10/05/10 FCST: AZ

[Warren Faidley]

Looks like a rare "official" chase day in C / SE Arizona today and possibly tomorrow.

Details highlighted in the 13z SPC slight risk discussion with a 2% tornado probabilistic outlook. A quick look at the latest 12z RUC / NAM data hints of a narrow region of max instability, shear and acceptable surface LCL's heights from TUS to the west, later this afternoon, with CAPE values around 1,500 J/KG, lifted index of -5 / -6 and mid level shear around 50 KTS. Some concern over surface shear / inflow and clustering of convection. It will be interesting to see if last night's precipitation left any boundaries, but the orographics in the region can enhance low level shear.

Such conditions would make for an interesting chase day in the Plains. It's nice to have it in your own back yard.

W.

 

[David Wolfson]

Unusually prominent dryline through western Maricopa and Yavapai Counties should advance somewhat eastward. Shear is good but moisture is marginal for big severe after it mixes out in the afternoon IMO. I think it's a little premature for the southern Maricopa warned cell. I will be looking mid-late afternoon along the upslope axis out of the valley from Apache Junction to Prescott.