A stormy couple of days ahead

The weekend weather is beginning to come into focus, with several complexes of thunderstorms looking to move through Michigan in the coming hours.  Some will most assuredly carry a risk of damaging wind and large hail.

SPC day 1 outlook

Pretty much all of lower Michigan is under the gun today.  A complex of thunderstorms was generated over states to our west yesterday.  This complex is now moving through the state, and its doing so a bit later than expected.  I wouldn't expect it to clear the state by 5PM; before then, however, everyone should get at least some rain.  This complex doesn't look particularly intimidating and I doubt we're going to see even a single severe gust out of it.  Nonetheless, it puts a damper on my beach plans.

The next round is a bit more difficult to forecast.  These storms are going to be initiated not by a cold front, but by an outflow boundary of rain cooled air generated by the first storm complex.  The models have handled the forecasting of this boundary very poorly, but the general consensus is that this disturbance should move through the state sometime between 7 and 9PM.  Normally, when multiple lines of storms come through like this, some of the energy is sucked up and the second round isn't as severe.  That isn't going to be the case this time around.  That NAM number of 3000-5000j/kg of CAPE is beginning to look as though it actually occur, with most of the other models now suggesting that much is possible.  This insanely unstable air will fuel storms from just about any disturbance, and there should be considerably more dynamic winds for them to work with this afternoon.  Damaging winds and hail remain the primary threat, though an isolated tornado isn't out of the question either.

SPC day 2 outlook

Tomorrow is a bit more difficult to forecast right now.  This is when the cold front is due to come through.  As of now, the SPC maintains a slight risk for most of central/SE Michigan including the Tri Cities and Thumb area.  Depending on when it comes through, it's going to have as much instability to work with as today.  The SPC's wording on the day 2 outlook makes them sound a bit more certain on the timing than I am, and their thinking is that it's going to come at peak heating time.  I'm still not so sure, but we'll see how this looks as the day progresses.