SPC AC 231625

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1125 AM CDT Thu Mar 23 2017

   Valid 231630Z - 241200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
   EVENING OVER PARTS OF THE HIGH PLAINS...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
   MN/IA SOUTHWARD INTO TX...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER CENTRAL AND
   SOUTH FL...

   ...SUMMARY...
   Strong to severe thunderstorms are expected from parts of the
   central and southern Plains to the mid Missouri Valley late this
   afternoon into tonight, offering hail and damaging gusts. 
   Thunderstorms with a marginal risk for severe wind and hail are also
   possible today across parts of central and southern Florida.

   A large upper trough is moving eastward across the western states
   today.  Upper-level height falls and associated large-scale forcing
   for ascent will spread into the High Plains this afternoon, helping
   to initiate scattered thunderstorms. Activity will likely form along
   the dryline over western KS and the western TX Panhandle, but also
   in a region of stronger low level warm advection and lift across
   western and central NE.  This scenario will result in a
   several-hour-long period of risk of severe storms capable of large
   hail and damaging winds in these areas.

   ...TX/KS...
   The primary forecast problem today is the limited low-level moisture
   and capping inversion in place.  12z models suggest that storms will
   develop in the 4-6pm window as stronger forcing impinges on the
   dryline.  Forecast soundings suggest this activity will be mainly
   high-based.  This will promote strong downdraft winds and
   occasionally intense updrafts capable of large hail.  Present
   indications are that storms will not progress very far eastward this
   evening before beginning to weaken due to the onset of diurnal
   cooling.

   ...Northwest KS/NE...
   Forcing for convection will be more subtle over NE this afternoon
   and evening.  However, this area will be in proximity to the surface
   warm front and weak cyclogenesis, where stronger low level vertical
   shear is forecast.  Storm mode will likely be more
   discrete-supercell in this area, with the potential for an isolated
   storm or two capable of very large hail or significant wind gusts. 
   Low-level moisture will be limited, which should preclude a more
   substantial tornado threat.

   ...FL...
   Few changes have been made to the Marginal risk for this region. 
   Strong daytime heating and sufficient CAPE will promote scattered
   afternoon thunderstorms today.  Relatively steep low and mid-level
   lapse rates suggest that hail will be possible in the stronger
   cells.  The coverage of severe storms is expected to remain low, so
   will maintain the Marginal categorical risk.

   ..Hart/Coniglio.. 03/23/2017

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