9/3/05: NOW: MN/IA

Very strong supercell in an extremely sheared environment in southern MN. This thing has been sustained for quite a while, and as it continues to propagate south-southeastward, I expect to last for quite some time. This storm has VERY strong low-level rotation, and spotters have already confirmed a funnel cloud with this storm about 20 minutes ago. I'd bet that it'll be producing more...
 
I'm not seeing any significant rotation. The meso and TVS algorithms have tripped a few times, but we all know how useful those are. I'm seeing some infow into the storm, but nothing that looks rotational in nature. Not that this thing isn't a BEAST on radar...


BC
 
Where do you see the very strong low-level rotation? I've seen intermittent rotation, but nothing that I'd call very strong. The presence of the OFB evident on MPX imagery immediately ahead of the storm confirms that this is a very weakly unstable environment -- it has the look of a "scoop" forcing inflow above the relatively cool outflow. Radiational heating has been able to occur on the southwest side of the cirrus should associated with previous convection, so that has helped with the development of some instability. Low-level shear is very strong, though the obvious downside is the lack of much instability. The storm is occurring well north of an OFB associatged with the previous convection cruising through southern MN right now. The storm looks half HP and half small line IMO.
 
Looking back through those scans you mentioned, I see some broad circulation. Certainly not textbook tornado indication. I wonder if perhaps the funnel cloud report was legit. Not saying it can't be, but I've seen too many bogus reports from trained spotters that I have to question them a lot of the time. MPX doesn't seem to think it is much of a tornado threat, since they opted for an SVR.


BC
 
Where do you see the very strong low-level rotation? I've seen intermittent rotation, but nothing that I'd call very strong. The presence of the OFB evident on MPX imagery immediately ahead of the storm confirms that this is a very weakly unstable environment -- it has the look of a "scoop" forcing inflow above the relatively cool outflow. Radiational heating has been able to occur on the southwest side of the cirrus should associated with previous convection, so that has helped with the development of some instability. Low-level shear is very strong, though the obvious downside is the lack of much instability. The storm is occurring well north of an OFB associatged with the previous convection cruising through southern MN right now. The storm looks half HP and half small line IMO.

Right, I have been watching it for a while, and I don't see "Strong" Low Level Rotation at all. I will also sometimes see small rotations, but nothing Huge, It looks like a supercell, however. Nick, where did you get reports of wallclouds/funnel clouds with this thing?
 
Looking back through those scans you mentioned, I see some broad circulation. Certainly not textbook tornado indication. I wonder if perhaps the funnel cloud report was legit. Not saying it can't be, but I've seen too many bogus reports from trained spotters that I have to question them a lot of the time. MPX doesn't seem to think it is much of a tornado threat, since they opted for an SVR.


BC

NOt sure if you saw that there was a tornado warning a few but reissued it to a Severe. This did look nice on radar but shortly after the TOR warn you could see outflow pushing out ahead of the almost hook. which is now looking linear again
 
NOt sure if you saw that there was a tornado warning a few but reissued it to a Severe. This did look nice on radar but shortly after the TOR warn you could see outflow pushing out ahead of the almost hook. which is now looking linear again
Yeah, I saw it. What I was commenting on was that they chose not to continue with TORs.
 
Velocities are pretty strong with it right now... I'd have to bet that this thing has +61KT gusts associated with it - it's bowing out quite nicely...
 
Yeah, velocity is pretty strong, still yet. I also saw that outflow boundary that pushed forward from the possible, gust front. Their is a rotation segment of 1.5 nm right now. The storm eventually broke through the outflow, however.
 
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