Upcoming chance of rain looks sadly similar to the last system

Friday's chance of rain may determine whether or not the State of Michigan's fire marshal temporarily bans consumer fireworks (as well as burning) ahead of the Fourth of July holiday. Our conditions are beginning to become dangerously dry in a lot of areas, and while no federal fire risk zones have been issued for Michigan yet, the threat is there and I don't think we're that far away from at least an elevated risk day if we don't get some rain soon.

Our chances may be a bit better than last time, at least according to some meteorologists. The system is forecast to reach deeper into Michigan this time around. However, I'm concerned that what we'll be seeing is nothing more than a repeat of last time for the Thumb with only a slightly more eastern reach. The system may dry out as it crosses Mid Michigan and be completely gone by the time it hits the Thumb. The Thumb would once again remain mostly dry as the system rebuilt to the east over Ontario, and to the south over Ohio. It would be enough to get Mid Michigan wet, but east of Bay City would be out of luck.

With that in mind, the last system was forecast to dissipate sooner than it did last time, with thunderstorms forecast to form over the Thumb. I was supremely confident in the forecast as literally every model was in agreement as to what was going to happen, and atmospheric observations all pointed to the same scenario. Because of this, I along with quite a few experts were left shaking our heads last weekend. If the models repeats their same mistakes, we could wind up getting something out of the remnants from the previous day after all. I hope that this is what happens, as not only are the plants going to suffer but me as well; my allergies are pure misery thanks to the looser pollen/dust in the air and I know a few people in the same boat (the cottonwood trees have been nothing short of brutal). 

For the sake of a loud, eventful holiday free from fire disasters, may all of Michigan get a good soaking this Friday.

Shocked beyond all measure - The storms skip us once again

I just have no words left for this. I never anticipated that storms would completely skip the Mid Michigan area once again. Everything - every model - put storms in our area right around now. Unfortunately the cold front moved a bit faster, and now the forcing for ascent is to the east of our location.

This frustrates me to the point where I don't even know what to say. I was very wrong about this forecast and I can't figure out Mother Nature at all right now. I am thinking we may be looking at a major drought this year at this point. Our only salvation this week may arrive Friday, but it doesn't look that impressive and with the fizzling of this one - one that looked so promising - any optimism I have left is gone. Next week paints the picture of widespread rain and storms, too, but again, it's all a crapshoot at this point.

100% chance of thunderstorms this afternoon - Severe wind possible

I'm posting my first true disagreeing outlook today. The SPC only expects a marginal chance of severe weather, but with what I'm seeing in the models, surface observations, and feeling in my gut when I go outside, I'm thinking we're dealing with a slightly greater threat for damaging winds this afternoon.

Hi-res NAM4KM guidance is showing explosive thunderstorm development this afternoon in SE Michigan. The HRRR guidance is also starting to indicate some strong cells forming between 2 and 5PM. I anticipate a severe thunderstorm watch to be issued by 3PM EDT and it should cover most of the counties I've shaded in yellow. The biggest threat will be damaging winds from wet microbursts. I think this is a real possibility this afternoon as these storms should explode in a very moisture rich environment. Storm mode is beginning to look more linear in nature, which leads me to believe we could wind up with some bowing structures with some real energy behind them.

We should know a lot more within the next one to two hours. My gut tells me today will be active.

Western U.P. may be in for rough ride today, while Mid Michigan & Thumb get it tomorrow

The most severe weather in our state thus far this year has actually been in the U.P., where a tornado watch was issued a dozen or so days ago. It looks as though the same area will be under the gun as some rather intense storms are forecast to develop over eastern Minnesota and move eastward.

A very small sliver of the U.P. actually finds itself under an enhanced risk for severe weather. Most of the western portion is under a slight risk, and most of the rest, a marginal risk. This comes from the same system that will hit Mid Michigan tomorrow. The slight risk and marginal risk areas have actually been expanded in the SPC day 2 outlook, as I expected to happen.

Becoming cautiously optimistic for widespread Sunday rain in eastern lower MI

Two more model runs have come in since my original 50/50 sitting-on-the-fence skepticism post, and I'm delighted to say that the results are looking good for rain in the eastern portion of the state. The high-res NAM model in particular has put out some really nice indicators of just the type of soaking we'll need, though there's still some question as to how much coverage areas will see. If storm mode is discrete, as what's currently indicated, some areas may see very little to even no rain. Others may see a ton of rain. Here're some graphics to give you an idea:

This is taken from the 18z (2PM EDT) run of the high-res NAM4KM. As you can see, it predicts widespread rain to the tune of 2"+ over a great portion of lower Michigan. However, it's predicting a discrete storm mode where some counties and areas of counties will see much more than others. In a linear storm mode, coverage has better quality thanks to no gaps between storms. And while it remains to be seen if we'll be dealing with a discrete mode, linear mode or no mode at all (praying not), the 12z (8AM EDT) run has even more discrepancies, and higher totals over some areas due to it predicting some "training" of thunderstorms:

Huron, Tuscola, and Sanilac counties in particular would get a ridiculous amount of rain from this particular forecast, where as the rain would be much more limited to the southeastern portions of the state. Of course, this run can't see past its maximum distance, which means those areas still could get some decent rain coverage, and this is likely a massive exaggeration by the model, but you get the idea.

The other side of the coin of this forecast is storm severity. At this point I'm actually thinking the slight risk may increase in coverage over a wider portion of southeast Michigan, and some of the area might actually be looking at more of a widespread severe weather event should these forecasts verify. The storm mode these two runs have put out indicate discrete severe multicell clusters or discrete supercell thunderstorms, and some areas in particular would be looking at some enhanced potential for such storms. The storms themselves all appear to be right-moving in nature, which is of some concern. I'm not so sure on the large hail risk anymore due to some of the mid-level lapse rates looking a bit sheepish as compared to earlier forecasts, but there is definitely a damaging wind risk being forecast here. Tornado risk is still looking fairly low, but definitely non-zero, and storms that are discrete in nature have a greater chance of spinning up than do storms of a linear nature. Lake breezes are also a wild card in regards to turning non-tornadic storms into tornadic ones. I do not see much of a risk for significant tornadoes at this point, as wind profiles still remain forecast to be on the modest side and shear appears somewhat unidirectional, and even backveering in places. 

Overall, I'm still on the fence. The cap could still hold, and we could wind up with a whole-lotta-nothing. However, I'm definitely leaning more toward storm initiation than against at this point - about 60/40 in confidence level. The severe risk looks legit, but it'll definitely be worth it to get some much needed rain into the soil and onto the trees, which are quickly becoming dry kindling.

We'll get a much clearer picture by tomorrow throughout the day.

SPC issues day 3 slight risk for Thumb area, Mid-Michigan

The latest SPC day 3 outlook has actually exceeded my original outlook for severe weather on Sunday. A categorical slight risk has been designated over Mid Michigan specifically, matching up almost perfectly with the "WNEM" counties.

I'm not sure I'd have gone as far as to issue this outlook just yet. Considerable uncertainty remains regarding some fairly crucial details, not the least of which is capping. While there appears to be ample instability forecast, recent trends show that can be very misleading. There's some indications in the latest models that storms would develop to our south and east over Ohio and Ontario, but completely ditch Mid Michigan once again. Nonetheless, ample moisture should be present at the surface and models do show 850mb dewpoints recovering by 5PM. I'm going to fall in line with the SPC for now, though I'm somewhat skeptical. I could see this outlook falling back to marginal by tomorrow morning.

Thinking positively, this storm system is forecast to suck up quite a bit of moisture from the Gulf this time around, to the tune of 2 inches+ of precipitable water. PWat is a great measurement of rain/thunderstorm potential. If all of the moisture at a given point were to fall as rain, it tells you how much would be available. Once you start getting into values above 2 inches, you're dealing with a very rich, well-fueled storm system. The system in question does appear to be a bit more impressive than what we've dealt with so far this year, at least in terms of moisture and position. The center of a fairly strong closed low is forecast to be present over extreme eastern Manitoba/western Ontario, which is a great place to produce thunderstorms in mid Michigan. We're going to be well into the warm sector, with temperatures again shooting for 90°. The upper level support appears to be quite strong, too, with 250mb winds forecast at 90kts+ just to our northwest. I'd be a lot more concerned if the strength of the low-level jet was higher. As it stands, 30-40kts of bulk shear is the best we're going to have. This should be sufficient for a damaging wind and hail threat in any areas where thunderstorms do form. The tornado threat right now appears small.

My hope is that some convection is able to form this time and we can tap into some of that rich moisture rather than watching it all go to waste again. This state is quickly approaching the point where problems could occur if we don't get some good, widespread rain soon. Unfortunately, in the interest of pure honesty, despite very consistent model guidance, I'm not that confident in this forecast. Too many limiting factors remain in question for me to be liking this, such as capping/subsidence drying and just what kind of mid-level lapse rates we're going to be dealing with. The models have been vastly underestimating capping potential this year, which is one of the reasons they've been so hokey. I'll be more confident if I see a few models showing adequate storm coverage Sunday over Mid Michigan over the course of the next two days.

UPDATE: I'm a little more optimistic after seeing the 12z NAM4KM simulated radar, shown below. This shows either two semi-discrete lines or one semi-discrete broken line which would pivot through the area, bringing a good bit of rain through most of the Thumb. When I've seen this before it tends to indicate a phenomenon called "training" which can lead to a LOT of rainfall - storms form one behind the next like train cars, and douse the same areas over and over. Normally this would concern me for flash flooding potential, but as dry as we are, I can only say, "Bring it on!" Hail/damaging winds/isolated tornadoes would appear likely in this storm mode, too, validating the slight risk, but it'll be worth it if it means not going up like a powder house on the Fourth of July, and if we can have some vegetables in the fall. 

Decent instability, modest shear Sunday

With yesterday's storms restricted to the southernmost areas of Michigan, our next chance at significant rainfall appears to be Sunday. With all of the troubles the models have been having with the forecast in our state this year, I'm going to try something different going forward: I'm going to discuss each model I have access to individually, briefly touching on the more significant factors that the models are contributing to the forecast, then summarize my opinion.

• NAM: Instability is forecast to increase throughout the day ahead of a cold front which would be approaching from the northwest. A weak cap would be in place and is forecast to erode over most of the state by 2PM EDT. This would support thunderstorm development in the afternoon. Very modest unidirectional bulk shear of 25-30kts would be present around this time, so this forecast does not advertise much of a severe threat. Still, some marginally severe weather (namely, hail) would be supported in the areas of highest instability. The NAM is predicting very high temperatures approaching 90ºF. It has the cold front begin to move through Michigan around 2PM, and thunderstorms throughout the afternoon.

• GFS: The extent of decent instability is forecast to be a bit more limited by the current GFS run, indicating greatest convective potential along and south of the US-10 corridor, and especially east of I-75. Capping is forecast to be a bit stronger in these areas as well. This could go either way - either the cap would erode enough so that thunderstorms, likely initiated elsewhere, would grow in intensity as they approached, or there'd be just enough left to choke off the fuel supply. More time and more runs are necessary to make that determination. Like the NAM, shear is forecast to be modest, in the 25-30kt range, but lapse rates would support a hail threat. Timing of the cold front appears to be similar to the NAM's timing.

• ECMWF: A bit of an outlier in that it has the cold front approach much earlier, and much less instability is forecast to develop over the state, although in a pattern similar to the GFS with the highest instability south of the US-10 corridor and to the east. Same as the rest in terms of shear values, though if this forecast's timing verifies it may not matter. Storms would likely fizzle out due to the cap not having enough time to burn off.

Summary: I'm going with the NAM/GFS on this one as the similar timing overrules the ECMWF solution. Rain and thunder will be likely Sunday afternoon, with a marginal severe threat, especially toward SE Michigan where instability should be a bit higher. The mitigating factor will be cap strength, and whether or not it will erode prior to the arrival of storms which should initiate farther north and west. I do not anticipate any widespread severe hazards at this time. NWS Detroit mentions severe thunderstorm possibilities in latest forecast discussion, though I'm still of the opinion that conditions will be marginal at best due to weak shear values. The SPC lists day 4 (Sunday) potential as too low for a 15% risk area, so they would appear to be in agreement. As such, my official outlook is "isolated severe" for areas along and south of US-10 and east of I-75 (limiting northward extent at this point to favor GFS solution on moisture), and a general thunder risk everywhere else.