5/22/07 FCST: TX / OK / KS / NE / SD

[Fritz Kruse]

Looking at this mornings NAM for 00z Wed has me thinking of the area from Almena to Dodge City with the bullseye around Ness City. This is the area where 50 knots at mid levels crosses over the 2m theta-e axis with CAPEs over 3000 J/kg. What others have noted are the lack of stronger winds at the jet levels.

Not sure if I remember correctly, but didn't the F3 Almena tornado of 3 June 1999 have weak upper level winds?

Will need to take a look at real data Tues morning and adjust the area, but at this time the low to mid level shear profile and instability certainly supports tornados, especially as the LLJ cranks up around dark.

 

[Rodney Price]

Not sure if I remember correctly, but didn't the F3 Almena tornado of 3 June 1999 have weak upper level winds?

Here's a link to SPC's archived upper air charts for that evening:

http://www.spc.noaa.gov/cgi-bin-spc...Time1=00&MyDate2=&Time2=12&Align=V&Levels=All


Rodney

 

[Brian Stertz]

Yes you are right Fritz...it was a 35-40 kt. flow day...I think the CAPEs were higher for the Almena F3 event than the forecasted ones tomorrow. I totally agree that Ness City KS may be the spot to be tomorrow about 4pm for sfc based supercells and tornadoes. Looks like there is a 700/500mb wave that kicks things off meanwhile areas further south of Ness City along the dryline look to remain strongly capped until possibly later towards sunset or after.

 

[Jordan Hartley]

The only problem I see with storms that fire north of DDC would be the amount of time the storm's updraft can remain free of the ffd. Granted a storm that fires invof of Ness City will have more daylight to play with I think the real show will be S/E of DDC especially once you get the LLJ crankin in towards sunset. Of course if in position one could catch a storm north of Dodge and ride it untill the updraft gets undercut by outflow, then jump on a storm to the S towards/after sunset. Either way we have a chance to see some tornadoes tommorow and im hoping that I still get to go pending I can still take off. Suppose to hook up with Mikey tommorow sometime dont know when were heading out yet. Good luck to everyone out chasing tommorow and be safe

 

[Donald Giuliano]

If it were the weekend I'd go chasing today/tomorrow, but to me the setup doesn't look good enough to justify taking time off work. The main problem I see is moisture, especially on Tuesday, when it's likely a stout cap will be in place in the warm sector. Hodographs look great Tuesday evening...but unfortunately we need a near-70 dewpoint to get rid of the capping/high CIN, which is not likely to happen, so I'm not too excited. There's no way we'll be able to sustain surface-based convection overnight with dewpoints in the low-mid 60s given the vertical temperature profile, which is very unlike May 12, 2004, and May 4, 2007. Both of these days featured warm sectors that remained uncapped long after 00Z, so the storms were able to continue cranking, remain surface-based, and take advantage of the strong LLJ that developed as the sun set. To further complicate things, one could also make a strong argument for south central NE based on the 12Z HI-RES NCEP WRF runs.

My hope for Tuesday is that maybe a storm will be able to go up and stick around for a little while in the narrow axis of weak CIN ahead of the dryline as it slowly moves east. I'll be keeping an eye on things, and be ready to head northwest after work should things look interesting. Given the very favorable shear profiles, I'm not going to write this off just yet, but I am concerned the strength of the low-level shear is largely a function of the strength of the cap, as it often appears to be.

**EDIT: Removed high LCLs as a negative as they don't look overly high on forecast soundings; capping appears to be the main issue.

 

[Chris Hayes]

Im beginning to be a bit concerned about the cap for tommorow as well. I'm hoping the storms forming in SW KS now dont form into an MCS tongiht and leave a lot of cloud cover behind for tommorow's event. An OFB would be nice though, to help initiate convection and aid in rotation. NAM is still forecasting 3000+ cape for tommorow and good helicities.

 

[Mikey Gribble]

I just glanced over the 00Z NAM and boy does it suck compared to what it has been showing. DDC sounding has deep layer shear at 27kts and 5km SR winds at 11kts. 3km EHI has been divided by three. That dog just ain't gonna hunt. Dewpoints are back down in the low to mid 60's. I am thinking we will see 66 or so over Kansas tomorrow, but not much higher. The hodograph would look good if it was twice as long. I don't know what to say other than I really hope the NAM is out to lunch on its latest run. It seems like the NAM throws a curve ball the night before some times and it doesn't verify, so I'm not too worried. I guess we'll just have to see what the other models and morning obs are showing. Not that I buy the precip. being shown by the NAM, but DDC would be my target tomorrow because I want to keep the North option open in case it looks like the cap may hold a little farther South. I don't think the cap will hold though and I want to get as far South as Ashland if possible.

 

[Fritz Kruse]

Worried about Outflow Dominate Storms

Taking a quick look at the NAM and the cap strength, I am having reservations that the cap will break near the triple point at Ness City until after dark and the storms that do pop in the lesser cap in the north will become an outflow driven line of junk at the cold front.

Just when the upper support comes in the cold front is close by, but any storms that can form ahead of the cold front will be lacking good shear and may also be outflow dominant because they are just east of the upper support.

