Wednesday August 19th Potential Great Lakes Severe Weather Outbreak

I was going to make a post about this last night, but I figured with the events of yesterday afternoon still ongoing for some, it would be best to focus on that and wait to induce more stress until today. I also wanted to give the models one more day to hash this out. The reason being is that as of yesterday morning, the event that originally looked like it was going to occur on August 20th began to look a bit disjointed and timing started coming into question.  This actually reduced my confidence of severe weather for August 20th, which was reflected in the morning outlook.  Throughout the day, though, the GFS runs began speeding things up, and now it's looking like severe weather may strike a day earlier... and potentially much harder.

SPC Day 5 Severe Weather Outlook

Confidence in this particular event is high - so high that the SPC has issued a relatively rare Day 5 slight risk for the Great Lakes region extending south into the Missouri Valley/Arklatex region.

The things to be aware of with this one are as follows:

• This is taking shape as the culmination of a potential multi-day severe weather event for the Midwest, which begins in the plains on day 3, and moves into the Mississippi Valley day 4 before targeting our area day 5:

Day 3 Categorical Outlook

Day 4 Categorical Outlook

• The storm system looks to be taking on a negative tilt.  I'll make another post about what that means after this one, but know for now that it's a big factor in producing significant severe weather.

• The setup is beginning to take on the appearance of November 17th, 2013, which for those who are unaware, looked like this:

The way that this is looking, it's going to be one of those days where how much instability is available will be a marginal factor. This system is going to produce severe weather, and a lot of it - question right now is how severe, and where. The only real factors in how severe storms will be and what hazards they're going to produce are going to be timing and location of storm initiation.

I will be making many more posts about this upcoming event in the days to come.