Mesoscale Discussion 0770
   NWS Storm Prediction Center Norman OK
   0600 PM CDT Sat May 30 2020

   Areas affected...western Montana

   Concerning...Severe potential...Watch unlikely 

   Valid 302300Z - 310030Z

   Probability of Watch Issuance...5 percent

   SUMMARY...A few strong to severe thunderstorms are possible across
   western Montana into this evening. Marginally severe wind/hail are
   the main threats, but a watch issuance is unlikely.

   DISCUSSION...A vigorous upper low is moving northward over northern
   California helping to displace an upper-level ridge over the
   Intermountain West and lowering heights across the region. Broad
   large-scale ascent is overspreading much of the Pacific Northwest
   and into northern Rockies. However, with the strongest forcing for
   ascent west of the northern Rockies, terrain-induced circulations
   and temperatures rising to the upper 80s to low 90s F with dewpoints
   in the 50s F have helped initiate convection over western Montana
   and vicinity. Steep mid-level lapse rates (8+ C/km) per mesoanalysis
   and forecast soundings and effective bulk shear of 30-40 knots
   indicate the potential for stronger, organized updrafts capable of
   large hail. Additionally, relatively high LCLs and steep low-level
   lapse rates indicate the potential for downdrafts with DCAPE in
   excess of 1200 J/kg per mesoanalysis and forecast soundings. 

   Storms may persist beyond sunset. However, the storm environment
   becomes less conducive over northern/central Montana, which is north
   of the lifting surface front and within higher heights/warmer
   mid-level temperatures. Overall, the severe threat is likely to
   remain marginal and isolated.

   ..Nauslar/Thompson.. 05/30/2020

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

   ATTN...WFO...BYZ...TFX...MSO...

   LAT...LON   47721154 47421108 46611046 46031053 45821085 45941148
               46051217 46271422 46791444 47391428 47851381 48081335
               48121275 47991210 47721154