5/5/07 FCST: NE/KS/OK/TX

[Jim Bishop]

Saturday still looks big. Yesterday I think I looked too much into one single model run. Based on the latest GFS & WRF models, convection should fire along the dryline over much of Western Kansas, and the cold front will likely be the initiator in Nebraska. Both should result in supercells with tornadoes. I mean, 35+ knots at 850mb from the south-southeast over a large region. And on top of that 3000 j/kg CAPE or more. Get ready for the first big Saturday chase in May.

What I find interesting is how the WRF breaks the cap all along the dryline down to West Texas. If that verified there would supercells from the SD/NE broder to near Mexico! Looking at the GFS, not only does it show the CAP breaking by 00z from the NE/SD border to near Mexico, but it actually shows convection firing in all those regions!

I'm not going to speculate on this being a big tornado outbreak or not, but it certainly looks like a big supercell outbreak. And if you think the tornado potential looks good...well then, this looks like a big event.

 

[Donald Giuliano]

Based on the 12Z NAM it looks like we're in for a bigtime severe weather setup with possibly a very significant tornado outbreak on Saturday. Not to say Friday or Sunday look bad, but Saturday...sheesh. I'm especially concerned for Plains residents given the distinct possibility of extended periods of tornadic activity after dark Friday/Saturday, a situation more common in the southeast US, and always more dangerous than daytime stuff. We'll see how this situation pans out, but I'm not surprised the NAM is pulling the 850mb low back toward the Rockies and expanding the risk area further west, as that seems to be the norm for the NAM this year. Looks like the real difficulty Saturday may be figuring out where to go, since one can easily make an argument for anywhere from the Dakotas to west TX.

 

[Brian Stertz]

Significant for sure

I agree with you Donald...there will be multiple strong targets on Saturday and it will be a fun one to forecast & find that one magic supercell. Big strongly sheared warm sector means that things could rock on well into the night. I have just started to pour over the 12z ETA and it looks like tornadoes a plenty for Saturday.

 

[David Wolfson]

Looking at my virtual bank balance, I dread being sucked up too far north into SD and other points northeast, because the rest of the week I'll want to be back in TX east of the caprock as the dying upper low spins down. As others say, place your bets anywhere from way up north down to TX.

So as of now I plan to make it virtually back to DDC tomorrow night and then run down US283 toward Vernon, TX, on Saturday. The model CAPE is nothing short of spectacular, helicity is decent, and I can hardly wait to be virtually cored by an HP monster.

 

[Mark Farnik]

Oh God I want to chase this SOOO bad... this has all the red flags of a major tornado outbreak. But alas, I have a commitment Saturday night which I CANNOT get out of... sigh. I already know that I'm going to miss something spectacular on Saturday. I just know it.
I hope this excellent pattern keeps up through at least the end of the month, as I'm done with school on Monday and will be free to chase whenever for a few weeks.
My virtual target for Saturday would be Goodland, KS. That way you could shoot back south towards DDC or rock north towards LBX if necessary. But given western Kansas's tornado track record thus far this spring, I'd say that this area is probably a very solid target.
The only negative with this outbreak (as with 3/28) is that there will likely be a lot of tornadoes after dark. After my near death experience driving into a rainwrapped tornado near Bird City on that historic night just over a month ago, I'm not terribly keen on nocturnal tornado chasing. All who do chase into the night, please excercise due caution!

 

[Bill Hark]

Saturday looks impressive but I am concerned about early morning convection left over from Friday night. There is also some model divergence on the postion and strength of the low. There is a nice trough approaching with 50 to 60 kt winds from the SW across most of Kansas, western NE. A surface low will shift northward and then southward over the Texas Panhandle and northeast New Mexico by 0Z (if you believe the 12 Z NAM) and there is a hint of a low in northcentral NE. Surface winds are nicely backed and CAPE's of around 3500 with forecast helicities of 200. Farther south and east, I think the cap will be too strong looking at the NAM 700 MB temps. I am worried about the precip forecast. There will be ongoing precip at 12Z. Recovery and convection may wait until after dark Saturday night. Right now, I am thinking between Dodge City and Pratt. Another area of possibility would be near the Nebraska/South Dakota border ?Valentine. Although dewpoints are slightly less, there is still great upper level support and backed winds.

Bill Hark

 

[Matt Hines]

As mentioned earlier, this looks more like an evening/night event, at least down in the southern part of the severe risk. Dryline will likely set-up near the central Panhandles and race back to the west around sunset with strong height falls occuring in New Mexico. Be weary of the NAM as it has been too far east with the dryline placement, even the day of an event here so far this spring. We just had over three inches of rain here last night, so the ground is very wet and that will help the dryline to set-up farther west. Everything looks pretty impressive dynamics wise, so this has the potential to be another big one. Will be more interested in seeing the 0z runs on Friday evening and the 12z runs Saturday morning before I get too excited about any one area.

 

[Donald Giuliano]

Still a ways to go before Saturday and a lot of details to flesh out, but the 18Z NAM/GFS are looking downright apocalyptic. Shear/instability profiles are comparable to May 4, 2003 (a significantly different setup, though), except this time it's over an even larger area. Storm motions look to be a little speedy, but not unbearable.

