2013-10-10 FCST: NE/KS/TX

[James Gustina]

This setup popped up about three days ago with a neutral/slightly negative ejecting out of Arizona/New Mexico Thursday afternoon. The biggest problem with this setup lies in the quality of boundary layer moisture and with the gulf being as devoid of quality moisture as it is, its all going to hinge on day of moisture return. The one plus with this is that the wind profiles in western Kansas/panhandles are absolutely gorgeous. The 12z NAM was putting backed surface winds along the "dryline" in the central TX panhandle up to almost Goodland where the surface cyclone is located as well as almost due SE H85s aoa 40 knots by 00Z. That same run only has dewpoints in the mid 40s progged for western Kansas and mid 50s in the TX panhandle by 00Z though which is definitely cause for concern. The thermodynamic environment is also pretty iffy on the NAM as a result of the anemic moisture return and the low sfc temps in the late afternoon.

I'd be more inclined to watch this closely if moisture was likely to get that far north and it didn't fall on the Thursday before OU/Texas, but as of now I'm less than impressed.

 

[Marcus Diaz]

Been watching this setup too. The moisture looks meager, but could work out if the dryline holds back west in higher elevation. Don't like the northern half of this system as the upper level winds become almost due south. I remember May 29 this year doing the same thing and that day went linear in a heartbeat. If the instability axis can become wider, we could have a great day wherever there's good divergence. Looking further down the pipes and it looks like this could be the last setup in a while. The key is to find that sweet spot were CAPE is maximized in the area with the best wind profiles.

 

[James Gustina]

A mesoscale accident south of Groom would not surprise me at all if enough moisture pools in the canyons. The SREF was more progressive with moisture (granted not by much) but upper 50s in the panhandle are more than adequate especially if the dryline stays back a bit west of I-27. The other thing is that the panhandle will be in the sweetspot of the right exit region of the jet streak where there won't be massive subsidence like up in Kansas. If dewpoints hit 57F+ then I will definitely be trying to find a way to escape my calculus class in the afternoon on Thursday.

 

[Marcus Diaz]

James, my thoughts exactly. Another fly in the ointment will probably be a cloud cover as the bulk of the energy approaches. This in turn is what's holding back on surface temps, thus keeping instability questionable. But I think you're right, if an updraft can root down it may have a shot at becoming a supercell, maybe even dropping a brief tornado with the amount of shear in the area.

 

[James Gustina]

I'm becoming a little more hopeful for Thursday. The gulf is recovering slowly (I think most of the NW GOMEX is up to 58-60F now) and dews are in the 40s in most of north-central Texas. The 12Z NAM and 09Z SREF are both being bullish with moisture not even hitting 45F by 00Z Thursday but I'm more inclined to just go by sfc obs at this point. The kinematics with this system still look highly favorable with the panhandle being in the lower right quadrant of the jet streak and 9/10 members of the SREF are putting deep-layer shear=> 40 knots over the northern panhandle and western Kansas.

 

[cdcollura]

Good day all,

I am watching this very closely (and almost making a go or no-go decision on it as well).

Yes, the shear is very high, along with steep lapse rates, weak to moderate cap, and cold air at 500 MB by Friday 0z (Thursday evening 10/10).

The negatives are the obvious lack of moisture, with the GFS bringing 50 to 55 degrees dewpoints with a temperature around 70 into NW Kansas by that time. The NAM is similar, with the moisture corridor narrow, and mixing less as you head west into NE Colorado.

Also, the wind directions, although strong, veer from SSE to S in the lower levels, but remain S to barely SSW all the way through 500 MB and on up to 250 MB. This meridonal flow will parallell the dryline / front and make for fast motions to the N or NNE (if storms form).

The meridonal flow and rather quick veering of the winds ahead of the surface low, which will depart quickly out of NE Colorado and move NNE into Canada by the same time on Friday / Saturday (0z to 6z time frames).

There may be high-based supercells initially (around 22z if everything comes together Thursday near W KS), but a quick evolution to a squall line because of the linear forcing by about 1z. If we can get the storms to fire farther south, then there may be more of a SW flow aloft ... That's my take.

 

[Brett Roberts]

After reviewing the 12z guidance, I really doubt a significant surface-based supercell/tornado threat will be realized Thursday. The situation regarding low-level moisture already looked borderline (at best), and has only trended worse on the last few runs.

This one might be a little more frustrating to watch than your typical moisture-starved autumn tease because there's broad ridging across eastern North America, which would normally be a green light for moisture return. Sadly, the weak upper low stalled over the Mid Atlantic and associated northerly flow into the Gulf will likely prove a show-stopper.