7/14/09 FCST: MN/NE/IA/MO/IL/WI

[Derek Weston]

Seems as though things would kick off a bit west of the Missouri river in SD through the N half of Nebraska... cap seems like a big issue in the southern half of Neb and points south. Directional shear is nice in this region, problem is that the best low level shear is further east over MN/IA. (ahead of the best CAPE and upper level support -- as others have noted) This makes me question what our tornado potential will be... and if we've got a meager cap to the north, along with big forcing... storm mode might get messy. That said, if we could fire off some cells that could remain discrete through the evening as they enter Iowa... just might encounter a more favorably sheared environment that might be favorable for tornadic supercells. As of right now, would likely target the NW IA/SE SD area... where capping ought to not be so much a problem.

Edits: looking at the latest NAM run... no way on the southern target, looks like a cap bust. Up north looks like a line perhaps... precip models certainly think so. Trick is probably going to be finding the southern most storm in the line and hoping for some rotation.

 

[Dan Rupnow]

00Z NAM is out and shows better H7 temps of 10-12C over SW IA/NW MO vs. temps aoa 15C in earlier runs. Hopefully this trend continues in later runs.

 

[Brandon Sullivan]

Seems as though things would kick off a bit west of the Missouri river in SD through the N half of Nebraska... cap seems like a big issue in the southern half of Neb and points south. Directional shear is nice in this region, problem is that the best low level shear is further east over MN/IA. (ahead of the best CAPE and upper level support -- as others have noted) This makes me question what our tornado potential will be... and if we've got a meager cap to the north, along with big forcing... storm mode might get messy. That said, if we could fire off some cells that could remain discrete through the evening as they enter Iowa... just might encounter a more favorably sheared environment that might be favorable for tornadic supercells. As of right now, would likely target the NW IA/SE SD area... where capping ought to not be so much a problem.

Edits: looking at the latest NAM run... no way on the southern target, up north looks like a line perhaps. Trick is probably going to be finding the southern most storm in the line and hoping for some rotation.

I like the 00z for the southern target. H7 Temps have cooled off in the south which is the first thing I was looking for!

It did look like the NAM sped up the CF some, which I didn't like too much. But, remember, if you are looking at models now, you aren't seeing the 4km HI-Res, so if anyone is going of FCST CREF, a blob could really be a supercell, or a broken line of supercells.

Frankly, im still game for south..

NOTE: System won't be on sure till 2moro, so if it stilll looks good 2moro night, then we get excited

 

[Brandon Lawson]

Yes. Somewhere along the IA/MO border into Iowa looks mighty nice based off the latest model runs. West vs. East depending on which model you trust. The GFS kicks the shortwave out a little quicker, pulling the 850 winds with it. Even still, since we're not really dealing with a dryline setup here, and the backed 925mb winds are equally strong, I'm optimistic about the setup. Plus you have a really juicy atmosphere.

GFS was showing lifted indeces in the -12 to -13 degrees range. Maybe it's because I dont' always look at that parameter, but it just seems like I haven't seen that in a while. May 4th, 2003? LCL's are going to be ridiculously low as well if the forecasted dewpoints really turn out and the temps don't get out of control. But I would expect the models to overdue the moisture. And then you still have capping issues. But I'm more willing to take a chance on a strong cap vs. no cap at all.

I'll reserve my excitement for tomorrow if things still look as good or better than they do now.

 

[Brandon Sullivan]

Yes. Somewhere along the IA/MO border into Iowa looks mighty nice based off the latest model runs. West vs. East depending on which model you trust. The GFS kicks the shortwave out a little quicker, pulling the 850 winds with it. Even still, since we're not really dealing with a dryline setup here, and the backed 925mb winds are equally strong, I'm optimistic about the setup. Plus you have a really juicy atmosphere.

GFS was showing lifted indeces in the -12 to -13 degrees range. Maybe it's because I dont' always look at that parameter, but it just seems like I haven't seen that in a while. May 4th, 2003? LCL's are going to be ridiculously low as well if the forecasted dewpoints really turn out and the temps don't get out of control. But I would expect the models to overdue the moisture. And then you still have capping issues. But I'm more willing to take a chance on a strong cap vs. no cap at all.

I'll reserve my excitement for tomorrow if things still look as good or better than they do now.

Good Points.. If cap holds south, it will be a chase in IA with less favorable parameters....

Growing season is at peak right now, so transpiration is going to be a factor also.. So maybe things wont be too overdone...

 

[jshields]

i'm liking tonights 0Z runs alot better than prior runs. as mentioned the 700 temps have come down, so the cap looks alot more manageable. i would like more low level shear as those values are a little low, but bulk shear is still there to get some big supercells. so far this year it seems like the cap has almost always won, so i'm still hesitant. i think another big factor will be the mcs that is forecast to move through somewhere over eastern nebraska and iowa on tuesday morning. if that can stay far enough east then i'll feel better about the chances on tuesday. something i can say i dont remember ever seeing is the falls city, ne sounding for 0Z wednesday. it shows a CAPE value of 8329!!. there's a lot a storm could do with that amount of available energy!

