Severe Threat May 15-16, 2025

[andyhb]

On Thursday, my main questions are the exact timing of the trough, the degree of backing/veering of the surface winds, and if moisture reaches the progged levels (and doesn't mix out too much, especially further south). It's still a bit early in this return flow pattern although most models are sufficient.

Friday still has some variation amongst guidance as to how that secondary impulse rounds the base of the upper low in the Northern Plains, which will determine the degree of LLJ response. Moisture looks like a non-issue, but I do wonder about storm mode and how strong the wind fields get. Could be a pretty widespread severe episode, and I'd think at least a substantial MCS is in the cards especially for the Lower Ohio Valley. Supercells TBD.

 

[Atlantic]

Though doesn’t see significant tornado threat but with strong instability all rules can go out the window…

Welcome to May!

 

[Kds86z]

Welcome to May!

I did mean to say Trey said this in his video. About Instability making up for less shear.

 

[CheeselandSkies]

I did mean to say Trey said this in his video. About Instability making up for less shear.

What is all this talk about "less shear"? You have a low deepening to the low 980s (according to the 12Z NAM) and a southerly low-level jet. There is going to be shear and plenty of it.

 

[Kds86z]

What is all this talk about "less shear"? You have a low deepening to the low 980s (according to the 12Z NAM) and a southerly low-level jet. There is going to be shear and plenty of it.

Idk what soundings he was looking at and showing. Seemed like a lot of forcing and such.

 

[Austin Dawg]

We may be at the tail end of the front on Friday, but we have to watch it because of the big hail storms. It's the time of year for us to get hail storms. It's least going to break the unbelievable heat here. It's forecasted to be. 107 degrees tomorrow. 103° today, unbelievable!

 

[cniemczura]

I don’t mean to divert, but why were there people in here several weeks ago saying we were ‘done’ for the season? I’m no met, but the severe weather probabilities are right there on SPC, with a map, and dates lol….

 

[CheeselandSkies]

12Z RRFS is notably slower than all other guidance thus far, but still initiates supercells in southern WI/northern IL around 00-01Z Friday (7-8 PM CDT Thursday).

 

[slenker]

I don’t mean to divert, but why were there people in here several weeks ago saying we were ‘done’ for the season? I’m no met, but the severe weather probabilities are right there on SPC, with a map, and dates lol….

I don’t recall people saying we were “fully done” just that we probably weren’t going to see any more of the really big synoptically evident days anymore, like 3/14-15 or 4/2. With the pattern we entered in the latter half of April and beginning of May, as well as the general consensus by some that May would be quieter than usual this year, it’s easy to see why that sentiment persisted for a bit. And who knows, maybe this Thursday and Friday do end up being nothing too substantial.

I am starting to get worried about the big trough ejection over the plains after this one though. Both Euro and GFS ensembles look pretty nasty for Sunday into Monday of next week. Trey highlights it in his new video at the end and it’s definitely a concerning look.

 

[Grand Poo Bah]

I'm surprised to see no 30% outlooks today, but Andy's explanation definitely provides some clarity. In fact, I haven't seen any METs getting overly excited about the set up yet.

 

[tennessee storm chaser]

I'm surprised to see no 30% outlooks today, but Andy's explanation definitely provides some clarity. In fact, I haven't seen any METs getting overly excited about the set up yet.

I see a derecho coming down the pike. …. U will see 30 percent probs In the tomorrow mornings outlook….

 

[ColdFront]

I don’t mean to divert, but why were there people in here several weeks ago saying we were ‘done’ for the season? I’m no met, but the severe weather probabilities are right there on SPC, with a map, and dates lol….

I don’t think people saying our higher end outbreaks are probably done for the year was saying we were done with severe weather.

 

[andyhb]

Friday is really beginning to have the look of a widespread, significant severe event with how that secondary shortwave pivots around the base of the parent upper low with strong shear and large instability over a large expanse of real estate. Could yield both tornadic supercells and an intense MCS/derecho.

12z CIPS analogs are chock full of significant events for the region.

 

[tennessee storm chaser]

It would not surprise me if the new day3 outlook here soon adds a 30 percent percent probs. Southern Wisconsin to. Other Illinois….

 

[ColdFront]

Friday is really beginning to have the look of a widespread, significant severe event with how that secondary shortwave pivots around the base of the parent upper low with strong shear and large instability over a large expanse of real estate. Could yield both tornadic supercells and an intense MCS/derecho.

12z CIPS analogs are chock full of significant events for the region.

View attachment 41391

Wow, 5/11/2003 and 5/23/2011.

 

[slenker]

Wow, 5/11/2003 and 5/23/2011.

Any time I hear May 2003 as an analog for something, it's got my attention.

 

[tennessee storm chaser]

Any time I hear May 2003 as an analog for something, it's got my attention.

Yes sir better believe that…. Trust me , I was on the door step of a ef4 Jackson tn. That night may 03

 

[ColdFront]

Yes sir better believe that…. Trust me , I was on the door step of a ef4 Jackson tn. That night may 03

You going to get some pictures for us Friday?

 

[Kds86z]

Day 3 late

 

[Jbop]

Day 3 late

I'm surprised they are late with it. Might be an upgrade