3/21/2007 FCST: TX / OK / KS / NE / IA

[Brian Stertz]

SC Nebraska looks very primed to me after seeing all of the ETA 12z pkg. Rich and Ryan Thies will be heading off to Hastings NE tomorrow night to get into place. Initiation looks like sometime after 5pm or so Wed. on the triple pt. I will fine tune my target with more data absorption tonight into tomorrow. I would probably say now with fairly high confidence that this will garner a MDT risk scenario for SC Nebraska and extreme NC Kansas.

 

[afischer]

The last couple runs of the NAM do indeed look delicious. I'd be more excited if it was the morning of; as it stands, the parent upper trough is still offshore. The 12Z GFS remains remarkably consistent in showing the lead shortwave trough approaching & crossing the dryline at around 18Z. I'd assume if there's any zest to this disturbance, that there could very well be subsidence in its wake... so that continues to concern me with respect to typical afternoon-ish initiation of surface-based storms on Wednesday. Upshot is, I bet we'll know more in a day or two.

 

[Roger Hill]

Can't argue with what's been said. It will be interesting to see what Tuesday's convection does for Wednesday's set up. Hopefully the 850 winds won't veer as badly as the 12Z GFS shows. If so, the good juice may get pushed too far away from the dryline and the triple point area, leaving us with a bunch of high based mushballs. But, I agree with Brian, sc NE looks interesting. I too have the time to chase about any day this week. I may have to play the wait and see game on this one. Hmmm, eastern TX ph or sc NE, tough choice. The devil's in the details this far out.

 

[Stan Rose]

yeah, great. these great setups always happen while im at work.
OK, just east of Plainville, KS, 5:34 pm. an inspired guess.

 

[matt patterson]

Like Roger said the one aspect thus far keeping me on the DL is the Veering 850s up north as opposed to the 850 winds which are straight out of the south along the DL in W OK/E TX PAN... We will have to see what the Model Gods have in store for us later on today..
Also i have noticed that saturday may be shaping up to be a decent day as well, but that is like 130 hrs away, so ill stick with the time being...

 

[Darren Addy]

As everyone has said, lots of model runs to go but hard not to be especially hopeful about Wed. (particularly since it is in my "neck of the woods")**

Models are indicating 70-75 knot winds at the 250mb level, while at the 500mb level they are only in the 50-55 range, while the 850mb is in the 30-35 knot range, so we ought to see some nice tilt. The ribbon of high cape is narrow, but there is a good deal of vorticity in the 60 hour (0z Thurs) between Hastings and the NE/KS border. Based on that (with plenty of adjustments expected in the next 48 hrs) I'd be thinking about planting myself between Smith Center, KS and Red Cloud, NE. The wildcard may be what sort of precip and outflow boundaries we get on Tues. night into Wed. and how much daytime heating/clearing we see in-between.

**shouldn't we edit the subject line of this thread to more accurately identify the States involved?

 

[Jay McCoy]

**shouldn't we edit the subject line of this thread to more accurately identify the States involved?

Not sure Darren. There will be 2 areas of focus wednesday. The Tx panhandle area and up in Nebraska so we either need to adjust the title or start a new one for the central plains (Ks/Ne) since we will have chasers going after both areas. I say split them but its up to admins to decide if we create another or just rename this.

 

[BrandonWhittington]

Not real sure what to think anymore with the models.... Seems like they keep changing with every run. My focus now is more on Friday into Saturday.... Nevertheless, Wed does have the potential to be a pretty good severe weather day. 2 main factors will play the biggest role for the potential event.........

1: How Strong the Cap will Be?
2: How much and where the rain will fall on Tuesday?

