5/15(northern half) & 5/16(southern half of subforum) Severe Wx Threats

[largetornado]

Satellite as of 12:05. Good pockets of CU developing. 

15Z HRRR has pretty significant cell right over Chicago metro. Could be a very costly hail storm if that happens. 

[madwx]

79/69 at the house.  feeling pretty good so far.  Only real concern is if things form just a little northeast of here.

[Torchageddon]

The last time Michigan experienced a tornado rated F4 or higher was on April 2, 1977 (48 years!!!) in Augusta, Kalamazoo. The most recent strong tornado was that EF3 that struck Gaylord on May 20, 2022 - the strongest tornado in the state in 45 years. Will today break one of the longest met streaks we know of?

[CheeselandSkies]

4 minutes ago, madwx said:

79/69 at the house.  feeling pretty good so far.  Only real concern is if things form just a little northeast of here.

That does look like a strong possibility. I'll probably head to Sun Prairie or Columbus as a starting point.

[ILSNOW]

Chicago NWS Izzi update

Strong instability and strong and strengthening shear profiles
will favor supercell development along the dryline this
afternoon. Orthogonal nature of the shear vector orientation
with respect to the boundary suggests that storms could break
off the boundary and potentially remain discrete/semi-descrete
supercells as they move across the CWA. Primary threat should be
large, potentially destructive hail up to 3" in diameter.
Locally damaging downburst winds are also a threat.

[A-L-E-K]

3", let's go

[nwohweather]

Enhanced risk expanded slightly south and further east to Detroit, 30% sig wind introduced over Northern Indiana and Southern Michigan. They're expecting mature supercell's ahead of the line so some areas could have a tornado threat and then damaging wind right behind it 

You’re not in a bad spot there. Some of the soundings to your south and west were rather ominous along with the HRRR guidance. Have to sigh at yet another post sunset tornado threat, they’re never very fun

[yoda]

Sounds like Tor Watch coming soon for parts of MN/WI per latest MCD 

https://www.spc.noaa.gov/products/md/md0786.html

 

[madwx]

Can’t argue for much more in low level wind fields

[largetornado]

Red Sharpie for tomorrow. Wind Driven Mod. 10/45/30 all hatched. 

[sbnwx85]

The first watch of the day is out.

Public | Counties | Probabilities | Aviation | Warnings | Initial RADAR

Hazard Tornadoes EF2+ Tornadoes Likelihood Moderate Moderate Severe Wind 65 kt+ Wind Moderate Low Severe Hail 2"+ Hail Moderate Moderate Note:  The expiration time in the watch graphic is amended if the watch is replaced, cancelled or extended. Note: Click for Watch Status Reports. SEL1 URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 251 NWS Storm Prediction Center Norman OK 1245 PM CDT Thu May 15 2025 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Central Minnesota West-Central Wisconsin * Effective this Thursday afternoon and evening from 1245 PM until 800 PM CDT. * Primary threats include... A few tornadoes likely with a couple intense tornadoes possible Scattered large hail and isolated very large hail events to 3 inches in diameter likely Scattered damaging wind gusts to 70 mph likely SUMMARY...Rapid thunderstorm development is anticipated within a narrow warm sector moving into the region. Strong buoyancy and robust deep-layer shear will support supercells capable of all severe hazards, including very large hail from 2" to 3" in diameter, strong gusts, and tornadoes, a few of which could be strong. The tornado watch area is approximately along and 70 statute miles north and south of a line from 15 miles south southwest of Alexandria MN to 55 miles east of Eau Claire WI. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU1). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Tornado Watch means conditions are favorable for tornadoes and severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. && AVIATION...Tornadoes and a few severe thunderstorms with hail surface and aloft to 3 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 20035.

[andyhb]

Those are some impressive obs across N/central IL right now. Lots of upper 80s temps/low 70s dewpoints with backed surface winds. Should moisture stay near that level, this could really change the game (in a bad way) for the Chicago area later.

[Jackstraw]

Looking like a N/S splitter here which is fine with me. Took a break from the track today, back at it tomorrow thru Sunday 

[SchaumburgStormer]

Temp popped, 92/73

[Castaway]

86 right now with 68 dews and 14mph southerly winds in imby in dupage

[SchaumburgStormer]

Last few runs of the HRRR wanna pop a supercell basically over my head and roll it into the metro. 

[sbnwx85]

Ready to see my social media flooded with those weirdo Chicago tornado sirens.

[largetornado]

I wouldnt be suprised to see a storm develop along the indiana/oh border. cap seems to erode as the day goes on as an arc of 500mb vorticity traverses NE.

[CheeselandSkies]

A little bit of early day crapvection might have actually helped the threat with this one. So unusual to see such a near-total lack of it with a setup in this region, but now the temperatures are getting too hot, primarily in Illinois where the better chance of a longer-lived discrete mode is.

[SchaumburgStormer]

2 minutes ago, CheeselandSkies said:

A little bit of early day crapvection might have actually helped the threat with this one. So unusual to see such a near-total lack of it with a setup in this region, but now the temperatures are getting too hot, primarily in Illinois where the better chance of a longer-lived discrete mode is.

