Confidence growing in severe weather event tomorrow evening

Well, I'm gonna have to bite again, even if the apple is snatched away at the last second, because the models have changed their tune big time. I no longer think we're going to be capped on Thursday night/Friday morning, and we could easily wind up with a nocturnal MCS if not a true derecho plowing across the state.

Some of the instability levels being forecast by the SPC ENSEMBLE - not just one model but the weighted average - are on the order of 3000-4500j/kg MLCAPE. That represents an EML plume; an "elevated mixed layer". The "mixed layer" is the area in the atmosphere where all the action takes place. This is the area is the battlefield where the war between warm and cold air is fought. The 'deeper' the mixed layer - that is, the more vertical space on the battle field - the more carnage can take place. The mixed layer is considered "elevated" when it reaches very high up, is particularly deep and very unstable - lapse rates (temperature of air as you get higher) tend to be steep. Such conditions usually result in a weak cap at the lower levels of the atmosphere which prevents thunderstorm activity until peak heating. This is when you can get the explosive growth of supercells and severe multicell clusters depending on how favorable wind shear is for said development. 

Bulk shear of 40-50kts should be more than enough to drive explosive thunderstorm growth, and most of the models are coming in with supercells developing into an MCS over the upper peninsula in the late afternoon. This will drape southward across the lower peninsula by late evening/overnight, likely bringing a significant damaging wind threat.

I do see our probabilities going up if this forecast continues to show up as is over the next day, so make sure you're spending tomorrow night in substantial shelter. As I've had a bit of an active week, I'll do my best to keep everyone posted about this. I don't think lack of sunshine is going to shut off the severe threat this time around, as this system is fueled by the torrid heat and humidity settling in over the central US, and actually looks like it'll be on the powerful side.

As heat watches and warnings are issued for the central U.S., Michigan enters the Ring of Fire

Unless you count the above normal temperatures and the completely baffling level of dryness, it has been quite the uneventful summer in Michigan, weatherwise. Save for two Fridays ago, we've really had no significant nor widespread severe storm days thus far, and truly we've been devoid of even meaningful variety in our forecasts. Days which looked like they could be active have for the most part been duds, and overall predictability is quite low.

It's tough to say that this is going to change, at least for me, at this point. Watching the models, I see similar patterns to what I've been seeing since the end of May: potential for big storms. But that's the key word: potential. A couple of weeks back, I was all but certain we were going to be seeing a meaningful thunderstorm event in Michigan, and it failed to materialize in epic fashion. Some areas to the south and extreme east did see some thunder, but it was hardly noteworthy, and the central portion of the lower peninsula in particular has missed out on just about everything. We are deep into drought at this point, and we're likely to be looking at drier than normal conditions until the fall at the very least. Will we be as dry as June? Probably not. It would take incredible bad luck for this to happen (especially in the coming week), and I just can't imagine (or perhaps just don't want to) the systems refusing to drop any rain over our areas the way they did in June. With that in mind, the overall pattern remains what it is, and it very well COULD be another 1988-style summer.

Some good news is that the pattern forming is a bit more extreme than the one in June. The flow of the jet stream is similar, but this time around a torrid, ridiculously hot pattern is building into the central midwest. We're talking heat levels that are prompting warnings in areas that routinely see 100°+ heat indices each summer. 115-120° heat indices are not only possible but likely in those areas this week. These are extremely dangerous levels of heat that can be life threatening, so if you plan to be in these areas or know someone who is, spread the word of caution. Michigan's position will be just outside this area of heat, in the shadow of the jet stream flowing from northwest to southeast. Normally, I'd say that this would mean a high likelihood of severe weather in the coming days. With the year being what it is, however, I'm going to take a more measured approach. Could we see severe weather? Absolutely. Will we? I'm actually doubtful.

The reason is that I'm seeing a lot of the same behavior out of this upcoming system that I've seen in the past. The system will build up a lot of energy just to our north and west, probably ignite some furious thunderstorms, and then they will likely fizzle out in epic fashion just as they reach Michigan. This is best shown by the latest NAM model. The western U.P. could see some impressive storms, but the rest of us are going to be lucky if they last long enough to dump any meaningful rain. Convective turnover and subsequent capping has been the villain of the season in Michigan, and it doesn't appear that anything's changing even with the additional energy.

Perhaps nature will defy the model predictions and my overall gut feeling on this one, but each and every time I think that we're settling into a more rainy pattern, I'm kicked in the teeth. The shoe has to land on the other foot sooner or later, but I'm now of the opinion that it will be later.

More big time severe weather looks possible for tomorrow

A pattern which to me looks a bit similar to last Friday's will be making its way into the region tomorrow. Once again this system looks to have some power behind it. Latest guidance has pushed some of the power down a bit - 50-60 knots of bulk shear was being advertised in previous runs but now only 40-50 knots are - but this might have something to do with the system becoming a bit more "stretched" which would actually put storms into our area rather than to the west where they were showing up in previous forecasts.

Regardless, 50kts is still plenty of horsepower and combined with even marginal instability would be enough to drive severe thunderstorms. The questions that remain are how much instability will be able to develop, as more potential energy always helps, and whether or not overturn will occur. What's driving my decision in posting the outlook that I'm posting is that the NAM4KM has been a bit more accurate over the last few weeks, and it's predicting a train of thunderstorms through the Mid Michigan area in its latest run. I'm actually a bit more concerned about flash flooding with this one, but in looking at it I'd say all hazards are possible. On a scale of 1 to 10, I'd say it looks like a solid 5, hovering around the storm strength we saw last Friday.

