Severe Weather Threat 4/28-4/30

[notsoencrypted]

Accidentally posted this is Severe Weather 2025 earlier.

If you want to see a textbook example of an overreliance on models, just look at our most popular local weather station here in Iowa this morning. Completely underselling the threat. This is the same station that was focusing on a different storm as a tornado entered Greenfield last year. I hope this doesn't make people overly complacent.

Oof. That's rough to see. Thankfully it looks like KEYC in Mankato, which covers a decent bit of northern IA, is taking it seriously:

Dangerous storms, tornadoes possible today

Today could be a very dangerous severe weather day, especially for central and southern Minnesota and northern Iowa. Conditions are right for thunderstorms that could produce strong, violent tornadoes, 70 to 80 mph wind gusts and hail the size of golf balls or larger.

www.keyc.com

 

[TornadoFan]

What is 3 CAPE?

 

[Atlantic]

What is 3 CAPE?

I would ask the same thing.

 

[ColdFront]

I would ask the same thing.

CAPE levels below 3KM. So basically just cape measured in the lowest 3KM above ground level

 

[Kds86z]

Oof. That's rough to see. Thankfully it looks like KEYC in Mankato, which covers a decent bit of northern IA, is taking it seriously:

Dangerous storms, tornadoes possible today

Today could be a very dangerous severe weather day, especially for central and southern Minnesota and northern Iowa. Conditions are right for thunderstorms that could produce strong, violent tornadoes, 70 to 80 mph wind gusts and hail the size of golf balls or larger.

www.keyc.com

… “violent “

 

[pr0t0genluvswEeather]

I'm thrilled for tomorrow's severe weather threat here in central Ohio! I'm gonna stand outside and watch the storm roll on in!

 

[Atlantic]

I'm thrilled for tomorrow's severe weather threat here in central Ohio! I'm gonna stand outside and watch the storm roll on in!

Spoken like a true storm watcher. /j

 

[pr0t0genluvswEeather]

Spoken like a true storm watcher. /j

I've actually had a hyperfixation on weather since I was like 3. every time there was a big, nasty storm, I'd go outside and just watch it. I do have a threshold, though, when it gets too severe and I gotta get inside.

 

[slenker]

60/50 probs on first watch that was just issued.

 

[FLPanhandle91]

What is 3 CAPE?

Low-level instability in the lowest 3km of the atmosphere. Large 3CAPE values, particularly those above 50 j/kg, indicate an environment that is very efficient at verically stretching low-level vorticity. Think of a horizontal spin in the lowest 1km or 3km area of the atmosphere caused by directional or speed shear. Now pull and tilt that spin vertically via high instability near the surface into a rotatating column of air.

High 0-3km SRH values overlapped with high 3CAPE can give a good idea at where supercells could produce tornados.

 

[notsoencrypted]

The sun is finally out here in Dane County, though there still are clouds around, but the temperatures have really started to jump.

 

[Ozonelayer]

I recommend looking at the Sioux Falls radar, it seems that there are some more dominant storms along what appears to be the dry line.

 

[TornadoFan]

 

[pr0t0genluvswEeather]

this is from 7 hours ago, but I think it may still be valid.

 

[Grand Poo Bah]

These storms popping up in Minnesota already look like they're in a very favorable environment

 

[Ozonelayer]

Mini supercell forming near Sioux Falls, SD. It might move off the dryline in the near future.

 

[lake.effect]

Storms initiating in SW Minnesota already have "the look"

 

[DanLarsen34]

These storms popping up in Minnesota already look like they're in a very favorable environment

View attachment 40579View attachment 40580
View attachment 40581View attachment 40582

I'm a little surprised that this first watch was not a PDS watch given that it does overlap with part of the moderate risk for tornadoes. The environmental conditions right now are already supportive of EF2+ tornadoes.

 

[Grand Poo Bah]

Severe warned storm east of Sioux City is now entering 4000 surface cape

 

[ColdFront]

Environment those dryline cells in MN are about to move into. Still a bit of an inversion, but it’s almost completely gone in southern Minnesota.