July 28-29 Severe Potential

[Jim Marusak]

and as I type that, Watch 399 is out. counties in MN involved, roughly DLH to STP and ANE (not including MSP). WI Counties, DLH area to GRB, LSE to MKE, including MSN, EAU, and AUW.

 

https://www.spc.noaa.gov/products/watch/ww0399.html

 

[SRRTA22]

PDS watch

[HillsdaleMIWeather]

They forgot to add the PDS text at issuance lol

[Indystorm]

When in doubt go big.  Almost all of WI is included in the watch.  I know the focus has been rightly upon svr wind and possible derecho, but those helicity values in certain locations on SPC meso concern me.

[CheeselandSkies]

Already what looks on radar like it could be an incipient supercell northwest of Wausau. Unwarned as of yet.

Watch includes (as already noted) most of WI and all of my employer's market coverage area apart from Grant and Crawford.

[Indystorm]

With CAPE values as high as what we are seeing when these storms form they will certainly explode as they move south/se.  Not very often do we get a PDS svr storm watch particularly for the night hours.

[HillsdaleMIWeather]

3 minutes ago, Indystorm said:

With CAPE values as high as what we are seeing when these storms form they will certainly explode as they move south/se.

Right on cue, four new warnings for the cells ahead of the line 

[CheeselandSkies]

Latest HRRR kills the western half of the complex and brings the most intense activity near/south of Green Bay, over LM and into the IN/OH/MI border region by Thursday morning.

[Sydney Claridge]

Part of me feels that SPC went with a Severe Thunderstorm Watch specifically so that they could label it as a Particularly Dangerous Situation for straight-line winds. Tornado probabilities are at the maximum (20%) for a SVR watch, while the SPC outlook has a 10% tornado probability (within 25 miles of a point); normally we would expect a Tornado Watch with a 10% on the outlook, barring some post-outlook "nowcasting" suggesting lower probabilities.

Typically I've noticed that 10% contours almost always lead to Tornado Watches, while 5% contours can go in either direction (that is, either a SVR or a TOR watch).

[CheeselandSkies]

5 minutes ago, BrandonC_TX said:

Part of me feels that SPC went with a Severe Thunderstorm Watch specifically so that they could label it as a Particularly Dangerous Situation for straight-line winds. Tornado probabilities are at the maximum (20%) for a SVR watch, while the SPC outlook has a 10% tornado probability (within 25 miles of a point); normally we would expect a Tornado Watch with a 10% on the outlook.

Yeah, rather bizarre situation there. Just looking at the radar almost right off the bat, it seems things want to line/bow out pretty quick so looking like the longer-lived/strong (supercell) tornado threat won't really materialize. Not to say there couldn't be a stronger (EF2 or even 3, like that Chicago 'burbs one a few weeks ago) spin-up with an HP supercell embedded in the QLCS as it takes shape down the road.

[HillsdaleMIWeather]

Western portions of the line are developing rotation

[Indystorm]

With svr storms forming as far west as Itasca I am not so sure that western areas will escape unscathed.  I-90 special in a broad arc from east of Green Bay in Lake Michigan down through Madison and west to LaCrosse IMHO.

[Indystorm]

Just now, HillsdaleMIWeather said:

Western portions of the line are developing rotation

That is where the greatest helicity has been located.

[Sydney Claridge]

1 minute ago, Indystorm said:

That is where the greatest helicity has been located.

And there is now a TOR warning on the MN/WI border SW of Grantsburg.

[Chinook]

possible tornado at MN/WI border

[CheeselandSkies]

I may have to eat my words here shortly with that Grantsburg cell, although of course it is in the worst of the radar hole equidistant from KDLH and KMPX.

[StormfanaticInd]

These storms are looking beefy 

[CheeselandSkies]

SPC with little change at go time on the 01Z outlook.

[OrdIowPitMsp]

Looks like we will stay dry in the Twin Cities. 

[TheNiño]

EAA Oshkosh Airventure is going on right now. This is the scene there. I hope they are taking measures before it hits.

[HillsdaleMIWeather]

Already looking nasty and the LLJ hasn't even kicked in yet

[A-L-E-K]

7 hours ago, A-L-E-K said:

gonna ride instability gradient down I90 into ne il

 

 

 

[WaryWarren]

1 minute ago, A-L-E-K said:

 

I see that and raise you: 

 

[Chicago Storm]

Just now, A-L-E-K said:

 

Looking bank for now.

Current trajectories would bring it across a large portion of N IL. I'm still not sold on any quality severe potential by that time, but an MCS would still be nice. I'm on a mid at ORD tonight too.

[tiger_deF]

Power outages are spiking in NNE Wisconsin

[tiger_deF]

[CheeselandSkies]

May just be distance from the respective radar (but warning wording is also stronger on it, too) but the eastern cluster riding along and east of US 51/I-39 looks to be the more impressive right now.

 

Quote

This is a DANGEROUS SITUATION. These storms are producing widespread
wind damage across Lincoln County. SEEK SHELTER NOW inside a sturdy
structure and stay away from windows.

 

[CheeselandSkies]

Now tornado-warned.

[TheNiño]

Wausau is getting absolutely hammered.

[OrdIowPitMsp]

I was able to see the far western edge of the complex to my NE this evening.