3/22/09 FCST: NE, KS

[Dann Cianca]

Okay, I'll bite ...

The last few GFS runs have been consistent about painting a nice little area in SW Nebraska (maybe NW KS). The shear isn't GREAT, but it's good. The same could be said of the instability. There will certainly be a capping concern, but I think the western edge is weak enough for storms. We won't have the forcing of Monday, but there will be some.

Anyone else think this could be a sleeper day? It definitely could be a good hail day ...

 

[Michael O'Keeffe]

Yeah Dan this looks like a classic day before the day IF the moisture can make it that far north in time which is up in the air. However it if does verify such as it does in the 12z NAM then I think there is a good bet for a few tornadic supercells over S NE and maybe W Kansas. I really like that classic dryline bulge setting up near Kearney, NE. The instability axis looks a bit wider in Nebraska too with CAPE approaching 1500 j/kg in C Nebraska. The shear ain't too shabby either with a stiff southerly LLJ and nice SW 500mb flow ahead of the monser trough.

 

[Matt Hughes]

I agree with the O'Keeffes about the day before "the day" setup. The last few model runs have peaked my interest as well. With the main wave of energy still progged to be SW it probably won't be widespread. However, if we see some serious daytime heating though then I'll probably be there!

 

[Derek Weston]

Ha, I had been thinking the 23rd thread was about the 22nd. (why I was assuming everyone was talking UTC time... beyond me, don't ever seem to do that here)

At least I know I wasn't going crazy with my upper level support worries, ha.

Yeah, as a day-before-the-day I like this. The just released 12z NAM certainly likes West Central Neb into N Central Kansas with some good CAPE. Upper level support looks to be lacking, of course... but maybe we get lucky.

 

[Dann Cianca]

Yes, the 12Z NAM definitely makes me feel a bit better about this day, especially further south along the dry line. We'll definitely see a chance of more surface-based storms as opposed to those up north along the warm/quasi-stationary front. I'm definitely planning on being out for the Sunday show.

 

[jshields]

i was taking a look at things too for sunday. the potential is there i think right along the ks/ne border in sw nebraska and nw kansas, however i just don't see enough forcing for anything to really pop. (maybe thats why the spc hasn't higlighted anything yet for sunday) shear is great and cape is there though, so maybe we'll get lucky.

 

[Andrew Stoller]

After reading a few AFDs, a piece of energy from the trough may eject out on Sunday, but short of that, I agree, the jet stream just isn't there Sunday. If the system speeds up a bit and we can get a short wave to eject out by 00z, then heck, I'd say Sunday is better then Monday!

 

[George Limpert]

I agree that model soundings don't look too shabby in SW Nebraska/NW Kansas around 00Z Monday. The GFS has shown, at least for the past few runs, a lead shortwave or two ejecting out ahead of the main system. However, the 12Z and before that the 00Z runs of the GFS have been placing the area of interest under shortwave ridging with a shortwave having already pushed east of the region and an MCS developing over eastern Nebraska. If convection could initiate over the region, I agree that supercells would be very possible. But I have some doubts about convection being able to initiate.

 

[Jared Farrer]

It still looks possible, IMO. Storm motions wold be slower. The Kearney, NE area and west sw, to just east looks like the spot. But there is potential for places further south. It would depend on being able to set-up for both days without compromising one or the other.

Interesting to see how this looks in the next few runs. Because right now there is definit potential!

 

[Dann Cianca]

Looks a little better after each run to me, even along the dryline in Kansas. Looking at a couple of soundings from the area, it's looking uncapped by 0Z along the dryline with some good CAPE to work with and enough shear to get the towers turning. Forcing may not be an issue at all ...

... and the western Dakotas might be in for some isolated severe too!

 

[Chip Redmond]

I am still very intrigued by Sundays setup. CAPE is very lack luster, but maybe underplayed still by the models. Moisture is mid-upper 50s in the panhandles and western KS, o-3km helicity improves greatly by 0z and continues after dark with values 150+ in this area, not as much speed shear will exist but directional shear from W at 500mb to S at the surface. Although its not as good as the Dakota's look its much closer to where my base will be for the week.

Chip

edit- I was looking at the wrong time for shear, weak surface winds before 0z may not be such a help. While winds pick up by 3z greatly.

