5/4/07 FCST: KS/OK/TX

[Jeff Snyder]

Tomorrow looks pretty tasty, though I may be slightly biased since it's the only day in the next 7 that I can chase. The 12z NAM continues the trend of the 6z NAM in shifting the threat area a little farther SSW, and it remain consistent in forecasting a dryline bulge across southwestern KS. The surface flow response to this dryline bulge is very backed flow in northwestern through southcentral KS. With 45-50kt 500mb flow progged, 50-55kt deep-layer, 3500-5000 j/kg CAPE, and strong low-level shear ahead of the dryline in KS, I think there is a reasonable chance of tornadic supercells tomorrow afternoon and evening in KS.

The 250mb jet streak is just starting to nose into the moist sector by 0z, so I have concerns that, if it slows down, we'll not have much in the way of upper-level support. The 00z/13 ECMWF run forecasts weaker 500mb flow Friday, and the 00z/13 GFS run is slower / weaker than the NAM at 500mb as well. So, I remain slightly cautious, particularly since the performance of the NAM so far this season has been quite underwhelming. Attm, I like the area between Hill City and Pratt (HLC - P28), but I'll obviously have to refine more in time. My wife and I are leaving Saturday morning around 7am to drive to FL, so I'm not sure a NE/KS border region chase is possible (unless I want to drive all night back home to OKC before driving non-stop to FL -- yuck).

 

[JF Massicotte]

We'll be heading to Wichita tonight and spend the night there since it seems action may occur further south.

 

[David Wolfson]

I'm virtually bedding in Dodge City tonight per plan. The 36-hr RUC (21Z) is holding the best surface dynamics and params back to the southwest a bit compared to the longer cycle models. My plan is to see if the morning's data reflects this. Assuming it does, I want to be ready for storms to fire off the dry punch. I will be watching the surface obs and be expecting to virtually amble north toward Hays. I'm a bit concerned about the cap, but storms that develop should be worthwhile.

 

[Jim Bishop]

From the WRF's perspective this day looks pretty darn good for Western Kansas. I'd say from near Dodge City to I-70(ish), er maybe a bit further east. As long as the whole system doesn't slow down (like Jeff mentioned), there will be enough upper support for initiation. Supercells with a few tornadoes will be the primary convective mode. Man oh man, this season is rockin.

 

[Mikey Gribble]

I really like the area just North of DDC. I can't find a forecast sounding in between DDC and Hays, but I think the area right in between is going to be the bullseye for tornado potential tomorrow.
Deep layer shear >50kts and CAPE in the >2000 will be supportive of supercells. The shear vector should be normal to the boundary along and just North of the dryline bulge, which should favor discreet storms. In this same area 1 km SR winds are around 25kts which looks good for both supercells and tornadoes. IMO everything looks good for tornadic storms in that area tomorrow. I will fine tune my forecast tonight and tomorrow morning, but as of now I am going to target just North of DDC.

 

[afischer]

I get off work tomorrow at 3pm and may head west toward the triple point between HYS and DDC to try to catch something "in time." The NAM guidance looks kind of messy to me. It forecasts quite a bit of convection in central NE/northcentral KS 15-21Z, and I am suspicious about this being the reason for convergence forecast to strengthen significantly near the triple point 21-00Z. Not to say something like this couldn't happen if an OFB materializes. As has been covered, the GFS continues to be a little slower with the mid- and upper-level jet energy coming out... and trying to pick out whether a decent well-timed impulse will eject toward the target area tomorrow is next to impossible attm. The GFS also has a more stout EML spreading northeastward into west KS by tomorrow morning (700 temps ~10C), and indicates weaker low-level convergence near the triple point by peak heating (it forecasts no elevated convection in northcentral KS). I think if a storm or two manages to go up by sundown, look out... the LLJ ramps up and there could be a major league tornado. Of course, initiation is required first. At least if I head out there and bust, I'll still be in position for Saturday.

 

[Rocky Rascovich]

ducking the flying monkey wrenches

This Friday does look good and I'm looking forward in getting on the road and continue my track record, largely in thanks to Charles Edwards and a few others who have had a phlethora of data at there disposal to guide us to our pot of gold

Meanwhile, I reactivated my Wright Weather account for the season which really helps me out on the finer details to be examined http://www.wright-weather.com/ . One of which as alluded by others is the dry punch as depicted by most models coming up from between GCK to west of P28 by 0Z... But..I noticed that the 200/300mb. charts doesn't have that good punch coming out ontil afterwards, probably after dusk in these areas and on toward GBD. Also, the EML (Elevated Mixed layer) may be an issue with possible capping issues south of a HYS/SLN line.

Just these issues alone probably is why SPC took out the hatched area for svr for tomorrow but maintained the 30% risk.
Surface capes still should be close to 3K j/g and helicities around 250, maybe 300 m/s. Ironically I saw that the SREF had the shear levels down more than others. Still, surface flow almost running due east up toward I-70, great turning of winds with height, moisture should be advecting north with ease. I still have a hunch that a MOD will be issued tomorrow though.

In summary, as of todays data... a late show, probably 0Z maybe a little earlier, but not by much. I would think to be somewhere around HLC, HYS, RSL by then and enjoy the show...

 

[Jim Bishop]

Rocky - yeah that dry punch is bad news for Kansas south of I-70. But I'd say north/northwest Kansas and Southern Nebraska will be fine. That's north of that dry punch and on the good side of the nose of the 250mb jet streak. I'd almost like to say Nebraska is the place to be tomorrow, but I-70 north will probably be good too. Either way it'll still be a late show. But I'd say there's a good shot at some supercells with a few tornadoes on the ground by 8/8:30pm.

