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4/21/05 TALK: KS/MO

The morning after.......welcome to Canada, central Oklahoma. LOL.

Well - first of all congratulations to Shane, Chad, JR, Jeff and everybody else who had faith in the SE KS target, yesterday. We knew watching those storms from home that they would, most likely, be tornadoing.

Secondly - a little bit of post-event analysis. I put it past anybody to have forecasted the mesoscale accident that led to the development of those tornadic supercells last night.

Around 12.30pm or 1.00pm yesterday afternoon, a convective mess developed in SE KS and trundled its way across Joplin and into Missouri. At this point, had one not been watching satellite, you would have had no idea what was about to transpire.
The convective mess pushed a cold pool of outflow westwards back into Kansas, whose boundary rested up in Allen/Neosho.Labette counties. Meanwhile, the convective mess had driven far enough into Missouri that it had also left a large pocket of totally clear skies, into which the strong mid-afternoon sun shone, modifying the outflow region. Winds along the outflow boundary and in this area of outflow then proceeded to BACK to the SE.

Tcu intercepted this boundary in the aforementioned counties, and re-initiated thunderstorms all over again. But this time, the surface winds were backed and the profiles changed adequately by the modified outflow air from the previous convective mess to support almost the only respectable tornadic event of the day. The easterly movement of the storms ensured great low-level inflow, and it was second nature to these storms to tornado.

In short - a true mesoscale accident. You cannot forecast outflow boundaries cooking under the afternoon sun. I am sure when the convective mess went up in this area around 1.00pm, everybody who had stayed home was well and truly satisfied staring at their computer screens. Well - HA HA - nope! Guess again. Mother Nature still gets the one-over on us in this day and age......and that's very comforting to know.

KR
 
Originally posted by Karen Rhoden


Secondly - a little bit of post-event analysis. I put it past anybody to have forecasted the mesoscale accident that led to the development of those tornadic supercells last night.
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Karen - with all due respect - I think you are being too self-assuring for having missed this event. Really - the feature that coalesced to make this an interesting event in se KS was not entirely an "accident" precipitated from interaction with the mid-afternoon convection. Yes - that development undoubtedly aided the later storms - but a mesoscale low was noted during the morning forecast discussion across nc OK - sc KS - and it was pointed out even then that this would be an important feature to track during the day - and I quote myself here "......so if there is adequate convergence to get a storm this might be the big mutha of the day. Just follow the bullseye of moisture convergence." Ok - let's see how well that played out:

http://locust.mmm.ucar.edu/case-selection/...1/$122%201/$123


First - skip to the 12-14Z time frame - I think you can clearly see the mesolow feature that was evident in the morning. Now, step forward in time. While it lost some definition during the early afternoon - it firms up nicely by late afternoon - before the new storms fired. Admittedly - I had started losing some faith in this region getting it done later in the day - and the mesoscale accident you mentioned probably helped salvage this region some - but to say it was not predictable in advance I think is wrong - and is evidenced not only by prior forecast discussions undoubtedly by others than myself but more importantly by the success of chasers who knew to stick with this feature.

Glen
 
After analyzing the mesoscale conditions yesterday morning I think most everyone in the Southern Plains felt that extreme NE Oklahoma and SE Kansas was the area to take a chance on since this was the only location the boundary layer wind shear was respectable.

For anyone that was watching the radar during the Parsons, KS supercell's tornadic lifetime....I find it very lucky that Shane, J.R. and others were to the north in Chanute, opposed to others that missed the tornadoes to the south. The tornadic supercell was sandwiched between two other large HP-ish supercells (one to the north and one to the south), but it initiated a little further to the west and propagated ESE and then once east of Parsons merged and presumably ended its tornadic lifecycle. Anyone chasing to the south would've gone with that southern flanking storm since I'm sure it had some quality updrafts. Those to the north near Chanute were at the right place at the right time to not get caught up with the southern storm and caught the prize of the chase season thus far. The ESE deviant motion of the Parsons supercell surely helped with its inflow characteristics and led to some impressive tornadoes. This goes to show that you can be in the premium location, but a little luck here and there never hurts when you're making critical decisions on which storm to jump on!
 
