The 12Z data is in, and things still look on track as far as the large scale synoptics. I orignally had some concern when it comes low level moisture, but current OBS show numerous reports of +65F Td's (even creeping into WI), with several +70F reports across eastern IA/MN. Current ETA suggests that this moisture will move eastward into lower MI tomorrow afternoon, with Td's in the low to mid 60's... Given the current OBS, I wouldn't be surprised to see some upper 60's to near 70F dewpoints.
I decided to extrapolate the 500mb shortwave track based on the WV loop and RUC analysis for the past 24HRs... Which would put the "center" of the 500mb low (or trough axis) near eastern Lake Superior by 00Z TUE (mean speed of the shortwave was found to be 20KNTS). ETA and GFS show a nice dry air intrusion at 700mb pushing into MI between 21Z-03Z, which would suggest a line of thunderstorms beneath the highest RELH.
Wind fields are decent, with a 40-50knt jet developing just behind the dry air intrusion. Modifying soundings across the region for a parcel of 80F/65F yields >2500J/KG across much of the region (I believe 65F is possible given upstream dewpoints). Of course max temps will be based strongly on how much cloud cover is present, but 80F shouldn't be too hard to hit.
My guess is that a squall line will likely develop and track eastward across the region given the linear linear look to all of the forcing mechanisms (dry air intrusion, convergence, etc.). Looking at the derecho "check-list", there are a few parameters missing, such as monster CAPE values and conditions extending downstream for 250nm (since a derecho is defined as having a long track). However, a local "derecho" (AKA squall line) still seems like a pretty good bet...
(Rob doesn't work, because there is already another Rob)
