The SPC has
finally released a categorical update that includes an Enhanced Risk for lower Michigan, reaching the same conclusion I did a few days ago regarding today's severe weather potential. It feels quite vindicating.
I've deferred to them regarding the U.P., as it now doesn't look like enough instability will be in place for storms to really get off the ground there. Last night's NAM4KM run depicting that insane right-moving line of thunderstorms is still fresh in my mind, but this morning's forecasts more of a June 22nd style event, once again. This includes a slightly higher tornado risk:
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| SPC forecast tornado probabilities, August 2nd, 2015 |
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My current thinking is that this is the more likely of the two scenarios, being that it has shown up in most of the model runs. However, this morning's run also doesn't show thunderstorms showing up until around 4-5PM in most areas of lower Michigan. This makes me worry that something called occlusion may be occurring, and that can take thunderstorm intensity to an entirely different level. Occlusion occurs when a cold front outpaces and overtakes warm front. This causes
insane forcing upwards of warm air, and helps create robust updrafts necessary for strong tornadoes. Other factors have to be present, and occlusion certainly doesn't need to take place for strong tornadoes to occur, but it helps, especially when instability is lacking. Occlusion was a huge factor in the
November 17th, 2013 Great Lakes Tornado Outbreak.
Regardless, this isn't a typical weather system by any stretch of the imagination, and I'm not too concerned about something on that level occurring as far as tornadoes go at this point. Timing is still very questionable. As with all severe weather events, this remains a "wait and see" situation.
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