The SPC is forecasting ...Severe thunderstorms expected over parts of the central Plains this afternoon and evening....   Please read the latest public statement about this event.  View What is a Watch? clip.

   SPC AC 151628

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1128 AM CDT Thu Jun 15 2017

   Valid 151630Z - 161200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
   CENTRAL...SOUTHERN...AND EASTERN KS AND NORTHERN OK...

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   MODERATE RISK FROM PORTIONS OF WEST TX TO NORTHERN OK AND MUCH OF
   KS...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   ENHANCED RISK ACROSS PARTS OF THE CENTRAL AND SOUTHERN PLAINS TO THE
   UPPER MISSISSIPPI VALLEY...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE LOWER MISSISSIPPI VALLEY TO THE TENNESSEE VALLEY REGION...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING
   SLIGHT RISK AREAS ACROSS A BROAD AREA OF THE CENTRAL AND EASTERN
   STATES...

   ...SUMMARY...
   Widespread severe and potentially destructive winds are forecast to
   accompany thunderstorms across parts of central, southern, and
   eastern Kansas into northern Oklahoma this afternoon into the
   evening. Severe storms with hail and wind will also be possible
   across a broad area from parts of West Texas to the upper
   Mississippi Valley, eastward to the Great Lakes region to the
   Southeast.

   ...Central/southern/eastern KS into northern OK...
   Confidence is increasing that supercell development will occur near
   a surface cyclone near/west of the Hays and Hill City KS area in the
   1900-2030Z time frame. Mesoscale convergence will be enhanced near
   this cyclone, marking the approximate intersection of a synoptic
   boundary extending northeastward and a residual outflow boundary
   extending southeastward. Anticipated MLCAPE around 3000-4500 J/kg,
   and little residual capping by mid afternoon on the periphery of a
   midlevel speed maximum, suggest that a cluster of intense updrafts
   will likely evolve with strong outflow winds supported by DCAPE
   around 1500 J/kg.

   Severe hail -- possibly significant -- may accompany incipient
   updrafts. Coalescing outflow should quickly support upscale
   convective growth, with this activity organizing into one or two
   forward propagating MCSs, with leading convective lines exhibiting
   marked bowing characteristics amid 30-40 kt of effective shear.
   Preferential cell development into the high theta-e air south of the
   synoptic boundary will encourage southward propagation, with
   eastward midlevel flow encouraging elongating cold pools/forward
   propagation to the east. This will translate to MCS activity
   spreading into parts of northern OK and eastern/southern KS through
   the evening hours. The latest observational data and CAM guidance
   offer increasing support in a focused corridor of bowing MCSs with
   the likelihood of severe winds -- including significant severe winds
   -- warranting upgrade to Moderate Risk.

   Southeastward spread of the MCSs will likely persist into the
   evening/overnight from parts of central/eastern OK toward western
   parts of the Ozarks, though this activity will weaken as outflow
   outpaces parent convection and inflow static stability increases
   nocturnally.

   ...West Texas into western OK...
   A diurnally sharpening dryline will be the focus for storm
   development this afternoon. Steep midlevel lapse rates support very
   strong buoyancy, and long mid/high-level hodographs suggest that
   severe hail -- some significantly severe -- may accompany this
   activity. The Enhanced area has been extended southwestward.

   ...IA vicinity...
   Southeast of the aforementioned synoptic boundary that will extend
   northeastward into the upper Mississippi Valley, strong instability
   and relatively long midlevel hodographs suggest that splitting
   storms and convective clusters may occur as a large-scale ascent is
   enhanced around a midlevel speed maximum. Isolated to widely
   scattered severe potential will exist with this activity into the
   overnight hours as activity spreads toward the Chicago area.

   ...Lower Mississippi Valley to the TN Valley region...
   Relatively steep midlevel lapse rates above a moist boundary layer
   will support ample instability/DCAPE for widely scattered damaging
   wind potential with storm clusters intensifying along/ahead of a
   southward-advancing outflow boundary. The greatest severe risk will
   extend from the ArkLaMiss region to northwest GA where the greatest
   destabilization is anticipated ahead of the outflow boundary.

   ...Great Lakes region to the Southeast surrounding the lower
   Mississippi Valley/TN Valley vicinity Slight Risk...
   Isolated severe wind/hail may accompany generally pulse convection
   through the early evening. Weak deep shear amid relatively weaker
   midlevel lapse rates, and/or less organized antecedent cold-pool
   formation, should limit severe coverage.

   ..Cohen.. 06/15/2017

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