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06/13/05 TALK: Midwest through Oklahoma

As long as we can get some moisture, I'll be targetting NW iowa. Better moisture to the east, more backed winds to the north. Maybe trying to intercept storms that are near Waterloo?
Share some of Glen's concerns w/ this stacked low setup today. However, like the depth of surface low and still think there could be some nice deep layer shear, as well as low-level helicity, developing out ahead later this afternoon. Ongoing convection over N central MO appears to be weaking as of this hour, and satellite shows good clear slot behind over central KS, NW MO, and much of IA.

I'll be staying home today, but if anyone needs nowcasting help, just PM me. Good luck to everyone chasing today!
Chase target for today, June 13

Chase target:
20 mi west of Centerville, IA (Appanoose CO.).

Storm initiation 3 PM CDT.

Storm type and intensity:
Supercell storms capable of winds to 70mph. There is also a small tornado threat.

Potent shortwave will round base of negatively-tilted upper trough/low lifting NEWRD through NE this afternoon. At the surface, a pressure trough/wind shift line will develop along I-35 by 21Z. This feature will serve as the focus for thunderstorm development by mid-afternoon. Ample instability with MLCAPE’s to 2500J/kg coupled with very high 0-6km shear to 60kts will support storm organization with supercells. Tornado threat may be minimized with anticipated straight hodographs, however if winds in the lower levels back more then predicted by models, very large SRH values will result, potentially enhancing tornado threat. Hail threat should be minimal given relatively high WBZ values around 10,000 ft.

- bill
It sure seems like it's slow to warm up today in the warm sector. 11am local time temps in the low and mid 70's? CAPE is rather minimal as well. I realize it's still pretty early but I would have expected things to be heating up considerably more by this time.

On the positive side though, a nice cumulus field has already developed across much of IA.

Watching and waiting right now, the sun has come out and there's plenty of talk about tornados on the local TV and NWS stations, I live in CedarFalls Iowa and am ready to chase/spot today. :D
Went to bed last night knowing my chase day depended on the amount of sunshine available for the system. Woke up at 10:30 and all I needed to do was look out the window. Was hard finding as single cloud! Game on!

I agree with the mixing of dews concerns but am still going out there.


I'm not exactly sure of a target right now but figure staying ahead of the game is a wise thing to do at this point. Heading to Des Moines for now and will take another look at things there. Good luck to all heading out.
Andrew Pritchard and I are en route to a Keokuk-Keosauqua line (along Rt. 2) in SE IA. Hope to see some of you out there.

Can not make it all the way across IA. Will head for Ottumwa and hope for the best. Like the IA NE border at the moment but a late start forces us to head W on route 34 and look up till we hit a tornado. :D

See you all out there. Good luck.

Tom Hanlon
Hanging out in Des Moines

Hanging out in Des Moines!

Well, I have two sick kids and I'm fighting the cold too. I'll be staying close to home again today. Feel free to contact me if you are in the area - I'm on the west side near the I-80 / I-35 interchange.

Here is a website which may be helpful to some of you. The Iowa Environmental Mesonet (IEM) collects environmental data from cooperating members with observing networks. The data are stored and made available on this website.

Another website used by Iowa storm spotters:

Current conditions at approx 12:15pm:
Partly Cloudy
Temp: 76 degrees
Humidity: 64 %
Wind Speed: SW 18 MPH
Barometer: 29.66" (1003.8 mb)
Dewpoint: 63°F (17°C)
Heat Index: 78°F (26°C)
Tornado watch box issued for SE SD. They're saying things are going to start heating up about 2-6 pm.

MDT zone has been pushed back a little more west around Minnesota. I think I'll be out tonight. If I could just get out of work earlier :evil:
The region closer to the sfc low - East of FSD eastward into Southern MN - is looking more appealing than it did yesterday.

Improving sfc moisture and a nice little low level speed max progged to nose in to the area per RUC. Nice clearing in this region this morning also.
Instability finally starting to build up from S MO, but hope the convection to the NW of Springfield doesn't become too organized -- wind profiles much too unidirectional over that area now. As for now, real action appears confined to areas NE of surface low where surface winds can back. Strongest deep layer shear should nose into IA a little later this afternoon. The uncertainties for severe breakout in IA include 1) will widespread linear convection break out to the S in MO, cut off advection of moisture and limit instability and 2) will strong surface low slip/trough out too far north, too soon causing surface winds to veer from same direction as the 850/500mb flow?
All the deep moisture seems to be trapped in southern MO and IL south of this mornings convection. Dewpoints in the low and mid 60's? Not very impressive to say the least. This may severely limit convection in IA and northern MO. With additional mixing the lower levels will likely get even drier unfortunately. I would say the tornado threat in IA is relatively low the way it looks now IMHO. Ingredients are there however for a powerful damaging bow echo by early this evening crossing the Mississippi.
I agree with Joel... The lapse rates shown on the 18z soundings around the area are pretty poor. There are some mid-upper 60 Tds coming into southern IA, but I don't think we'll see any sort of significant instability develop with the unimpressive lapse rates aloft and the marginal low-level moisture. Winds, while strong aloft, are largely unidirectional. I'm really not sure about the 15% tornado risk other than the fact that, given fast storm motion, a short 1-2 minute tornado may cover the same ground as a 5 minute tornado on other days.

EDIT: The southern part of the MDT risk area may hold more potential IMO. Mid-70 Tds are streaming into the area, though I'm not sure of the wind profile in that area. The 18z ILX sounding showed good low-level lapse rates, but mid-level lapse rates are nearly moist adiabatic or a shade more steep than that...
Some storms already have initiated across SD and the first signs of severe weather across IA may be forming along the MO river. One cell now just west of Denison, IA looks to be getting its' act togther. I'm keeping a watchful eye on those, and wouldn't be surprised to see the next watch come out within the next 30 min...
New Tornado Watch

New tornado watch just issued:

Dewpoint in Des Moines around 65. Temp is 80.
I'm watching western IA.
Looks like a bit of a baroclinic disturbance at the surface in in central MO now...0-3km SR Helicity at 200 m2/s2 w/ instability building nicely over the past hour. Severe warned storm N of Lebanon, MO showing some rotation along w/ strong VIL
And SD gets the first tornado warning with things firing up towards the SW from there...


EDIT: Already been cancelled..hopefully that's just the top of the iceberg.

Looks to be a line forming up in western IA. Good luck all! Hopefully my fiance and I can bag our first nader tonight.
Iowa Tornado Watch

Probably Old News by now, but a tornado watch just went out for Iowa.

A couple of cell are starting to get better organized in Western Iowa.
Guys, be careful out there today chasing. Storm motion on cells developing is ENE to NNE from 25 to 40 mph, but some individual cells have shown movement even over 50 mph. Alot of the activity is fairly linear, so getting in position to intercept a cell may easily place you in the path of another one coming from behind at fairly fast speed.
North Norman getting hit pretty decently right now. Cells starting to fire all the way back through Lawton. They may need to nudge the watch down here west and south a tad. Other stuff firing in North Texas as well in Throckmorton and Shackelford counties.
If you have a chance take a look at the visible satellite loop in northern TX. There are large scale gravity waves propagating westward against the mean flow...should be interesting to see how they interact with the front to the west.