SPC AC 181703

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1203 PM CDT Mon Jun 18 2018

   Valid 191200Z - 201200Z

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

   ...SUMMARY...
   Severe thunderstorms with large hail and wind damage will be
   possible across parts of the central Plains Tuesday afternoon and
   evening. Marginally severe thunderstorms may also affect parts of
   the central High Plains and mid to upper Mississippi Valley
   east-southeastward to Virginia.

   ...Central Plains...
   An upper-level low will remain in place across the northern Rockies
   and gradually fill on Tuesday as an upper-level trough moves into
   the central Rockies. At the surface, a cold front is forecast to
   move southward across the central Plains with the moist sector
   located from the lower to mid Missouri Valley extending westward
   across southern Nebraska. Thunderstorm development is expected to
   take place Tuesday afternoon along the front from northwest Kansas
   extending northeastward into southeast Nebraska. Convection is also
   forecast to initiate in the higher terrain from northeast Colorado
   northward into eastern Wyoming with storms developing and moving
   eastward into the central High Plains. As storm coverage increases
   during the late afternoon and early evening, MCS formation will be
   possible across parts of Kansas and Nebraska.

   Forecast soundings for 00Z/Wednesday across the slight risk area
   from North Platte, NE eastward to Grand Island, NE and southward to
   Dodge City, KS generally show impressive thermodynamics coinciding
   with supercell wind profiles (0-6 km shear in the 35 to 45 kt
   range). This combined with 700-500 mb lapse rates around 8 C/km will
   support large hail with any supercell that can develop in the late
   afternoon. Conditions for supercells may be greatest in the western
   part of the slight risk area due to the closer proximity to the
   upper-level trough and stronger deep-layer shear. As convective
   coverage continues to increase in the early to mid evening,
   multicell may become the more favored mode as a line-segment
   organizes and moves east-southeastward across west-central Kansas
   and southern Nebraska. Wind damage would become the favored severe
   threat if a linear MCS can organize.

   ...Mid to Upper Mississippi Valley/Ohio Valley/Mid-Atlantic...
   A broad region of anticyclonic flow will be in place on Tuesday from
   the mid to upper Mississippi and Ohio Valleys extending into the
   Mid-Atlantic. At the surface, a cold front is forecast to move
   southward across the mid to upper Mississippi Valley, Ohio Valley
   and Mid-Atlantic. Thunderstorm development will likely take place
   along much of the front Tuesday afternoon as surface temperatures
   warm. Due to the presence of the upper-level ridge, deep-layer shear
   is forecast to be generally weak across most of the east-central
   U.S. This will make multicell and pulse convection the favored storm
   modes. Areas that locally heat up the most from near and to the
   south of the front, may have the greatest threat for strong
   thunderstorm development. Although some hail will be possible near
   instability maxima, marginally severe wind gusts would be the most
   likely severe threat. The potential for strong wind gusts should be
   maximized during or just after peak heating when low-level lapse
   rates will be steep.

   ...MAXIMUM RISK BY HAZARD...
   Tornado:   2%     - Marginal
   Wind:     15%     - Slight
   Hail:     15%     - Slight

   ..Broyles.. 06/18/2018

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