That storm in SE Kansas was definitely great, but there were other storms that had some nice signatures too. If storms stayed more single-cellular in SE Nebraska and NE Kansas, there would have been more tornadoes... I can almost be sure of that.
A small supercell southwest of Nebraska City had some very promising velocity signatures, as well as a well defined BWER with an elevated hail core giving returns over 60DBZ. Had it not underwent 3 cell mergers from north-moving cells, it more than likely would have produced a tornado or two near Nebraska City. Some high moisture convergence values were also evident, as posted above.

Congrats to everyone who saw tornadoes yesterday! :)
 
Originally posted by Glen Romine+--><div class='quotetop'>QUOTE(Glen Romine)</div>
<!--QuoteBegin-Karen Rhoden
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Secondly - a little bit of post-event analysis. I put it past anybody to have forecasted the mesoscale accident that led to the development of those tornadic supercells last night.
Click to expand...

Karen - with all due respect - I think you are being too self-assuring for having missed this event.

Glen[/b]
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I completely agree. In fact, Gabe and I noticed that several versions of the RUC (including the FSL version, a couple of experimental runs, etc.) initiated precip in far ne OK and sw MO by early afternoon on late-morning model runs! I partially discarded those solutions, since the precip lasted only 2-3 hours in the model. That said, we did discuss the fact that the it could lay down an OFB, locally back winds and lower LCLs, and this was at like 10am. Additionally, the 12z NAM showed backed surface flow east of a N-s line out of Tulsa. So, to me (and others presumably), it was pretty evident that this area was the place to be if one couldn't make the action farther into ne KS. By 2pm, with SSE sfc winds in the area, we realized that there was indeed a tornado threat.

So, I think you, Karen, were essentially saying that those of us who were in se KS/ far ne OK just "got lucky". If it makes you feel better about your decision to stay home, then that's fine. But don't discredit other people's choice to target this area by implying that nobody saw that coming... Nobody's always right, but I can admit my forecasting flaws when I miss an event without saying that everyone else just got lucky.
 
I would have to disagree with Karen as well. I originally targeted SE Kansas and stayed put until around 4:30. I started to haul North for the warm front, but then I had second thoughts and turnded around and went back to Yates Center. I checked sensors and saw where the backed winds were. I noticed the updrafts repeatedly trying to get going and failing NE of Tulsa. And I was definitely looking at the convection along the Ark., Miss. borders. I admit that I thought the tornado potential was seriously damaged by storms to the east and southeast. Once the storms did go up in Kansas, I had a pretty good idea that the Neosho storm was going to have better air to work with since the storm farther South was closer to the earlier convection. I also considered the possibility of an outflow boundary from storms that were collapsing earlier on the North side of the more persistent storms along the border. There was certainly some luck involved, but I and I am sure most chasers on the storm were not ignorant to what was going on around them. When you sit for hours waiting for storms to develop, there is ample time to analyze your environment and consider the possibilities.
 
My words here will likely fall on deaf ears.....so this will be the last post I make on this thread in an effort to avoid inflaming any others emotions....I don't waste time doing objective analyses like these in order to make myself feel better.

Is it not baffling that not one SPC/NWS discussion from any area or any other texts coming out of SPC actually mentioned this "mesolow", then? Seems strange that nobody saw it except those who were there - if it was so "obvious" even during the morning...??

The MCON graphic that Glen linked to showed moisture convergence increasing upstream of where the storms re-initiated - BUT - this was due to local backing of the winds that was clearly attributable to the outflow from the previous storms.

