3/24/07 FCST: KS/OK/TX Pan

[Chris C Sanner]

Due to time constraints, I'm almost certainly going to be chasing the dryline a bit farther south than the most prime area but right now its looking like a chase day for sure. Considering the WRF is STILL underforecasting our moisture and it still manages to muster CAPEs AoA 2000 j/kg in NW OK/SW KSS, I'm optimistic instability could be a bit higher tommorow. Shear looks good as well. Right now, my biggest concerns are getting some sunny skies and some insolation. If we get that, I see no reason why the cap can't be beat with some forcing from the upper system as well as convergence along the dryline.

I haven't checked the forecast soundings yet or anything, but my initial plan is to leave noon-1pm for an area from Elk City, OK to Dodge City, KS depending on where the best heating will take place. I will also be looking for outflow boundaries and such laid down by the complex of storms expected to roll through the target area overnight. Our first March storm chase and I'm moderately excited, its a rather classic setup taking shape

 

[Adam Atkins]

I'm crossing my fingers for the triple point to see some clearing and insolation tomorrow because the wind fields are absolutely lovely. ESE surface winds, 30 kt SE 850mb, 40kt S 700mb, and 50-60kt SSW 500 mb with an associated upper level jet streak. The directional shear is much better with the northern target and since its a Saturday I'm willing to drive up near Colby/Goodland for initiation.

It seems the ejection of the shortwave and surface low translation doesn't get out of Colorado before initiation. I'm starting to believe this is because diabatic heating east of the dryline won't be very present so there won't be very strong surface pressure falls. The surface low isn't progged to move out of E Colorado until after 00z so the warm front should be firmly in place along the KS/NE border for any storms to take root should they fire in the warm sector off the dryline to the SW.

Goodland/Colby is option #1 and backup would be somewhere centered around Dodge City. Directional shear is lacking further south but insolation might only be present to the south...dryslot looks to punch in from SW Kansas after 18z so maybe a bit of surface heating between 2-6pm will heat up the boundary layer further north...we'll make up our minds in the morning.

 

[Michael O'Keeffe]

I agree with everyone. I'm currently in Phillipsburg, KS and am pretty excited about tomorrows setup. It looks classic and has the potential to be quite the system if we can see the sun peak out for a while. I agree tds are underdone and instability. Not positive on a target, but for sure somewhere in the Hill City to Phillipsburg to Hastings area.

 

[Verne Carlson]

Currently bedding down overnight in Colby, KS. Gotta agree with a Colby to Hill City, KS target tomorrow. ETA/NAM showing an almost vertically stacked setup but with enough offset to get nice helicities in place. Insolation from mid-morning to 21Z will be key for tomorrow. If we can get those same dynamics that were in e NM today up into w KS tomorrow we should all have a fun day.

Good luck to all chasing tomorrow! Keeping an eye on next Weds...

 

[afischer]

Rocky isn't the only one who passed on NM/TX today. Oops. Chased a little in SW KS today, having thought tomorrow's target would be more easily reachable that way. Anyway, I'm in Wakeeney now for the night so won't have far to go. I think if the 7H dry slot is anywhere near as tenacious as the NAM has progged, that everything else will fall into place for a classic cold core event. I'm also glad to see the mid-level low slow down a bit from previous forecasts... with any luck that will keep us from getting too far into the wastelands of far SW NE.

 

[Joey Ketcham]

Chris Wilburn and I are at the Modern Aire Motel in Smith Center, KS. The rain, thankfully has stayed away... hopefully get some good daytime heating to get things kicked off tomorrow afternoon.

 

[Adam Atkins]

Wouldn't it be nice if the night before's two main models (GFS and WRF) showed some agreement? Ugh...GFS shows a bit more of a drive for us Okies (WF setting up in S Nebraska), but the bottom line is we'll have to look at data in the morning.

My first observation from tonight's convection is it will most likely pass through the target area in NW Kansas before tomorrow morning/afternoon. Any mixing will probably clear out the boundary layer stratocu early for mid-afternoon convection. Most models had precip progged all day over the target area, which isn't good.

 

[Doug Mitchell]

Set-up looks good but everything depends on the evolution of the overnight MCS. Models are painting a grim picture with precip in the NW KS/SW NE area all day tomorrow. Hopefully things will clear out. I'm just going drive west on I-70 and stop in Hays, KS and go from there.