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

 

[Skip Talbot]

I'm looking at SW IA or NW MO. One of my main concerns is forcing and lift in this area. I'm thinking that we might get it as the shortwave intersects an MCS enforced warm front or outflow boundary in this area. The rest of the parameters are there on the 12z WRF:

Cape over 3000 J/Kg extending into Iowa:
http://68.226.77.253/models/eta/central/CENTRAL_ETA212_ATMOS_CAPE_36HR.gif

A nice hole in the cap extending down to Kansas City:
http://68.226.77.253/models/eta/central/CENTRAL_ETA212_ATMOS_LSI_36HR.gif

50 knots of effective shear across southern IA and into MO:
http://68.226.77.253/models/eta/central/CENTRAL_ETA212_ATMOS_ESHR_36HR.gif

300 m2/s2 effective srh on the IA/MO border:
http://68.226.77.253/models/eta/central/CENTRAL_ETA212_ATMOS_ESRH_36HR.gif

If the WRF's interpretation of the morning MCS's track and its erosion of the cap are correct, the ingredients definitely support tornadic supercells in SW IA and NW MO. This forecast is highly dependent on that morning MCS, however. If that MCS doesn't enforce the warm front to the south, but instead tracks north and clears out in time, I may well be shifting up to NW IA where the cap will be less stout. This is the less favorable option in my opinion, however, as the best directional shear will be well ahead of the cold front, and our surface winds are much less backed as we'll be away from the primary low way up north and that secondary low the WRF is showing near KC. The 4km WRF is also quiet except in far NW IA. I'll definitely be adjusting this forecast in the morning.

 

[Andrew Pritchard]

I'd rather just sit on the lake here in Wisconsin than bust again in 2009, but the prospects in nearby southern Minnesota have my attention. The southern target area is well out of consideration for leaving the vacation spot.

Worthington area in sw Minnesota seems like it might be a good place to be sitting tomorrow afternoon. Hodographs will be pretty sweet in that area, especially near the warm front as the SPC notes in their latest discussion. Current prog'd 1500 j/kg in that area, potentially higher if clouds get out of the area early would be more than adequate for supercell formation and associated tornado threat. Early morning satellite imagery will be the teller tomorrow on whether or not I give up a relaxation day for a chase day.

 

[Jeremy Den Hartog]

I am also eyeing southern Minnesota as I think the warm front will be a good play (especially if things clear out). Initial target looks like Blue Earth, MN as its near a good east/west road (I-90) and good north/south road (highway 169)...

 

[Dennis Dennison]

OK-for reasons other than chasing I find myself in Hastings,Ne--I am limited in how far I can travel on my own, I can catch a ride as it were with others--but it looks like Tuesday 14th might be some action in the general area--Anyone want to give me a real good spot--I can go E/W on 80 but need to stay fairly close--I think I will run toward Lincoln-I am in a tan PU with a white shell and AZ plates--Hope to run into someone tommorrow and maybe get some action.

Also-any ideas of the SD &CO stroms holding together and getting into Central NE tonight?

 

[Jeremy Den Hartog]

OK-for reasons other than chasing I find myself in Hastings,Ne--I am limited in how far I can travel on my own, I can catch a ride as it were with others--but it looks like Tuesday 14th might be some action in the general area--Anyone want to give me a real good spot--I can go E/W on 80 but need to stay fairly close--I think I will run toward Lincoln-I am in a tan PU with a white shell and AZ plates--Hope to run into someone tommorrow and maybe get some action.

Also-any ideas of the SD &CO stroms holding together and getting into Central NE tonight?

Your guess is probably as good as anyones at this point. There are a lot of factors to be played out yet (like morning convection) which may affect things drastically so basically my suggestion is to wait and check things in the morning and go from there...

 

[Michael O'Keeffe]

Well after a closer look at the 0z NAM it appears that NW Missouri doesn't look too shabby at all near and just east of St. Joseph, MO. A secondary surface low looks to develop backing the winds and allowing some stronger surface winds to take hold allowing for good inflow, something we have lacked this season. CAPE, moisture, and SRH won't be a problem and LCLs north of the warm front will be quite low. The 850s are veered but they aren't horrible given the WNW 500s. The NAM also shows the cap breaking in NW MO at 0z and 700mb temps are about 10C-12C which is doable. It is nice to see precip breaking out in NW Missouri as well. What really caught my eye was the size of the hodographs and greet veering after dark!

Check out the forecast hodograph at 03z for Chilicothee, MO.
http://beta.wxcaster.com/cgi-bin/parse_skewt_trace_all.cgi?model=NAM&STATIONID=CDJ

 

[Brandon Lawson]

Seems that veering 850 winds don't seem to be as much of a limiting factor in setups east of the plains. NAM is also showing 500 winds with a northerly component in northwest Missouri, which would probably compensate for the veered winds at the lower levels. Still, i don't know whether to be excited about it or not.

The GFS just came out and shows a pretty ugly cap. Best chance of even getting a storm will probably be limited to the northern target fwiw. I'm waiting for the 4km wrf to come out.

 

[Brandon Sullivan]

Seems that veering 850 winds don't seem to be as much of a limiting factor in setups east of the plains. NAM is also showing 500 winds with a northerly component in northwest Missouri, which would probably compensate for the veered winds at the lower levels. Still, i don't know whether to be excited about it or not.

The GFS just came out and shows a pretty ugly cap. Best chance of even getting a storm will probably be limited to the northern target fwiw. I'm waiting for the 4km wrf to come out.

Good Point.. I really like the 00z NAM..

Caveat: It didnt capture the ongoing precip very well though...

I would like for the MCS to roll through, re enforce the boundary/effective WF.. Then clear off, insolation.. Cap goes.. There will be good tors..

Thats all a wishcast though, and the morning will tell.. I am on my way out now, and will stop and evaluate in the morn before continuing...

Also waiting on 4KM WRF.

 

[Michael O'Keeffe]

Also something to note the NWS here in KC issued an AFD at 10:00 saying an MCS will move through NW MO after 09z so this will hopefully reinforce that warm front and get that cap broken.