2011-04-25 FCST: KS, MO, OK, TX, IL, AR

[Mike Smith]

I'll go ahead and start this thread, also.

This could be an "outbreak" day with very strong jet stream, rapidly falling pressures, and unstable air flowing north. The outbreak may last into Tuesday. Timing still a question but right now my highest risk would be from just west of the Lake of the Ozarks to TXK.

 

[Trey Thee]

There are a lot of dynamics yet to be ironed out for Monday and of course it varies by location. At this point I think Monday may be an active day from the I35 corridor back to the east. A lot of these outstanding issues could come together in the next 24 to 48 hours and we could have a substantial risk on Monday for a significant weather event.
I think tomorrow will help dramatically with bringing this event into focus.
Additionally, Tuesday also holds some SVR potential for the southern plains.

 

[Benjamin Rock]

Personally, with the NAM and GFS still out of alignment for this one, I would say the SE MO/NE ARK point would be the play. The GFS is showing a good swath of instability by the 21z hr, however, that puts it dangerously close to night fall. The NAM is barely showing slight instability. Shear is only at 40-50 kt and CIN is around -20kg. Dew points are only look to be near 15C. If the models verify and convective diurnal heating can get going, it might be worth the bad road network and terrain.

 

[John Farley]

Focusing on the MO/IL aspects of this system, lots of "ifs" with this. Looks like both the GFS and NAM bring the surface low and warm front up to the I-70 corridor, but winds in this area are more unidirectional than the last couple systems, with upper winds less veered and lower winds more so than with the previous storms. Also instability looks to be less, although this will depend on how much daytime precipitation there is tomorrow before the main system moves in. If it clears in the warm sector, instability could be more than the models are predicting. Instability looks better in southwest MO and northwest AR, at least on the NAM, but that is terrible chase country and it doesn't look like storms will get to the better terrain of the MO bootheel and eastern AR until after dark. Despite the lack of directional shear, I do think that if things can destabilize enough to get strong storms - a big "if" - tornadoes will still be possible if these storms fire along the warm front in eastern MO or southwest IL, due to the localized increase of shear along the warm front. But that is a whole lot of "ifs."

 

[Dan Robinson]

A major logistics consideration for those chasing in northern Arkansas and southern Missouri tomorrow is the rather extreme flood event that is in progress now, and based on most short-term model guidance, may worsen overnight into tomorrow. Storm total rainfall forecasts are in excess of 10 inches in these areas. I would expect numerous closed/impassable roads, many which may not be signed.

Every model so far limits destabilization into southern Missouri, but if this region is able to clear out in advance of the low (highly unlikely as currently depicted), backed winds along the warm front just south of St. Louis may offer tornado potential later in the period from a Poplar Bluff-Cape Girardeau-Carbondale line. However, again, this area is ground zero of serious flooding problems with widespread closed roads, which combined with likely nighttime supercells would make chasing logistically unadviseable.

 

[Paul Sherman]

As Dan says above the recent multi day MCS's that have affected the areas further towards the MO/AR Border would have me settling further South, if the crapvection can clear out today would expect around 2,000jkg of Cape and favourable LCL's around the C Arkansas area, the Jet streak nosing in around 22z should initiate Supercells racing North Eastwards from NE Texas and NW Louisiana. Trick today obviously is to keep in the Warm sector below the Warm Front as when those Storms cross over the cold boundary Spin Ups will suffer.
A lot also has been said of the Chase Terrain in Arkansas but I have listed below in the Blog the areas I have found to be very favourable in Arkansas over recent years with great visibility

http://plainschaser.blogspot.com/2011/04/monday-25th-april-2011-chase-target.html

 

[Michael Riedl]

HRRR shows the warm sector barely getting in to Arkansas and just a total mess for today. Any Play IMO would be SC to SE Texas, better CAPE shear is manageable, 0-1KM Helicity is alright in that area as well.