2012-10-02 FCST: IN/OH/KY

[Bob Hartig]

Looks like there's a chance at a late-season chase setting up tomorrow for those of us who live near the Ohio Valley region. The NAM is the model that gives hope and has been doing so, with variability, for several runs. The GFS moves the surface low eastward faster and is less gracious with dewpoints and instability. The NAM grants CAPE of 1,000 +/- J/kg and more robust 850 mb winds, although the 12Z run has backed off on the 850s. Maybe the NAM will align with the GFS. But if it holds its own, then the combination of greater moisture, a good lower wind profile, and good bulk shear could render a chaseable setup. The wild card will be whether sufficient diurnal heating can occur, given the likelihood of cloud cover from earlier convection.

 

[Jeff Duda]

I'll preface this with "I haven't looked at ANY model forecasts", but based purely on how this system has behaved so far, I would suspect the overall threat is pretty low. Seems like poor lapse rates and cloud cover have really held instability down and kept many storms from producing sustained rotating updrafts, even though there have been occasional strong spin-ups that last one or two scans on the 88Ds.

 

[Bob Hartig]

Yeah, it has been disappointing to watch. Since I first posted, the NAM has painted an increasingly unfavorable picture, and it was the model I was rooting for. Instability has dropped like a stone in Ohio, and low-level helicity was never that hot to begin with. Too far to travel for too marginal a setup. Oh, well. Good day to stay home and get some work done.

 

[Dan Robinson]

I've been watching visible satellite all morning, and I don't think this day is done yet. The WV/KY/OH tri-state region has cleared out nicely, with great bulk shear values over the area and backed winds (though weak) at the surface. The SBCapes of 1000-1500 j/kg shown would be more than enough to get it done in this environment. I would not be surprised to see a few tornado reports, particularly into WV where the most insolation has occurred. The Cu lining up into streets seems to suggest line segments will emerge, but if any cell can remain discrete, I would expect it to have a good shot.

To this day, there are no known photographs of a West Virginia tornado - I'm thinking that may change this afternoon. Wish I could be there.