06/17/10 FCST: SD/ND/MN/IA/MO

[jamesmseitz]

Rob Hurkes and I noticed this date when we were chasing in Colorado Thursday and Friday 6/10-11. After tearing it apart for a few days now we are thinking that this area finally is going to get in the act for severe weather.

Early in the day there looks to be a trough that comes of the Rockies about lower Montana. Added by a through and good shear it seems to amplify and move through the ND/SD areas with its weak front. The Front will bring some cooler Temps to the 700mb level to make the cap breakable. With cape 3000+ throughout the SD/NE and good directional shear (about 90*) and Helicity (above 300) storms will be likely by 5 PM with the cap eroding. Also of note the EHI is amazing throughout MN/IA areas with storm motion being NNE with relative inflow SW.

With that said there also is what seems to be a 100 MPH jet that is forecasted to literally Streak across the area of the low so that will need to be watched very closely. Either way this day deserves very close attention! (The Jet is no longer to be that strong but still is progged to Lower MN upper IA)

 

[Andy Jackson]

I'd say SW MN could be the show with strong instability/ low level shear.
Here's a sample skew-t for that area: 18z run as of 6/14/10 -

I'd say thurs/fri could be back to back days.

 

[Derek Weston]

Surprised more people aren't talking about this one. Most potent setup in a while. (well, since June 5 with Illinois, I suppose)

50 + kt 500 jet streak on top of SSE 850s pushing or over 40kt coupled with a good sized area of CAPE at 2500-3000 J/kg +

Very nice looking 850/500 crossovers. (healthy EHI/Helicity values)

Cap looks to erode by late afternoon...

Initiation somewhere near the I-29 corridor... late afternoon. I like extreme west central Minnesota.

(biggest concern might be evolution of MCS the night before... though it ought to clear by show time)

I see plenty of supercells and a regional tornado outbreak possible. (and given some of the values the NAM is spitting out, perhaps a few strong across W Minnesota)

 

[Jeremy Den Hartog]

I agree, this day continues to look very good to me. My initial target is around Morris, MN but it will likely need to be adjusted come tomorrow. Even the SPC is saying tornadoes are likely this day. Plenty of CAPE, low CIN, good shear and storm motion that isn't crazy fast will hopefully add up to a very successful chase day for us - and finally in MN

 

[Rob H]

Surprised more people aren't talking about this one. Most potent setup in a while. (well, since June 5 with Illinois, I suppose)

It's not KS/OK and no one wants to drive to central MN

The SPC already has it at 30% hash, so at least they're taking it seriously, unlike the local media. The only downside I see to this event is that the weak cold front/overtaken dryline is the primary lift mechanism. The CAPE has backed off slightly in MN from earlier runs, but forecast CAPE of 2500 is still more than plenty. Almost everything else about this setup looks very good for chasing, although I feel like we'll be in more of a spotter role considering the lack of chasers coming out.

The road network is pretty crummy with all the lakes out there, so I29 might be nice to set on depending on where the front is. I'm thinking I'd like to be sitting in Wheaton, MN at 3pm ready to go. It will be odd going from convergence+V2 in CO to this...

 

[Mike Heitz]

ya i'm actually not going to be moving very far probably hang around my apartment in grand forks i really like the northern part of the line where the front is going to arc back towards the nw seems like the best ehi values and the best shear, probably will remain discrete the longest also, i think the northeast nd and northwest mn areas might see quite a large outbreak.

 

[Mikey Gribble]

I literally just looked at this for the first time the other day. At first glance it looks like a really good setup, but there are several things that leave me wondering how this will really play out. One is 10km SR winds. They are very weak all across the threat area and are even coming at the storm from the opposite direction of storm motions later in the day. That is kind of wierd.
This is a very tricky setup with an unusual shear profile and a rapidly moving boundary. I am going to have to spend some time looking at this one before I have any real opinion on the tornado potential. Just by glancing at it I would think you are almost cetainly going to get at least a few tornado reports given the strong wind fields in the mid and low levels and potentially strong instability. You don't see many strong troughs come through this time of year without getting a handful of tornado reports. Still a weird setup though so who knows. This forecast is going to take a lot of scrutiny if you plan on chasing.

 

[Rob Gardner]

Debating a trip to western iowa... Sheer environment is better farther north, but the cape values better farther south... Just don't want to drive 12 hours to minnesota and bust... Also sounds like this could be more of a linear event, which with the road systems could make for a difficult chase....