The tornado potential seems to have taken a few steps down for me, but will see what the morning brings.

 

[Mike Hollingshead]

For what it is worth, the gfs seems to offer a bit more hope than the wrf, if a bit more to the north. If it is right I'll be somewhere north of I70 in nw KS.

I don't care for the 0z wrf either. If it's right, I'd probably just chase the coldfront in NE and save the gas money.

 

[Skip Talbot]

The 0z WRF has seen most of its parameters degraded to some extent, although they are still favorable for supercells and I think some may squeeze a good chase out this. Hopefully its just a bad run.

Although the cap looked rather friendly initially, holding down initiation until proper surface heating was available and keeping things more discrete, I fear its the enemy now. Supercells may indeed go up but you are going to have a pretty narrow window to operate in. A hole in the cap breaks at 0z in southwest KS, and this may be the one shot for storms on the dryline. The problem though is that the cap is filled in solid by 3z again. So if you don't have your storms by sunset, its over. The best spot for initiation appears to be the triple point as shear is better here, but then you are racing against the cold front, which will swoop down during the evening to gobble up anything that fired too far north. Playing further south might be a cap bust.

This setup is too much of a gamble for me to pull a one day solo marathon on, but it could be a very rewarding chase for those of you on your chase vacations.

 

[Jeff Snyder]

Not much to add since just got home from the TX panhandle. At least Tues looks like we'll see much better instability / CAPE and considerably deeper moisture. Unfortunately, deeplayer shear will remain marginal for supercells given meager flow aloft. I agree that cap strength appears to be one of the primary potential inhibitors tomorrow south of I70. I am interested, however, in the TX panhandle dryline section... 00z/22 NAM indicates weakening CINH immediately ahead of the dryline down from Perryton to Clarendon area. NAM forecast soundings indicate a breakable cap given the forecast 850mb UVVs / convergence along the dryline. 2000-3000 j/kg CAPE and 30kts 0-6km shear may provide for one or two supercells, though multicell-supercell mixed mode may be present if cap is weaker than forecast.

Model consistency has been quite poor the past 48 hrs, at least in terms of dryline positioning... Of course, the left-field complication could be ongoing, but weakening, convection across parts of the Plains.

 

[Tim Marshall]

TARGET: LAVERNE, OK TIME OF DEPARTURE: 9 AM. Despite the progged strong cap, I think a cell or two cap pop up on the dryline farther south from the sweet spot in west-central KS. PROS - Upper system approaching the area with ample winds aloft over the target area -say DDC to Canadian, TX. Also, I like the backed winds I'm seeing on the morning RUC extending southward through the eastern TX panhandle. That should shunt some of the higher dewpoint air into the target area. CONS - Those progged 850 temps are high so I expect a stout cap to extend up to DDC. But, twice this year I have overshot the target romping up into Kansas when a lone supercell forms back in the Canadian River valley to my south. TM

 

[Mikey Gribble]

I think SPC did a nice job with the forecast and the tornado probs. I am not nearly as optimistic about the tornado potential as I was the other day. I still think we could see dewpoints close to 65 near the triple point, but I don't think that good of moisture will arrive until shortly before dark. Regardless, LCL's will be towards the higher end of the spectrum with dewpoints in the low 60's, but they should be OK. Getting on the tail end storm is going to be key today IMO. I just hope a storm can stay isolated and sustained on the tail end instead of that constant building from one area of convergence where you get one storm popping right behind another. The WRF precip. graphics doesn't show that happening, so I'm not really worried. I could just see that ruining our tornado potential if it happened. I am going to head out of town by 11AM for the triple point. I am going to set up just East of there and watch moisture convergence and the cu field and fine tune the target. I am always optimistic in May, so hopefully we will get some action today. Good luck to everybody who is going out.

 

[Ray Walker]

Guys I think the models are underdoing cape today. I think cape could exceed 3000j/kg today across much of the target area. Also I dont think dewpoints will be a problem today. Dews are already in the mid 60s across central Oklahoma and with the strong LLJ bringing the moisture north, I just dont see capes staying in the 2000j/kg range. Also there is no cloud cover here in liberal right now just a few low level clouds here and there. I know that may cause temps to rise and in turn the LCL's but this year has been a doosy so far and today should be a very good chase day. Also I like the area of low pressure forming in SW Kansas, this should allow the winds to back all the way down the dryline and allow the deeper moisture and instability to work its way west to areas due east of the dryline. I think there are three really good targets for today, one is canadian Texas, Liberal Ks, and Ness city. Today is one of those May days that suprise alot of people who downplay the setup.

 

[Chris Hayes]

My target for the day is Hays, Kansas. I'm gonna go ahead and play the triple point for today. There are at least 6 wifi hotspots in Hays, compared to none that I could find in Ness City. The east-west and north-south roads out of Hays will provide me with the routes I need to go to the storms that fire. Good luck out there everyone.

Go to http://www.jwire.com to look for wifi hotspots.

Edit: The RUC has a signficantly weaker cap near the Hays areas at 00z, with no cap SW of Hays. I'll be leaving from Salina at 12-1'oclock.