SPC AC 011724

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1224 PM CDT Sun Oct 01 2017

   Valid 021200Z - 031200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS UPPER MS VALLEY
   TO CENTRAL HIGH PLAINS...

   ...SUMMARY...
   Isolated severe storms are possible from the central High Plains to
   the Upper Mississippi Valley late afternoon and evening on Monday.

   ...Synopsis...
   A highly amplified upper pattern will persist with a longwave trough
   in the West and ridge across the East. Two primary shortwave
   impulses are expected to evolve, one along the northern Great Plains
   international border and the other from the Great Basin to central
   High Plains. At the surface, a quasi-stationary front modulated by
   convective outflow on D1 should oscillate north and then again south
   over the central Great Plains and Upper MS Valley. 

   ...Central High Plains to Upper MS Valley...
   Primary change is to shift the Marginal risk area to the southwest
   and expand west over parts of the central High Plains. Considered a
   Slight risk over parts of NE, but low confidence in the degree of
   surface-based storm development yields deferral on an upgrade to
   later outlooks.

   Fast mid-level southwesterlies will remain prevalent along and west
   of the quasi-stationary front with near-neutral to weak mid-level
   height rises expected over the frontal zone through much of the
   period. However, low-level warm advection/isentropic ascent across
   the boundary will strengthen Monday evening as a southerly low-level
   jet intensifies in response to the ejecting Great Basin/Rockies
   shortwave trough. This should result in increasingly widespread
   convection on the cool side of the front within an anafrontal
   regime. Appreciable MUCAPE will likely be confined near the front
   with increasingly scant amounts to the north/west. However, amid
   steep mid-level lapse rates within a remnant elevated mixed layer
   and very strong speed shear, instability should remain sufficient
   for a risk of severe hail. Surface-based storm development appears
   unlikely, but is most possible along the front in NE where the
   CAPE/shear environment would conditionally favor a risk for all
   hazards.

   ..Grams.. 10/01/2017

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   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z