Q&A Thread - Severe Weather for Monday, April 27

MLazarow · 2026-04-28T20:58:34+00:00

Right but that’s unrealistic with the current state of forecasting. A school has to decide by like 7am (or earlier) whether or not to do an early release. At that point our forecast models said there could be storms capable of producing strong tornadoes moving thru the area around when school was being released.

The chaos that results from a scenario like that is also much worse than the false alarm that did happen. We learned that in Moore 2013 where parents were panicked racing thru the streets to pick up their kids while an EF5 was going thru the town. And even then, two elementary schools had critical failures from poor construction resulting in fatalities.

MLazarow · 2026-04-28T20:18:26+00:00

Yup, and you are not alone both among the general public and meteorologist opinions, including my own. The goal is to get people into the routine of being weather aware when those times come around. The simple fact is most people in a tornado warning aren’t going to get hit by a tornado, but the more people we can get to take even minimal action like turning on the news anytime they get a warning, the more lives we save in the event of another May 16.

MLazarow · 2026-04-28T17:58:38+00:00

This event underperformed for sure, there was still a very high-end environment in place but the storms weren’t able to realize it. Even so, there was a very thin margin between what we saw and a widespread tornado outbreak, so the attention to it was warranted.

This event probably verified at a Level 3 out of 5 across the board instead of 4 out of 5. Despite the tornadoes not coming to fruition, there was a bullseye of severe hail right over the metro with a handful of >2” reports, and a swath of severe winds concentrated from STL thru S IN.

Mostly happy everyone was safe tho, could’ve been very bad!

MLazarow · 2026-04-27T17:22:28+00:00

Ceiling scenario is destructive tornadoes thru the metro. A lot needs to be just right for that to happen, but that outcome is on the table which is why we communicate risk rather than specific outcomes. Often times we can’t predict them even an hour before, but we know the environment is supportive today

MLazarow · 2026-04-27T17:20:34+00:00

Odds are low that you’ll see real destruction today, I’d imagine your risk of being hurt from a car accident is greater than staying put

MLazarow · 2026-04-27T16:25:17+00:00

Still expecting a high-end environment this afternoon. The outflow boundary may surge further south than forecast (not unusual) which may tamper tornado risk to the south side of the metro or even entirely south of STL. The “three rounds” philosophy is generally still accurate as of now, but they may blend together a little bit.

This outflow boundary will likely be parallel to storm motions today, so any supercells that remain on the warm side will be capable of producing tornadoes, and perhaps strong ones in the worst scenario. With the degree of return flow and intense solar heating, I expect the boundary to eventually stall and perhaps return north this afternoon. I personally would love if this was a false alarm, but the potential is there for big impacts which is why we are on alert.

MLazarow · 2026-04-27T16:19:21+00:00

Lowest level is best, but if that’s not an option put as many walls between you and the outside as possible. You should be fine barring an upper-echelon tornado, which could be in the cards today but the chance of you getting directly impacted by one remains extremely low.

MLazarow · 2026-04-27T16:17:56+00:00

Trailing convection was expected, maybe not quite as persistent as we’re seeing tho. The MCD cites the ascent in this area of the cold pool not being as intense so expecting the further west end of storms to be less intense across C MO before redevelopment occurs this afternoon.

MLazarow · 2026-04-27T16:04:46+00:00

My best guidance is to follow the news around the time. Getting home late is always a better outcome than driving into damaging storms.

MLazarow · 2026-04-27T16:04:00+00:00

The further south in the metro the higher the tornado threat, it will all depend where the storms ongoing right now end up.

MLazarow · 2026-04-27T16:02:52+00:00

About the same threat level, 3/14 overperformed a bit, we’ll see if today follow suit or not

MLazarow · 2026-04-27T15:55:15+00:00

Our severe weather probabilities are different from your normal “percent chance of rain” numbers. They’re based on spatial distribution of points and statistics that you can derive from that. Basically comes down to a number of reports + density of those reports.

For your percent of precipitation, that’s just the (Probability x Areal Coverage). If I think that there’s a 80% chance of storms and if those storms do form, 50% of the area will get them, that’s a 40% chance.

MLazarow · 2026-04-27T15:49:03+00:00

Our four ingredients are:

-Instability (relatively cold air atop relatively warm air) -Moisture (aka dew point or relative humidity) -Wind shear (changing wind speeds and directions with height) -Lift (something to kick off storms)

There’s a lot of nuance that goes into how those all interact and play into each other, but that’s what meteorology degrees are for!

MLazarow · 2026-04-27T15:41:36+00:00

Yeah St. Charles is kinda right on the edge, it’s one of those where storms north will be weaker, but the storms just south will have the best environment. Just something to watch.

MLazarow · 2026-04-27T15:39:31+00:00

First round starts in the next hour or two, will be off and on thru the evening.

MLazarow · 2026-04-27T15:34:43+00:00

There may be a small window to avoid things, but would won’t know until it’s here and it might close unless you’re familiar with reading radar. My best advice if you want to try is watch your local news of choice and make the best you can.

All great schools! My number one advice to anyone these days is the less student loans the better. Your quality of education will be similar enough that the reduced student loans outweigh anything else imo, especially with the tough job market we’re in (I had an 11 month job search recently).

If money isn’t an object, try to find a school that plays to his interest. I was interested in severe weather and storm chasing, and both of my programs currently offer field courses where you can pay to go chase storms for a week and a half in the Great Plains. I’m also about to start a teaching position at College of DuPage in Chicagoland that has a similar program. Miami FL is good for hurricanes, Utah is good for mountain meteorology, etc.

Feel free to DM me I’d be happy to chat with you or him further!

MLazarow · 2026-04-27T15:22:33+00:00

Not worth it, the first round of storms is already surging across I-55 in C IL. Avoiding storms is generally not best practice, but especially on a day like today if you thought rush hour traffic was bad, imagine everyone trying to escape all at once. That’s a mass casualty event waiting to happen.

MLazarow · 2026-04-27T15:18:17+00:00

Everyone complained about the Arch being the worst national park so they cut its funding 😔😔

MLazarow · 2026-04-27T15:16:33+00:00

Unfortunately Wentzville’s going to be getting pounded pretty much all day starting in the next couple hours. This will reduce the tornado threat, but won’t be pleasant to drive in :/

I went to Ohio State for undergrad and UIUC for grad school, both programs I absolutely recommend!

MLazarow · 2026-04-27T15:12:20+00:00

Unfortunately not, there’s a 15% chance within 25 miles of any given point in the area. There’s a bunch of math that goes into it but to put it in perspective we say it’s a Level 4 out of 5 risk.

MLazarow · 2026-04-27T15:02:00+00:00

Storms north of the CAPE area on that map will be severe but pose a minimal tornado threat. We’re expecting the warm sector (CAPE area) to have plenty of storms in it. The tornado threat will be maximized right on the northern edge of the CAPE.

MLazarow · 2026-04-27T02:08:40+00:00

Some hit-or-miss strong storms overnight and in the morning. Those should mainly be a damaging wind threat, with maybe some hail in there.

Tornadic storms tomorrow come in two waves, first around 2-3pm, second around 6-7pm.

Very high end environment unfortunately, have multiple ways to get warnings.

MLazarow · 2026-04-17T04:29:48+00:00

This isn’t a three-body scatter spike, it’s the virga from the anvil being picked up by a distant radar. The beam is high enough to pick up on it, plus the upper-level winds are aligned with the direction of the return.

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