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Mesoscale Discussion 121
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   Mesoscale Discussion 0121
   NWS Storm Prediction Center Norman OK
   0248 PM CDT Wed Mar 14 2018

   Areas affected...Eastern Nevada...western Utah

   Concerning...Severe potential...Watch unlikely 

   Valid 141948Z - 142215Z

   Probability of Watch Issuance...5 percent

   SUMMARY...Strong thunderstorm activity is expected to develop,
   particularly by the 4-6 PM MDT time frame.  Some storms may become
   accompanied by a risk for strong gusty winds and perhaps severe

   DISCUSSION...Ahead of large-scale upper troughing progressing inland
   across the Pacific coast, insolation beneath a cold (and cooling)
   mid-level environment is contributing to boundary layer
   destabilization across much of the Great Basin.  Although this may
   remain generally weak to modest in magnitude, it may become
   maximized in corridor across far eastern Nevada into the vicinity of
   the Wasatch mountains, within a plume of relatively higher
   precipitable water (in excess of .5 inches).  Model output indicates
   that this will coincide with strengthening forcing for large-scale
   ascent associated with a short wave trough now turning across and
   northeast of the southern Sierra Nevada.  

   Scattered deepening convective development is ongoing, with isolated
   thunderstorms already in the process of forming.  It appears that
   this may continue another couple of hours, before a more substantive
   increase in coverage and intensity commences during the 22-00Z time
   frame.  Activity will tend to move northeastward in the presence of
   southwesterly deep layer mean flow in excess of 40 kt (perhaps
   approaching 50 kt).  

   Although the boundary layer may not be particularly deeply mixed,
   downward mixing of higher momentum in downdrafts may still
   contribute to strong surface gusts at least approaching severe
   limits.  It does appear that vertical shear could support the
   evolution of isolated supercell structures, which would provide the
   most appreciable risk for any hail reaching severe limits.  A
   tornado may not be completely out of the question, though this
   potential still seems rather low.

   ..Kerr/Hart.. 03/14/2018

   ...Please see for graphic product...


   LAT...LON   39691452 41101365 41071204 38441285 37541422 37901485

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