I am intrigued by the setup for localized tornado event in south-central Kansas tomorrow. It is shaping up to be an event with similarities to 26 October 2006. I think (a) tornado(es) may occur farther west than the current Day 2 SPC (the 1st, 06z, issuance) outlook slight risk in a small corridor where upper 40s to lower 50s dewpoints will sneak west along the Highway 54 corridor from Wichita to Kingman. Surface vorticity will be maximized in this area due to the presence of a significant middle tropospheric potential vorticity (PV) anomaly. I like to look at 400mb for wind speed fields and related PV anomalies. It is just downstream of a 400mb PV anomaly where surface cyclogenesis (in the wind field) is maximized (dZeta/dt at the surface for you meteorologists out there!). I think if surface based storms form in this zone, it will take advantage of a tremendous source of vorticity in the low levels — both vertical vorticity and horizontal streamwise vorticity. Given the substantial ageostrophic motions present in the low levels in response to a small scale jet streak like this, there will be an enhancement in ambient vertical wind shear as well as the atmosphere tries to restore itself back to geostrophic balance. Okay, that’s some heavy meteorology, but that’s what is going on in these small space/time scales. Timing is critical. Like 10 November 2008 and 26 October 2006, the event occurred in a very short time window…usually centered around 21-22z. If the current NAM model holds, then the best area at the 21-22z time frame will be along the Highway 50 corridor somewhere in a Cheney Lake-Kingman-Wichita area. Below is a conceptual model I put together for an informal presentation back in January at a local AMS High Plains chapter meeting regarding these special events. What is very interesting about my conceptual model is that the area I drew this conceptual model — south central Kansas — is exactly where I think things may unfold tomorrow (very near the yellow area on the graphic!).
Below is the 33-hour forecast from the NAM valid 21z April 9th. The graphic is of 400mb wind speed and surface wind barbs. I annotated where the 400mb PV anomaly would be based on the wind speed field…as well as where the greatest vertical vorticity would end up being as well. This all seems to point to the Wichita area or points just west at 21z:
This day has the makings of one where there will be tornadoes in the area you highlighted in this forecast, but then be bust everywhere else (though I do think SE KS looks good, it is just a too small of a window of good terrain for me to chance it). If anyone does target this area, be there extra early or you might miss it by a county like I did on the Nov 11, 2008 setup in SW KS.
Comment by Wes — April 8, 2009 @ 12:09 pm
Great analysis on the cold core setup. This is very interesting because there will probably be cold core tornadoes in south central Kansas in the mid afernoon. Then a bit later there will probably be the more classic warm sector tornadoes near the dryline/warm front intersection further east near the Kansas/Oklahoma/Missouri border region.
Good luck tomorrow.
- Jim
Comment by Jim Bishop — April 8, 2009 @ 12:16 pm
Nice forecast Mike. I think you’re on to something which would be awesome for those of us in Wichita!
Comment by Matt Hughes — April 8, 2009 @ 1:06 pm
Mike excellent discussion I also like that area around Wichita. The 5KM model from 12Z has isolated cells from Tulsa- Wichita looks good also ahead of the Dl. http://charlie.wxcaster.com/wrfcentralnojava.php?fcsthour=36&type=1000-500_SLPTHKPRP®ion=S-PLAINS
Comment by Jeff Piotrowski — April 8, 2009 @ 3:15 pm
Hey Mike, I want to thank you for this wonderful educational analysis. Although some of it was over my head, I was able to absorb much of the discussion. Good luck to you if you decide to chase this event.
If you don’t mind me asking…what software suite do you use for forecasting?
Comment by Adam Wolff — April 8, 2009 @ 3:38 pm
Thanks for the comments everyone.
Wes- I remember seeing you on SpotterNetwork to the southeast of me that day. I purposely tried to make it out to Elkhart on November 10th by no later than Noon in order to make sure I positioned myself the best I could…to limit the potential of “reacting” to things occurring far away if I would have left late. I can’t tell you how many times I’ve left too late for a chase, LOL.
Jim- The more “traditional” play certainly does look interesting. What is interesting, though, about November 10, 2008 and October 26, 2006 the areas in the right-front quadrant of the 300-400mb jet didn’t produce. I think for much of the day tomorrow afternoon, southeast KS and northeast OK will be in the right front quad of the small jet streak…it will not be until 00z or so when the best forcing (at least at the nose of the jet or getting closer to the much more favorable left-exit region) reaches the better low level moisture/warm sector. I think the “warm sector” event will be mid-late evening from far southeast KS into the Ozarks. The “cold-core” play is strongly dependent on diurnal timing, hence 20-22z or so, I’d be favoring ICT or so. Obviously, this is better chasing territory, too. I think the occluded front will bulge northward over a couple county area around ICT, based on past experience…and the clustered tornado event, if it occurs, may be NORTH of ICT… like Newton perhaps!
Adam- On the internet, for more detailed model interrogation, I like to use ARL Ready maps (http://www.arl.noaa.gov/READYcmet.php). That is how I created the 2nd image in this blog. Otherwise, I use the same sources as everyone else, like College of DuPage, UCAR Weather, NCO/NCEP pages, and OU “Hoot” page (http://hoot.metr.ou.edu/models/)
Comment by Mike U — April 8, 2009 @ 4:03 pm
Thanks for the response Mike. I spent the last hour on the site you provided with great success. I will definitely be referring to it in the future.
Comment by Adam Wolff — April 8, 2009 @ 11:46 pm
Mike,
I really like your posted graphics! Matt Chatelain, Lela Davis (formerly Knight), and I developed a model with close resemblence to the “Dynamic Conceptual Model” posted above for our Capstone Project last year titled: “Cold-Core 500mb Close-Low Tornadic Events: Analysis and Forecasting Techniques”. We focused our attention on tornado events associated with ‘occluded’ surface boundaries seperated from the traditional ‘warm sector’ (basically west or northwest of the traditional ‘warm sector’). We found that in most cases the traditional ‘warm sector’ (all these terms are so relative and subjective) never produced tornadic storms. Basically, after analyzing GFS and NAM 0z Forecasts and current data I agree there is a good chance this type of event could occur tomorrow/today. The traditional ‘warm sector’ will possibly be ‘heavily’ capped and too far east of UPA support that it appears (like you stated above) there is a small window of opportunity for tornadic cells along an occluded surface boundary in the early afternoon. No way, unless the environment changes drastically from what the models are currently forecasting, would I be caught in the traditional ‘warm sector’ region tomorrow/today.
Simon
Comment by Simon — April 9, 2009 @ 1:17 am