3/1/06 FCST: Great Lakes


18Z NAM continues trend of the 12Z to sneak up a nice little low-topped squall line event with strong winds in the Great Lakes from MI to IL/IN late Wednesday afternoon into Wed night. 996mb low transitions across Green Bay through the Soo and brings along a nice cold front, with CAPE to 500, LI -3 and Helicity to 300. Certainly not outbreak numbers but more than ample for the first day of March around here!

GFS however still suppresses the system WAY south, 1002mb low over northern IN/OH, with icing over the same area NAM has storms!

12Z EC leans in the NAM direction.
The 18z NAM also shows SBCAPE of up to 1000 J/kg in central and wrn IL, with SBCAPE of up to 500 J/Kg all the way to NW IN (your's truly's area). I think the storms have a good opprotunity to become surface-based, and a couple discrete supercells may be possible, either ahead of or embedded in a squall line. If the 0-1km SRH values end up being higher than currently indicated by the NAM, a couple tornadoes may also be possible.
I'd be interested in the the STL towards SE IA and into IL. if it wasn't for the fact that the atmosphere will most likely remain capped throughout the day. Surface temps and 850mb temps are generally the same between 14-16c with 700mb temps at 4-6c. Latest NAM shows -150 j/kg of CINH at 0z. Moisture doesn't look to bad though with 55-57 degree dewpoints in the area and a nice area of 850mb 10c isodrosotherms. The LLJ really does begin to fire up between 45-60kts. Latest SREF indicates 500 j/kg MUCAPE mostly in MO, with around 200 m2/s2 0-3km SRH (most of which is located in the 0-1km layer). Unless they are some big changes, most likely will end up with some after dark mariginally severe storms.