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Severe thunderstorm potential
New data is now trickling in tonight. There has been strong consistancy in the models with the set up for Thursday. More on this below. Thank you for participating in the blog question from yesterday. I posted all of the comments, although there are a few more to go through tonight. We will process all of your ideas and comments. And, all of the other feedback as well from every direction. Now, back to the potential severe weather outbreak.
Above is the upper level wind forecast by the GFS for 6 PM Thursday. The strongest winds show up in the shade of blue. This places Kansas City on the left front quadrant of this jet streak. This will provide tremendous lifting near the dry line by late in the day.
Just like on March 12th, there is no cap. So, it will be easy for thunderstorms to be generated which could limit the potential for supercells, but it won't rule it out. Let's see how this sets up. We will have to see how high the dew points get, and where the upper level vort max tracks. There are many factors to consider, but there is still a strong possibility of a severe weather outbreak on Thursday afternoon and evening across our region. Many things can still go wrong so let's see how it sets up.
Posted by at March 28, 2006 7:47 PM
Gary - Impressive divergence (or is it difluence - I can never get that right) aloft! Is this a result of being in the left-front quadrant of the jet (ie the northeaster point of fast winds aloft is to our southwest) or does the divergence, or whatever actually encourage the jet? Interesting to know!!! The divergence, difluence aloft I have come to believe, is like a chimney, evacuating the lower levels of the atmosphere,only to be replaced by other parcels and so on, therefore more lift.
The stratus possiblity - I wonder whether that could retard the warm-front, forcing it to set up near us once again? I really hope not - warm-fronts aren't nice things. But then again, from March 12th, we saw that even being in cool air, if that is a thin enough area, doesn't protect one from those spinning creatures!!!
Get some sleep before Thursday!!!
Thanks for the advice. I will get a good nap in tomorrow after I am done with working on KMBZ and WDAF at 9 AM.
Posted by: StormDog at March 28, 2006 8:09 PM
Gary, I am curious on something..a learning opportunity for me. You mention no cap, inviting thunderstorm development, but limiting supercell potential. How does that work? Seems if there was no cap that tops could grow even higher? Help me understand that. Also..looking at the vorts I can't pin them down yet, even as close as we are to it now. I get a feeling Thurs will be very busy...indeed..get some rest..you will be busy Thurs!
A cap can prevent a thunderstorm from developing. But, it has nothing to do with how high the top of the thunderstorm will be. Now, the supercell potential is there. But, we will have to look at the soundings Thursday morning and see how it is setting up.
Posted by: Scott at March 28, 2006 8:32 PM
How many rounds of Thunderstorms do you expect this Thursday?
We really have to wait and see how things come together tomorrow. At this point, I would say it's possible to have a round of morning thunderstorms... and then more in the afternoon/evening. But we'll have to see where our boundries set up, how much sun we see, how high our dew points really get... etc.
Posted by: Benjamin Tracy at March 28, 2006 9:49 PM
Makes sense. I did a bit more reading and better understand now. What type of information shows capping potential? Are these shown in CAPE values for instability, or where do you find values/models for warm air aloft? Would these be shown in the 500mb temps? I feel so challenged with so much data available, and so limited knowledge in reading it! Thanks for the heads up on the cap, and I will continue to read to catch up on the rest.
A cap is best seen on a sounding. Here is a link to the latest sounding from Topeka:
On this mornings sounding, the cap is 11.3.
Here is info on what numbers indicate a strong or weak CAP:
0.... No cap
.1 to 1.9... Weak cap
2 to 4.... Moderate cap
4.1+.... Strong cap
When the CAP is 2 or less, storms are likely to develop... if the only thing preventing them IS the CAP. If it's greater than 4, something ELSE will need to happen for the CAP to be broken.
The CAP is very important since it can BOTH promote severe weather OR prevent storms from even forming. If it's too strong, rising air will not be able to penetrate it. But, as this supression is going on... heat and moisture will be building up below the CAP... and this can gradually weaken it. Once the CAP is broken, we could see an explosive development of thunderstorms.
But sometimes there is just not enough forcing... and that can mean NOTHING for us! Sometimes the CAP prevents storms, alltogether.
Hope that explains a little more...
Posted by: Scott at March 28, 2006 10:34 PM
Well it appears like the most recent runs of the numerical models are still very bullish on a severe weather outbreak from the area tomorrow. From what I have read, can this be a very potent scenario in place that seems more concentrated, much like the May 3 1999 OK/KS episode or possibly the June 2 1984 Upper Midwest outbreak?
