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Mesoscale Discussion 1160
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   Mesoscale Discussion 1160
   NWS Storm Prediction Center Norman OK
   1100 AM CDT Tue Jun 27 2017

   Areas affected...Portions of central and southern New England

   Concerning...Severe potential...Watch possible 

   Valid 271600Z - 271800Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Thunderstorms are expected to develop/increase in coverage
   through the afternoon. Hail up to an inch in diameter and isolated
   thunderstorm wind damage may occur with the strongest thunderstorms.
   A watch is currently not anticipated, but conditions will continue
   to be monitored.

   DISCUSSION...A shortwave trough moving across the eastern Great
   Lakes will continue to move east across New England this afternoon.
   Ahead of this trough, widespread cloud cover across New England has
   kept surface temperatures from quickly warming this morning. These
   relatively cool temperatures (low-to-mid 60s), coupled with surface
   dew point temperatures in the mid-50s to low-60s, have kept
   instability modest across New England. However, recent satellite
   imagery suggests thinning and/or breaks in the cloud cover
   developing across eastern New York and spreading east through the
   early afternoon. These breaks should allow for a modest increase in
   instability and the development of isolated to scattered

   Given the modest instability, thunderstorms are expected to remain
   fairly low-topped, limiting the overall large-hail potential despite
   mid-level-lapse rates steepening to between 7-8 C/km. However,
   deep-layer shear values on the order of 50-60 kt will support
   supercell-like structures, which would tend to favor development of
   hail at least up to an inch in diameter. Additionally, despite weak
   low-level lapse-rates, the overall strength of the mid-level flow
   may support isolated thunderstorm wind damage.

   Current thinking is that the limited instability and low-topped
   nature to the convection will result the majority of hail to remain
   below an inch in diameter, and that any wind damage potential would
   remain fairly isolated, precluding the need for a watch. However, if
   instability is greater than currently expected or thunderstorm
   organization greater than expected, a watch could eventually be

   ..Marsh/Guyer.. 06/27/2017

   ...Please see for graphic product...


   LAT...LON   41597463 42887460 44137252 44997038 44976934 44476875
               43326943 42857023 42437019 42186998 41406942 40986998
               40717135 40507253 40437325 41597463 

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