@NWSSPC  12:30pm CDT #SPC Day2 Outlook Enhanced Risk: from oklahoma into the ozark platea.
Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1229 PM CDT Thu Apr 27 2017
   Valid 281200Z - 291200Z
   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM OKLAHOMA
   INTO THE OZARK PLATEAU AND LOWER OHIO VALLEY...
   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM A PORTION OF
   THE SOUTHERN PLAINS INTO THE OHIO VALLEY...
   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   SLIGHT RISK...
   ...SUMMARY...
   Numerous severe storms remain possible on Friday from a portion of
   the southern Plains into the lower to middle Mississippi, Ohio and
   Tennessee Valleys.
   ...Southern Plains through lower Mississippi and Ohio Valleys...
   Not much change from earlier thinking regarding the synoptic
   features for this outlook with some details concerning some threats
   still nebulous at this time.  Embedded within a broad synoptic
   trough, a lead shortwave trough initially over the central Plains
   will deamplify and weaken as it moves into the Great Lakes area.
   Farther upstream an upper trough will amplify near the Four Corners
   region. At the surface a warm front will develop northward through
   north TX and OK eastward into the OH Valley, while a cold front
   advances south through the central Plains.  A dryline will evolve
   across west-central into northwest TX or southwest OK during the
   afternoon where it will intersect the warm/quasi-stationary front.
   Height rises will occur from the southern Plains to the TN Valley in
   wake of the lead shortwave trough that will move toward the Great
   Lakes. Limited synoptic forcing for ascent and convective inhibition
   resulting from eastward expansion of the EML should limit
   thunderstorm initiation during the day over most of the warm sector.
   A convective signal is apparent in the last 4 runs of the ECMWF and
   more recently in the GFS for isolated to widely scattered
   thunderstorms during the late afternoon/evening near the OH-MS river
   confluence and lower OH Valley.  Forecast soundings show a
   conditional environment very favorable for severe thunderstorms
   within the envelope of considerable 500-mb height rises.  There is
   large uncertainty whether storms will develop, but if storms become
   sustained, a significant risk for hail/tornadoes may accompany the
   cellular activity.  Farther west in the southern Plains, some chance
   for isolated thunderstorm initiation will exist at the intersection
   of dryline and front over northwest TX into southwest OK by late
   afternoon.  Large CAPE and strong vertical shear will favor a
   conditional risk for supercells with very large hail and a few
   tornadoes should such initiation occur. Rich low-level moisture with
   large CAPE but strong convective inhibition will reside south of the
   warm/quasistationary front. The best chance for widespread
   thunderstorm initiation will occur during the evening and overnight
   from OK into northern AR, MO and into the TN and OH valleys as a
   strong, broad low-level jet enhances convergence and isentropic
   ascent within the strengthening baroclinic zone. Strong vertical
   shear profiles and instability will support organized storms
   including supercells with large to very large hail and damaging wind
   the main threats, though a few tornadoes may also occur with any
   surface-based storms developing closer to the warm front.
   ..Smith.. 04/27/2017
