SPC AC 021935

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0235 PM CDT Sun Jul 02 2017

   Valid 022000Z - 031200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
   CENTRAL HIGH PLAINS...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   SLIGHT RISK OVER A LARGER PART OF THE GREAT PLAINS...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PORTIONS OF
   THE MIDWEST...

   ...SUMMARY...
   Scattered strong thunderstorms will impact parts of the Great Plains
   and Midwest.  Large hail and strong to severe winds are possible
   with this activity.

   ...20Z Outlook Update...
   Minimal changes were made to the previous outlook for this update. 
   Models and observations suggest a relative minimum in convective
   activity across parts of northern Iowa - probably as a result of
   subtle height rises and difluent surface flow in portions of the
   region.  The marginal area across northern Illinois/southern
   Wisconsin and adjacent areas of Lake Michigan was confined/trimmed
   some to reflect ongoing convective activity, which has recently
   experienced an uptick near Milwaukee.

   Farther west, storm initiation across the High Plains remains
   likely, along with evolution into linear clusters and
   forward-propagating MCSs later in the afternoon and early evening,
   especially across the slight risk area in western Nebraska and
   Kansas.  The Marginal area in north-central New Mexico was nudged
   westward some to include isolated thunderstorms developing in that
   region that may pose a marginal hail/wind risk.  Isolated/marginally
   severe thunderstorms also remain possible in portions of Oklahoma
   and western Arkansas into the evening.

   ..Cook/Kerr.. 07/02/2017

   .PREV DISCUSSION... /ISSUED 1107 AM CDT Sun Jul 02 2017/

   ...Plains States...
   Multiple clusters of afternoon thunderstorms are forecast to affect
   portions of the Plains region.  Forcing mechanisms for this
   convection are weak and subtle, but the 12z CAM consensus suggests
   the most likely area of organized activity will be across parts of
   western NE/KS where slightly stronger northwest flow aloft and full
   sunshine will enhance the potential.  Storms that form over the high
   Plains will drift eastward into the SLGT risk area, posing a risk of
   locally damaging wind gusts and hail for several hours this evening.

   Farther east in eastern NE, western IA, and eastern KS, Considerable
   cloud cover is present this morning.  This will lead to slightly
   lower CAPE values and weaker low level lapse rates.  Given the
   already-weak vertical shear profiles, it appears unlikely that
   storms would exhibit more than a marginal severe threat.

   ...OK...
   A remnant MCV over western OK will track eastward and likely
   re-initiate thunderstorms this afternoon.  Strong instability will
   be present in this region, along with some mesoscale organization
   from the remnant circulation.  This may result in isolated severe
   storms capable of damaging winds and hail.

   ...WI...
   A surface cold front is moving southward across WI.  Thunderstorms
   are expected to form along the front this afternoon, spreading into
   northeast IL before weakening.  The strongest storms may pose a risk
   of gusty winds and hail, but the overall coverage of severe storms
   is expected to remain marginal.

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