Big time nastiness this Tuesday in the Great Lakes region

Everything is beginning to come into focus, and it isn't looking good for the southern Great Lakes region/Ohio Valley.

Jet core forecast by GFS 06z model run for Tuesday March 15th

Jet core forecast by GFS 12z model run for Tuesday March 15th

Jet core forecast by ECMWF 00z model run for Tuesday March 15th

Currently, I don't believe the bullseye will fall on us for this scenario. The models are in fairly good agreement for what could essentially be a repeat of the situation, with Illinois and Indiana or even northern Kentucky bearing the brunt of this system. The setup doesn't look quite as mean (yet) as the November 17th 2013 situation. For example, the jet core for that event was around 140kts, and the jet core for this is forecast to be about 120kts. Nonetheless, that could change in either direction. I don't see it particularly *decreasing*, as that 120kt forecast has been fairly consistent in both models for the last several runs.

The low level jet and moisture content are what's going to make or break this situation. For now, the GFS is forecasting a 45-50kt low level jet intensifying to 50-60kts as the surface low matures. Again, that's a little less mean than the November 17th event, but that can always go up once the short-range models start coming in. Either way, that amount of shear should be strong enough to drop some significant tornadoes across a widespread area. Instability will be marginal - 500-750j/kg of SBCAPE - but that matches the November 17th event.

I will be actively monitoring this situation as it develops, and should start being able to plot the exact bullseye for the event in the coming days. For now, I've introduced a widespread severe risk for the two southernmost lines of counties, a general risk for the two lines north and easternmost of that area, and a marginal risk up to the Arenac County line.