 

[Roger Hill]

I just don't see a whole lot of good for a Sunday play based on 12z models today. A weak, ill timed wave. Shallow moisture and limited CAPE. Nothing decent to force convection. Maybe a high based storm or two off the eastern end of the Cheyenne Ridge at the nose of the dry punch, moving into Nebraska. But will it be worth chasing? Doubful. Guess we better hope for some dryline circulation to develop and work its' magic. Sure looks like an "elevated convection north of the warm front" day to me.

But, it is Friday, and we have two days for things to become better refined. Keep your fingers crossed.

 

[Dann Cianca]

I just don't see a whole lot of good for a Sunday play based on 12z models today. A weak, ill timed wave. Shallow moisture and limited CAPE. Nothing decent to force convection.

Yeah ... the models really tanked the instability this morning. Both the NAM and Goofus. Sad too, as the GFS had been consistent for like three days.

 

[Brandon McClung]

i have been watching this day a little bit. i am looking at areas in the TX panhandle. i have seen it before where you get marginal instability and a lot of heating, that a few storms will go. this happened on March 7th, and there was a brief tornado, or sheriffnado, reported.

the LL lapse rates seem in place and the precip models show a precip max between 18-21z. there is also a good amount of shear, and the 500mb vort map showed plenty of forcing in the area. the shear vectors on the NAM were fairly normal to the forcing mechanism.

in all, it is the last day of spring break and i have $1500-2000 of camera equipment. if anything, i might get some lightning in KS after dark.

 

[Bill Schintler]

Chase Targets for Sunday, March 22

Chase target - south:
Coldwater, KS (45 miles southeast of Dodge City).

Chase target - north:
Gothenburg, NE (21 miles east of North Platte).

Timing and storm mode:
Surface-based convection should develop in both targets between 5 and 6 PM CDT. Supercells with impressive storm structure will be possible through 8 PM, after which time storms will become elevated as the nocturnal capping inversion strengthens. Hail and marginally severe wind will be the primary severe threats. Storm motion will be towards the northeast at 35 mph.

Synopsis:
UA analysis indicates a digging trough over the WRN CONUS with 12hr H5 height falls of -60m centered over NRN CA. A couple of mid-level SHRTWV’s are embedded within increasingly SWRLY UVLV flow, with a lead H5/H7 wave analyzed over ERN CO and an upstream wave over CA. The WV loop indicates large scale assent with the lead wave spreading from ERN NM through WY. Convection within a region of upsloping SFC flow in NERN CO and in the NE and OK panhandles appears to be associated with this lead wave. SFC moisture remains very limited with dewpoints between 40 and 45F in NE and KS, and with the deeper moisture confined to the Gulf coastal areas. Upstream soundings indicate steep mid-level lapse rates in excess of 9C/km over the four-corners area into WY.

Discussion:
A vorticity ribbon will eject from the main trough and translate through KS and NE between 18Z and 00Z, 03/23/08. Insolation will be a concern with cloud cover persisting over much of the area during peak heating hours while an area of precipitation pushes through NE. A N/S-oriented band of CI, associated with the vorticity ribbon, will push E through NE and KS, with the leading edge of the cloud cover reaching the MO river by 22Z, and the back edge oriented along US-83 by 21Z. Low cloud cover will also be problematic, as a 45kt LLJ transports 10C H85 dewpoints NWD, resulting in a broken SC shield which will blanket much of NE E of US-83 through 00Z.

SFC low pressure will develop over NERN CO, with a SFC boundary extending EWD along I-80. Backing SFC flow is indicated N of this boundary, with impressive hodograph curvatures with a veering LLJ flow just above the SFC. LLVL moisture will slowly increase through the afternoon N of the boundary while a DL mixes E from CO. Instability will remain limited with MLCAPE’s AOB 800J/kg, owing to the meager LLVL moisture as SFC dewpoints struggle into the low 50’s F. The triple point, just E of LBF, should be a focus for SFC-based convective initiation after 22Z. Convection will then develop S along the DL into KS to near DDC. A concern is timing of a wave of subsidence in the wake of the lead wave, which may inhibit SFC-based convection entirely, however it appears as though a second wave of assent will arrive from CO and NM by 00Z.

- Bill

9:30 PM CDT, 03/21/09