2013-10-28 FCST: OK/KS

[James Gustina]

The 2013 season seems to be making attempts at sticking around and getting me to un-mothball my chase gear. The past several 12/00Z runs of the GFS have been throwing out a decently sheared, mildly unstable environment over northwestern Oklahoma and very far southwest Kansas. A modestly deep cyclone (1006-1004 mb) over southeastern Colorado looks to be gradually deepen over the course of Monday afternoon into the evening with backing sfc winds ahead of the dryline that will sharpen by 00z and mix east to just past the OK/TX state line. The other good sign is the cold front stays well back from the dryline and doesn't actually get through Oklahoma until that Tuesday night. The SW H85s look like they'll be offset by the extreme veering between 850-700 mb with almost due westerly H7s. Except for that little hiccup, the shear profile looks very favorable with deep-layer shear aoa 45 knots if the current run of the GFS (00z) is correct. The most recent run doesn't give a very favorable thermo environment (max 1000 j/kg mixed-layer) but I'm not one for setting too much stock in the GFS's attempts to throw out CAPE values. Moisture shouldn't be a problem with low-60s progged to hit Wichita by 21Z or so. Moisture return looks like it'll be rapid the day of, which is probably what is making the GFS throw out low-CAPE values because of the cloud cover that'll likely accompany it. An essentially neutral/slightly negative trough should be going through New Mexico/Texas Panhandle around 00z with western OK right on the nose of that jet. With any luck it'll speed up a bit to make sure nightfall doesn't become a factor if storms do indeed go up.


All in all, something to watch but its gonna take a lot to get me out the door at this point.

 

[Jeff Duda]

This event seems to be a shortwave trough embedded within an extremely positively tilted longwave trough. As such, cold air looks to be right on the heels of this system, if not beating it to the area. Also, I've been following FIM and GFS runs the last day or two and have noted quite a bit of inconsistency between runs within a single model and between models as well. They don't even remain consistent on the timing of this system (it had been looking like Tuesday would be the day, now they're saying Monday). Minus some veered 850 mb winds, the wind profile looks great. However, it appears there will be issues with capping and moisture depth. The GFS especially is showing some dryness at 850 mb across NW/W OK, which is manifesting itself as a very shallow layer of quality moisture in soundings in the area. Also there's a noticable inversion in the 00Z profiles around 850 mb across W OK, providing for some moderate-high CIN. Despite moderate SB/MUCAPE, I'm not impressed by the degree of capping and the cold air flying in behind this.

Bottom line: looks like a rainmaker for SE KS, OK, TX, and points east. Severe weather wise: it's still too early to know for sure, but right now confidence isn't very high in a robust severe weather threat.

 

[Marcus Diaz]

Been watching this the past couple of days on the NAM. Seems like the better chunk of the energy will hold out for Tuesday. Nevertheless, a good day might be in store in the southern plains. Decent moisture should be in places along the dryline, which the NAM is hinting at a decent buldge in the TX panhandle. Looks like the shear is in good order with WSWly mid to upper levels and SSEly 850s. Though I wish they were stronger, I'll take what I can get in late October. That reminds me, this is late October. This is the time of year where the setups have to be perfect. That said, the moisture is a tad low, but with enough heating, it may work out. MLCAPE values between 1,500 and 1,750 and 0-3km CAPE of 150 is nothing to blow off when sitting in a nicely sheared environment like tomorrow has showing. The 5km NAM soundings from DDC look pretty good. The further north though, the more shallow the moisture seems to be. I think for a tornado to happen its going to have to be a perfect storm, riding that fine line between the better shear and the better moisture. Doesn't look like that's impossible, but these fall setups are very tricky to forecast. All in all, I expect a busy day along the 64, 160, and 400 corridor in southern KS/NW OK.

 

[Skip Talbot]

This looks like a modest but chaseable setup that you could squeak a few tornadoes out of I think. My biggest concern would be catching one before night. The models don't tighten up the dryline until after 0z (after dark thanks to those early sunset times). Before then, if storms fire, I'd expect them to fire on the dryline where the dews are closer to 50 as the 60's are pretty far east of the boundary. Modest upper level support, a little bit of a diffuse dryline, and hints at some capping issues might stall initiation until the evening. Lift on the Caprock or some upper level disturbance might get storms going before sunset, but Skew T's are showing large temp/dewpoint spreads and that inverted V. You might start off with some high based, outflowy storms. Conditions for tornadoes improve dramatically after dark when the dryline tightens and the low level jet strengthens. If you can keep your supercell surface based (it's going to be fighting the cooling boundary layer and it's own cold pool when T/Td's spreads were higher) there might be a decent after dark tornado show. I'd expect some high based storms in the Texas panhandle and into SW Kansas before then though.

 

[James Gustina]

The other issue is that the best dynamics stay off to the west well into the evening. I could see one or two supercells spitting out sunset/after dark torns up along the KS/OK state line and into the DDC CWA but with how much the boundary layer is supposed to cool tonight I think that'd be a brief window. Cloud cover doesn't look to be a problem further north, but moisture return is far more modest than I thought. I'm sitting today out due to class conflicts but good luck to anyone going out.

 

[Bob Schafer]

DDC kind of throws a wet blanket on the forecast. I have thought about chasing tonight, but I doubt if I will. I'm just a couple hours west of DDC.

http://www.crh.noaa.gov/ddc/?n=webbriefing

 

[Skip Talbot]

Lubbock to Silverton to Childress, TX or bust for a shot at a daytime tube I think. Surface winds and vis sat show an area of moisture convergence here, a building cumulus field and hints of some upper level energy arriving from the west. The cap doesn't stay open very long though. The RAP shows it filling back in starting in just two hours. If you want a shot at a tornado, you'll need an established updraft before then when the boundary layer cools. Another area to watch right now is near Clovis, NM where another small patch of cu is building. A storm firing that far west is going to take some time to get into the better moisture east of Amarillo though and it may very well be after dark by then.

 

[Skip Talbot]

Looks like we've got initiation just northeast of Clovis, NM way out on the fringe of the dryline and instability. It's going to take some time for that cell to track into the better moisture east of Amarillo, so you've got some time to get into position for a tornado play if you're in the area. This looks like it might be the only shot at a daylight play with only a couple hours of good light left.