Going to start off with some of more standard radar images...
Developing hook echo near Aplington at 4:55 p.m. Image on the right is the velocity - red is winds going away from the radar, green is winds coming toward the radar. Where they meet indicates rotation.
Hook echo is now quite evident. The tip of the hook tends to be where the tornado is located, and you can see it moving right through the town of Parkersburg. Strong rotation showing up in the same location.
Supercell and its hook echo continue to progress to the east toward New Hartford. It's 5:04 p.m. and much of Parkersburg lies in ruins. Strong rotation still occurring.All right, now for a three-dimensional perspective. In the following images, we'll be looking at the storm as if it were to our northwest. I've peeled away part of the storm so we can focus on a certain feature. What we're going to look at is something that's getting researched because it seems to coincide well with tornado development.
Notice the circled feature in the first image. There's a "blob" that develops and, as time goes on, descends. That's called a "descending reflectivity core." We're not sure why it happens, but it seems to happen just before/as a tornado develops. You can see how the "blob" eventually becomes part of the hook echo where the tornado is located.One last set of screenshots, similar to the ones immediately above. You can see that descending reflectivity core in the left image. The image to the right is a 3D display of the rotation calculation. Look how it threads right up that core...
Click here for video from NBC affiliate WHO-TV in Des Moines. One of the storm spotters they interview, Ben McMillan, is a friend of mine.
7:30 Post: Lots more aerial pictures are posted on the Iowa Environmental Mesonet (IEM) - click here for the aerial survey performed by Iowa Helicopter. The pilot is John McLaughlin, chief meteorologist at KCCI in Des Moines. If you want to see the location of the photos, click here for the Google Maps interface.
If additional footage is submitted to the IEM, you'll find it by clicking here.
I'll have radar images of the storm as it went through Parkersburg in a little bit.
If you have any questions about the pictures or radar images, please ask! One of the great things with this blog is that we can show you more and explain better than what we can on TV.
Original Post: More information to be coming out of Parkersburg, Iowa this evening. Preliminary rating from the Des Moines Weather Service office is "potentially at least EF3 pending further assessment Tuesday." I'll have some aerial pictures from Iowa Helicopter later this evening, as well as additional radar images.
(2:32:16 PM) kcciwx: Prelimary continuous damage swath was 43 miles. Extended for 2.0 miles south of Aplington to 1 mile southwest of Fairbank. Maximum observed damage width from the helicopter via gps was 1.3 miles.
In the meantime, our weather is looking quieter... some storms possible this afternoon/evening around Interstate 88.
9 comments:
hey justin. i noticed on kwwl's website, there is a photo of a huge tornado. is that the same tornado that we are looking at now from parkersburg.
Thank you Justin for all of the information about the Tornado that hit Parkersburg, IA last evening. The arial views have left me absolutley speechless.
The radar, velocity and 3D images you provided give such interesting views of a Tornado in action. It really helped me get a little better perspective on Tornados.
The only thing I was really trying to figure out were the colored graphs that were provided on the left side of the images you provided.
As I was looking at all of your info, I receved a notice of a special weather statement from the National Weather Service. They are calling for a Pneumonia Front...I have never heard of that. Would you be able to elaborate on that a little as well? I appreciate it.
Keep up the great work..you guys are the best!
From what I read, basically when the front comes through, we may have 40 mph wind gusts around midnight and drastic temperature drop.
I had never heard of a pneumonia front until this afternoon. Tony nailed the description. Milwaukee dropped 30 degrees in an hour! By the time it gets here, it shouldn't be *quite* as strong, but still plan on a quick drop in temperatures and some gusty winds.
Carrie - are you referring to the "DBZ" and "KTS"?
Thanks Justine, not only for great post on the Parkersbug tornado but also the great job you & Eric did last night. All you guys are the best.
I sure hope the temp drops. Our temp in the house is 83 degrees and we did not turn our AC on and it has been very humid in our house. So hopefully the drop in temp will cool our house off also.
Thank you for taking the time to explain what happened yesterday and how. Included with the chat it makes it easier to comprehend. It was so nice to see the interaction and how to best handle the situation for where we lived. It is much appreciated that you all took time to answer the comments in real time. Here at our house put us at ease. So, helpful especially when a storm is approaching so close to bedtime.
Justin, Yes..I was referring to the DBZ and KTS.
Sorry for the delay in the response..I do appreciate your help though.
The "normal" radar view we show is called reflectivity. The radar sends out a beam of energy and rain/hail/snow/whatever will basically reflects some of that energy back to the radar. The radar then determines how much came back... the more energy that returns, the higher the reflectivity. It's measured in decibels, abbreviated DBZ.
The velocity images measure the wind in knots (KTS), rather than miles per hour. 1 knot = 1.15 mph. We can't really measure actual wind speed with doppler radar... we can just see how fast it's moving toward or away from the radar. However, that kind of information is helpful to find where the winds are moving in opposite directions right next to each other.
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