10/5/09 FCST: OK/KS/TX

[Matthew Piechota]

since nobody has started a thread for this day I thought I would.

monday looks like it could possibly be a good day, positive tilted trof will set itself up sunday into monday with good southwest flow around the base of it. wind profiles look pretty good and good flow at 500 between 40-50kts out of the wsw and 850s out of the southwest around 30kts.

12z GFS has a 998 sfc low in western KS with southerly flow and backing near the TP. moisture and instabililty dont look to be a problem with 70's in OK and mid 60's up into central KS along the DL. CAPE values nearing 2000 in OK.

still days out but this system looks to have the possibility of producing some supercells and some tornadoes. will need to be watched closely. what you guys think?


Matt

 

[Bob Hartig]

Yes, both the NAM and GFS want to pull decent moisture up into Kansas and overlay it with good 500 mb and 250 mb winds. If that picture establishes some consistency over the next couple of days, my plans for heading up to Mackinac may change to heading west.

 

[Ryan Wichman]

I think many other states will need to be added to this thread as we get closer, but in the mean time....

This is a day which I have been watching for quite a few runs now and like what I have been seeing. A deep low ejecting out of the rockies will result in a very dynamic set up wherever it does eject. Right now it looks like KS triple point play on Monday, but I would hate to overlooking Tuesday. The low continues to deepen and moves east as a negatively tilted low, progged to be a sub 996 low Tuesday at 12z. And a sub 988 low by 12z wednesday.

An 80 kt 500mb streak, combined with 130+ kt jet streak will create excellent UA support. Moisture return on a strong low level jet will certainly be there. By far the best we have seen all year. The smaller scale features will have to be resolved as we get closer, but this far out it's pretty clear that something significant could happen somewhere in the plains/midwest early next week.

 

[Jeff Duda]

With all due respect, Ryan, Tuesday doesn't look too good according to the 12Z GFS (obviuously that could change). Looks like winds at all levels will be really veered so that shear would be unidirectional. Thermodynamics look pretty good, though, but I question whether or not 70s Tds will make it as far north as progged (N MO and C IL). A similar thing also doesn't look all that good for Monday, as winds above the surface are fairly veered as well, but surface winds are nice and backed. Hell, the warm front even makes it to the IA/MO border by 00Z Tuesday! I may be able to see something.

ADD: It also appears to me by the GFS and ECMWF runs that the trough will remain positively tilted to neutral through Tuesday as part of the energy disconnects over the Great Basin as a cut off and the remainder cruises ENE as almost a shortwave.

 

[Brandon Sullivan]

I think many other states will need to be added to this thread as we get closer, but in the mean time....

This is a day which I have been watching for quite a few runs now and like what I have been seeing. A deep low ejecting out of the rockies will result in a very dynamic set up wherever it does eject. Right now it looks like KS triple point play on Monday, but I would hate to overlooking Tuesday. The low continues to deepen and moves east as a negatively tilted low, progged to be a sub 996 low Tuesday at 12z. And a sub 988 low by 12z wednesday.

An 80 kt 500mb streak, combined with 130+ kt jet streak will create excellent UA support. Moisture return on a strong low level jet will certainly be there. By far the best we have seen all year. The smaller scale features will have to be resolved as we get closer, but this far out it's pretty clear that something significant could happen somewhere in the plains/midwest early next week.

I am with you Ryan! Very dynamic setup for sure.

A positive tilt trough will be set up, with the main speed maximas located over the northern portions of the target area. Input from the 02.00z NAM showing dry mid levels and clearing in the morning which should promote diabatic heating across the area.. Established return flow should advect sufficient moisture northward during the day.. With pockets of MLCAPE reaching 500 J/KG by 12z.

Favorable 0-6KM Deep Layer Shear and sufficient backing winds in lower levels, should prove favorable for supercells along the drylne in the afternoon...

Still a ways out.. But it's got my attention.. Not quite the makings of an epic event.. But I'm in need of another chase out yonder..

 

[Mike Hollingshead]

Looks like one would get some rather nice low level turning and strong speed shear with Monday's setup, which is still there on the GFS. Instability still a bit hosed in KS I guess cause mid-levels fairly warm and sfc progs not all that warm. It's developing that circulation towards MN ahead of the sfc low in sw KS which isn't helping things. Either way the day has that look like one that pays off.

Hopefully it sorts out these issues better between now and then as the potential sure is there for a nice day.

http://www.rap.ucar.edu/weather/model/eta84hr_sfc_dewp.gif

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

Just looking at those two for Monday morning makes the day look damn interesting to me.

