2013-05-20 FCST: IL/MO/OK

[chrisbray]

I'm really struggling right now tryingto figure out if I need to leave Illinois tomorrow, or will be fine in western Illinois, or shouldn't even bother. NAM and GFS showing quite different pictures in regards to instability. NAM seems to think an overnight mcs goes through the illinois/missouri border overnight sunday, which could really mess things up.

Neither model seems to initiate much in the afternoon or evening Monday.

I'm starting to get concerned...is anyone else chasing western Illinois?

I know everyone is focusing on today for the most part, and then probably oklahoma tomorrow, but any input for this area's monday forecast would be most welcome

 

[chrisbray]

Well updated SPC Day 2 is out for tomorrow....Is anyone else thinking of targeting eastern Iowa/Western Illinois? Seems like they highlighted that region only for the vorticity max that some models show going through in the early afternoon. Fields look decent for supercells overall, but from what I can tell, not necessarily for tornados. Forecast soundings for 18z show hodos in that area looping back around like a figure 8 almost...

 

[chrisbray]

Ok the day has arrived. RAP, NAM and GFS all paint different picture for Illinois today. NAM pretty much shows no instability above the bottom third of the state, RAP likes west central Illinois as the evening progress, while GFS likes west central early but quickly moves favorable parameters northeast from there towards the Chicago area by nighttime. SPC day 1 outlook this morning was pretty much useless for target area purposes. I think we are going to head out to west-central Illinois and see how the forecast evolves from there. Better moisture looks to advect there as the day moves on, and the instability should increase nicely. Any other thoughts from people chasing Illinois?

 

[Jared Orr]

Oklahoma is looking poised for another significant tornado event. Pattern recognition would suggest a similar initiation pattern as seen yesterday, with more discrete cells to the south and bowing segments to the north. However, the pattern today is father south than yesterday. Even though helicity values are not progged to be very large, yesterday has shown that with extreme buoyancy, this deficiency is compensated for. Storm motions are very reasonable due to the steep drop off in wind speed below 500mb.

The influx of a >60kt jet max will help provide additional lift along the dryline, allowing for earlier initiation (1-3 pm) considering the weak capping inversion. My team will struggle to make it to Duncan, OK in time, but this would be my ideal target.

Be careful when chasing these rain-wrapped tornadoes...HP will be the dominant mode for any storms that move off the dryline due to precipitable water above 1.5".

 

[amytierney]

What is the day looking like for Northeast Missouri???

 

[Jared Orr]

Btw, reflectivity showing a potential outflow boundary extending from NE to SW in a location between OKC and the OK/KS border. May provide interesting dynamics if storms manage to interact with it.