4/17-4/18 Severe Storms Threat

[Brian D]

10 minutes ago, Brian D said:

Another resident in town mPinged 1" hail near the shoreline EDIT: 0.75" hail

Reports of 1" - 1.5" hail that scooted just E of my location on the shore. Just missed it.

[A-L-E-K]

Nice sup in nw il

[Chinook]

Ryan Hall showing debris was generally visible in Lena Illinois on a web cam.

[Chicago Storm]

Timmer got a big rain-wrapped wedge in NW IL.

[nwohweather]

Timmer got a big rain-wrapped wedge in NW IL.

That thing is absolutely buried inside that cell

[SchaumburgStormer]

Was in Lena, IL all day for work, left about 2:30. Sounds like they took a hit from that tor 

[Jackstraw]

13 minutes ago, nwohweather said:

That thing is absolutely buried inside that cell

Yes it was. Might be cycling out to a classic hook now. Was the tail end charlie of that initial prefrontal line. This might be the long tracker of the day. Clean uninterrupted juice flowing into it from the south.

[luckyweather]

18 minutes ago, SchaumburgStormer said:

Was in Lena, IL all day for work, left about 2:30. Sounds like they took a hit from that tor 

Damn man, close call there. Saw it hit from water tower webcam. Was legit. Looked like it was swallowing the town. 

[sbnwx85]

Hard to believe this would be a common map before polygons. 

[HillsdaleMIWeather]

A moderate risk for tornadoes 100% would have verified today, every storm in that area is spinning up something right now 

[Mogget]

So far, just a garden variety t-storm in southern WI.  Hope it stays that way, too.

[SchaumburgStormer]

That sup riding the border is wicked. 

[mob1]

That cell just north of Black River Falls is likely about to drop something (if it hasn't already). 

[pen_artist]

MD on that Rockford cell

 

Mesoscale Discussion 0480
   NWS Storm Prediction Center Norman OK
   0442 PM CDT Fri Apr 17 2026

   Areas affected...Southern Wisconsin and far northern Illinois

   Concerning...Tornado Watch 129...131...

   Valid 172142Z - 172345Z

   The severe weather threat for Tornado Watch 129, 131 continues.

   SUMMARY...Leading supercells across northern Illinois and southern
   Wisconsin will likely pose a tornado (possibly significant) and very
   large hail threat as they move downstream over the next 1-2 hours.

   DISCUSSION...A pair of leading supercells continues to precede a
   broken line of storms along the IL/WI border. Regional radar imagery
   continues to indicate that these cells are rather intense with a
   three-body scatter spike, a bounded weak echo region, and a recent
   3-inch hail report noted with the southern storm. An improving
   downstream convective environment is noted in recent observations
   and analyses (0-1 km SRH values remain between 200-250 m2/s2 per the
   KMKX VWP, and STP values have recently increased to 2-3 per recent
   mesoanalysis). Additionally, the southern storm will also likely
   propagate along a subtle surface theta-e gradient draped across
   northern IL to southern WI. Given these trends and the presence of a
   well-established updraft/mesocyclone with the southern cell, the
   potential for very large hail (likely in excess of 2 inches) and
   strong tornadoes will likely persist for the next couple of hours
   downstream into southeast WI and far northern IL.

   ..Moore.. 04/17/2026

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

   ATTN...WFO...LOT...MKX...DVN...

   LAT...LON   42138771 42158906 42268948 42378957 42608965 42798955
               42968903 43188791 43108770 42848764 42588767 42138771 

   MOST PROBABLE PEAK TORNADO INTENSITY...140-170 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...2.75-4.25 IN

[Jackstraw]

About to have a fairly significant cell merger west of Springfield IL. They're out ahead of front all by themselves moving into ever increasing instability and shear with plenty of backing surface winds. If they can get rooted look out, there's nothing in the way. Big overshooting tops.

[Chinook]

possible tornado near Rockford IL

[Chinook]

Storm chasers see funnel cloud outside of Rockford IL

[Chinook]

tornado rolled over Reed Timmer

[SchaumburgStormer]

Looks like the Rockton/South Beloit area may be under the gun real soon. 

 

[Jackstraw]

Timmer on it, this time of day on a Friday, densely populated area approaching Chitown burbs, every hill dilly jack boot armchair chaser is gonna be on that thing with Old Styles and IPhones hanging out the windows lol. No thanx

[Mogget]

Ok, we have hail.  Not spectacular hail but some nice pea-sized or slightly larger specimen.

Siren goes off every ten minutes, too, but nothing to see in the rain.

[pen_artist]

90 mph warned winds headed toward Davenport

 

[hawkeye_wx]

We got nothing over here.  The first cells developed east of CR, then the frontal line was broken into mostly little garden-variety cells, which mostly went around me.  I only got 0.13" of rain.

[Chinook]

insane triple storm with one tornado warning

[Chicago Storm]

4 fatalities in Lena, IL.

[mob1]

Confirmed tornado just south of Janesville. Possibly twin tornadoes.