The top image is what the NAM4KM is predicting will occur over the next 42 hours. The bottom is what it would predicted would happen last Friday. Note both the similarities and differences, but I think we have a fair shot at some pretty severe weather tomorrow.

This forecast could easily change. I think this has the potential to be a bit more widespread if certain things happen. On the flipside, it may be a complete dud. We'll know a lot more once some more models are able to run and things come into focus.

Rough weather may be on the way again tomorrow

Some thunderstorms are moving through the state this afternoon but it doesn't look like anything truly nasty will come from the line. An official 20% chance of severe thunderstorm watch remains in effect until this evening per mesoscale discussion, though at this point I think the chances are lower. The good news is that rain chances may be on the rise as the line seems to be holding together well.

However, tomorrow afternoon could be a different story. A slight risk of severe weather has been issued by the SPC for the majority of Michigan, both upper and lower.

The models are diverging a bit on this one. The 12z NAM puts the nastiest weather through Mid Michigan once again, while the 18z run confines very nasty weather to the southernmost portion of the state. The two runs can be compared below:

Each dark green swath represents the path of a potentially severe thunderstorm that the model predicts will strike.

With this divergence, it's tough to say where the biggest storms will be tomorrow until more runs come in and more data can be obtained. I suspect that tomorrow will yield another watch.

Very active afternoon draws to a close - Possible gustnado funnel captured

Some very intense thunderstorms will make July 8th 2016 one of the highlighted severe days of this year. This system really amped up as it approached Michigan this time around, which is exactly what we're going to need going forward if we want to get out of the drought.

This picture sums up the day for me. Thanks to Brenda Kelley for the awesome photo - I got video of this but no pictures. I called this one in to NWS Detroit as it appeared at the time to be a textbook funnel/wall cloud. I was told that it was probably a shelf cloud, but I know my shelf clouds, and this it was not. Looking at it now, though, I do think that it WAS part of a shelf cloud; this is a phenomenon known as a gustnado (or gust funnel, since there's no evidence that it touched the ground). Shearing winds along the gust front of a storm can generate these phenomenons, which can touch the ground and produce damage similar to a weak to moderate tornado. They usually don't last very long. Either way, quite the sight!

Widespread severe weather event unfolding across Michigan

A significant severe weather event is now unfolding across the state. Numerous reports of damaging wind and large hail are coming in with discrete supercells forming across the lower peninsula. As it stands, the north is currently bearing the brunt of the storms, but conditions are actually more favorable in the south, especially across the Saginaw Valley and Thumb area.

A Severe Thunderstorm Watch is currently in effect for essentially the entire lower peninsula as this dangerous and powerful front makes its way across the state. The SPC has upgraded most of the lower peninsula to an enhanced risk for severe weather, with a 30% chance of damaging winds and large hail. The tornado risk remains relatively low, but I believe that it is more localized to the thumb area where no storms have yet occurred, which is why we've yet to see any tornado warnings. I will be observing this system very carefully as it approaches and attempting to keep everyone in the loop with new developments.

Severe thunderstorms likely today with elevated tornado threat

Yesterday's atmosphere managed to produce some pretty powerful storms in Mid Michigan. Over 2,500 customers are without power in Saginaw County after a severe warned storm moved through. Most of the Thumb got a good soaking from that storm, too. A great deal of the state wound up seeing some thunder last night, and I'm hoping that the conditions in the forecast for today equate to an even better coverage of rain than yesterday's. Unfortunately this rain may also come with a fairly decent chance for severe hazards, including tornadoes.

These graphics represent something known as "updraft helicity". What the model does is first predict that a thunderstorm will form over a given area. It then predicts how much "spin" the storm's updraft will have, and the momentum of that spin. The stronger the values, the more rotation it predicts. The swaths you see appear in dark green and yellow represent the paths of storms predicted to form this afternoon. The HRRR model is calling for some pretty strong rotation to be associated with these storms. Last night's NAM4KM run also predicts strong rotation in some of the storms expected to form.

It goes without saying that the more rotation is present in a storm, the higher the likelihood of severe hazards. At this point, the SPC has designated most of eastern lower Michigan for a 2% tornado risk, and a 15% damaging wind/hail risk.

I'm actually thinking the chances of severe weather today should be pretty good. Unlike the previous systems we've seen come through the state, this one has some power - to the tune of 40-50kts of bulk shear. That means that wind speeds will increase by 40-50kts between the surface and the tops of the thunderstorms. Timing is also on our side this time, and capping appears as though it's going to erode by the early afternoon while CAPE levels rise to around 2000j/kg or more. The setup has also seemed to fall right in line with and in some cases even outperform what the models have predicted thus far.

As much as I don't like the idea of anyone getting hit by a tornado, I'm of the opinion that any storms we get that don't carry some severe risks wouldn't be able to offset the drought at this point. We need some more powerful storms that carry very heavy rains to reinvigorate the earth in our area. A few days of storms like this, once a week or so for the next couple months, is a great prescription for a drought recovery. If any tornadoes do strike, I'm hoping they'll be over open country, in front of someone with a camera.