Storm Prediction Center Mesoscale Discussion 1391

   Mesoscale Discussion 1391
   NWS Storm Prediction Center Norman OK
   1025 PM CDT Mon Jun 29 2026

   Areas affected...portions of central and northeastern Nebraska

   Concerning...Severe Thunderstorm Watch 418...

   Valid 300325Z - 300530Z

   The severe weather threat for Severe Thunderstorm Watch 418
   continues.

   SUMMARY...The potential for severe wind gusts (potentially including
   significant gusts up to 75-90 mph) and large hail is expected to
   expand northeastward over the next 1-2 hours.

   DISCUSSION...Ongoing convection across Severe Thunderstorm Watch 218
   has been slow to develop/organize thus far, but an uptick in
   convective intensity has recently been noted across central Nebraska
   over the past 30-60 minutes. This activity is occurring along the
   northern periphery of a surface instability/theta-e gradient and at
   the northern tip of a strengthening southerly, low-level jet sampled
   by the UEX VWP. While latest high-res model guidance has somewhat
   struggled with the overall placement of convection, guidance
   continues to suggest that upscale growth into a compact, bowing
   cluster/complex will occur as convection evolves (and potentially
   accelerates northeastward) along the aforementioned gradient. 

   While uncertainty remains regarding the exact convective evolution
   over the next 1-2 hours owing to the complexity of cell/convective
   interactions, strong to extreme instability (MLCAPE of 4000-5000
   J/kg indicated by latest objective analysis and the 00z OAX observed
   sounding) along and southeast of this gradient coupled with strong
   effective shear (50-60+ kts) and steep mid-level lapse rates would
   favor an increasing severe threat in this scenario. Severe to
   significant wind gusts up to 75-90 mph (perhaps locally greater in a
   higher-end scenario) remain conditionally plausible pending the
   organization of ongoing convection into an organized cluster. Large
   hail also remains possible with any semi-discrete or embedded
   supercell structures, with additional potential for wind-driven hail
   to accompany any stronger cluster.

   ..Chalmers.. 06/30/2026

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

   ATTN...WFO...FSD...OAX...GID...LBF...

   LAT...LON   41239886 41269914 41409943 41659942 41939927 42389866
               42649826 42769802 42889768 42919723 42779671 42579656
               42309649 42089666 41899692 41629743 41389811 41239886 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
   MOST PROBABLE PEAK WIND GUST...75-90 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN