Hallam, Nebr.,Survey: 2.5 Miles Wide at Times!!!

[Suzi Q]

My daughter is in Irving and was out for dinner when people started standing outside looking at the GREEN sky. She obviously left and barely made it home, torrential rain, violent CG lightning, she's lost power once already. Flooding occuring now in Lewisville. All of Dallas Metroplex under flash flood warning, urban and small stream, etc., etc., etc. I knew it was bad when she said I would kill to be there right now.

I'll echo Alex's remarks-PLEASE PAY ATTENTION AND STAY SAFE AS THIS COULD BE ANOTHER TUMULTUOUS WEEKEND.

And Alex, you're welcome for the video. Sobering to say the least.

Hugs and prayers to all who have been or may now be in harm's way.

Suz

[Cumulonimbus]

Suz:

In case you haven't heard even WE are in on the action. To emphasize how STRONG this incoming trough is, a TORNADO occurred this afternoon near Tenino, WA which is south of Olympia WA. This is the second tornado in western Washington in the past 3 weeks. The state has already had 4 this spring. It was only an F0 and tore the roof off a barn but it shows you what is on the way. I have lived here for 43 years and I don't ever remember a tornado in the western part of the state. And now we have already had 2.

Again thanks for the video and I will say my prayers for all of you for this weekend and beyond.
Stay safe!!

Alex

[Suzi Q]

Twister time in Washington? Now that's a new one on me. I bet most of the people are just as surprised as you. I used to have family up in eastern Washington-snow they got, but not twisters.

Could be an action packed weekend.

[weatherwunder]

Just think how we were feeling in Lincoln when all of this went on, it was getting a little close.

[Nate-Gillson]

I apologize for the bump but the tornado was actually 1.5 miles wide. What made it seem 2.5 miles wide was the RFD (Rear Flank Downdraft) also did a lot of damage to Hallam (straight-line wind damage). The RFD is believed to be a key factor for tornado formation. Cold dry RFD kills tornado formation. On the other hand, warm moist RFD is very important for tornado formation. Unfortunetly, the process is hard to explain and I cannot elaberate any further at this time.

PS: RFD winds can be as strong as a weak catagory 4 hurricane.

[PurdueWx80]

Yeah, there is a lot that goes into quantifying and describing what exactly makes up the circulation of the tornado. In my Radar Met class, we have been looking at very high resolution radar data from the Doppler-on-Wheels (DOW). There have been all sorts of very intriguing images documented for the first time...so there are lots of new things being learned with this technology. I'll try to post some of the images (they aren't that new...but are still used in research more and more all the time).

The DOW is especially useful because a tornado's circulation may not always be visible, especially if there is no condensate or debris within it. FYI, there is also ongoing work on redefining a damage or intensity scale...others have been built off the Fujita, but the one being worked on now is supposed to revolutionize everything. It'll take a lot of work to implement this into the gov't, but it will be well worth it since the Fujita scale is extremely subjective, prone to error, and not always helpful to structural engineers and such.

[P.K.]

That was obviously some tornado there.