Storm Prediction Center Mesoscale Discussion 2131

   Mesoscale Discussion 2131
   NWS Storm Prediction Center Norman OK
   0140 PM CDT Fri Sep 26 2025

   Areas affected...southern Arizona

   Concerning...Severe potential...Severe Thunderstorm Watch likely 

   Valid 261840Z - 261945Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Thunderstorms capable of large hail and damaging wind
   possible this afternoon.

   DISCUSSION...A secondary wave of thunderstorm development is ongoing
   across the low deserts from Tuscon to areas south of the Phoenix
   Metro. A wave of early afternoon/morning convection continues off to
   the north of Phoenix, which produced a few instances of 1-1.75 inch
   hail. Behind this earlier wave, skies were partly sunny south of
   Phoenix which encouraged air mass recovery, with temperatures
   heating into the mid 80s to 90s and low to mid 60s dew points
   yielding MLCAPE around 1000-1500 J/kg. Deep layer shear around 30-40
   kts for organization remains in place across southern Arizona. This
   is also well sampled by the 18z sounding from TUS in addition to
   steep low to mid-level lapse rates around 7 C/km.

   Afternoon development may support a more widespread severe risk into
   the afternoon, with potential for large hail and damaging wind owing
   to the steep lapse rates, ample shear, and favorably unstable
   profiles. A Severe Thunderstorm Watch may be needed to cover this
   threat in the coming hours.

   ..Thornton/Mosier.. 09/26/2025

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

   ATTN...WFO...TWC...FGZ...PSR...

   LAT...LON   31901096 31861077 31781040 31791013 31870987 32010960
               32260945 32630939 32820952 33491044 33891104 34161152
               34301183 34321227 33941276 33621283 33411263 33331252
               33061234 32761211 32271163 31901096 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN