06/07/07 FCST: TX / OK / KS / MO / IA / IL / WI

[Ben Prusia]

Looks like another day of severe weather to set up across the central and southern Plains States on Thursday as the GFS sets up a strong dryline across the middle and eastern halves of Kansas, Oklahoma, and into Texas. The GFS at 108 hours shows some sort of dryline bulge in SE Kansas with Td's in the lower 70's across SE Kansas, Missouri, Oklahoma, and Texas. Instability will be extreme from SE Kansas, southward along the dryline with the GFS forecasting SBCAPE values in the lower-mid 5000's J/Kg across SE Kansas, and into the 4000's as you head south along the dryline. With surface temperatures in the lower-mid 80's with Td's in the lower-mid 70's in SE Kansas, this could set up for a favorable day of severe weather. Mid-upper level winds are highest the farther north you go on the dryline to meet with the upper level jet. With a substantially weaker cap to play with than on Wednesday's setup, looks like there will be a better chance for some severe weather on Thursday.

 

[Jeff Snyder]

6/7/06 FCST: TX / OK / KS / MO / IA / IL / WI

Unseasonably strong southwesterly flow aloft will remain over much of the central US Thursday, as substantial Gulf moisture streams northward. current progs indicate strongest instability along the cold front in the southern and central Plains, but an unstable airmass will develop farther north into the western and central Great Lakes region as well. Surface winds may very well be veered to the SW ahead of the front (though the coldest air lags the front, or a second cold front exists farther west), which won't do a lot for low-level shear. Despite this, very strong mid-level flow within the warm sector (~50kts in SW OK, increasing to ~85kts in WI per the NAM, slightly weaker on the GFS) will yield supercell-sufficient deep-layer shear (45kts in OK ahead of the front, increasing to 65-70kts in WI per NAM; weaker on GFS). Storm motion and orientation of front look like squall line may be the preferred mode, but I wouldn't trust 84hr model progs too much. The GFS gives me a little more hope for supercell mode in southeastern KS and OK.

 

[Ben Prusia]

Looks like the 12Z GFS model is still setting up a dryline situation for portions of east central Kansas into SE Kansas and NE Oklahoma that is ahead of a frontal boundary that will set up in northern parts of Kansas during the day on Thursday. 500 mb level winds are still progged to be at the max more towards a Kansas target area. There still isn't a strong cap progged for the day but strong enough for some isolated supercells, which should be broken through with the progged strong instability. Surface winds are in all sorts of directions which could hurt any decent chances for some severe on Thursday, but the GFS paints a target around SE Kansas into NE Oklahoma from around Burlington, KS to Nowata, OK.

Meanwhile, the 12Z NAM is a little different on the day as it brings in the system a little faster than the GFS. Though it is the trend for the GFS to slow systems down the closer the day approaches (Wednesday now way into north central SD/south central ND).

 

[Brandon Sullivan]

A very nice setup indeed... Lots of parameters coming together... SPC SREF showing a nice setup.. The slowing of the system advertised by the 12z models puts a favorable timing setup.. Cant wait for the 3 day tommorow..

 

[Jim Zandonai]

Day 3 looks good here in N.IL too with what appears to to be a little later in the day into the evening or so. In any event it looks good for A Tornado set up with good wind shear and good instability.

 

[John Peters]

Looks like sheer profiles will be more than adequate to support a strong tornado in any of the storms that remain isolated (as mentioned in the 3 day outlook). NAM 0000 UTC JUN 07 deepens the low to 976 mb, which could make for a very windy day in the upper plains/midwest. Even GFS which has been a little bit more conservative on the strength of the low deepens it to 978 by 1200 UTC.

 

[Brandon Sullivan]

Well, Im certainly not surprised with the moderate risk on Day 3. Im actually liking the SW area of the moderate risk. Which seems to have a nice combo given the location of the LLJ and frontal placement.. But then again, I have considered waterloo given that it is in the middle of the area.. I dont know how much it is worth looking at, but the latest SREF doesnt seem as impressive as last night.

Also, the Lacrosse AFD this morning brought up an interesting point. Given the slightly lower instability on Day 3. The stronger amount of shear could shear off thunderstorms before they can mature.. Wonder if the 1730 Day 2 will go high risk?