Placement of the 250MB jet stream velocity maximum points a very scary finger at the Interstate 35 corridor (and 125 miles either side of that line) from near Gallatin MO to Norman OK. Based on the data that I have gathered the most recent GFS and UKMET model output seems to have a better grasp on the structure of the 500MB cyclone (hybrid, neutral tilt), and actually tries, through UVV predictions to mimic supercell formation in NE, KS, OK, NW AR and W MO. And while MuCAPE and LI measures do not that seen extreme, those values are more than adequate it has been suggested this is nearly textbook alignment of upper level and surface features. Once the "show" gets underway tonight with the rapidly advancing low level jet (strong storms in the Dallas/Fort Worth metroplex), the ultimate progression of the severe weather will be into the Corn Belt and lower Great Lakes on Friday.
So what do you think? Is it still to early to know? I see SPC has us under a "Slight Risk" for severe weather, so does that mean this outbreak is not likely? Do you think SPC will upgrade the risk to Moderate or High based on the latest information? I really need to know! :-) Keep up the good work.
Brian (Aka Doc)
We are under the threat of severe storms today--a moderate risk! It could shape up into a very busy afternoon!!
Posted by: Doc36 at March 29, 2006 7:51 AM
Yes, that helps alot. Between rap,unisys,spc, and nco..I seem to get all the models I need..just need a bit more time to learn it all..LOL..but now I much better understand cap and where to read it.
Posted by: Scott at March 29, 2006 11:02 AM
Two questions..1, is there data for soundings for KC? Can't seem to find them. 2. Did you all archieve or know where there might be archieves of soundings for March 12? I think it would be interested to compare to the upcoming storm.
There are no soundings done in KC. I know, it is frustrating... but that is just the way it is right now! You can see *forecasted* soundings, though. Here is a link:
I am not sure about the archives. You could contact the NWS about that!
Posted by: Scott at March 29, 2006 12:44 PM
I know it is still like 24 hours or so away but what is your gut feeling about the setup for severe weather on thursday? I would love to see some strong storms. I live in Raytown and all the strong stuff seems to go right around us as if there is some sort of "force field" around Raytown!! It gets frustrating because I love watching the weather outside. Anyway, thank you and the whole weather team for being so heads up about everything all the time. You guys really help everyone out when it counts. Keep up the excellent work.
We have felt the same thing about the "force field" concept... around KC when it comes to snow! :)
We still do have the chance of severe storms on Thursday. It would most likely be in the afternoon or early evening... and it looks like at some point there should be a line forming. But where will that line form? We will be tracking it, so be sure to watch Gary tonight!
Posted by: ryan at March 29, 2006 12:48 PM
It seems right now the potential for tornadic cells--while not impossible--is very low. On the models I've been looking at I seem to see southerly and southwesterly flow at the surface. On 12 Mar, I noticed we had an easterly component to the flow that seemed to enhance the shear and create a more favorable environment for the tornadic supercells that formed. If I had to guess, with the lift provided by the Jet max and the moisture that will probably be pumped in by a southerly flow, we should probably get ready for more hail damage sales.
The set up is definitely not the same as March 12th. But we still have the risk of severe storms, supercells included. Hail and wind damage look to be the most likey, but supercells can, and do, produce tornadoes with little or no warning. So we have to watch it closely!
Posted by: Mike from Warrensburg at March 29, 2006 2:06 PM
Thanks for the link. Running it for KMCI -24hr shows some interesting things [forecasted]
Cap - 5.1
Helocity - 471!
KI - 33
RH - 73.9
Hope things pan out..we shall see.
Posted by: Scott at March 29, 2006 3:43 PM
Gary...sorry but this is in answer to yesterday....continuous coverage is the only way to go...I know is difficult and people complain about reg programming, but w/ tornados abounding we need your expertise ringing in our ears...there is no discussion when it comes to people's saftey and lives...we would like to see you/or crew on Sat and Sun morning, also...you do have the best forecast...why doesn't your station have a week-end morning news?????...keep up the great work...theory is interesting and am looking forward to more about it....am old enough to see a change in the seasons and crazy weather...winters are so warm anymore and not those big snows.....
Thanks for the feedback! We will see how we handle this on Thursday.
Posted by: Faith Konink at March 29, 2006 9:53 PM