Glen/Jeff/everybody else - if the winning forecasts yesterday morning for SE KS were made because of the existence of a mesoLOW, then I'm going to have to see more evidence than just a MCON graphic. As and in itself - the existence of a mesoLOW can only be concluded by a local sustained minimum in the pressure field to go along with a wind circulation. Looking back at surface data for all of yesterday, there is no evidence of a cyclonic circulation in the surface winds most of the time preceding initiation.

Many blew off SE KS and NE OK yesterday because of the southwesterly surface winds throughout.

Other colleagues of mine have saved and plotted all of yesterday's hourly surface obs and satellite images. At no time did they see ANY sign of backing winds in SE KS until the modified outflow air left its mark.

This event WOULD have been NOW-castable......if one were paying very close attention to visible satellite loops and anticipated the series of events beginning with the generation of cold outflow air from the convective mess, and ending in tornadic supercells forming in the modified outflow. Would there have been time to nowcast it and get there? Doubtful...

Now - I'll say it again like I said before - I commend each and every chaser who managed to catch this event and see its tornadoes. I couldn't be more happy for you all. Well done! I feel just fine about missing it - because from MY point of view (and many others I have been talking with) it was unforcastable. I'm not sitting here crying into my soup, pouting or biting my nails at the demise of my chase season for the year......really.

It's a real shame that there's very few places one can discuss events like this objectively without treading on some poor soul's emotions.

KR

EDIT: I also maintain that there *was* no dryline left by yesterday afternoon. I'd love to see it if anybody can show me the "dry"line that was there.....as there was no drying behind it. I think we were left with a pure cold front......although the cold front did seem to stall later in the day.
 
Originally posted by Karen Rhoden
Well done! I feel just fine about missing it - because from MY point of view (and many others I have been talking with) it was unforcastable. I'm not sitting here crying into my soup, pouting or biting my nails at the demise of my chase season for the year......really.
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LMAO... Unforecastable? Nobody "official" was forecasting it? Do you remember the 5-15% tornado prob? Do you remember any of Tulsa's HWOs?

Originally posted by Tulsa HWO issued at 9:33am
STEEP MID LEVEL LAPSE RATES COUPLED WITH INCREASING FAVORABLE SHEAR WILL SUPPORT SCATTERED LONG LIVED SUPER CELLS WITH GOOD POTENTIAL FOR VERY LARGE HAIL AND POSSIBLE TORNADOES.
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OK Mesonet showed SSE sfc winds from Bartlesville eastward from mid-late morning onward. I would me more considerate here if it sounded like you weren't being so haughty, but I guess you feel like you're treading on my emotions (such a "poor soul" I am) ...
 
Karen the backed winds I was refering to were showing up more than an hour before storms finally started.
There was a survey from the Neosho county storm. They confirmed two tornadoes yesterday. The first was an F3 and the second one was an F1. I think the second one probably could have been an F2, but there wasn't very much damage from it once it got stronger.
 
Karen, this is what I wrote at 11:10am on the 04/21 forecast thread when some of the folks down in OKC started becoming concerned about the surface winds veering from the SW and W early on:

Well, if you look at some of the basic wind surface forecasts between now and 5:00pm, looks like what is going on is the low pressure/wind shift line is tilted from NW to SE, and that is consistent with the surface observations in central OK. For example, surface winds forecast from due S at Tulsa at 11:00am and then actually forecast from SE at 2:00pm while at the same time wind has shifted to WSW at Ponca City while still from due south at Wichita!

