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Mesoscale Discussion 1447
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   Mesoscale Discussion 1447
   NWS Storm Prediction Center Norman OK
   0813 PM CDT Fri Jul 12 2019

   Areas affected...Parts of southern Montana

   Concerning...Severe potential...Watch unlikely 

   Valid 130113Z - 130315Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Isolated severe storms are expected to persist across the
   area into the early evening hours. Large hail and damaging wind
   gusts are expected to be the primary threats with the more intense
   storms. Given the isolated nature of the severe threat, a WW
   issuance appears unlikely.

   DISCUSSION...Multicellular, to occasionally transient supercellular
   storms, have been intensifying over the past few hours across
   portions of southern MT, where buoyancy has been gradually
   increasing (with up to 1000 J/kg MLCAPE noted). A well-mixed
   boundary layer is in place, with a dry sub-cloud layer extending to
   nearly 3000 m above ground level, suggesting that storms will be
   high based in nature. A roughly dry-adiabatic layer (with subsequent
   steep lapse rates of 7.5 to over 8.5 C/km) extends from the surface
   up to about 500 mb, suggesting that efficient precipitation
   evaporation/cooling should take place with the heavier cell cores.
   While overall MLCAPE is relatively marginal overall, much of the
   aforementioned CAPE is confined above the freezing level, suggesting
   that at least a few marginally severe hail stones are possible with
   the stronger, more organized updrafts. 

   The overall lack of higher instability across the area will temper
   the severe threat to a degree, with severe hail/wind being
   relatively isolated in nature, and a WW issuance is not expected.

   ..Squitieri/Hart.. 07/13/2019

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

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

   LAT...LON   45000925 45511155 46121212 46601202 47161109 47120949
               47020789 46580674 45850591 44990768 45000925 

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Page last modified: July 13, 2019
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