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Mesoscale Discussion 765
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   Mesoscale Discussion 0765
   NWS Storm Prediction Center Norman OK
   0515 PM CDT Thu May 18 2017

   Areas affected...central and north-central OK into far southern KS

   Concerning...Tornado Watch 235...239...

   Valid 182215Z - 182315Z

   The severe weather threat for Tornado Watch 235, 239 continues.

   SUMMARY...A heightened tornado risk may evolve northwest of the OKC
   metro---dependent on slightly less supportive storm-scale
   interactions resolving in the near term.

   DISCUSSION...Radar mosaic shows as cluster of tornadic supercells
   over northwest OK and supercells with a history of tornadoes over
   central OK near the I-40 corridor in west-central OK.  The
   near-storm environment is forecast to become more favorable for
   strong tornadoes over the next 2 hours as backed east-southeasterly
   low level flow strengthens in the inflow regions of the established
   supercells.  Forecast soundings show 0-1 km SRH over central and
   north-central OK in the 50-75 m2/s2 range (NAM/RAP).  This is in
   contrast to observed KTLX VAD data showing around 150 m2/s2 0-1 km
   SRH with weaker SRH near KVNX.  The short-term models indicate SRH
   will increase and the expectation is for 0-1 km SRH to increase into
   the 150-300 m2/s2 range.  This will likely prove favorable for
   intensifying low-level mesocyclones/increased tornado potential.  As
   storms move farther east, a reservoir of richer low-level moisture
   is located over north-central OK (likely a partial function of
   evapotranspiration due to excessive rains earlier this month).  As
   storms encounter the slightly higher moisture (into the upper 60s
   degrees F) and strengthening low-level shear, an intense longer
   track tornado may develop over central/north-central OK this

   ..Smith.. 05/18/2017

   ...Please see for graphic product...


   LAT...LON   35839885 36359891 36929885 37409849 37389769 37089723
               35939744 35479850 35839885 

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