 

[cdcollura]

Good day all,

Currently targeting the NE / SD MDT day2 right now ... But also considering a jog a couple of hundred miles east and being in great position for Thursday! I am favoring central to NE Iowa right now!

Just be careful as Wednesdays "show" evolves to a bombing MCS if anyone plans to drive the I-80 / I-90 corridors east prepping for Thursday ;-)

 

[Eddie Natenberg]

The latest NAM forecast shows a general trend of slowing down of the low center and better resolution to the advection and strength of the trough axis. Although surface winds may not back enough in the 0-3 km for insane SREH values, I've seen too many tornadoes in strong cyclogenesis situations like these. The downfalls will be fast storm motion and large scale mass forcing via intense area of CVA. This leads me to believe storm mode may transition to LEWP structure quickly with a significant threat for well organized complex after dark. That being said, if 850 LLJ can stay strong storms may stay organized beneath strong pressure falls along the trough axis. I do expect there to be a chance (conditionally) for strong tornadoes if storms can stay isolated. Although capping looks fairly weak :frown:, I am very impressed at the discontinuity of the Td spread as the trough ejects into eastern IA.

CURRENT TARGET(best guess): 50 miles ENE of KDMX

I don't plan to miss this one.


Eddie

 

[Joel Wright]

Looks like Wednesday evening's activity will largely stay away from Iowa. This should allow full insolation on Thursday. Mid level winds are insane for this time of year. I can't recall them this strong so deep into spring.

Moisture and instability will be there. I'm a bit concerned about the slight lack of directional shear by mid afternoon. Hopefull a small wave can develop along the front to help keep the winds backed a little more.

 

[Brandon Sullivan]

Exactly.. High Temp forecast here is 94 degrees!!! I just got done being a pessimist about the Wednesday forecast.. I think our day holds better potential.. I know it at least holds less "iff's. 21z SREF looking even better and better with the system, with Sig Tor and Sup composites going crazy!!!! Im pumped. I will leave work and head west at lunch.. I will hope for a 1730 high risk tommorow.. Well see if we get that lucky.

 

[Joel Wright]

This thread is suprisingly quiet. I think there's great potential for this day.

The latest GFS shows a weak low over eastern KS by afternoon. This may be just enough to keep the low level winds from veering too much to it's east.

Moisture should be much less a problem for Thursday for obvious reasons. It's looking like the cap should hold into the afternoon, before it gives way. Unlike the previous day, it will give way.

I agree with Brandon. I believe this will get boosted to high risk eventually.

 

[Brandon Sullivan]

Ya, I Was trying to stir up some activity myself.. I have been told by some others to head out on 136 into northern mo in the afternoon.. I think I will head in that direction.. Not sure where.. But I have said all along I like the SW portion of the Moderate.. Another wx smart person and I were talking, and we agree that the only real problem we see is the storm motions, some up to around 50kts.. Also sometimes cold front supercells can be undercut.. But I am looking for a nice setup and will be ready in the morning to see the new outlooks.. Im going to bed now though.. lol..

 

[John Wetter]

I'm really starting to think Thursday will really be the show. Wednesday just looks too capped and then a monster MCS. I think MN could get in on the action thursday as well, though it'll be throughout the day... Not necessarily great storms to chase.

-John

 

[matt patterson]

I have been somewhat quiet in the forecast threads as there just seem to be too many unknowns.. However, i think that E KS/NE OK need some love as the parameters seem to be really coming together for a decent round of severe weather. We will be Capped for a good part of the day, but with mid to upper 60s Tds and 50+ knots at H5 and out of the WSW and strong 850 flow out of the S, it would seem that it would be ideal. Also the distance from the main upper low will keep forcing from being too strong like we may see farther north. This coupled with not so great directional shear may lead to more of a LEWP/quasi linear line of storms/supercells. There will defintely be more storm reports up north, but i think we will see a handful of sups down this way thurs afternoon. The mode should be supercellular and they should be moving to the ENE which is a favorable direction in this part of the country.. Will be interesting to watch..