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Mesoscale Discussion 1013
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   Mesoscale Discussion 1013
   NWS Storm Prediction Center Norman OK
   0232 PM CDT Tue Jun 13 2017

   Areas affected...North-central Nebraksa...East-central South
   Dakota...Southeast North Dakota

   Concerning...Severe potential...Watch likely 

   Valid 131932Z - 132030Z

   Probability of Watch Issuance...95 percent

   SUMMARY...A severe threat is likely to develop this afternoon from
   central Nebraska north northeastward into southeastern North Dakota
   and west-central Minnesota. Large hail and wind damage will be
   possible after cells initiate but a tornado threat should also
   develop as cells mature. A weather watch will likely be needed
   across the region by 20Z.

   DISCUSSION...The latest surface analysis shows a 999 mb low over
   north-central Nebraska with a cold front extending
   south-southwestward from the low. Surface winds are backed across
   much of eastern South Dakota where low-level moisture is maximized
   with surface dewpoints in the lower to mid 70s F. This is
   contributing to a pocket of strong instability in eastern South
   Dakota and northeastern Nebraska where the RAP is estimating MLCAPE
   values in the 3000 to 4000 J/kg range. In addition, water vapor
   imagery shows a shortwave trough over the central and northern
   Rockies. A vorticity maxima associated with the shortwave trough is
   analyzed by the RAP across western Nebraska. As this feature moves
   across the central and northern Plains this afternoon, large-scale
   ascent will support the development of numerous thunderstorms along
   the cold front and to the northeast of the surface low into
   southeastern North Dakota and west-central Minnesota.

   Forecast soundings along this corridor show favorable wind profiles
   for supercells with strong speed shear in the low to mid-levels with
   0-6 km shear forecast to be in the 35 to 45 kt range. This combined
   with very steep mid-level lapse rates exceeding 8.5 C/km across
   parts of the MCD area will be favorable for large hail with
   supercells. Hailstones of greater than 2 inches in diameter will be
   possible within the strongest cores. Cells that do not form into
   supercells may still be severe with a threat for hail and wind
   damage. As the low-level jet increases in strength late this
   afternoon and as the storms become mature, a tornado threat will
   also be possible across the MCD area. The most favorable area for
   tornado development could be across northeastern South Dakota,
   southeastern North Dakota and west-central Minnesota.

   ..Broyles/Hart.. 06/13/2017

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

   ATTN...WFO...MPX...FGF...FSD...OAX...ABR...GID...BIS...LBF...
   UNR...

   LAT...LON   44779673 43899777 42009819 41229878 40989984 41040067
               41620126 42560114 44610060 45909999 46979834 47239723
               47129619 46629560 45949546 45129631 44779673 

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Page last modified: June 13, 2017
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