4/29/09 FCST: KS/TX/OK

[Andrew Stoller]

I know everyone that's been out over the weekend is catching their breath right about now (I just got done with a marathon drive back from OK to CO Spgs), but if Wednesdays forecast holds, it might be time to charge up the batteries and pack the gear again, especially for a trip to southwest KS.

The 18Z NAM is showing the western trough holding firm, and the front that's been draped across the center of the country sagging out to the southeast. Return flow ramps up on Tue., and by Wed., surface dewpoints are back into the mid 60s all across the warm sector. Upper level flow isn't very strong, but some impulses look to eject out from the trough once again. Surface to 850 winds look to be impressively backed around southwest KS southeast of a developing surface low around northeast CO. CAPE and SRH look moderate.

 

[Michael O'Keeffe]

Yea I noticed this too on the 12z run of the NAM and the 18z looks even better for the SW Kansas area in the Dodge City-Garden City area where it appears a nice dryline bulge will setup. Very nice ESE surface winds along what looks to be a warm front or boundary of some kind and 60-65F+ dews will likely come together over this region and CAPE looks good with 3000+ j/kg over the area with helicity around 300-400m2/s2.

Another region that looks interesting is the TX Pan say around Tulia, less CAPE but a nice dryline bulge there as well.

If this verifies we could see several isolated cells over the High Plains with a few tornadoes a good bet!

 

[Kevin Polston]

I too like the southwest KS area....especially near DDC late in the day. I think it could be a very productive day. Will be interesting to watch the models the next few runs and see if they still point to this area.

 

[Patrick Martin]

I've been watching the Wed setup for a few days now, and I think it could possibly pan out for a SW Kansas play. Of course this is biased to some degree by needing to chase it as an out and back from Denver.

Both GFS and NAM seem to of been fairly consistent the last couple days with Wednesday's outlook for SW KS. Pros are that moisture will advect into wrn KS during the afternoon in response to surface low pressure in SE CO, resulting in plenty of instability and some decent directional shear. Cons are that convection Wed morning could throw things off a bit and a strong cap could be an issue in the afternoon. If the cap can be overcome, could get a few discrete cells.

I had to sit out the weekend fun, so I'm hoping this plays out. When I got to work this morning, I put in for Wed off, so if the next few runs continue to be consistent, I'll be out with the masses Wed afternoon.

 

[Jeff House]

Agree with the potential for two DL bulges; therefore, two targets. If model waves are correct one comes out over southwest KS and the other over the southern TX Pan. Very tricky relying on smaller model details two days out, but Vapor does show multiple jet streaks off the Southern Calif Coast that are tracking toward both targets. Timing will of course need to work out, esp for these subtle features. Southern target could have better thermodynamics but northern target may have more intersecting boundaries to work with, esp if they all lift north quickly during the pre-dawn hours.

 

[Andrew Stoller]

It looks like the better upper level dynamics/shortwave comes out over west central TX, but the better surface dynamics will be in place over southwest KS.

 

[Eric Bucsela]

36 hr out, the NAM shows very weak winds at 500 mb and 300 mb in KS (< 30 kts at 300 mb). Much better winds near the dryline in W TX (> 50 kts at 300 mb), with instability and helicity also good. But of course KS has the surface low.

BTW, anyone given any thought to SW NEB?

 

[Matthew Grzych]

From this morning's 12UTC runs, it appears that W KS is no longer a good target. Upper level winds of 30kt or less spells HP if any supercells do form. I think the primary target should be between AMA and CDS. Both the GFS and NAM show a decent dryline centered over AMA and LBB at 00UTC. A weak impulse is apparent at 500mb, which could give a little dynamic lift to the area. More importantly the upper level flow is more than sufficient for supercells in this region. Just east of the DL, 2000-3000 j/kg of CAPE is forecasted with great low level turning of the winds from the surface to 700mb. The CDS forecast sounding (00UTC) looks real nice with relatively low LCLs, lots of CAPE, and a great wind shear profile. If the current forecast verifies, one would expect storms to fire on the DL near the CapRock and roll east or east-southeastward into this environment near CDS. One complicating factor could be ongoing MCS convection to the east, but that also could produce a nice outflow boundary to help in tornado formation.

Far SW NE (near Imperial) might be a secondary target. However, here there's less instability forecasted and upper level winds might be a bit weak. There's basically 30-40 kt from 500mb all the way to the TROP. There's also a weakness in the 700 mb flow and environmental helicity. If the main jet core noses further south than expected, this region could do just fine.

 

[Ilya Neyman]

I think tomorrow...Wednesday...has the potential to be a sizeable episode for severe. A rather large area, or rather several zones look like potential hotspots throughout the day. Glances at both NAM and GFS and 18z data the area from northcentral TX north across central OK is a possibility as a southern stream impulse shoots into the southern plains. Another zone may set up right along and ahead of the dryline over the TX panhandle as instability is maximized and another wave may spark initiation during the afternoon.

