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

[Bob Hartig]

Thanks for those insights, Fred. Wish my forecasting skills were advanced enough to where I could think that deeply. And I hope you're right. I'd love to see an aggressive moisture return and higher CAPE on up into Kansas.

As it stands, comparing the 12Z GFS and NAM, the NAM wants to pull things back more to the west. If I take my cues from it, the best compromise between moisture and upper-level support is in the panhandle region. That 994 mb surface low may have what it takes to crank in ample moisture. The GFS weakens the low and moves it farther east, with the moisture lobe working up into central and eastern Kansas.

EDIT: So after I hit the "send" button, voila! There's the 18Z NAM, shifting moisture farther north and east. I can like that.

 

[Andrew Ryan]

The 00z NAM keeps the warm front south, thought it moved it north a touch. Right now, I'm thinking a play on the warm front is the best option. The shear is not the best, but anything that rides the front has potential.

It's a little early, but if I were head out, I'd target around Quanah, TX. It's right on the warm front. Surface winds are backed nicely. On top of that, the theta e ridge and a nice helicity bullseye are centered there.

Overall, not a bad set up. The only thing that concerns me right now is the veering 850s, but they're not veering that bad. Have to wait and see what the GFS says.

EDIT: Wow. The GFS is in pretty good agreement. The GFS is converging on the NAM solution. It's interesting how the models are keeping the warm front so far south.

 

[Jared Farrer]

Yeah the forecast soundings/Hodographs look great per 00z NAM! And the cap looks breakable for sure, nice surface based cin. I am a little worried about the dryline(not very distinct on the nam) being able to push anything up with not a ton of forcing present from the looks of it. Nice dry push at midlevels. 850s arent bad at all! Definitly looking like it has potential. Could get a couple isolated sups, with a couple hours of good juice and shear to do something.

You know the drill though, models rarely peg a good system but the general feel and look is good, moisture is the main issue but I tend to agree with placment I bet we see decent return by monday afternoon.

Yeah I like the look of this system as compared to the last one.

 

[Matthew Piechota]

Looking at the 0z NAM, this day has potential for sure. nice 50kt jet streak at 500 into the area of best CAPE with descent 850s in the region, would like to see a more distinct dryline to help something go up. looks like the main energy does stay off to the west but we'll have to see how that plays out.

the WF does look like the best play with backed sfc winds and nice SRH values along it. anything that could latch onto that would have a shot. think its still to early to pin a target but id say right now, CDS to HBR looks pretty good to me for a shot at an isolated sup or two as the theta-e axis noses right into southwest OK along the red river.

moisture return this run looks pretty good with upper 60s along the red river into southwest OK with CAPE readings between 1500-2000 j/kg. going to wait and see what the GFS shows. hopefully they can come into agreement in the near future. if more moisture and instability can work their way north the the TP would also be a good play.

Matt

 

[Ryan Wichman]

36 hours after I wrote my initial post, excited about this day, I am now bowing out of the race to chase this day.

Three main reasons:
Remenants of TD Olaf will create precip and cloud cover across NW Texas and SW Oklahoma. This will leave big question marks as to the amount of instability that can be generated.
Secondly, where it does appear that storms will be surface based they will not be in the favorable area of shear (we're talking 20-30kts for these storms, not 50-60kts to the north).
Lastly, Each model run the chase area gets push more to the south and is smaller than the last time. At this rate by the time Monday rolls around we will be in Brownville, TX.

Too many question marks for such a long drive. But is often the case, those of you in OK/TX have a front row seat if something were to happen. FWIW....This is the last ditch effort to hex the jinx that I started 36 hours ago.......

 

[Bob Hartig]

No lack of helicity or bulk shear. Instability is the question mark. 6Z NAM and GFS model soundings paint very different pictures for CAPE. The NAM looks pretty bleak, while the GFS promises plenty of instability to work with in places such as Wichita Falls and Lawton. I've got another day to make up my mind whether to make the drive, and am hoping the GFS has got the better handle on CAPE.

 

[cdcollura]

Good day all,

Currently, the GFS is actually WEAKENING the surface low on Monday (on 10-5) (sound familiar?) ... Anyway, the low is FCST to rapidly eject (again) and sweep a cold front through on early Tuesday (10-6) with the low over IL by that time - Yuck!

The only possibility will be in the TX / OK / KS (panhandles) area late Monday if the GFS does not verify and the SFC low is stronger. Sunday night may show some hope for the event (or failed event) come Monday.

Warning: The models are JUNK this year, especially 36+ hours out!!! Don't get "suckered" ;-)

 

[Mike Hollingshead]

Didn't seem the models were that crazy last system....especially with timing and capping concerns...gfs for sure anyway, consistently saying it would fly through on the second day for several runs out. Take out that little morning wave that produced badly veered 850s all morning long into the early afternoon and I doubt the NAM was off much with dews. I remember seeing low 60s in NE. But alas, there were other obvious issues showing up on the runs that a lot of us just knowingly ignored for the just in case it's wrong day. Doesn't seem they are doing that terrible with this one either...at least within 7 days.

