2011-04-14 DISC: OK/KS

[Warren Faidley]

Tulsa TV 6 preparing to go live on the internet when 1st. srv. breaks. I'm sure OKC stations will also.

http://www.newson6.com/category/184619/severe-weather-embedded-live-stream-kotv2?redirected=true

W.

 

[David Hoadley]

There were several comments yesterday similar to this one from Mikey Gribble (below).

"I am surprised at how sloppy and clustered storms were today over central and northeast Oklahoma, coming off the dryline. Every time this storm would start to look like it was going to get its act together, some convection would come in from the south and merge with it... I was really hoping for a better storm today..."

It has been my experience over many years of chasing that closed upper lows often produce messy storm days --even with a negative tilt. The open low is to be preferred, when one has a choice. - - - David Hoadley

 

[Chip Redmond]

I agree with David as the low was pretty much cut off which prevented the movement of the dryline to prevent backbuilding. There was also little CIN to prevent convection and pretty much allowed any upward movement to continue. Had the low been more open, vorticity advection would of occcured outside the low and coupled with higher CIN along the dryline, the only convection that would've occured was that around the vort max. This would create only a few discrete cells to fire along the dryline instead of the whole thing lighting up.

Chip

 

[Warren Faidley]

I was seriously considering flying out for the event, but I pulled the plug in the early AM for the aforementioned reasons, including the potential issue of surface RH values if convective initiation was earlier than expected / low CIN. One of the things I like to do after a "potentially" big day goes bust is to do a forecast postmortem of the event. I have found this site [http://locust.mmm.ucar.edu/] to be most helpful with archived data.

W.

 

[Steve Miller TX]

Regarding the Tushka tornado, here is an interesting satellite image I captured at 1633Z. I added the green circle to depict my best guess as to where Tushka is based on the Red River contour. This persistent feature over Oklahoma remained in place for a couple of hours after, but eventually faded away an visible satellite. However, I think the correlation of visible features and the resultant massive tornado may not be a coincident. The parent supercell went "bonkers" as it moved into this zone. I want to stress that this feature was very pronounced and persistent for a few hours and barely moved. One theory I have is that it is a larger more pronounced horizontal roll along a zone of confluence and similar to horizontal convective rolls. I certainly would welcome others' input on this.

Thanks to Robert Dewey for the link to the visible animation:http://www.rap.ucar.edu/weather/sat...=large&endDate=20110414&endTime=21&duration=6

http://www.rap.ucar.edu/weather/sat...=large&endDate=20110414&endTime=18&duration=4

 

[CZandbergen]

Steve, I noticed the same feature yesterday as well. It was very well defined and it didn't move. I had the same assumption as you. It had to be some type of boundary. Looking at the image you posted there also looks to be a boundary running to the SW from where you have Tushka depicted. the intersection of those two boundary features could very well explain why the storm went "bonkers". One would think stream wise vorticity would be maximized in this area.

 

[Todd Renshaw]

Forgive the possible stupid question, (still have a lot to learn about forecasting and radar interpretation), but I was seeing a faint nearly stationary line on radar yesterday too. It snaked a bit as it moved through the clutter surrounding the radar I was watching. (KINX or KTLX? Don't remember which and I didn't get any screen captures.) It was definitely organic looking and did move past the center very slowly, so I know it wasn't an anomaly. It was way bigger than an outflow boundary.

Same thing as Steve Miller's satellite image? (But this would have been around 20 - 22z, I'm guessing. So quite a while after that sat image.) Anyway, sorry if this is a stupid question. Hope it isn't an obvious answer like a front or something.

 

[Steve Miller TX]

I was seeing a faint nearly stationary line on radar yesterday too. It snaked a bit as it moved through the clutter surrounding the radar I was watching. (KINX or KTLX? Don't remember which and I didn't get any screen captures.) It was definitely organic looking and did move past the center very slowly, so I know it wasn't an anomaly. It was way bigger than an outflow boundary.

Same thing as Steve Miller's satellite image? (But this would have been around 20 - 22z, I'm guessing. So quite a while after that sat image.)

That was the dryline about that time. Dewpoint at OKC dropped from around 61F to 18F quickly when it passed. Later, the cold front caught up to the dryline and they merged after 00Z.

 

[Todd Renshaw]

That was the dryline about that time. Dewpoint at OKC dropped from around 61F to 18F quickly when it passed. Later, the cold front caught up to the dryline and they merged after 00Z.

Damn. I was hoping to have something to contribute to the conversation for a change. Ah well, good to know. I'll watch for that now that I know. Thanks, Steve.

