2014-07-27 MISC: KY/WV/OH

[JamesCaruso]

SPC has been talking about a tornado threat in this region during the past couple days' outlooks (although more conditionally now in the 6Z Day 1). The 6Z Day 1 notes strong shear and clockwise curved hodographs. The Jackson KY AFD also notes strong shear. But I am having trouble seeing it in the models. See attached forecast sounding for 18Z in northeast KY near the border with WV and OH. Winds appear to veer only from SW to W. There is speed shear but I am not seeing how this translates to clockwise curved hodographs and a potential threat for discrete supercells. While the referenced AFD does mention the potential influence of outflow boundaries, the rest of the AFD and the SPC discussion still talk about synoptic parameters producing shear that is not dependent upon locally backed winds. Usually when I miss something in my own analysis I can go back and find it after reading SPC, but in this case I am having trouble understanding how these conditions can be producing enough shear.

 

[Skip Talbot]

You don't need a lot of veering with height in order to get nice helicity values. If you've got a lot of speed shear, the hodos can curve nicely even with little veering with height. A forecast sounding from the Ohio River valley for this afternoon shows a nice little curved hodo and 3km helicity of over 300. Not too shabby given the SW surface winds. It's those 40 knot 850's that are really kicking that hodo into shape.

 

[JamesCaruso]

Thanks Skip, that makes it a lot clearer to me!

 

[calvinkaskey]

WV, MD PA

Thanks Skip, that makes it a lot clearer to me!

Right now the supercell composite is highest in sw pa where there has been more daytime heating I think. Future radar shows intense cell going from Pittsburg to near Chambersburg by 9 pm. Rain over Huntington, WV right now near noontime still with cape like 500 or less. That was my original target. Wondering about significant tornadoes in the pa md and maybe northern wv area. capes already 1500 over highest supercell area in pa. Low level shear I also good in sw pa and into Md.

 

[calvinkaskey]

Was thinking bout hanging in northern wv then go north toward pitt then over toward chambersburg pa.