Moisture doesn't seem to be the issue, but the moisture slamming into a ton of cold air too soon......clouds. NAM is consistently showing crap for instability. I'm actually hoping it is junk as if that were the case, perhaps we'd build the instability up into KS like the system needs.

What GFS are you looking at? Last night's? 12z isn't out just yet. Yesterday 12z GFS said 1001mb sfc. Last night 0z 1002mb sfc. Probably not enough to worry about, especially given the other issues. (and fwiw 6z gfs had it back to 1001mb)

Bet south option will still hold some promise.

 

[Bob Hartig]

Last night's GFS run did show the low progressively weakening from around 21Z on, while the NAM showed a deeper, more consistent low at something like 994 mb. Today the 6Z NAM wants to weaken a bit, too, from 21Z to 00Z, but we're talking a rise from 996 to 998, still punchier than the GFS at its best. Both models show progressive weakening overnight as the low shifts to the northeast and a new low center strengthens by the Great Lakes on Tuesday. By then, the two models are a world apart. As far as Monday is concerned, I'll settle for a composite of junkiness. I like the deeper low that the NAM is painting, but I want to believe that it's severely underforecasting instability.

 

[Mike Hollingshead]

I thought we were talking about models run to run deal as far as weakening the sfc low, not time of day weakening of the sfc low. 12z gfs is actually out now and has it 999 at 0z Tues. SFC temps and instability still el-fubar'io. GFS sure trending towards NAM in that whole scenario. Think I'm taking my fork out now and even handing it to the fat lady, so that will bode well for future runs lol.

 

[Brett Roberts]

I noticed a disheartening trend on most of last night's 00z runs toward ejecting the shortwave faster, which may have helped explain the weaker surface low and more veered low-level winds by Monday afternoon. This morning, both the 12z NAM and GFS are slower with the wave again, and the GFS shows a stronger surface low than last night with manageable 850 winds. But as with everything in 2009, when you fix one problem, another is bound to take its place: both models are hanging up the warm front pretty far south, and show no CAPE north of the Red during the day Monday. I'll leave it to the pros to asses the realism of that happening.

EDIT: A little encouragement from the GFS ensembles on the thermodynamic situation. Compare 12z op GFS 2m temps vs. 12z GFS ensemble mean, both valid 00z Tue. Also, probability of CAPE >500 J/kg. The 09z SREF indicates that the operational 12z NAM is also an outlier; the SREF mean has the 25°C surface isotherm running from Elk City to Anadarko to Ardmore by Monday evening, while the NAM doesn't warm anyone in OK above 20°C through the day. Weird to see both operational models at odds with their ensembles in the same way.

 

[Rocky Rascovich]

Looked briefly at the WRF and GFS for the time period between 18Z to 0Z, think that there is some potential for scattered severe storms from near CDS to SPS to ABI, capes are better in this region along with acceptable shear profiles, although 500mb. flow does improve as you go further north, but you don't have as much cape. Looks to be a potential dryline set up in this area as well. I have not analyzed past data so I'm not up on the consistency of what the models are doing.. but if the 12Z data does verify, I would start out from around Quanah, TX. and adjust from there. I do think there will be a bigger bust potential as we may be dealing with lots of mid and upper level cloud cover limiting insolation, but if we can get enough of a break between the series of impulses we'll be dealing with most of this upcoming week, it could get interesting enough that somebody might get "lucky".

 

[Jared Farrer]

Well the NAM really let that go to s*** with the most recent run (0z). Great shear though its a shame. But I guess that means very little given the spread in the models even this close, should be different tomorrow. It just keeps cutting back on the moisture, which I have a hard time believing.

 

[Brandon Lawson]

Well the NAM really let that go to s*** with the most recent run (0z). Great shear though its a shame. But I guess that means very little given the spread in the models even this close, should be different tomorrow. It just keeps cutting back on the moisture, which I have a hard time believing.

Yes. It's really unfortunate. How much of an impact is Olaf having on the warm front being kept so far south? The NAM shows a slower and stronger system, with a 995mb surface low in eastern Colorado, and the warm front can't move?

EDIT: Cloud cover is really going to inhibit the amount of day time heating on Monday. Where the NAM looks almost saturated through 500mb, the GFS is drier aloft. The GFS also has the warm front making it up to the red river in western Oklahoma, but the CAPE is still confined well south of that. I was really hoping there would be a play from a Childress to Altus line, but this would probably be a more favorable scenario for somewhere around Abilene. And who knows what tomorrow's runs will look like. There is still hope, though... the ukmet! Or will Olaf the destroyer win?

 

[Bob Hartig]

Something smells fishy to me. The 00Z NAM shows plenty of moisture at 850 mbs, with 14C dewpoints extending as far north as Hays, KS, by 00Z, courtesy of a healthy LLJ. Makes me think the NAM is underforecasting surface moisture. Here's a map showing 850 Tds at 21Z.