Both of these in my opinion are the 2 main forecast challenges. Dew points are not a problem at all. Expect 60+ in the Panhandles. Looking back into the past. It always seem to be ironic that the cap seems to break in Beaver County, OK up to Clark County, KS. I'm not sure what it is, but the cap seems to break in that area first on setups as this one. Rainfall probally is my biggest concern. BUT, I think most of the morning crap will stay far enough east and south (in Oklahoma) and away from the Eastern Oklahoma Panhandles. As the day goes on, temperatures will warm as the warm front races back to the north, and that alone will burn off morning crap/fog............... Just using my gut on this one, I think Beaver county will be the place to be, if we can make it to around 75 degrees with clear skies....This will break the cap...hopefully.

 

[Dal Archer]

Does the lack of upper level support along the dryline in OK/TX concern anyone else? As much as I would love to stay closer to home, I am inclined to shoot north as I am concerned that there may not be enough upper level support to get things going down south along the dryline. I may be way off base though. I would love to hear some other thoughts!

 

[matt patterson]

the upper support you speak of has yet to come onshore.... The models are flipflopping all over the place... We are going to have to wait until tomorrow to refine where the upper support will actually be... 100-200 miles in either direction will make all the difference in the world...

 

[BrandonWhittington]

In my opinion, Storms that do manage to break the cap along the dryline will go severe rather quickly. Now looking back through the past. If the dryline is sharp enough and there is a slight buldge in it, it does not take a whole lot of support to get a huge isolated cell going on the dryline, the convergence alone in my opinion will be enough to get 1 or maybe 2 cells going. Just a little support will do the trick. The dryline in a fabulous area to watch for on setups like this.

 

[Mark Blue]

After reading the posts and reviewing the latest models, I'd have to shoot for somewhere between the Red Cloud / Hastings NE region at this point, as one would have the ability to go north, south, east or west with the better than average highway system in that area depending on the latest available data and ever changing conditions. With the basic ingredients such as the proximity of the surface low, the decent dewpoints, the strong LLJ, and surface based cape values in that neck of the woods - my money is on South Central Nebraska!!

 

[Brandon Sullivan]

OK/TX/KS/NE/IA/MO

I would like to see the thread extended to include KS NE IA MO.

I will write this post as if the are included.

Just looking at the SPC SWODY 3.. And 12z GFS/WRF looks like Moisture feed and associated CAPE progs have been stretched further north.. Copious moisture will stream northward through out the warm sector.. Dew points f 55-60 not uncommon anywhere in the area.. and even nicer to see LI's at -6 all the way up to the southern tier of IA counties!! CAPE progs show a 1000+ j/kg clear up through central IA... Kinda so so on the 1 KM and 3 KM helicity, but bulk and effective shear ought to be favorable for rotating updrafts.. This threat will continue eastward and become somewhat linear as the period progresses.. IL may become a threat late Wed. into Thurs, but will leave out for now due to timing issues.. Not to "Rehash" the SPC outlook. But they make it clear that they are looking at higher probabilities.

 

[Adam Atkins]

I agree with the above post. Typically the southern target is capped and the lack of strong positive vorticity advection in positively tilted weakening shortwave troughs weakens the upper level support.

Thermodynamic parameters still look great for March. The lack of strength with the trough appears to exist due to warm air advection across the Pacific Northwest which is leading to a cut-off situation in the four corners region, and blocks the cold, Canadian air preventing height falls, a digging trough, and significant vorticity advection. The lack of a good temperature gradient/pressure gradient weakens the wind fields at mid and upper levels.

Models paint an ugly picture for the northern target Wednesday in terms of discrete supercell potential, but the southern target is still an option, AND a lot can change between now and 48 hours. It's only March...

EDIT: GFS paints a different picture with the lead impulse shortwave just entering the southern plains which places the surface low further south and and more significant pressure falls in the afternoon and evening. (On the bright side of model forecasting)

 

[Ray Walker]

This system, to me looks and feels like one that is going to suprise alot of chasers. Wednesday looks good up north into Nebraska, Kansas, and Iowa. However the dryline I a huge quetion mark. If storm pop along the dryline watch out. If the cap hold strong then we may just be sitting under blue skys all day. I think the dryline will be a very good target given the weather pattern we are in.