 

[Van DeWald]

Between Hutchinson and Great Bend Kansas looks like a fine target to me. Just east/northeast of the dryline bulge, within an area of backed surface flow, up to 25 kts of 0-1km shear, right on the eastern edge of the steep lapse rate plume, LCLs about 800 m if you can believe the dewpoints will make it to 70. Don't think they will, but it could be close.

Hutchinson Sounding: http://beta.wxcaster.com/cgi-bin/parse_skewt_trace.cgi?model=NAM&fcsthr=033&STATIONID=khut

 

[Mike Hollingshead]

Why am I getting the impression there's going to be some insane convergence between Dodge City and Hutchinson KS tomorrow?

Oh yeah this is why: 18z Nam fcst sounding for Pratt at 0z And for 3z ouch Hodo on roids at 3z for Great Bend

EHI of 12. Damn. That should be what is in place ahead of the sfc dl bulge wherever it winds up. My current target is Kinsley KS. I plan to leave around 8 a.m. tomorrow. See everyone and their dog on the one or two big storms out there tomorrow.

I guess there are still some big differences between the nam and the gfs, so maybe I shouldn't be so sold on sw KS instead of nc/nw KS.

 

[Doug Mitchell]

Meso-NAM is continuing the trend of taking the DL bulge further to the S back in to SW KS. Given such a small target area, I'll wager that tomorrow will be Horrible with a capital H for chaser convergence where that one storm decides to go up. The triangle of Great Bend, Pratt and Dodge City is my bet as to where it'll go down. I'll set up shop in Great Bend giving myself good SW and S options.

 

[Mike Umscheid]

I guess there are still some big differences between the nam and the gfs, so maybe I shouldn't be so sold on sw KS instead of nc/nw KS.

Fortunately at work here, I have the luxury of comparing the NAM up against higher skill global spectral model solutions like the GFS, UKMET, ECMWF and the Canadian (on the web). At first, looking at the NAM, I was like "uh oh, long-track tornadoes possible and a busy night for me on the radar here in SW KS".... but the NAM is currently outlier in the surface response and convective feedback issues. The convective parameterization of the NAM are quite bullish when it comes convective initiation. My gut instinct is that the May 3rd version of the NAM model looks far too bullish on surface based convection over a lot of Kansas... and thus, it impacts the near surface kinematic fields. The GFS, Canadian, and UKMET show far much less QPF in KS... except for the northwest corner of the state over a good portion of GLD CWA. I would be quite cautious of going too far south tomorrow. I think the best area for tornadoes will be just north of the greatest surface response to the larger-scale dynamics at play... which will be along the KS-CO border by "go time". I think Pratt-GBD is too far east and also too far south? This thing will be coming out slow... and the response in the low levels will be farther west... any dryline storms developing against the +9 to +10C @ 700mb will be isolated and farther west as well I would think. I just don't trust how the 30-36hr NAM is handling this thing yet.. This looks like a GLD CWA show to me.

 

[Joshua Jones]

Meso-NAM is continuing the trend of taking the DL bulge further to the S back in to SW KS. Given such a small target area, I'll wager that tomorrow will be Horrible with a capital H for chaser convergence where that one storm decides to go up. The triangle of Great Bend, Pratt and Dodge City is my bet as to where it'll go down. I'll set up shop in Great Bend giving myself good SW and S options.

Doug I think I will be setting up shop in Great Bend as well. Actually I will be in Hoisington, but that is besides the point. That area of the state I think is a great place to be as you can go any direction and get anywhere in a short amount of time.

Josh

 

[Jim Bishop]

Fortunately at work here, I have the luxury of comparing the NAM up against higher skill global spectral model solutions like the GFS, UKMET, ECMWF and the Canadian (on the web). At first, looking at the NAM, I was like "uh oh, long-track tornadoes possible and a busy night for me on the radar here in SW KS".... but the NAM is currently outlier in the surface response and convective feedback issues. The convective parameterization of the NAM are quite bullish when it comes convective initiation. My gut instinct is that the May 3rd version of the NAM model looks far too bullish on surface based convection over a lot of Kansas... and thus, it impacts the near surface kinematic fields. The GFS, Canadian, and UKMET show far much less QPF in KS... except for the northwest corner of the state over a good portion of GLD CWA. I would be quite cautious of going too far south tomorrow. I think the best area for tornadoes will be just north of the greatest surface response to the larger-scale dynamics at play... which will be along the KS-CO border by "go time". I think Pratt-GBD is too far east and also too far south? This thing will be coming out slow... and the response in the low levels will be farther west... any dryline storms developing against the +9 to +10C @ 700mb will be isolated and farther west as well I would think. I just don't trust how the 30-36hr NAM is handling this thing yet.. This looks like a GLD CWA show to me.

Mike, I'm glad to hear someone else mention this. I noticed the GFS & ECMWF agree in a northwest/Southern Nebraska initiation, with a slower ejecting system all together. And yes the WRF seems to be a bit bullish on surface development as well as convective initation.

I personally think I-70 may be the southern extent of convection tomorrow with the best stuff north of the Kansas/Nebraska border. Like Mike metioned, things may be even further west than models suggest.

 

[Michael O'Keeffe]

I agree with the Great Bend target. Sig Tor parameters are maxed out in this area!!!! I think the areas already mentioned are going to be prime for significant tornadic supercells that will develop after 7pm and sustain themselves well into the night and possibly into the morning. This will be hazardous to the general public due to the chance of overnight naders. I bet anywhere from around the Hays, KS area to maybe Pratt will be the main area of action. I agree with Doug on the major chaser converjence in this area. I also like the area because it is at the nose of the extreme CAPE and very high tds. Tomorrow will be very rewarding to many chasers!

Good luck to all who chase and stay safe.

Target: Great Bend Time of Departure: 11am