5/1/09: KS/OK/TX

[nickgrillo]

5/1/09 FCST: KS/OK/TX

I'm surprised nobody has started a thread for Friday, but I'll make it quick: The latest 00z NAM run shows a very favorable setup for sustained supercells -- with precip breaking out along and just south of the front in northern OK by 21z -- as insolation and boundary layer convergence rapidly lowers LFC and removes the layer of convective inhibition. The degree of surface-based instability (i.e. sbCAPE 3000-4500j/kg across the warm sector) and substantial low-level shear (i.e. 200-350j/kg 0-3km SRH along the surface front) supercells should be the main convective mode with tornadoes and very large hail likely. I'm leaving tomorrow afternoon for the plains.

 

[Darrin Rasberry]

Just checked out the NAM on this a couple of hours ago. 12z and 18z both broke out precip around the Wichita Falls area 00z-03z, and that's where the excellent CAPE values (and a dryline bulge on both models) are. The SRH at 1km and the winds are a bit lacking, but the CAPE can make up for it, and given the notch of SE winds there that turn noticeably with height I wouldn't be surprised to see an isolated supe track across or near my old home county of Wichita (Texas). I may just do this, especially since my mom's been ill and I ought to take a trip home for the weekend now that I have a few days off before finals.

 

[Dave Kaplow]

Wow, anyone seen the 4km WRF-NMM precip graphics for tomorrow? At 00z it has a single isolated supercell with an insane hook rampaging from the Red River southward through N.Central TX. At one point the simulated radar actually shows a "damage ball" type hook echo on the storm - although I'm sure the model isn't really trying to simulate a large tornado, it doesn't have the necessary resolution. Still, I don't think I've ever seen such a clear signature of a tornadic-looking supercell from this particular model before, and the updraft helicity product at that point is practically off the chart.

Of course, I know it's just a model, one that only occasionally gets things right... But if this even comes close to verifying, Friday will be yet another in a series of big slight risk days.

 

[Derek Weston]

yeah, basically what Nick said. Very small area in the SW corner of OK through N Texas... another weak speed, but good directional shear setup... probably just enough to get it done. (see last few days) Trick will be getting the CAP to break and a sup training through the rich SRH we ought to have pointing north towards the front... latching onto a nice OFB in the area would seal the deal.

(now... no more talk of potentially slow moving photogenic supercells... too painful)

 

[Jason Boggs]

I can't chase on Friday, but I'll throw my 2 cents in anyway.

Cold front will probably make it's way down to Wilbarger county and swing SW to near Lubbock. The dryline will not be real defined, so convergence along it may not be all that adequate for storm initiation. But, CAPE will be extreme due to the high Td and daytime heating. Also, the wind fields don't look to bad. The speed shear won't be terrible but the directional shear looks very good which will help with rotating updrafts. Storm speed should be pretty slow, with an E/SE storm motion. Daytime heating will be strong which will help erode the cap, which looks to be about 8 degrees celsius at 700mb near KSPS.

There may be a decent tornado threat early on as storms stay discreet, but large hail will definitely be in order due to the extreme CAPE progged by the NAM to be near 5,000 j/kg at KSPS. Also, some very nice storm structure will be had with the strongest cells, so you structure nuts may have a great time with some excellent photo opportunites.

Again, I have to work, but if I could go, this would be my target:

 

[dirtracer4life63]

Looks like going home sweet home to chase.. What time do yall think this will all start?

 

[nickgrillo]

I hate making short forecast posts, but I don't feel like writing a lot about today -- it sort of speaks for itself. 12z RUC shows precip developing in southwesk OK/northwest TX along the the OFB -- east of the dryline, in a background environment charactorized by extreme CAPE (i.e. 12z RUC projecting 4500-6500j/kg sbCAPE along the OFB between 21z and 00z) and very strong low-level shear (i.e. 12z RUC projecting 300-500j/kg 0-3km SRH between 21z and 00z along the surface boundary in extreme southwest OK into northwest TX). 4km explicit-convection WRF shows an isolated convective cell developing between 22z and 23z near Wichita Falls, TX with additional deep convection developing to the north in southwest OK after 00z and RUC also initiates precip over the same region at 22z. I'd have to say any sustained, surface-based supercell that develops in the warm sector this afternoon -- particularly in an area roughly from Altus, OK to Wichita Falls, TX where the strongest ambient low-level shear will coninside with extreme surface-based instability, and where both the RUC and WRF initiate convection between 22z and 23z -- will have the potential to produce a significant tornado. I'm in Clinton, OK and will head south on US-183 towards Vernon, TX.

 

[Brendon Lindsey]

Well going off the ruc, which failed me last night, I'm going to sit here at home and work some, and wait for a storm to fire in this 3000 CAPE and -11 LI in EC NE OK... And get me some hail hopfeully. I hope this crap from this morning isnt here all day....

 

[Andrea Griffa]

Looking at the new run of WRF-NMM it's gonna be a very nice day: in comparison with RUC, WRF is improving the low level shear as well as mid level flow.Hodos are awesome. I don't even make mention about extreme instability in place. I just think that all the stuff could have a nice probability to remain quite isolated and slow. My opinion is that SPC will soon upgrade in a small moderate risk.

 

[Greg McLaughlin]

Dan Robinson and I are currently on our way down to Seymore, TX from Tulsa. There are several things about today I am really liking....most of those things have already been covered on previous posts. I am keeping an eye on an outflow boundary sagging south of the Red River near Wichita Falls, TX. I am hoping this boundary doesn't completely wash away by initiation, however I have a feeling it will be nothing more than a memory.

I am concerned about initiation occurring along the front, however not so concerned as to write the day off. I am ready to see tornadoes. It is May......FINALLY!

 

[dirtracer4life63]

SPC up to moderate risk and up to 45% on the hail. Heading to my home town of Wichita Falls. Kind of hoping today doesn't turn into another Terrible Tuesday type ordeal

 

[Elinor McLennon]

Driving from NOKC north, the temp dropped about 8 - 9 degrees about 30 minutes ago. Cold front is on the move.

 

[Chris C Sanner]

Good day from ksps! Looks like extreme instability is here for the afternoon. Decent turning of the winds along with ok speed could all combine for explosive supercell development. I'm personally not a fan of frontal forcing but the cap looks strong visually. Sat. and mesoanalysis backs this up. Again slow storm motions. Could be a good day

 

[Greg McLaughlin]

I am not excited about how strong the winds behind the front are in central and western OK. I can see this turning into an MCS fairly quickly if we get too much convection to go at once and the agressive front undercuts the storms. However it is promising to see 700mb temps around 11C which could be the only thing that keeps convection supercellular. I am glad to see there is a strong cap in place.

 

[Larry J. Kosch]

Outflow Boundary in OK??

I've looked at the VIS SAT over OK and things don't look too good. I do see what appears to be a outflow boundary running SW to NE. There is a group of storms in the NE sector of OK right now. And they are moving off the reservations, so as to speak, into AR and MS. This group of storms is probably responsible for the outflow. Just my two bits, that's all.