4/13 - 4/14 Severe Threat

[nvck]

figured it's probably due, almost a lock that someone in the sub's gonna see some action today or tomorrow. primarily hail/tornado risk.

[pen_artist]

Bit of an appetizer ahead of likely busy next few days

 Mesoscale Discussion 0395
   NWS Storm Prediction Center Norman OK
   1103 AM CDT Mon Apr 13 2026

   Areas affected...portions of extreme eastern Iowa into
   western...central...and northern Illinois

   Concerning...Severe potential...Watch possible 

   Valid 131603Z - 131730Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Some hail (possibly over 1 inch in diameter) may occur
   with gradually intensifying storms over the next few hours. It is
   unclear if these storms will pose the greatest severe risk this
   afternoon, or if the greater risk will occur with later storms.

   DISCUSSION...850 mb troughing is underway across the Plains states
   into the Midwest, with 15Z mesoanalysis showing the northeasterly
   terminus of a LLJ currently positioned along the IA/IL/MO border.
   Here, an 850 mb Td gradient exists, with modest WAA likely
   supporting the gradual intensification of elevated convection within
   this regime. The 12Z ILX observed sounding and 15Z mesoanalysis
   depicts 700-500 mb lapse rates in the 8-8.5 C/km range, contributing
   to MUCAPE approaching 2000 J/kg. These storms are encroaching on a
   region of stronger 500 mb southwesterly flow, driven by a departing
   upper trough over the eastern U.S., which is resulting in 30-40 kt
   of effective bulk shear ahead of the storms. If storms continue to
   intensify, it is plausible that at a hail threat may materialize
   over the next few hours, with some stones potentially exceeding 1
   inch in diameter.

   Short-range high resolution ensemble guidance is providing mixed
   signals regarding the evolution of this convection. Some
   deterministic CAMS show that the ongoing storms eventually
   consolidate and develop into stronger supercell structures in
   northern IL by afternoon. Other guidance members depict the ongoing
   storms oscillating in intensity, while stronger storms develop
   later. As such, there is an appreciable degree of uncertainty as to
   the evolution of the longer term severe threat with these WAA
   storms. All this being said, convective trends will continue to be
   monitored for the need of a WW issuance.

   ..Squitieri/Guyer.. 04/13/2026

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

   ATTN...WFO...LOT...ILX...LSX...DVN...

   LAT...LON   40829153 41349115 41809076 42269021 42318942 42178872
               41918839 41478835 41028850 40608866 40238895 40058932
               39988999 40039043 40249121 40829153 

   MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN

[nvck]

Surprised that the D2 update at 1730z didn't introduce any sort of ENH in Michigan

[A-L-E-K]

 

 

[Chicago Storm]

the spc has 50 million types of hatching now, but somehow still couldn’t figure out how to put one across the area for hail today.

[nvck]

MD and then watch just issued pretty much back to back for IWX area 

[King James]

Pretty good storm. Lots of wind, continuous throughout the storm