5/31/09 FCST: MN/SD/NE/IA/MO/IL

[jshields]

i'm still really liking southeast nebraska into soutwest iowa. both the 12Z NAM and GFS at 0Z 6/1 show the cap being breakable, cape over 3000, and the hodographs look pretty good too with 850 winds 30+ kts out of the ssw which should help rotation. lcl's aren't bad either especially in southwest iowa. at 03Z the 0-1 km srh really go up but the cap starts to strengthen too. hopefully we can get something to go late afternoon and last thru sunset. if models continue to show this, i'll plan on heading out sunday afternoon

 

[Michael Towers]

i'm still really liking southeast nebraska into soutwest iowa. both the 12Z NAM and GFS at 0Z 6/1 show the cap being breakable, cape over 3000, and the hodographs look pretty good too with 850 winds 30+ kts out of the ssw which should help rotation. lcl's aren't bad either especially in southwest iowa. at 03Z the 0-1 km srh really go up but the cap starts to strengthen too. hopefully we can get something to go late afternoon and last thru sunset. if models continue to show this, i'll plan on heading out sunday afternoon

I’ve been eyeing SW Iowa myself. NAM & ETA precip forecasts aren’t that favorable but I question their reliability, especially this far out. Moisture return should be less of a concern than areas further north and if initiation can be realized forecast parameters depict a relatively favorable environment for sfc based sups. 12Z NAM & GFS forecast soundings for Clarinda, Iowa at 0Z 6/1 show healthy CAPE (NAM 4500+, GFS 3500+), adequate instability (NAM -9.2 LI, GFS -6.2), EHI of 5.7 & 5.9, as well as LCLs <900 & 800 respectively. Upper support is a concern but if something does fire in the late afternoon it could be quite a show and I want to be there. It’s a long Sunday chase from my home but it could be worth it and if prospects hold up for the same area Monday I’ll just overnight it and take a long overdue day off to chase again.

NAM Kicl: http://beta.wxcaster.com/cgi-bin/parse_skewt_trace_all.cgi?model=NAM&STATIONID=_kicl

GFS Kicl: http://beta.wxcaster.com/cgi-bin/parse_skewt_trace_all.cgi?model=GFS&STATIONID=_kicl

 

[Sam Hall]

Big bullseye of CAPE over that area Craig, just seen that myself... but what the heck is happening with that CIN on the WRF?!!! 18 and 0Z?? LOL... MASSIVE area shaded... is that some kind of error or actually a possibility??

Currently, it looks good over quite a wide area, from KS up to MN so, need to keep monitoring this through tomorrow to position ourselves! SPC progging a 30% chance up in MN for Sun, but there's no CAPE until 0Z apart from a marginal value in W/C parts of MN. I know that storms can occur in low CAPE environments with other parameters at play and well, especially if that CIN is real, I am not surprised - stuff will explode especially with those much better winds in W/C parts of MN. Nice DPs and temps for surface and 700 mb too. With those southerlies, hopefully the moisture will be the key... ATTM, somewhere near Redwood Falls **may** be a possibility...

Will update as and when lol... this is so interesting at least!!!

 

[Jeremy Den Hartog]

My initial target is also near Redwood Falls, MN but I will obviously adjust that as needed tomorrow morning...

 

[Van DeWald]

Don't give up on the warm sector firing in east Central Nebraska late Sunday afternoon. The 12z Nam is now supportive of the stalled front moving north as a warm front, with 0-1km shear pegging 20-25 kts in the Platte River valley along with MUCAPES around 2500-3000 J/kg. Nice backed flow along the front, 21-03z looks Very interesting in my opinion in my local area between Columbus, NE to to Denison, IA. Of course, the GFS says that nothing will happen in this area and that a cap will hold.

 

[Derek Weston]

Still not seeing exactly what the SPC is with N Iowa and S Central MN

NAM doesn't place any meaningful CAPE in this region.... plenty of shear, but that's it.

Should we actually have nice CAPE in that area, we could have some nice supercells to work with.

I suppose the area could be marked for late hour wind damage potential... but aside from that...

 

[Craig McPeck]

SPC did a shocker and move it further north and northwest which to me seems very odd considering that most of the CAPE is over eastern nebraska, western iowa NW missouri;

http://www.spc.noaa.gov/products/outlook/day2otlk.html

 

[Darrin Rasberry]

30% area in MN should be for wind > 7PM. Best potential for MN will be when stuff fires along the front at 7, near the projected EHI along the positive CAPE values by Alexandria (where me and my girl are staying at a lake with her 'rents!). Might take off at noonish tomorrow to head a bit south and west into SD around Huron, where the best CAPE will be realized, but if it turns out to be too far into the night (12z precip run has storms breaking out right at the 7 PM mark) then I will make it a backyard lightning/hail chase to warm my girlfriend up to another one of my weird habits.