Yeah, temp is overperforming by a couple degrees here

[OrdIowPitMsp]

Bout to get rocked here. Southern metro watch out. Tor warned storm entering the I-35 corridor 

[Floydbuster]

https://x.com/TornadoWIS/status/1923091119270662400

 

These kids are insufferable. 

[yoda]

Tornado Watch likely in next hour or two for S WI/ N IL

https://www.spc.noaa.gov/products/md/md0791.html

 

 

Mesoscale Discussion 0791
   NWS Storm Prediction Center Norman OK
   0214 PM CDT Thu May 15 2025

   Areas affected...Parts of southern Wisconsin into northern Illinois

   Concerning...Severe potential...Tornado Watch likely 

   Valid 151914Z - 152115Z

   Probability of Watch Issuance...80 percent

   SUMMARY...A tornado watch will likely be needed this afternoon.
   Supercells capable of all severe hazards are expected within the
   next few hours.

   DISCUSSION...Cumulus continue to deepen both along a dryline and an
   area of confluence within the Mississippi Valley. Whether storms
   develop within the confluence or when the dryline reaches the
   Mississippi River remains a question. 40-50 kts of effective shear
   across these surface convergence zones will favor supercells as
   storms develop. Large to very large hail will be a concern as well
   as severe wind gusts. The 18Z DVN sounding sampled very steep
   mid-level lapse rates and a long hodograph. Tornado potential will
   also be present. Surface temperature/dewpoint spreads are near 20 F,
   but low-level shear and a supercellular mode will favor low-level
   rotation. The time frame of greater tornado potential will likely be
   22-00Z when the low-level jet increases in southern Wisconsin.

   ..Wendt/Mosier.. 05/15/2025

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...GRB...LOT...MKX...DVN...ARX...

   LAT...LON   41418999 41579025 41819042 42309082 42909119 43299134
               43549126 44009048 44358993 44438931 43978880 43168862
               42128827 41798867 41418999 

   MOST PROBABLE PEAK TORNADO INTENSITY...120-150 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN

[SchaumburgStormer]

1 minute ago, yoda said:

Tornado Watch likely in next hour or two for S WI/ N IL

https://www.spc.noaa.gov/products/md/md0791.html

 

Mesoscale Discussion 0791
   NWS Storm Prediction Center Norman OK
   0214 PM CDT Thu May 15 2025

   Areas affected...Parts of southern Wisconsin into northern Illinois

   Concerning...Severe potential...Tornado Watch likely 

   Valid 151914Z - 152115Z

   Probability of Watch Issuance...80 percent

   SUMMARY...A tornado watch will likely be needed this afternoon.
   Supercells capable of all severe hazards are expected within the
   next few hours.

   DISCUSSION...Cumulus continue to deepen both along a dryline and an
   area of confluence within the Mississippi Valley. Whether storms
   develop within the confluence or when the dryline reaches the
   Mississippi River remains a question. 40-50 kts of effective shear
   across these surface convergence zones will favor supercells as
   storms develop. Large to very large hail will be a concern as well
   as severe wind gusts. The 18Z DVN sounding sampled very steep
   mid-level lapse rates and a long hodograph. Tornado potential will
   also be present. Surface temperature/dewpoint spreads are near 20 F,
   but low-level shear and a supercellular mode will favor low-level
   rotation. The time frame of greater tornado potential will likely be
   22-00Z when the low-level jet increases in southern Wisconsin.

   ..Wendt/Mosier.. 05/15/2025

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...GRB...LOT...MKX...DVN...ARX...

   LAT...LON   41418999 41579025 41819042 42309082 42909119 43299134
               43549126 44009048 44358993 44438931 43978880 43168862
               42128827 41798867 41418999 

   MOST PROBABLE PEAK TORNADO INTENSITY...120-150 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN

[sbnwx85]

18z HRRR tries to pop a few supercells ahead of the main line. Impressively amps up the STP across Indiana and Michigan as the LLJ strengthens.

[SchaumburgStormer]

Tor watch is out for most of Wisconsin, clips the top line of counties in IL

[ILSNOW]

1 minute ago, SchaumburgStormer said:

Tor watch is out for most of Wisconsin, clips the top line of counties in IL

https://www.spc.noaa.gov/products/watch/ww0253.html

[OrdIowPitMsp]

Managed to get a few rumbles of thunder and 0.05” of rain. Can’t even call it garden variety. Big let down.

[TheNiño]

4 minutes ago, SchaumburgStormer said:

Tor watch is out for most of Wisconsin, clips the top line of counties in IL

I find it humorous they issued the watch but they almost specifically said “nope” to lake county lol. I’m sure another one will be issued just looks funny on the map.

[Malacka11]

Bit of a quandary because like always, I want to go on a dog-jog to the forest preserve hill a mile and change from my house to try and get some pictures if it works out that way but I think I'd rather lay down in a ditch and ride out a tornado than try my luck sprinting home in 50 cal hail if I fuck up (esp w pup along for the ride)