3/8/06 FCST: South-Central Plains/MO Valley

[Tony Laubach]

Wednesday's potential seems to be shifting further east that previously discussed. Latest NAM is showing potential from Northeastern Oklahoma northward into Southeastern Kansas.

A narrow band of moisture noses up through Eastern Oklahoma into Southeastern Kansas beneath 50kt 500mb winds which are rolling over the area at 0z Thurs. The NAM is forecasting a decent vort max over SE Kansas with another bulls-eye over Kansas City.

Seems the best instability is going to lie in Northeastern Oklahoma and nosing into the extreme southeastern portions of Kansas, roughly south of Hwy 160. Little cap is forecasted over the southeastern portions of Kansas.

GFS seems a bit slower and further west than the NAM, and is definately preferred cause of the topography which lies further west. GFS has the better CAPE further north into Kansas from roughly I-135 eastward to the KS/MO line. Seems the GFS is a bit weaker, however.

I would love to see the NAM's jet max over AR back west into OK, overlapping more the instability which is forecast to be sitting over NE OK and SE KS. Also, my biggest concern according to this run is the lack of SE winds over the area. While moisture transport looks decent, winds out of the SSW won't do a lot for low level shear. However, if Tuesday pans out, there is potential for some boundries to be present from overnight MCS; something definately worth watching for Wednesday. I'd like to be sitting right beneath on of those.

More later...

 

[beaudodson]

I am in Western Kentucky and have been watching all of this unfold. There seems to be several threats. Wednesday Night into Thursday appears to be favorable for severe thunderstorms across much of Arkansas up into this region. Perhaps there will be another thread for the threat on the 9th?

The biggest difference in the NAM and the GFS (and now the EC) is the placement and strength of the second low pressure area. The models want to develop a low in Arkansas that appears to rapidly deepen as it moves to near Chicago. GFS actually shows this low nearing 29.00 on Thursday.

850 mb winds are fairly impressive across this entire region. Moisture doesn't seem to be an issue but instability does.

The NAM is not as bullish with the second low pressure area.

It certainly looks like a significant risk for severe thunderstorms on Wednesday across portions of the Plains and into the Missouri Valley.

I am curious how the drought is going to impact the dry-line.

 

[Matthew Havin]

Quick rundown:

12Z models:
NAM - forms 992mb low by 0Z Thu near Ponca City OK
GFS - forms 990mb low by 0Z near Emporia KS
Canadian - forms 993mb low by 0Z east of Alva OK

18Z models:
NAM - forms 988mb (!) low by 21Z just east of Wichita

Initial thoughts are to head for an area east of Wichita to the MO border, along with the northeast edge of OK. 18Z NAM is a tad north of previous and I still prefer slightly west idea of the Canadian. If this was later today, I would head to Chanute or Independence and camp. 18Z NAM has this area at 2000+ CAPE , EHI 2+ at 21Z.

 

[Michael Auker]

Wednesday looks to be a pretty good day...I'm surprised it's not getting more attention?

 

[Chris C Sanner]

Originally posted by Michael Auker
Wednesday looks to be a pretty good day...I'm surprised it's not getting more attention?

I'd think most are focusing on Tuesday with it being the first event of the year, I'd expect this thread to heat up soon.

From the looks of the models (and SPC) it looks like we're in for a few supercells along the dryline and then more and more numerous storms eventually congealing into a line as they march east. Things look very potent for early March, and I will not be suprised to hear of a storm going bonkers given the right situation.

I think the biggest factor may be in convection from the previous day and where it might lay a boundary down at. I'm very pleased the maximum risk outlined by the SPC is Southern OK, makes it less of a drive after tommorow's long trek I have ahead of me up into N. Oklahoma...

 

[Jeff Snyder]

I won't post an in-depth forecast yet, but I will say that the new 12z NAM pushed everything to the west about 75 miles, with the instability axis (and surface low) in western OK and sc KS. Flow at 700mb is a little weak for my liking, but directional shear in the low-levels is nice. Strong lapse rates will advect out of the southwest tomorrow, which will help give us some CAPE despite rather marginal Td forecasts (upper 50s). In addition, DPVA should yield deeplayer ascent over OK by mid-late afternoon as the vort max begins to pull out of NM. Overall, I'm just excited about not having to chase east of I35 tomorrow!

 

[bbarjenbruch]

I anticipate dropping in from the North tomorrow in the early afternoon. Although the triple point invof Witchita (give or take) will be the optimal location for first initiation and convergence, I am very interested in just where this strong baroclinic zone and associated warm front will be setting up. Any storm that can ride along this zone for a decent amount of time will be sure to pick up a substantial amount of vorticity.

I for one will be rooting for a track slightly farther North and West than is currently progged (the latest trends have me excited) to allow for further advection of the 60+ dewpoints into northcentral and northeast KS. If early convection can get out of the way fast enough, I really think the warm front, especially near the triple point, as opposed to the dryline will be the best place to play for torandoes. It may be an ugly chase, but there could be some solid production.

 

[Bill Tabor]

This is looking to be primarily a nighttime event for the north central Tx area taking place somewhere between 6pm and 6am next morning. This will probably also include parts of southern OK as they have less Cinh.

It appears some type of mixing or similar will be taking place during the day robbing much of the lower level moisture (most likely the overspreading upper air system). This and lack of focusing mechanism and strong inhibition will prevent much from happening during the day although I'd give a small chance severe dryline along / just east of a Childress / Abilene line primarily before 0z. Even during the evening capping and inhibition may prevent storms from taking root in much / most of north Tx, but as the mid level wave and upper divergence passes overhead and targets the area near Wichita Falls and south toward Stephenville / Brownwood and over toward the DFW area I think some severe storms may finally be able to break out. The deepening mid level low overnight appears to be able to strengthen the surface low and refocus / back surface winds to 850 to some degree providing a period of time with low level directional shear supportive of tornadoes.

