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Mesoscale Discussion 1098
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   Mesoscale Discussion 1098
   NWS Storm Prediction Center Norman OK
   1117 AM CDT Fri Jul 20 2018

   Areas affected...Western KY...Far Southern IN...Far Northern Middle
   TN

   Concerning...Severe potential...Watch unlikely 

   Valid 201617Z - 201715Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Isolated damaging wind gusts and hail possible during the
   next few hours. Watch in the near-term seems unlikely but additional
   thunderstorms are anticipated later this afternoon which will likely
   merit watch issuance.

   DISCUSSION...A discrete thunderstorms has developed quickly about 30
   mi east of PAH in western KY. With the stronger forcing for ascent
   still farther west, forcing for the development of this storm is
   hard to determine but remnant outflow from earlier weak convection
   amidst the broadly confluent low-level flow may have provided enough
   lift within the recently uncapped airmass. Low-level airmass across
   the region is very moist (i.e. dewpoints in the mid 70s and 100mb
   mean mixing ratios over 18 g/kg) and unstable (i.e. MLCAPE over 3000
   J/kg per the latest mesoanalysis) and is therefore supportive of
   rapid and strong updraft development. Vertical shear is also strong
   (i.e. effective shear over 50 kt) and is expected to remain strong
   throughout the day. Both of this factor support storm organization
   and persistence. One negative factor the warm low to mid-level
   temperatures and the somewhat drier airmass above 850mb. Entrainment
   of this air could weaken updrafts, especially in the absence of
   greater forcing for ascent and related cooling/moistening of the low
   to mid-levels. As such, expectation for this early development is
   for it to be generally unorganized and sub-severe, largely as a
   result of the relative short updraft duration. Even so, given the
   strength of the shear and instability, observational trends will be
   monitored closely. Additional thunderstorms development is
   anticipated later this afternoon.

   ..Mosier/Hart.. 07/20/2018

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

   ATTN...WFO...LMK...OHX...PAH...MEG...

   LAT...LON   37038843 37758779 37828696 37408631 36848646 36488692
               36418789 36568835 37038843 

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Page last modified: July 20, 2018
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