Friday looks pretty interesting as well, though as has been discussed it appears that storms could come at a premium. Something of interest to note is that it's actually possible that the show could start from storms firing near the triple point before sundown Friday and continue (perhaps with a bit of a break or none at all) through the night and into the next day. The thermodynamic conditions at night do not preclude this from happening, as the cap is not especially strong in the wee hours Saturday morning and CAPE is plentiful. It could be interesting to work with a nice LLJ in the middle of the night, I recall this happened very early in the morning on May 8, 2003, when a monster wedge occurred in southern OK before the big show later during daytime. At any rate, as things stand now, if Saturday still looks like this on the models tomorrow I'd definitely go high risk on the day 2, as setups don't look any more impressive than this.

EDIT: 00Z NAM/GFS are out, and it's still looking like a monster outbreak for Saturday. The NAM/GFS are still hinting at the potential for some activity Friday night in Oklahoma. This continues to look really scary.

 

[mark plate]

This looks like it could be the best day as most areas south of Nebraska should remain relatively untouched by Friday night convection. Extremely large target area from the Dakotas to Texas and it all looks good...storms should be able to fire all the way down to TX although it may be pushing dark that far south. Less cap concerns Saturday than Friday in my opinion.

 

[Andrea Griffa]

It seems that the first thing we have to consider is how strong is the cap. Yesterday Eta run was for a stronger cap and for night convection. Today's run is for 00Z convection and convective explosion for the night.
It seems to me that we'll have different convective focuses. I'm focusing myself on Oklahoma ones, as I'm landing in Ok city at 8 pm. It looks like we'll have 3 main focuses in Ok: ok Panhandle-Elk City-Altus. That's what I'm thinking with this last Nam run. But there's a thing I'm concerned about: I don't understand the reason why there's a clou of precipitation south of Ok city. Maybe a double dry line(or something like an isolated convective development along the warm sector)?Anyone can give a right interpretation?

http://wxcaster2.com/CENTRAL_ETA212_SFC_SLPTHETA-E-CONV_51HR.gif

http://wxcaster2.com/CENTRAL_ETA212_1000-500_SLPPRPTHK_51HR.gif

 

[Mikey Gribble]

My forecasting has been minimal up to this point due to today's chase and forecasting demands, but I have started to get a feel for where I'll target tomorrow.
For some reason I can't get the right hour on the forecast sounding for Medicine Lodge to save my life, but I'm sure the paramaters and hodograph are going to be very impressive from Medicine Lodge to Woodward and I am focusing in on that area like a laser for Saturday. Deep layer shear and CAPE combinations will be extremely favorable for supercells.
I have been going off of Pratt's forecast sounding since Medicine Lodge isn't working. I am banking on a storm going up in the Ashland to Woodward area and tracking NE. I like this area because I think it is the best compromise between the better instability and the better shear. 500mb winds weaken as you head South and consequently so does deep layer shear. Instability decreases slightly as you head North of Pratt, but more importantly directional shear gets worse. I think the Woodward to Ashland area for initiation is the perfect compromise area.
All the indicators I look at to assess tornado intensity are indicating that this area will have the potential for strong tornadoes. Storms firing in this target area should realize >300m2/s2 0-3km helicity. SR 1km winds are 35kts. 5km SR winds are >20kts. LCL heights are plenty low. With that good of directional shear, instability, and inflow level winds I think there will be the possibility of one or two violent tornadoes tomorrow and with storm motions being as fast as they are long track tornadoes are a possibility too. I would expect SPC to go high risk over this area tomorrow.

 

[Brian Stertz]

I've been studying this outbreak scenario closely, and it seems as though the S.Kansas to W/C Oklahoma sector should have the greatest risk of right moving tornadic supercells. Parameters all point to strong tornadoes and possibly even a few violent tornadoes. There has been a persistent convergence target near Buffalo OK which tells me that something big and bad should fire near there by dinner time tomorrow. I certainly like how the ETA keeps pointing to that area so that is my target. I will probably first head to the Pratt library for some data, and then make my decisions from there. I am just having some pattern recognition thoughts that this may represent a slightly weaker and a bit further west version of the May 29, 2004 event. It certainly looks to be a prime tornadic supercell setup. Good luck to everyone and their brother chasing tomorrow. It should be quite a chaser frenzy !!

 

[Donald Giuliano]

Saturday is still looking like a really monster day as per the 12Z NAM. 40-50kt 850mb jet over the entire area of interest in the warm sector in May...are you kidding me?!? There are some questions about whether or not overnight/morning convection will throw a fly into the ointment, but it seems unless we have a really monstrous MCS it shouldn't have too much of an impact on the potential. I'm very interested in seeing what the 12Z hi-res NCEP WRF has to say, though, but it won't be out for awhile yet.

The real question to me at this point is where to go, as the entire warm sector has some major, major potential...where any overnight/morning convection occurs will likely play a big role in this decision.

Also, just for kicks, everyone talks about the so-called "four-year cycle" of 1991, 1995, 1999, 2003, 2007 (?)...well, a friend pointed out to me the following dates:

May 3, 1999
May 4, 2003
May 5, 2007 (?)

Hmmm...

 

[Joey Ketcham]

Saturday looks really good, but I'm almost starting to wonder if this won't end up being an overnight event.. or something that storms fire up right at dark.

 

[Brandon Sullivan]

Just some notes.. The 12z setup shifted the highest instability axis well to the south in OK with CAPE values into the 4500 range.. Helicity values cut down.. one plus is the nice jet support and moisture flow...

due to time constraints, I have to stay In IL on Saturday, im in the slight risk area, so maybe get some nice frontal activity.. well have to see.. I may head to MO on Sunday.. Good luck to EVERYONE today and tommorow..