 

[John Wetter]

I still like the SW MN/SE SD area for this event. With the front looking to slow down per the 12Z models and even lift it north as a warm front further south, it appears the warm sector will stay capped, but will be available energy for a pretty decent MCS. Could have some tornadoes early on but will then transition to a linear event with some pretty decent wind damage most likely. There is decent CAPE and good shear right around the MN/SD border. The further south you go, the weaker the mid-upper support. Right now I'm thinking the triangle of about FSD/MHE/ATY.

 

[Fabian Guerra]

TARGET: Clarinda, IA (in the far southwest corner).


Well, for better or worse my target for tomorrow is not even in SPC's slight risk so perhaps I am missing something. It's true, tomorrow’s setup in far southwest Iowa is not a sure thing and, as John alluded to, could end up being a cap bust but there are some positives to take into account as well (if one is to have any confidence in the latest NAM run). The low level wind shear looks pretty good showing surface winds from the SSE aoa 15-20 knots, a healthy LLJ with the 850mb winds coming in from the southwest around 30-35 knots and the 700mb winds from the wsw at 35 knots by 0Z. There is a narrow corridor in sw IA/nw MO/se NE with dew points from 60-65 degrees and CAPE values reaching anywhere from 2500-3500 j/kg. Forecast soundings also show LCL’s in 900-1150 range so if storms can go up they should be able to become surface based. There should be strong cap for most of the day but the nam shows substantial eroding by 7pm in the far sw corner of IA. Of course its 2009 so the best upper level support is way up north where there is much less instability and moisture to work with (SPC's 30% prob area). I don’t see a big trigger so we’ll need a little help breaking the cap but if storms do go up I think there will be a halfway decent shot at a few supercells and a couple tornadoes.

Best of luck to any and all who venture out tomorrow...God knows we need it.

 

[Brian Stertz]

Target area: SD

Seems to me the best target is to jump on the storms early in life cycles in SE South Dakota. Looks like the 700mb wave will erase any capping concerns and the thing to realize is that this is an area of strong moisture advection....so the smallish CAPEs do not concern me. Will head off to Mitchell SD area and see what happens tomorrow. It could be a fun chase even if things do go to outflow domination as things move into SW Minnesota, NW Iowa...and far SE South Dakota.

Tornado threat not real high, but worth a shot.

 

[Jeff Duda]

TARGET: Clarinda, IA (in the far southwest corner).


Well, for better or worse my target for tomorrow is not even in SPC's slight risk so perhaps I am missing something. It's true, tomorrow’s setup in far southwest Iowa is not a sure thing and, as John alluded to, could end up being a cap bust but there are some positives to take into account as well (if one is to have any confidence in the latest NAM run). The low level wind shear looks pretty good showing surface winds from the SSE aoa 15-20 knots, a healthy LLJ with the 850mb winds coming in from the southwest around 30-35 knots and the 700mb winds from the wsw at 35 knots by 0Z. There is a narrow corridor in sw IA/nw MO/se NE with dew points from 60-65 degrees and CAPE values reaching anywhere from 2500-3500 j/kg. Forecast soundings also show LCL’s in 900-1150 range so if storms can go up they should be able to become surface based. There should be strong cap for most of the day but the nam shows substantial eroding by 7pm in the far sw corner of IA. Of course its 2009 so the best upper level support is way up north where there is much less instability and moisture to work with (SPC's 30% prob area). I don’t see a big trigger so we’ll need a little help breaking the cap but if storms do go up I think there will be a halfway decent shot at a few supercells and a couple tornadoes.

Best of luck to any and all who venture out tomorrow...God knows we need it.

I'm kinda seeing the same way you are. Best mix of thermodynamics and shear are in W IA E NE...give or take 100 miles north up to the corner of IA, SD, and MN.

 

[Michael O'Keeffe]

I also think SE NE/SW IA could be a play if the NAM tells us anything, there is a small piece of energy coming into that area if you look at the 500mb winds which is fairly strong compared to what we have seen the last few weeks and I have more confidence in better moisture and instability. Like Fabian mentioned the 850s and surface winds are decent too. One thing I am worried about though is the temp/dew spreads as they could get a bit high for a few hours before it cools off, but anvil shadows could help that a bit. I also like the helicity values in SW IA as well.

And if its worth anything the NAM breaks out a nice isolated cell in SE NE at 21z and has it tracking NE towards Omaha by 0z. I don't usually trust the precip models so who knows if its right but it may be signaling the cap may be breakable.

The sounding at Nebraska City at 0z Sunday looks pretty good.
http://beta.wxcaster.com/cgi-bin/parse_skewt_trace_all.cgi?model=NAM&STATIONID=AFK

 

[J Trueblood]

I agree with Brian on Mitchell, South Dakota. If things go north or south of it, one can adjust accordingly from there. I don't see a lot of veering with this though (isn't that a bad thing?)
The really interesting thing is 1 am in NW Iowa..Could be some very damaging winds..Depending on how the next run goes, I might just stay home and wait for the line..

 

[J Trueblood]

After looking at that Nebraska City sounding, and SW IA in the models..I completely agree with you guys (again)..why wouldn't the SPC notice this?