Storm Prediction Center Mesoscale Discussion 1566

   Mesoscale Discussion 1566
   NWS Storm Prediction Center Norman OK
   1221 PM CDT Sat Jul 05 2025

   Areas affected...Central Montana to northern Wyoming

   Concerning...Severe potential...Watch likely 

   Valid 051721Z - 051945Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Weak convection developing within the northern Rockies
   will intensify over the next few hours as it moves into central
   Montana and northern Wyoming. Severe thunderstorm watch issuance is
   probable early this afternoon as storms pose an increasing severe
   threat.

   DISCUSSION...Latest GOES visible imagery shows clusters of agitated
   cumulus and a few weak thunderstorms developing across far northwest
   WY and within the mountain ranges of central MT. Ascent associated
   with an approaching upper low combined with continued daytime
   heating will promote further development/maturation of convection
   over the next several hours. Latest forecast guidance suggests that
   lingering inhibition should be largely removed as temperatures climb
   into the upper 70s to low 80s. This is expected to occur between
   18-20 UTC and should happen as weak/shallow convection overspreads
   somewhat richer low-level moisture in place at lower elevations
   across central MT to northern WY. This will result in an overall
   intensification of thunderstorms during this time frame. Moderate
   flow associated with the mid-level wave will support effective shear
   values on the order of 30-40 knots. As such, a few supercells appear
   likely with an attendant risk for large hail (possibly as large as 2
   inches). This threat appears most probable along the MT/WY border
   where low-level moisture is relatively higher ahead of a weak
   outflow boundary and dewpoints remain in the mid/upper 50s. With
   time, increasing boundary-layer depth through the late afternoon
   should promote greater cold pool production and gradual upscale
   growth with an increasing severe wind threat. Given these concerns,
   watch issuance is anticipated in the coming hours as convection
   continues to develop.

   ..Moore/Hart.. 07/05/2025

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

   ATTN...WFO...UNR...BYZ...GGW...RIW...TFX...

   LAT...LON   44000610 43620651 43550733 43770801 43980841 44540870
               47160899 47580891 47890861 48100805 48130760 48100700
               47850667 45490585 44920578 44390589 44000610 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN