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6/21/09 FCST: MO, IA, IL

Joined
May 17, 2007
Messages
41
Location
Grand Forks, ND
0z NAM has rolled in this evening and depicts an interesting situation for northern MO, southern/central IA, and western IL on Sunday...

Large MCS should evolve late Saturday night into Sunday morning across eastern NE and western IA, as several weak shortwaves emanating from the large subtropical moisture plume through Mexico and Texas interact with an area of significant moisture convergence along the nose of a 45-50 kt low-level jet. This convection should organize and traverse around the edge of an upper-level ridge positioned across the Gulf Coast states, moving into northern IL by early afternoon.

0z NAM depicts a fairly significant outflow boundary that will either be left behind the departing MCS or perhaps outline its southern extent. A moderately to very unstable airmass should develop along the southern and western perhipery of the OFB as the day progresses thanks to breaks in the clouds and a very deep moisture profile. MLCAPEs of 1500-2000 J/KG should be attainable given the depth of the moisture.

Scattered thunderstorms should develop in the vicinity of the OFB, likely across S IA and N MO by mid-late afternoon, perhaps in association with another weak subtropical impulse notching through the area. 500mb flow increases to 30-35 kts as this impulse swings through, and given 10-15 kt SE'ly flow at the surface, should result in enough deep layer shear for supercells, or at least well organized multicells. Low-level shear will be maximized along the boundary, and could result in a few tornadoes given low LCL heights and the potential for storms to ride the boundary with expected slow SE or ESE storm motions.

Will certainly be keeping a close eye on this potential sleeper setup given that I'll be in Mercer, MO for a buddy's birthday party on Saturday night, and have the day off on Sunday.
 
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I am really liking the area around IOW for tomorrow, very nice looking sounding

http://beta.wxcaster.com/cgi-bin/parse_skewt_trace.cgi?model=NAM&fcsthr=024&STATIONID=IOW

nicely backed winds with a curved hodo, will have to see what happens with any ongoing precip before hand and if things can clear out in time. hopefully there can be an OFB that is the focul point for CI in the afternoon. good 500mb flow out of the west between 30-35kt with 850s strengthening throughout the day out of the SSW around 25kts. CAPE values will be AOA 2000 in the area with some higher numbers likely and dews near 70.
 
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Looks like maybe one last chase for me after all...here in DSM. The 4km WRF and latest RUC shows vigorous supercell development by 21z across WC/SW Iowa and spreading east and northeast. Looks like the 10% area may need to be adjusted a little west towards the I-35 corridor in my opinion. This looks like a "quiet" but potentially good SLGT risk tornadic supercell set up. Meaning little on the MDT risk hype...but possibly quite good on the results. I am going to hang here in DSM and monitor things....looking for the favorable bullseyes. There should be one such bullseye in my opinion forming over WC Iowa by afternoon. More updates later....
 
Today does look like somewhat of a sleeper day. If things can come together right there may be a nice 'bulls eye' area somewhere in Iowa. My initial target looks to be Mason City, IA but will probably be adjusted as things get going...
 
Today's tornadic potential has increased. My biggest concern on previous model runs was the weaker winds at 500mb. However, both the 12z NAM and RUC models show a broad area of 30+ knots with locally higher values over Iowa. Capping should not be as much as of an issue, at least in north central Iowa, as it was last Thurs.

Surface based cape values have been steadly increasing on each run, with 12z models showing a large area of 3000+ in most of the target by 00z. This will only be enhanced by the clearing on satellite moving north into Des Moines and points north. If our surface winds can stay east-southeast and cloud cover continues to clear, supercell development seems very likely.
 
Will be leaving Mercer, MO and heading for Ankeny, IA to meet up with fellow co-worker Nick Biermann. Will refine the target from there, most likely ending up between Mason City, IA and Grinnell, IA
 
After lastnight's miss, im going to shoot for Williams IA, right on the Hwy 20 and I-35 corridor, that way i got a NSEW option road wise. Good luck to all who go out.
 
After lastnight's miss, im going to shoot for Williams IA, right on the Hwy 20 and I-35 corridor, that way i got a NSEW option road wise. Good luck to all who go out.


Good call on that target, Im thinking about targeting near the Hwy 20 corridor myself but a little further west. Could be setting up somewhere between Humboldt and Webster City. Not too sure yet, definitely wanna be fairly close to 35 still.
 
I'm actually incredibly intrigued by this setup...except the Iowa part. I am a fan of a little further east though. Perhaps the 380 corridor and maybe a little further west of there. Surface winds are stronger and more backed there, and all three models are showing that. Of course will be monitoring obs and vis along the way to see where the WF and OFBs set up shop, but this could be a nice little sleeper setup.

We'll see what happens. It's Iowa, so my expectations remain deflated.
 
Well, since I am stuck at work once agian.....I think there is a slight chance for some nice activity in southern IA. The RUC seems to mush together a line of storms in a N-S fashion across Iowa. If this were to happen, the winds are still backed with favorable LL hodo's which could mean a sleeper tail-end charlie in SW IA today. I do like the set up further to the NW but since I can't be there I am just going to plug my ears, shut my eyes and ignore that area :)
 
MD out for the area, just leaving and targeting somewhere around the HWY 20 or HWY 3 corridor, WF will be drifting through this area as the afternoon goes on.
 
300mb winds positioned over W IA. Dewpoints are also high in the W portion. Helicity seems to be moving twards the NW corner of IA fron SE SD as well. There is little to no capping in this area. The warm front is tending movement twards the N Iowa border. CAPE values are 1-2000 range. I'm not very good at forecasting, but it looks as if NW Iowa may see some action today. I'm using the latest RUC as the guage...
 
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I am liking this as well. the cape seems to give way late afternoon..... Nothing big but a few tornados seem likely with the set up. It being fathers day I am not heading today but Waterloo seem the place to start if I was out.

Good luck everyone !
 
Currently driving in an undisclosed location north of Cedar Rapids. Liking today more and more with each RUC run. Should see initiation somewhat soon in WC Iowa...when it tracks closer to the WF, we'll be in business.

Will probably set up shop somewhere along 20 and see what happens. If nothing, then my anti-Iowa avatar will make a triumphant return.
 
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