2014-05-21 FCST: IL/IN/OH

[James Gustina]

Not a traditional chase day setting up, but what looks to be a possible derecho day across the Midwest.

The GFS has been very consistent in showing broad, 50-60kt NW H5 flow across Illinois/Indiana/Ohio starting early Wednesday morning as an upper level low centered over Ontario begins to drift south. A "ring of fire" pattern looks like it'll take over the eastern US for most of next week with a pretty strong high located over the Deep South. Moisture quality looks great with 65F+ dewpoints spreading across the Midwest south of a quasi-stationary front. This morning's 12Z run of the GFS put at least 3000-4000 j/kg of SBCAPE across the warm sector and directly under the best mid-level flow throughout the day. Add in the unidirectional profile and it looks like a classic environment for a derecho starting somewhere in Illinois or Indiana. Surface temps may be a bit more moderate than usual for a setup like this, but regardless this should give the shot for at least a mean squall line somewhere.

 

[chrisbray]

I was actually thinking the exact same thing, but was waiting a bit longer to make a post of it. GFS has been consistent in bringing a 500mb disturbance across Illinois/Indiana/Ohio on Wednesday, with plenty of cape and unidirectional wind profiles. Could make for some fun, though very quick chasing and photo ops.

 

[James Gustina]

It's got the classic calling card with the flow regime and extraordinarily moist and unstable corridor just south of that front. While 3000 j/kg is on the lower end of the "threshold" for derechos, it appears likely given the kniematics (15 knots of 0-6 km shear) and moisture environment that the GFS has been spitting out.

 

[Adam Adkins]

This severe setup will most likely extend over many more states further to the west like KS, NE, CO. 40-50kts effective shear in northeast CO by Wednesday evening and and 3000 j/kg. Supercells!