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Mesoscale Discussion 1344
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MD 1344 graphic

   Mesoscale Discussion 1344
   NWS Storm Prediction Center Norman OK
   0701 AM CDT Wed Jul 19 2017

   Areas affected...Parts of eastern Montana and much of the Dakotas

   Concerning...Severe potential...Watch unlikely 

   Valid 191201Z - 191400Z

   Probability of Watch Issuance...20 percent

   SUMMARY...A mostly marginal/relatively sparse coverage severe
   hail/wind risk may continue across parts of south central North
   Dakota and north central South Dakota through 8-9 AM CDT, before
   convective intensities begin to wane during the mid/late morning

   DISCUSSION...Lower/mid tropospheric warm advection continues to
   support an area of convective development, with embedded vigorous
   thunderstorm activity, across parts of east central Montana into the
   western Dakotas.  Aided by strong deep layer shear beneath 40-50 kt
   westerly 500 mb flow, CAPE has become sufficiently large in the
   presence of modestly steep mid-level lapse rates to support at least
   occasional marginally severe hail and gusty surface winds in the
   stronger storms.  This may continue another couple of hours,
   particularly with activity spreading across parts of south central
   North Dakota and north central South Dakota.  However, stronger
   supporting mid/upper forcing for ascent, downstream of the speed
   maximum propagating east northeast of the northern Rockies, is
   expected to support the continued eastward development of storms
   above a progressively drier and potentially cooler/stable boundary
   layer air mass still entrenched across the eastern Dakotas into the
   upper Mississippi Valley by 15-17Z.  As this occurs, it seems likely
   that this convection will undergo appreciable weakening trends.

   ..Kerr/Thompson.. 07/19/2017

   ...Please see for graphic product...


   LAT...LON   48849896 48219739 45549673 44329922 44540182 46370370
               46740475 47210563 48260441 48620252 48849896 

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