6/15/09 FCST: KS, OK

[Matthew Harding]

This is my first time posting in this arena (or atleast starting a thread like this), so please forgive me if I slip-up a time or two. I wanted to gather some thoughts about potential severe weather episode on Monday afternoon.

Decent agreement exists in the GFS, WRF, and NAM models on ejecting a shortwave out into the forecast region during the 18z-00z timeframe. Models diverge when it comes to placement of the stationary boundary, and trying to place the boundary will likely end up being a nowcasting venture. That said, there will likely be a dryline/triple point play somewhere in the Dodge City-Pratt-Woodward, OK triangle, depending on which model you believe.

The 00z Tuesday sounding from KICT (from NAM model and time sensitive): http://beta.wxcaster.com/cgi-bin/parse_skewt_trace_all.cgi?model=META&STATIONID=KICT

The 00z Tuesday sounding from Winfield, KS (from NAM model and time sensitive: http://beta.wxcaster.com/cgi-bin/parse_skewt_trace_all.cgi?model=NAM&STATIONID=KWLD

If I were chasing, I would probably start in Kingman or thereabouts and watch for something coming off the dryline/triple point because helicities really increase in SC KS after 00z.

Your thoughts?

 

[Matthew Piechota]

ya my play right now would probably be south south of the greensburg/pratt area to the border. 0-1 helicity isnt bad with values near 200 along the KS/OK border at 0z but due to the nice LLJ kicking in after that, the values really jump up at the TP and all along the warm front.

basing off the 0z WRF, your best 0-1 EHI values are along the WF which should play out somewhere along or close to the OK/KS border. also have nicely backed sfc winds with a good theta-e axis into the area and both models do bring down 700 temps by 0z so I dont think the CAP will be a problem tomorrow.

I will be nowcasting all day for a storm chase trip out there but will try to have more later on.


Matt

 

[Tim Supinie]

It's time for an update, now that we have the 12Z model runs. Looks like Monday is mostly going to be a warm-front chase, hopefully more fruitful than this past Tuesday was. I'm planning on being in Wichita Monday evening, anyway, for things completely unrelated to weather, so I might see if I can cheat my arrival time earlier.

As for dynamics, I like the 12Z GFS and NAM hodographs in the Newton and Wichita, KS areas for 03Z. Nice large loop due to the low-level jet, which really cranks up between 00Z and 03Z.

Newton, KS forecast sounding (time-sensitive)
Wichita, KS forecast sounding (time-sensitive)

For thermodynamics, the NAM has been underdoing the CAPE at 36 hours in the last couple days, so I feel reasonably confident that the actual values will verify higher than the 12Z run suggests. However, the thing that bothers me on both of the forecast soundings is that inversion layer developing right near the surface, which could force the storms to become elevated. In fact, the NAM dramatically increases CIN in all but a few spots in Central/Northeast Kansas by 03Z. The only upshot of this is it lowers the surface LCLs by 03Z, but it may not matter if the storms all get choked off.

That being said, hopefully, there will be a sweet spot between 00Z and 03Z after the low-level jet kicks in, but before the storms have a chance to get cut off. I'd like to chase it, but I'll have to see how my schedule works out.

One thing I've always been curious about is whether the co-location of CAPE and shear in the vertical matters. Obviously, it matters in the horizontal direction. I was noticing that on most of the forecast soundings, most of the shear is below the LFC, which I assume can be either bad or neutral, but not good.

 

[Matthew Crowther]

MDT just put out for KS- basically our last chase day, will it be lucky? Prelim target GBD-P28 and points east thereafter. What can mess this up? Forecast hodos/CAPE look quite enticing in the target. Good luck to those still chasing!

 

[Jeff House]

Nice first post in the Target area, Matt H. Well I wish I still lived in Wichita today. Looks like a good chase day, but I must sit out the weekday.

Looking at the 12Z 850 chart, looks like the lead shortwave has veered 850 winds. However, 850 winds in the TX Panhandle are still southerly, likely in response to the next wave. Believe 850 winds will correct themselves in Kansas late this afternoon, backing to at least south. Surface winds are nicely backed and heating will be impressive behind the morning rain. Oh yes, that morning rain is also helpful to reinforce boundaries. Low levels are in or will be in good shape by game time.