 

[Steven Howell]

Steve, if the time on the satellite imagery is correct, this would have been at 1133 am, before initiation of storms, it does look like some kind of boundary, possibly an old boundary from the storms that were in North Texas and Southern Oklahoma on Sunday night and into Monday morning?

Regarding the Tushka tornado, here is an interesting satellite image I captured at 1633Z. I added the green circle to depict my best guess as to where Tushka is based on the Red River contour. This persistent feature over Oklahoma remained in place for a couple of hours after, but eventually faded away an visible satellite. However, I think the correlation of visible features and the resultant massive tornado may not be a coincident. The parent supercell went "bonkers" as it moved into this zone. I want to stress that this feature was very pronounced and persistent for a few hours and barely moved. One theory I have is that it is a larger more pronounced horizontal roll along a zone of confluence and similar to horizontal convective rolls. I certainly would welcome others' input on this.

Thanks to Robert Dewey for the link to the visible animation:http://www.rap.ucar.edu/weather/sat...=large&endDate=20110414&endTime=21&duration=6

http://www.rap.ucar.edu/weather/sat...=large&endDate=20110414&endTime=18&duration=4

 

[Steve Miller TX]

Steve, if the time on the satellite imagery is correct, this would have been at 1133 am, before initiation of storms, it does look like some kind of boundary, possibly an old boundary from the storms that were in North Texas and Southern Oklahoma on Sunday night and into Monday morning?

To me, it doesn't look like an outflow boundary where I would expect to see it arced and with a thin line of cumulus bubbling along it as well as surface analysis identifying it. Check out the loop I posted...pretty interesting to see it in motion. http://www.rap.ucar.edu/weather/sat...=large&endDate=20110414&endTime=21&duration=6

 

[Warren Faidley]

I am wondering if it's not some type of gravity wave? If you study the sequences of satellite images http://locust.mmm.ucar.edu/ and rock the set forward, it appears to propogate much like a pressure wave. It begins at around 13:45 UTC, becomes very linier, then it morphs into a different structure by 17:45 UTC. Just a thought, but very interesting feature.

W.

 

[Jeff Bartlett]

Yesterday gave me a serious bout of deja-vu. I felt like I had played this game before. After a little searching, I found it...

http://www.spc.noaa.gov/exper/archive/events/050604/index.html

While there are distinct synoptic differences between the two events, the way it played out in Oklahoma were nearly identical. Moderate risk, with strong tornadoes possible along and east of a dryline pushing into the I-35 corridor. Capping was assumed to be strong enough to limit the quantity of storms. In the end, both days ended up very similar, with too many cells firing at the same time and competing with one another, with the only exception being the tail-end charlie(s).

Well, I thought it was an interesting comparison.

 

[Steve Miller TX]

I am wondering if it's not some type of gravity wave? If you study the sequences of satellite images http://locust.mmm.ucar.edu/ and rock the set forward, it appears to propogate much like a pressure wave. It begins at around 13:45 UTC, becomes very linier, then it morphs into a different structure by 17:45 UTC. Just a thought, but very interesting feature.

After looking at that extensive loop Warren, I tend to agree with your idea of it being an earlier gravity wave that became nearly stationary....kinda like an undular bore in a way. Other waves come in too later. Now, the question that pops up in my mind is what caused it? I surmise that it is from the compact and intense upper low...very sharp temperature gradient aloft with the colder air being more dense and pushing into the area....creating a wave so to speak like quickly pressing your hand on the surface of a pan of water. Could be some other factors too like jet dynamics. But, I'll stop there....my lack of a PhD in Meteorology is starting to show ~

 

[Jeff Duda]

After looking at that extensive loop Warren, I tend to agree with your idea of it being an earlier gravity wave that became nearly stationary....kinda like an undular bore in a way. Other waves come in too later. Now, the question that pops up in my mind is what caused it? I surmise that it is from the compact and intense upper low...very sharp temperature gradient aloft with the colder air being more dense and pushing into the area....creating a wave so to speak like quickly pressing your hand on the surface of a pan of water. Could be some other factors too like jet dynamics. But, I'll stop there....my lack of a PhD in Meteorology is starting to show ~

You can get a gravity wave pretty much anytime you have a strong inversion of potential temperature and a source of excitation. Gravity waves are everywhere, but they're hard to see when there's nothing to mark them. Clouds can mark gravity waves. I thought maybe that line was a gravity wave, but something about it is keeping me from wanting to call it one: its propagation speed appears to be too slow to be a true internal gravity wave. It still may be some kind of bore feature, though.