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

[sbnwx85]

New MD out for Illinois. Monster hail possible.

Mesoscale Discussion 0794
   NWS Storm Prediction Center Norman OK
   0322 PM CDT Thu May 15 2025

   Areas affected...Parts of central and northern Illinois

   Concerning...Severe potential...Watch possible 

   Valid 152022Z - 152215Z

   Probability of Watch Issuance...60 percent

   SUMMARY...Large to very large hail and severe winds will be possible
   with supercells that can develop later this afternoon. Watch timing
   is uncertain but is possible later this afternoon.

   DISCUSSION...Cumulus are developing along an eastward moving dryline
   near the Mississippi River. Ahead of this boundary, a strongly
   unstable airmass is in place (low 90s F temperatures and mid 60s to
   low 70s F dewpoints). With the strongest mid-level ascent to the
   northwest of the region, timing of storm initiation as well as storm
   coverage are uncertain. However, given the lack of MLCIN, a isolated
   to widely scattered development appears possible later this
   afternoon. 45-55 kts of effective shear will support supercells. The
   primary hazards will be large to very large hail and severe winds.
   The tornado threat is expected to be less than farther north given
   the slightly veered low-level winds and more sizable
   temperature/dewpoint spreads at the surface.

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

[iBrian]

I'm just north of you.  We haven't had a proper thunderstorm around here in??

[iBrian]

Has ORD hit a record high for the date, yet? My thermo was stuck at 93 while driving around.

[olafminesaw]

This cell headed towards Madison is trouble 

[madwx]

Cells popping up all over. Winds backed nicely.  Bases are a little high but cell level processes bring them down a bit

[madwx]

Plenty of supercells with hail but everything is still pretty sky high. Watching for any mergers or nudges. Especially the cells south of Madison

[SchaumburgStormer]

Things starting to unzip along the dry line in W IL

[OrdIowPitMsp]

Damn we are getting a dust storm here. Wasn’t expecting this. 

[cyclone77]

Nice towers going up in western horizon here.

[Nelson]

Had 1/2” hail here with a cell that formed right overhead.


.

[Harry Perry]

2 minutes ago, Nelson said:

Had 1/2” hail here with a cell that formed right overhead.


.

Yikes, going to be a wild ride this evening. Someone’s going to end up with monster hail out of this setup. 

[madwx]

At least some of these cells must be above the inversion at 850 mb

[cyclone77]

Continuous thunder with this cell coming in from the southwest.  Building quickly.

[Chicago Storm]

1 hour ago, iBrian said:

Has ORD hit a record high for the date, yet? My thermo was stuck at 93 while driving around.

Yes, it hit at least 93.

[Chicago Storm]

1 hour ago, sbnwx85 said:

New MD out for Illinois. Monster hail possible.

Mesoscale Discussion 0794
   NWS Storm Prediction Center Norman OK
   0322 PM CDT Thu May 15 2025

   Areas affected...Parts of central and northern Illinois

   Concerning...Severe potential...Watch possible 

   Valid 152022Z - 152215Z

   Probability of Watch Issuance...60 percent

   SUMMARY...Large to very large hail and severe winds will be possible
   with supercells that can develop later this afternoon. Watch timing
   is uncertain but is possible later this afternoon.

   DISCUSSION...Cumulus are developing along an eastward moving dryline
   near the Mississippi River. Ahead of this boundary, a strongly
   unstable airmass is in place (low 90s F temperatures and mid 60s to
   low 70s F dewpoints). With the strongest mid-level ascent to the
   northwest of the region, timing of storm initiation as well as storm
   coverage are uncertain. However, given the lack of MLCIN, a isolated
   to widely scattered development appears possible later this
   afternoon. 45-55 kts of effective shear will support supercells. The
   primary hazards will be large to very large hail and severe winds.
   The tornado threat is expected to be less than farther north given
   the slightly veered low-level winds and more sizable
   temperature/dewpoint spreads at the surface.

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

only watch possible?

[SchaumburgStormer]

Might have twin tors near Loyal, WI

[sbnwx85]

21 minutes ago, Chicago Storm said:

only watch possible?

Should have been issued a half hour ago.

[KeenerWx]

4 minutes ago, sbnwx85 said:

Should have been issued a half hour ago.

Out now! 

[Chicago Storm]

Should have been issued a half hour ago.

and then they go with a tornado watch, which is comical.

[SchaumburgStormer]

1 minute ago, Chicago Storm said:

and then they go with a tornado watch, which is comical.

With 50/30 tornado probs.

[Chicago916]

13 minutes ago, Chicago Storm said:

and then they go with a tornado watch, which is comical.

Don't agree with LOT? 

[Powerball]

That cell near Beaver Dam is looking pretty gnarly on the most recent frames...

[SchaumburgStormer]

7 minutes ago, Powerball said:

That cell near Beaver Dam is looking pretty gnarly on the most recent frames...

Tight couplet near oak grove

edit- looks like a cc drop as well 

[frostfern]

The northern edge of that 90 degree heat bubble could get interesting.

[andyhb]

Tornado in progress near Juneau WI right now.

[SchaumburgStormer]

5 minutes ago, SchaumburgStormer said:

Tight couplet near oak grove

edit- looks like a cc drop as well 

Debris sig really ramping up 

[Castaway]

87 with dews now up at 69 with gusts up to 34mph imby

[andyhb]

Tornado just made a direct hit on Mayville WI, pop. >5000.

[SchaumburgStormer]

[sbnwx85]

It will take me a long time to emotionally recover if these storms don't fire for me.

EDIT: I guess more accurate to say if they die out and get capped... I don't think the HRRR has a good handle on what's happening in Illinois if it's trying to kill those storms along the dry line so quickly.