More pictures & full account HERE

 

[Bill Tabor]

Finally updated my website for the many tornado pictures I took on this day. Still haven't done a detailed chase account, but check out the photos for now.

http://www.tornadoxtreme.com/Chases_By_Year/2007_Chases/April_21_07/april_21_07.html

I may post some dash cam footage soon - so check back. Below is one of my favorites of the elephant trunk. Also have a shot of the night tornado near Happy, but Gene's look better - whenver he gets around to posting them.

 

[Jason A.C. Brock]

4/21/07 Pics on weatherchase.com

Robert Sternadel asked if I would post to let everyone know he has posted some great pics of the Olton area Texas tornado on his website at http://www.weatherchase.com.
Great structure shots of this storm Robert!