Upper level support will only be moderate again. Should be a break behind morning rain; then, new jet energy will be over Kansas by late afternoon. Water vapor shows a nice streak coming through AZ/NM this morning, which should be in SW Kansas by late afternoon.

High CAPE should make up for what is lacking in the upper levels. Believe that OFB/warm front will light up from ICT to GLD. Could be lots of "other" convection so data or a good nowcaster will be important. I forecast 2-3 good supercells and perhaps one tornado that actually lasts more than a few minutes. Hopefully for those out there, that one can put on a nice cyclical show for a couple hours.

Happy chasing!

 

[Michael O'Keeffe]

Based on this morning's RUC I am becoming more optimistic that E Kansas may be a player in today's severe threat. The RUC paints an ominous picture with 4000+ j/kg of CAPE, decent shear and helicity, and what appears to be a moisture axis along with a very obvious OFB from this morning's convection. Things have cleared out nicely here and destabilization is underway.

The RUC also breaks out precip along the warm front by 23z. As of right now I am liking Topeka-Junction City as a target.

 

[Dustin Wilcox]

The RUC also breaks out precip along the warm front by 23z. As of right now I am liking Topeka-Junction City as a target.

Noticing that as well, though the only problem is the next wave will be a little slower to effect the area, also sfc-850 winds will be a little slower to back given the further displacement from the deepening low to the SW. That being said, the aforementioned OFB/WF will likely provide for some mesoscale features aiding in real localized backing. Still enough time to watch things materialize, after a marathon weekend and little to no sleep, I'll be leaving the office here shortly to give it another shot, NW KS is kind of scary to me, I can see something wicked coming out of the Oberlin area on the nose of the thermal ridge...

 

[Matthew Harding]

After 12z hand analysis, the 850mb warm front was located on a line from EMP-MPR-GBD, or along the HWY 56 corridor. This may be the first area to go due to differential heating. Agree with Dustin that the wave in question is slower to come out so the "main event" may not begin in earnest until after 21z. SPC still has area in MDT risk, but seem to highlight the damaging hail and wind potential. But remember last night, that should a supercell form and can stay sustained, we may just have some LLJ magic.

Good luck to all who will be out this afternoon/evening.

 

[Warren Faidley]

Looks like rapid initiation is under way just south of Ulysses.

Good luck to all:

W.

 

[Adam Lucio]

Liking the I-70 corridor as well. However am targeting closer to the dryline.

Ruc showed a bulge south and west of Hays and we will likely put ourselves near whatever triple point there is. I think things will play out like yesterday with initiation behind the dryline, once crossing into favorable enviroment things should go nuts. WF play also an option but given the areas coming together both targets appear to be playable.

Hodos are very similar to yesterday with some cuvature in the low levels then flat-lining. My biggest concern is the weak surface flow as it may be hard to get a cyclic supercell. I expect some HP beasts which may make things a little tricky. If the surface low can deepen and increase the surface flow especially near the warm front though we could be in business.

Another area of interest would be SW Kansas near the OK border, there some boundaries form overnight and morning convection could aid in a decent storm, right now we dumped that target given the stronger surface heating and higher LCLs but I wouldnt be surprised to see something pop down there.

Currently heading north toward Hays. Good luck to all today.

 

[Taylor Campbell]

I would play the area from Blackwell, OK to Chanute, KS. SBCAPE is in the 3500-4000j/kg range under the presence of high dewpoints of 70-73 F and steep lapse rates of 7-7.5 c/km. 0-1km storm relative helicities increase to around 100-200 m2s2 later this afternoon. 500mb winds will be around 40-50knts late this afternoon and evening that I believe will be sufficient enough to produce a tornado or two across this corridor.

 

[Chad Cowan]

Looks like there is a mesolow developing near Manhattan, KS along the warm front/ wind-shift line. Currently in Topeka probably heading west to that area. RUC has been breaking out precip during mid-afternoon in the area on the 12z, 15z and 18z runs, but with how it overdoes moisture (and resultant cap strength) I usually add 2 hours to whatever initiation time it says. I like the orientation of the boundary with the forecast storm motions. When the storm(s) fire they'll hopefully track east and hit the backing winds along the nw-se boundary and tornado. Already a nice cumulus field developing but I'm hoping it holds off for another hour or two and let the 850s pick up and the low-levels marinate a bit more.

Live stream and chat @ chasethestorms.com