 

[Derek Weston]

Depends how quick the CF moves. Agree that right on the front... could see some linear structures. If you can get things to pop a bit down stream, or if the CF doesn't move too fast... that'll be good for more isolated activity. (if things can move off the front)

Although this CF is almost more of a DL than a CF... if you look at the sharp gradient in dews...

 

[Jordan Manderfield]

Debating a trip to western iowa... Sheer environment is better farther north, but the cape values better farther south... Just don't want to drive 12 hours to minnesota and bust... Also sounds like this could be more of a linear event, which with the road systems could make for a difficult chase....

Cape values are really not much greater further south, 12z NAM indicates 4500 values all the way up into central mn, Also note from past expierences seeing 6000+ values could indicate a major cap. NW MN/ E ND looks the most interesting as far as tornado potential goes..For me I'm eyeing an area from Redwood Falls, MN to Marshall, MN as it's real close to home. Also latest runs have pushed everything back west by a couple hours I see.

 

[Eric Whitehill]

If anyone is thinking of heading to NW MN/Eastern ND, please remember there are a number of roads that are still washed out from the flooding over the last two springs.

It's a good way to get "Delormed"...

 

[Jeremy Den Hartog]

I'm liking the Brookings, SD area now looking at the latest NAM...waiting though for morning to really set things in stone. Eastern North Dakota and NW Minnesota are out for me and I think there will be a decent chance for tornadoes further south anyhow so I'll keep south.

 

[Nick Hartley]

Preliminary chase target for Thursday: Brookings, SD.
Threats: large hail, strong winds and probably a tornado or two.
Storms likely will develop between 3 pm and 7 pm along the I-29 corridor before moving east into an mesoscale convective system (MCS). Cold Front + Mid Levels should allow for recovery of atmosphere after early morning thunderstorms. Dewpoints in the 70s likely with highs around 90. Shear and high Convective Available Potential Energy (CAPE) should be plenty for severe storms!

 

[Mikey Gribble]

I like the Brookings, South Dakota target too. The top half of hodographs look better there than farther south. I think any semi-discrete storm tracking through this area will likely pose a tornado threat by late afternoon. I have concerns about the surging boundary and weak SR winds in the 5-10km area, but those issues aside it looks like a decent setup for a few tornadic supercells from Omaha up to North Dakota. I like the southwest corner of Minnesota the best. I'd probably put a 10% hatched tornado prob in that area.
I posted a little more on my blog, but I've spent way too little time on this forecast to risk the embarrassment of posting it on here lol. I just haven't had the time to follow this setup. I literally looked at it for the first time yesterday.
Overall its a decent chase day. I can't imagine not getting at least a few tornado reports tomorrow. It is rare to get a strong trough through the plains this time of year without a handful of tornadoes at least.
I'd chase if I could, but I'm burried at work right now. Hopefully we can get some good streaming video tomorrow so I can virtual chase from home. Good luck if you head out.

 

[Greg Blumberg]

For those reading, this is one of my model-less forecasts that I'm trying out for the summer so I will be giving a primarily synoptic forecast. By just looking at the observations, tomorrow could be a rather significant day in the severe weather category. From monitoring trends from the past 24 hours, this trough looks very prime for a severe weather outbreak of some kind. It has a very classic look for climatological severe weather outbreaks...jet streak moving into the base of the negatively tilted trough and diffluence aloft at the exit region of the trough. I'm willing to expect that the current flow pattern will persist through tomorrow a bit, with some slight modifications. I can see the trough or general flow progressing further eastward tomorrow, but I'm not sold on the speed mentioned from the forecast discussions. Today's moisture advection and destabilization has really helped prepare for tomorrow's event.

It seems that the moisture advection will continue overnight into tomorrow, bringing higher dewpoints into the area and increasing the CAPE values for tomorrow. Combining that and the lift from the upper air dynamics, I would not be surprised to see 3500+ J/kg values of CAPE tomorrow. Also, it looks as if deep layer shear should be sufficient for getting things rotating.

Overall, a very impressive setup tomorrow from the synoptic point of view. I would be checking the 12z Aberdeen sounding tomorrow morning to see how things have changed. I'm thinking the ND, SD, and MN border intersection area, but I wonder if tonight's convection will create some boundaries that will refine the mesoscale details for tomorrow.