SPC AC 051726

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1226 PM CDT Thu Oct 05 2017

   Valid 061200Z - 071200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SOUTHWEST KS
   AND OK PANHANDLE...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS KS AND SOUTHEAST
   CO TO EASTERN NM AND TX PANHANDLE...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LOWER MO VALLEY
   TO SOUTHERN HIGH PLAINS...

   ...SUMMARY...
   Scattered severe storms are likely from parts of Kansas and
   southeast Colorado south across the Texas Panhandle into eastern New
   Mexico during the late afternoon and evening on Friday. Very large
   hail, a few tornadoes, and damaging winds will be possible.

   ...Synopsis...
   A shortwave trough will amplify as it progresses east from the Great
   Basin into the central Great Plains through early Saturday. A belt
   of strengthening mid-level west-southwesterlies will accompany this
   amplification, becoming centered over the southern High Plains to
   Lower MO Valley by Friday evening. Lee surface cyclone should deepen
   in the Raton Mesa vicinity with a quasi-stationary front extending
   northeast across KS into southeast NE. This boundary will accelerate
   southeast as a cold front Friday evening as the shortwave trough and
   a Pacific cold front ejects onto the Plains. 

   ...Central and southern Great Plains...
   Have upgraded to Enhanced risk and expanded/shifted Slight/Marginal
   risk areas west/north. 

   Rich boundary-layer moisture characterized by 60s surface dew points
   will reside south of the aforementioned front. Unlike a typical
   widespread severe day in the Plains, mid-level lapse rates should
   remain modest outside of the central High Plains. As such, diabatic
   heating will be necessary to boost buoyancy and as surface
   temperatures warm into the 80s, MLCAPE will reach 1000-2000 J/kg. 

   Mid-level height falls/DCVA will initially overspread the High
   Plains portion of the region, aiding in scattered storms developing
   near the surface cyclone late afternoon/early evening. Convective
   coverage should increase during the evening east along the KS
   portion of the front, and south along the impinging Pacific cold
   front over eastern NM and northwest TX. 

   40-50 kt effective shear and increasingly elongated hodographs with
   very strong mid/upper-level speed shear will support several
   supercells, a couple of which may become long-track/intense in the
   southwest KS to northern TX Panhandle vicinity. Significant severe
   hail appears to be the primary hazard, especially given the highly
   favorable wind profiles in the hail growth zone. A couple-hour
   window will also exist for a few tornadoes. However, somewhat veered
   and initially moderate low-level winds should be limiting factors to
   greater coverage of the tornado threat. Given the strength of the
   forcing within the frontal zones, upscale growth into bowing line
   segments appears probable within a few hours of initiation, yielding
   a predominant mix of severe wind/hail. Towards midnight, storm
   intensity should rapidly wane owing to minimal instability east of
   the TX Big Country to eastern KS.

   ..Grams.. 10/05/2017

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