This all may actually begin tonight where, if surface-based storm formation occurs between the 00z and 09z timeframe, forecast parameters support potential supercell/tornadic development across a large portion of the W TX and panhandle region including Lubbock and north. Persistent upslope flow and the combination of several lifting mechanisms may induce/allow boundary-layer convection. Impressive forecast soundings and hodographs support this thinking.

Any storms that do go up will need to be watched especially if they can become/stay rooted in or near the surface layer as they advance eastward toward OK and the Red River region.

Depending on how the nocturnal episode plays out will have an obvious impact on daytime convection. Potential exists for either a continuation of overnight into daytime hours of intense convection or renewed development. A combination of the two is probably quite possible.

 

[Chris C Sanner]

Tomorrow will depend heavily on what happens with convection tonight and what the surface charts look like in the afternoon. If there is enough clearing and such I'd expect instabilities to be pretty high. Flow is ok, but if we get the 3000+ instabilities progged by the GFS we'd possibly be in business despite the only ok winds. Capping is an issue as well, and the departing MCS probably won't help things in that regard. Right now, I'd bet on something going along the dryline down in NW TX or the SE TX Panhandle (however you want to define it) given sufficient sunshine. Considering everything I'm probably going to head S and W, probably to any outflow boundary intersecting the dryline in an area of maximized instability...but all that can't be determined until tomorrow morning.

 

[Jason Boggs]

I really don't see the clouds moving out much for tomorrow. The convection as of now (2am) will only increase in coverage like the trend for the last hour or two. If the cloudcover breaks up, I may target the SE TX Panhandle (just SW of Childress) or SW Oklahoma. If we can get the clouds to get out of here and get some increasing moisture, this may be a pretty good day. I think the NAM and GFS is overdoing the CAPE values. CAPE of 1500-1700 seems more likely. Target as of right now: Matador, TX

 

[Jay McCoy]

That convectin this morning Jason didnt really develope and cover the panhandle like we expected and moved out of the southern panhandle by 9am leaving clearing skies and max heating. Today may be better than we expected since there isnt near the subsidence we expected. My target will depend heavily on where the dryline sets up but I do like the area SE of Amariillo down to Childress. I dont think the dryline will mix east too fast so maybe somewhere from Clarendon down to Turkey. Infact anywhere east of I-27 and south of 287 should be ok. Too early to name an exact target.

Going to take a half day off work and head out early afternoon.

 

[Tim Marshall]

APRIL 29, 2009 - FCST - TM

TARGET: RALLS, TX TIME OF DEPARTURE: 10:30 AM - A marginal chase day today, but I can't ignore that outflow boundary. PROS - Ample surface moisture is in place with upslope surface flow into W TX. Meanwhile, winds aloft will increase out of the west to around 40 knots. That kind of directional turning and speed will make for rotating storms that will be force fed inflow (like last night) as they move east. Obviously, the greatest low-level helicities will be along the boundary. Once again, the RUC is overdoing the CAPE fields, but the morning NAM still indicates the peak CAPE will be just off the caprock. CONS - Weak 700 mb flow will promote HP type supercells. Persistent cloud cover could limit surface heating. RUC and NAM differ on the placement of the dryline. RUC has it nosing off the caprock whereas the NAM keeps it on the South Plains near Lubbock. That makes a difference to me as I have to be at work in Austin, TX by 8:30 AM tomorrow morning. TM

 

[Patrick Martin]

I've got the day off from work, but I have to be back to Denver tonight for a Thursday morning appt. Since distance is a limiting factor, I'm going to hedge my bets, cross my fingers, and play the SW KS target. Pros will be good moisture, good CAPE, surface low in SE Colorado helping the dryline mix east. I am hoping the theta-e, heat axis, and semi-dryline punch advertised on the 12z RUC verify to help kick off an isolated storm or 2. Cons are the obvious upper flow issues and a healthy cap. I'll be leaving for Garden City KS by approx 10:30am MDT.

 

[BrandonWhittington]

Im actually starting to favor the central Panhandle a bit more. Clouds in the southeast are holding tuff, but they should start to clear out in the next few hours..Also to note, the dryline is still in Eastern New Mexico.

The central panhandles didnt recieve any kind of rain last night except for northern Hutchinson County.. Based on my experience, i have never had good luck with storms that form on or near outflow boundaries...Just me though =)

I will hanging tight here at home in Fritch today and hopefully something will fire pretty close. Temperatures should warm pretty nice here. If i were to pick a more define target, it would be from Dumas, to Herford, to Amarillo triangle..

Good luck to all that chases here today!!