West Tx (area mentioned above during day) I give a slight chance for severe with some hail, wind, and possibly a tornado. North Tx nighttime event I give better probabilities of severe (probably moderate) with supercells, tornadoes (15%), hail / wind (at least 25%).

Oklahoma alternatively won't be the focus of the vorticity maximum but wil nevertheless get the spoils of it with less inhibition and perhaps more Cape. I think southern OK has a good chance for severe as well but I would set the strength of the event lower than north Tx but Ok may have a slightly better chance of more likely occurring and wider spread severe.

Edit: I suppose I should add I didn't really look at KS. I mainly look at what I consider the primary area and what typically would be closest to home for me. Since my area is closer I looked no further. So as SPC has some area drawn in KS - maybe there is a shot - but I didn't look there other than to see IMO I'd believe further south has better opportunity.

 

[Mark Oerther]

Wah, Wah, Wah!

There are a lot of problems I have with tomorrow. The only thing I can say I really like is the amount of speed shear in southeastern OK, and north Texas. However, if there is no storms to be inbedded in the shear...then it doesn't really matter that the shear is there. 12z Eta progs inhibition over the entire 30% risk area given by SPC. Synoptic forcing is there with strong surface and upper-level winds. But that is the only vertical forcing I can really see. The dry-line sets up in far western OK and there is also a sliver of low 50 dewpoints in the 30% area that has me pondering.

With this being said I can not see why the risk is 30% over the forecasted area from SPC. Yes, if a storm were to develop or move into this region by 00z Thursday there is a possibillity for tornadoes. With the given lapse rates I would also agree that large hail is definetly possible. Yet if there are no storms, none of these things can happen.

 

[Mark Oerther]

Clarification

I would like to clarify that previous post was largely directed to the southern 30% target area. The Kansas 30% bulls eye is a much better shear set up as well as vertical lift with strong vorticity generated by triple point area. But moisture is still a major concern for this area. My feeling is that if something great is going to happen tomorrow it will be in the northern target area. Still I do not believe much will happen do to lack of moisture resulting in high LCL heights.

 

[bbarjenbruch]

I strongly agree with you that moisture is a potential problem. The good news is that since midnight last night, 50+ degree dewpoints advected from southern Oklahoma to Northern Kansas. WIth the LLJ firing up again overnight tonight, I anticipate at least the chance that the same will happen tonight, placing the 60 degree dewpoints currently in OK at the frontal boundary in Kansas by tomorrow noon.

One other potential problem I see is the same thing that happened today... clouds. Most of Kansas should be in the left exit region of the jet streak which could potentially equal a decent cloud shield. I'm hoping against it of course.

Barring some major changes in frontal positioning farther south and away from Lincoln, or a thick cloud shield, I will be in the field tomorrow. Watch for a University of Nebraska group and give us a holler.

More thoughts and updates to come.

 

[Jonathan Racy]

Re: Wah, Wah, Wah!

Originally posted by Mark Oerther

With this being said I can not see why the risk is 30% over the forecasted area from SPC. Yes, if a storm were to develop or move into this region by 00z Thursday there is a possibillity for tornadoes. With the given lapse rates I would also agree that large hail is definetly possible. Yet if there are no storms, none of these things can happen.

Mark, Keep in mind that the day 2 outlook issued with the 30% probability covers the time period 12Z WED to 12Z THU, not just through 00Z (chasing time) and is for all facets of severe (not just tornadoes). Most models are pretty consistent in developing widespread tstms across ncntrl TX nwd into cntrl OK after dark WED. The storms then move across the 30% area. It could be a rather active overnight, once the main wave migrates across the warm sector.

Jon

 

[Tony Laubach]

I believe the disection of SPC's analysis is the 30% over Kansas will be the lighted event; the 30% down south will occur after dark. If you're chasing for tornatic, daytime storms, my opinion is play in Kansas near the triple point. And for the record, I'm not saying the southern target won't have daytime storms, but I think the highest risk of that number is going for what's suppose to transpire after dark.

 

[beaudodson]

Both the 18z NAM and GFS are impressive with the deepening of this second low. NAM is showing a 977 low once it moves through Illinois.

Certainly will be interesting to see what happens along the triple point. PAH is already talking about the tornado threat in their HWO and their afternoon AFD.

 

[Bill Tabor]

As far as KS is concerned per NAM it looks like the triple point will be near Medicine Lodge, KS around the 18z timeframe or perhaps a bit closer to the OK border. The warm front will stretch across Ks to the ne with dryline / trough extending down into OK. The triple point may actually be on the OK side. Anyway problems with the KS scenario I see are lower dewpoints. And like today substantial Cinh and only weak wave interaction for lifting to break the cap near the interface. Primary uncapped cape I see during the day is mostly a small stretch in OK although it does appear to extend to southcentral KS by 0Z. Upper divergence may help break cap and start storms near 0z though. NAM shows only non-convective showers in KS although it isn't that great a predicting either. I only see decent low level directional shear for torns close to 0z map timeframe although helicity seems to remain reasonable. Best NAM forecast EHI readings in KS tomorrow are only around 1 - so nothing too special. Later toward 0z the best EHI focuses further south into OK.

I'm not too impressed for a daytime event here either. However inhibition may be less up there and allow stuff to break out. Model seems to show it capped but I didn't check a forecast sounding to see really how strong it looks. If overcast again like today and it probably will be I'd say slim chance. However it is the northern area and those areas behind the front and closer to the low often produce. It may be able to pull something out before dark.