 

[Andrea Griffa]

Looks like one would get some rather nice low level turning and strong speed shear with Monday's setup, which is still there on the GFS. Instability still a bit hosed in KS I guess cause mid-levels fairly warm and sfc progs not all that warm. It's developing that circulation towards MN ahead of the sfc low in sw KS which isn't helping things. Either way the day has that look like one that pays off.

Too lazy to start a forecast thread and probably already jinxing it as it is. Hopefully it sorts out these issues better between now and then as the potential sure is there for a nice day.

http://www.rap.ucar.edu/weather/model/eta84hr_sfc_dewp.gif

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

Just looking at those two for Monday morning makes the day look damn interesting to me.

And also GFS 00Z remarks this good situation, with the same confirmed low in western Ks and with a similar cynematic an thermodynamic enviroment: so far it looks like an harper county-ellis county setup. Hope it remains the same.

 

[Brandon Goforth]

The 12Z NAM is out and has the warm front stalled over north TX, keeping the best moisture and instability in C/NC TX and south of the stronger shear. I'd really like to see that lift north of the Red River. Last night's run of the GFS was much better in this regard, lifting it much further north, which is what I'd like to see.

 

[Mike Hollingshead]

What a setup minus the whole upper 50s(temps!) across most of KS Monday. Wonder what the odds are of that front being stuck/pinched like it is showing on the NAM. Hopefully the GFS brightens that picture a little cause otherwise the shear looks amazing.

 

[Skip Talbot]

I really hoped the 12z WRF would be contradicted by the 12z GFS,. and there is still a nice looking setup on the GFS, but it is trending negatively in regards to moisture return. On the 0z run of the GFS, the 65 Td isotherm was up in KS and now its been pushed south into OK on the 12z run. There is of course time for the models to come around, but if this continues they may converge on a southern solution in undersheared TX.

 

[cdcollura]

Good day all,

Posting my comment, re-inforced by me being suckered into chasing a setup that remained capped and moisture starved a couple days ago in Kansas.

Anyway, almost all the forecast models have been treating these systems like those you would find in late May (during a 2008 like pattern) with one major (and very serious) drawback - The moisture return has been grossly over-estimated, especially 36-48 hours, or more, before the "event".

Basically, moisture wise, we have the same setup as we did with the last system. Cold air in place behind a cold front that is pushing nearly to the Gulf Coast (with southern TX maybe not getting "swept"). Moisture return will take a while (days, not hours like on the GFS).

I see the next system (aloft) pushing into Kansas on Monday, with a "hot" dryline, capped mid-levels, and limited moisture at the surface - Despite excellent shear. Timing - again - will be the key (moisture axis at surface must couple with the dynamics aloft) ... Wednesday (9/30) was an example of what happens if those don't come together.

Tuesday (10-6) looks like another fast moving cold front and veered winds / squall line mode. Hopefully my lack of presence anywhere near the US plains will change that!

 

[David Reimer]

MODS: Can we add TX to the thread please?

Looking at the 12Z NAM, It looks like there could be a sleeper event along a warm front progged to be from ABI to INJ. Helicity looks decent, but thats the first run the NAM has produced for Monday.

 

[Fred Gossage]

This really looks like a situation when you have to look beyond the models. I find it about impossible to believe the warm front gets stalled that far south, when precip is long gone further north by Monday morning... and dry mid-level air and shortwave subsidence overspreads the warm sector by early Monday... and 850-mb temps are in excess of 15C and 1000-500mb thickness values are above 572dm. There's a reason why OUN is forecasting 81F and ICT is forecasting 77F, as of this writing. The NAM, and to some degree the GFS, had major issues with this kind of thing earlier this year and all year last year. We only need to look back to a day like January 7, 2008 to remember that. You take those NWS forecasted temps, which make sense...given the synoptic environment... and the dewpoints present where those temps ARE forecasted by the data... and you modify the forecast soundings over OK and southern KS based on that... and you get CAPE values ranging from 2000-3000 j/kg.

 

[Matthew Piechota]

I was also looking at that. progs are not putting out that much precip 12-24 hours before and dont see how the WF wouldn't be able to move north to atleast central OK or further north if the precip is already out of the area.

 

[Michael O'Keeffe]

Well if its worth anything the 18z NAM looks pretty good I mean MUCH better than this morning's run with 2000j/kg of CAPE over W OK with 65F dews into C KS. This seems more reasonable in my mind we shall see what the 0z says. Still a few days away.