SPC AC 241616

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1116 AM CDT Wed May 24 2017

   Valid 241630Z - 251200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THROUGH THIS
   AFTERNOON AND EVENING ACROSS MUCH OF THE CAROLINAS AND EASTERN
   GEORGIA INTO THE CENTRAL FLORIDA PENINSULA...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS SURROUNDING
   AREAS OF THE CENTRAL AND SOUTHERN APPALACHIANS...EASTERN GULF AND
   SOUTH ATLANTIC COAST STATES...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS
   SURROUNDING AREAS OF THE OHIO VALLEY AND SOUTHEAST...

   ...SUMMARY...
   Severe thunderstorm activity may impact much of the south Atlantic
   Seaboard today, accompanied by a risk for tornadoes, potentially
   damaging wind gusts, and some hail.

   ...Synopsis...
   Large-scale mid/upper troughing appears likely to slowly shift east
   of the Mississippi Valley through the remainder of this period, as a
   significant upstream trough digs through portions of the northern
   Plains/Rockies and intermountain region.  The orientation of the
   lead troughing may continue to take on more of a neutral to slightly
   negative tilt, as significant smaller scale impulse pivots through
   its base, east of the lower Mississippi Valley through the
   Southeast.  Farther north, an embedded lower/mid tropospheric
   cyclone is forecast to turn east of the middle Mississippi Valley
   through the lower Ohio Valley, and support further deepening of an
   occluding surface low to the west of the central Appalachians.

   Seasonably high moisture content air is initially suppressed to the
   south, off south Atlantic coastal areas through parts of southern
   Georgia/northern Florida into the eastern Gulf of Mexico, associated
   with a prior front.  However, model output indicates a substantive
   moisture return through the warm sector today, across eastern
   Georgia and much of the Carolinas.  This is expected to contribute
   to moderately large CAPE, in the presence of strengthening southerly
   low-level flow (30-50 kt at 850), as 50-70 cyclonic 500 mb flow
   overspreads the region.

   ...Southeast...
   Considerable strong/severe storm development is now well underway in
   the presence of increasing instability and shear, along the
   southeastern slopes of the southern Appalachians, southward through
   parts of eastern Alabama/central and southern Georgia and northern
   Florida.  The potential negative influence of a large thunderstorm
   cluster, now near/west through north of Jacksonville Fl area, on
   activity to the northwest remains at least somewhat unclear. 
   However, a general increase in thunderstorm development and
   intensity still seems probable through this evening, near the
   strengthening 850 jet, from parts of the Florida peninsula into the
   Carolinas.

   Activity now near the southern Appalachians appears aided by forcing
   in the exit region of the mid/upper jet, and may eventually
   merge/consolidate with activity to the south, while spreading east
   northeastward to the lee of the southern Appalachians through early
   evening.  This forcing is expected to track along a stalling or
   slowly retreating frontal zone across the southern Appalachians
   piedmont, which may provide a focus for storms capable of producing
   tornadoes, in addition to potentially damaging wind gusts.

   ...Ohio Valley into western slopes of central Appalachians...
   Delineation of severe probabilities is somewhat unclear across the
   region beneath the evolving mid/upper system.  The mid-level cold
   core appears likely to dig well to the southwest of the central
   Appalachians (Ozark Plateau through upper portions of the lower
   Mississippi Valley) through the daytime hours, and an initial area
   of convectively generated precipitation is now overspreading  much
   of eastern Kentucky and Tennessee, into the central Appalachians.

   It still seems at least possible that clearing beneath the mid-level
   dry slot in the wake of the lead convection will provide potential
   for substantive destabilization by late afternoon, as it spreads
   toward the central Appalachians.  Followed by increasing forcing for
   ascent associated with a mid-level cyclonic vorticity center now
   redeveloping across and northeast of the Nashville TN area, given
   any appreciable boundary layer destabilization, the environment may
   become conducive to low topped supercells.

   There also may be at least some short term severe weather potential
   in the vicinity of one initial surface low center near Cincinnati
   OH.  For details refer to SPC Mesoscale Discussion 827.

   ..Kerr/Cook.. 05/24/2017

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z