Can see why some of you in OKC area may be a little spooked by what you are seeing at the surface now, but in your mind's eye think about positioning NE of your current location, and then looking towards the west. By 5:00pm, may need to be crawling up the KS/MO border.
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I, too, was kind of skeptical/confused about identification of a "mesolow" in central KS. Then, when we started to hear about the winds veering down in OK, I took a very "low tech" approach and simply went to NWS's 2hr interval graphical forecast of wind direction over central plains. I noted that what was being observed in central OK was completely consistent with this forecast, and therefore held confidence of SSE surface winds in SE KS. Although the exact identification of the surface mechanism was subtle (wind shift line? dry line? cold front?) yesterday, I thought whatever was out there would be pushed through by the advancing flow at 500 mb. I had confidence in its rate of advance because I stayed up practically all night before monitoring the RUC. Now, I myself ended up chasing the Topeka-Atchison HP because of my location and the fact it was established right when we headed out. I do agree with you about the extreme difficulty in pinpointing convection based upon outflow boundaries; at least it is for me because I am not yet knowledgable enough regarding these mechanics, let alone how to accurately identify. Anyway, I hope there are no hard feelings here and I definitely don't mean to "pile on." I think we all learn from each other as we go. After all, you were the first one to raise the forecast for this week about a week in advance and explain to me the relevance of the 500mb flow in the first place. You basically planted the seed for me to plan my first chase in the plains after living on the east coast for 17 years, so I truly appreciate your efforts.
 
Also, I guess more in line with the current discussion going on here...I had to drive all the way up from Austin, Tx for this intercept. My forecast was from about midnight the night before the event. I had to leave early to head for my initial target of Emporia south of the expected triple point along the dryline interface. [Actually Emporia is not all that far from Shane's Chanute target]. Anyway, I got late on the initial target, but had a secondary plan of working my way further south along eastern KS and eastern OK. When I ran out of time on my initial plan to make Emporia or closer to the ongoing action at Kansas City I switched to my secondary plan. While headed north along I35 to near the KS border I totally ran out of cu. To me that probably indicates a dryline passage although I didn't have data at the time; regardless it was a definite wind shift line with less low level moisture. I knew this and I knew I had to get east. I caught some daytime action in SE KS before dark, but then finally had luck chasing in darkness in Missouri. Generally, I won't leave the house to drive 13+ hours if I don't have a good idea / feeling about a tornadic target. Myself, I call that forecasting - at least in my own way. Did I foresee a mesolow??? Not necessarily. I look at a lot of things that generally indicate a chance for tornadic cells. When I forecast I try and stack all these in my favor and maximize them at a point. I'd say I forecast for an area, but not necessarily a specific event or process. Truthfully it's been a few days and I forgot now what all I saw that made me go there, but there were a lot of positive indicators to say that the area had potential. I think if you notice SPC forecasts the same way. They pick an area and plot a probability. For myself I find the maximum probability, see if it appears that it will transpire, and then go for it if it will.
 
I don't know what it was I saw in SC Kansas that morning during my surface analysis. Mesolow, DL buldge, whatever. I read maps by visual recognition, I don't sit and crunch numbers and do 4D analysis of every minute detail. All I know is, I liked what I saw, and I knew I wanted to be east of it. The forecast for April 21 wasn't impossible, that's just silly. It's not like I expected what we got; I simply believed that area held the best opportunity for any discrete storms to become tornadic. I didn't leave that day thinking I'd see an F3 track for 20 minutes. I just felt that I'd see a better storm than anyone else who went somewhere else.

I'm not worried about people's feelings, I'm just discussing what transpired for me that day. I never once thought it lucky or amazing that we were right there when the cool sh*t went down. Seemed pretty obvious to me SE KS/NE OK was the hot target zone that day. But at the same time, I'm not surprised more chasers weren't out there. Those ssw surface winds certainly made me pessimistic too, but that "thingy" in SC Kansas was a creature I recognized from chases past...and I knew if anything was going to spin, it would be east of there. I also knew a lot of others wouldn't have that faith. It was a chance we took, and it paid off. Not luck, just believing. And therin lies the difference (IMO) between those that went and those who stayed home.

Sometimes you have to just believe. Mother Nature isn't always going to scribble across the sky where the tornadoes will be. Karen said something a while back about 2004 being full of easy events, outbreaks with obvious target bullseyes, and in the same breath, pondered the chances that 2005 would be a more classic year, filled with more obscure, non-outbreak events that would require chasers to actually "work" for their bounty. If last year was too easy and April 21 was too hard, what type of chase event is she talking about?
 
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