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Mesoscale Discussion 694
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   Mesoscale Discussion 0694
   NWS Storm Prediction Center Norman OK
   1144 AM CDT Thu May 11 2017

   Areas affected...Northern and Eastern Oklahoma...Southern Kansas

   Concerning...Severe potential...Watch likely 

   Valid 111644Z - 111915Z

   Probability of Watch Issuance...80 percent

   SUMMARY...A severe threat is expected to develop across northern and
   eastern Oklahoma over the next couple of hours. The storms should
   expand in coverage affecting southern Kansas as well. Large hail and
   wind damage will be the primary threats initially but an isolated
   tornado threat may also develop as storm coverage expands. Weather
   watch issuance will likely be needed across the region over the next
   hour or so.

   DISCUSSION...The latest surface analysis shows a 1008 mb low over
   north-central Oklahoma with a boundary extending east-southeastward
   from the surface low across northern and eastern Oklahoma. Surface
   dewpoints along this boundary are in the mid to upper 60s F and
   moderate instability is in place with MLCAPE values estimated by the
   RAP in the 1500 to 2500 J/kg range. As surface temperatures continue
   to increase into the mid to upper 70s F and as low-level convergence
   becomes more focused along the boundary, convective initiation is
   expected to take place across northern Oklahoma over the next hour
   or two.

   At mid-levels, an upper-level low is located across far northwest
   Oklahoma according to water vapor imagery with a 60 to 75 kt
   mid-level jet over southern Oklahoma. The mid-level jet was helping
   to enhance lift and create strong deep-layer shear profiles across
   Oklahoma which will support supercell development. Cold air aloft
   (500 mb temperatures of -16 to -18C) along with 700-500 mb lapse
   rates near 8.0 C/km will be favorable for large hail with rotating
   updrafts. As cells increase in coverage and downdrafts mature early
   this afternoon, a wind damage threat is also expected to develop.
   Although low-level shear is relatively weak across northern
   Oklahoma, a brief tornado can not be ruled out mainly with any
   supercell that becomes dominant.

   ..Broyles.. 05/11/2017

   ...Please see for graphic product...


   LAT...LON   34299567 34829629 35349745 35649834 36159956 36679989
               37439941 37799818 37799663 37269524 36739469 35589449
               34499459 34299567 

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