10/5/08 FCST: KS/OK/TX

[Greg Blumberg]

I've been watching the GFS for the past couple of days and there seems to be a consistent trend towards a cut-off low developing over the KS/OK area. This low seems to be producing a pretty shear setup in the 850 and 500 mb maps. Winds are definitely backing, but the 300 mb map jet needs to produce some faster winds for good upper-level support. CAPE seems to be definitely an issue in the models, however the GFS is developing quite a sharp dryline for fall standards, compared to the standards needed for a spring setup.

 

[Brandon Ivey]

I agree that this system is worth watching. Sunday, October 5th is what the GFS has progged right now for the plains, although in my experience, the GFS seems to be too fast with systems when your more than 3/4 days out. Time will tell!

If the current run is anywhere close to verifying for Sunday, I like the wind profiles and the low that develops in the Texas Pan. (That will help to back the low level flow over OK/Southern Kansas). Wind shear looks okay. The negatives I see are the quality of moisture return which would render low cape values and higher LCL's. If we can get a good return of gulf moisture, underneath the expected wind shear, then I would say Sunday is a chase day for me! For now, I'll keep watching.

 

[Dustin Wilcox]

Tonights GFS looks pretty sick, just really lacking in the moisture department. The 12Z EURO is in pretty good agreement with the GFS as well, though I would be a lot more excited if I had more faith in moisture making it in time, but by Sunday the gulf is completely open for business, for that reason I am thinking Monday may hold more potential somewhere across KS/NE. Plenty of time to watch the models once again slowly shatter my dreams...

 

[Mike Hollingshead]

God why can't we have the dews on Sunday. 12z GFS is nuts for the 5th. Sigh.

The low levels are nuts both the 5th and 6th...925mb winds....

http://www.rap.ucar.edu/weather/model/displayMod.php?var=gfs_925_wnd&hours=hr108hr132

Moisture may be ok by the 6th, but mid-levels really start to back to more southerly and I could see a linear fest ensue quickly that day. It is conceivable though to end up with a decent "dual area" day on the 6th, one north in NE area and one south in OK area, much like October 9, 2001. Sfc low with better backed low levels north helping out, and better veered mid-levels somewhere south along the dryline. Of course the 6th would have to also deal with the left overs from the day before.

Damn the dews! Hell, if it was far enough west, low to mid-50 dews could be interesting in the setup on the 12z GFS. It'd be nice to watch it all slow down, and have that 5th setup as it is now, be on the 6th with the better dews. I could almost see that happen too.

 

[Dan Rupnow]

Those wind fields are pretty tantilizing! I wouldn't write off the juice just yet, as both the 12z NAM and GFS have decent southerly flow starting early Saturday, and 55-60 dews over E KS by Saturday evening. 30+ knot S/SE 925mb flow on Sunday will definately help the cause too. I shall keep my fingers crossed!

 

[Adam Penney]

Ya, certainly going to keep an eye on this situation. If moisture wasnt an issue I would already be planning a chase day. However with CAPE only progged to be at best around 1,000-1,500 J/Kg, Im not getting too excited yet. It is possible that with such great wind fields it could make up some of the difference, but moisture is a major issue at this point.

 

[Andrew Stoller]

1,500 J/KG with temps in the low 80s in a highly sheered environment is perfect, but as it seems now, with dews on Sunday barely breaking 40, 1,500 J/KG is a pipe dream.

However, if things slow down like they likely will and we can actually get some 50 degree dewpoints east northeast of wherever the surface low sets up and points southward along the dryline, then we've got something to work with.

 

[Adam Penney]

However, if things slow down like they likely will and we can actually get some 50 degree dewpoints east northeast of wherever the surface low sets up and points southward along the dryline, then we've got something to work with.[/QUOTE]


Well i certainly understand what you are saying, however, even with "50" degree dewpoints, how many GOOD tornado days have there been with that kind of moisture? I'm sure there are many chasers out there that have had some success with these type of days. I'm just not sure it will be worth it for me to chase what would likely be atleast 750 miles roundtrip with that kind of moisture quality. But hey, if we weren't chasers, and always waited for the "perfect" setup, we would almost always be sitting at home, so we'll see. One cannot argue the dynamics with this system, but still the moisture quality as got to come along way for me to get more interested.

 

[Chris Wilburn]

Tonights run of the GFS does have a swath of mid to upper 50 dews from western KS down to the eastern TX panhandle. This of course will limit the instability and then you have quality and depth of moisture concerns. I guess upper 50 dews and 1,000 CAPE or so could at least make things halfway interesting. Deep sub 1,000mb surface low in eastern CO by 00z. Speed shear is really nice and directional shear is ok I guess. The surface winds don't really back much but the directional shear is adequate none the less. I think tomorrows run of the NAM will show 00z on the 84 hour forecast so you can at least compare the two by then.

 

[Dave Holder]

Taking a look at some of the forecast soundings, instability will definitely be an issue with this setup.

I think the biggest issue IMO is the lack of colder upper level temperatures, which struggle to advect southward once the low closes off.

It will be worthwhile to keep an eye on things, as the potential exists for severe weather with such an enhanced wind field.

 

[Greg Blumberg]

The 12z GFS has some hope for the instability problem. Dewpoints in the 60s seem to be promising, but the real question will be the quality and depth of the moisture. It looks like the moisture might be there just in time. The 850mb winds are being very indecisive as to their backing and veering from Sunday to Monday night. I'm hoping they pick backing. I'm not that happy with the upper level support on the 500mb map and 300mb map. Winds could be veered just a bit more in those levels and be a little faster.

Overall, I'm getting somewhat excited by the possibility with each model run. Let's hope it stays on this positive trend, huh?

 

[Andrew Stoller]

Moisture is now looking to be less and less of a problem, but the GFS and NAM are just not showing any instability what-so-ever.

 

[Mike Hollingshead]

http://www.rap.ucar.edu/weather/model/gfs084hr_500_wnd.gif

http://www.rap.ucar.edu/weather/model/eta84hr_500_wnd.gif

Pretty big difference in strength and timing between the 12z NAM and 12z GFS for 84 hrs out. All along(at least for the last while) the gfs has been wanting to push it through too fast and has been slowing down and digging a bit. Hopefully something closer to what the NAM has in mind will unfold. Later and stronger.

http://www.rap.ucar.edu/weather/model/gfs084hr_sfc_mslp.gif

http://www.rap.ucar.edu/weather/model/eta84hr_sfc_mslp.gif

Just a little different. Even if you take 12hrs off the GFS it's still a lot weaker than what the NAM has in mind. Look at that thing in the nw!(looks like a beast on the 850mb winds up there) .

Go NAM go.

 

[Michael O'Keeffe]

Whoa that is a change. The 18z WRF is showing 60F tds in W Kansas on Sunday now with 1200-1500 j/kg of Cape with nice helicities. If that is a continuing trend this could turn out to be a great chase after all. Now lets see if it verifies on the 00z.

 

[Brandon Ivey]

I agree that moisture is looking better for Sunday. Dewpoints are right around 60 along the Texas coast right now, but the layer of moisture is really shallow until you get down to the Brownsville sounding. I still think upper 50 to lower 60 dewpoints will not be uncommon on Sunday afternoon from SW KS to the TX Panhandle. Southerly winds will become very strong on Saturday and Sunday allowing moisture to rapidly return northward. I like the northern Texas Panhandle right now for a Sunday set-up. Monday is looking like western Oklahoma. I am sure I will be out chasing both days. It will be interesting to see how much the models flop between now and then. I just need another fix before the cold weather sets in! It will be a long wait until spring 2009.