 

[BrandonWhittington]

Well, I have been looking at the giant blob over the panhandles, and over the past hour, it actually seems to be decreasing in size, it might just be me though. If the msc continues to stay about where it is and continues to move more north than east, then there might be a decent chance of a decrete supercell in the far far eastern TX Panhandle and western OK. We will have to see how things are going in the morning, if someone can find an outflow boundary that has ample heating on it, supercells appear likely. I will just have to wait and see.

 

[Chris C Sanner]

For what its worth, I did a browse through some model skew-Ts and I'm liking what I see in NW Oklahoma. At AVK at 0Z there's an LI of -4.3, CAPE of 2000, and the Supercell Potential is 82.9 percent. I think if there's an outflow boundary that can be latched on to. Storm motion will be ENE most likely about 33kts which is more than manageable with the road networks available. If we get a deviant motion (in a best case scenario of being on an outflow boundary) I would think Tornadoes would happen underneath any storm up that way.

EDIT: Of course, now that I look at it and there's subsistence all over the area from the main forcing passing north, I'm not quite so thrilled with NW Oklahoma....

 

[Michael O'Keeffe]

The new SWODY was just released with a 10% tornado risk hatched across S NE and ex N KS. I will probably move north tomorrow instead of south. More in the morning, time for me to get some sleep before what seems to be a pretty decent day. This reminds me alot of what happened earlier today in terms of looking for that right mover.

 

[Adam Atkins]

The tornado prob is not hatched. The SPC sounded optimistic about boundary layer clearing but boundary orientation and storm motion are not optimal for long tracked supercell/tornadoes, however right movers have a better chance. Still planning on heading up to NW Kansas early tomorrow morning.

 

[Mikey Gribble]

This setup is very similiar to April 20, 2005 and that one didn't work out so well for me. As Adam mentioned, it is going to be hard to get a right mover due to storm motions being almost perpendicular to the front. I am still worried about getting enough insolation. The WRF radar reflectivity model didn't paint a pretty picture. Who knows though. It's Saturday and I got nothing better to do, so I am planning on heading up towards Hays tomorrow morning. I will do my forecasting and select a target from there. Good luck to everybody who is going out.

 

[Bill Schintler]

Chase target for Saturday, March 24

1 AM, 03/24/07

Chase target:
30 miles north of Hays, KS.

Timing:
Renewed convective initiation will take place at 5 PM CDT.

Storm mode:
Supercells, many of which should be associated with or embedded within larger segments of multicell convection. A small tornado risk will also be present.

Synopsis:
00Z Analysis indicated split flow with 60kt speed max ejecting from the H5 circulation over AZ and a zonal northern-stream flow with a compact wave entering the WRN Dakotas. A LLJ was developing from TX into IL, with H85 dewpoints generally AOA 8C over much of the Plains. An E/W oriented H85 baroclinc zone was located in NRN IA. At the surface, the main feature was a WF along the IA/MO border. At 04Z, an extensive area of convection was ongoing in the TX panhandle, WRN KS, and ERN NM; while another MCS was in CNTRL KS at the nose of 30kt H7 flow.

Discussion:
The forecast picture is murky as a large area of convection will be ongoing throughout much of the day. It appears as though a window of opportunity for discrete convection should exist after the main precipitation area lifts off to the north and east and portions of north central KS receive a period of insulation while H7 temperatures drop a few degrees with the approach of the upper-low. A dryline will move eastward while the exit region of a potent 70kt H5 speed max noses into the area. Forecast soundings (NAM, GFS, NGM) suggest between 500J/kg to 1000J/kg of MLCAPE will be available. As has often been the case lately, the NAM is the most optimistic with mid-level lapse rates and resulting instability. Modest CIN, on the order of 25J/kg, should be overcome by strong forcing. LCL’s in the 1000m range juxtaposed with SRH’s (SFC-3km) of 250m2/s2 and SFC-6km shear to 60 kts suggests a tornado risk.

Regarding opportunities for convection further south along the dryline in SRN KS into OK where moisture and instability are more favorable, there are no clearly definable areas of UVV’s. In fact, the GFS and UKMET both place strong subsidence in these areas which are in the entrance region of the 80 kt H3 streak.

- bill

 

[Daniel Christianson]

Well i plan on chasing tommorow aka today rather ... i just got back from chasing the cells in NE, couple of good cells with structre, small quarter sized hail but the lightning was great at times, i plan on hitting close to hastings, i just hope precip isnt all over the place, if we can get that clearing it will be a nice day, also there should be some outflow boundaries well i got to rest for a couple of hours then do it all over again today ;-) night"