MESOSCALE DISCUSSION 0483
   NWS STORM PREDICTION CENTER NORMAN OK
   1256 PM CDT TUE APR 16 2013
   
   AREAS AFFECTED...MUCH OF SRN OH/SERN IND/NERN KY/PART OF WRN WV
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 161756Z - 161930Z
   
   PROBABILITY OF WATCH ISSUANCE...40 PERCENT
   
   SUMMARY...POTENTIAL EXISTS FOR TSTMS MOVING EWD INTO AND/OR
   DEVELOPING ACROSS THE MIDDLE-UPPER OH VALLEY THIS AFTERNOON WILL
   INTENSIFY AND BECOME SEVERE.  WW ISSUANCE IS POSSIBLE BY MID-LATE
   AFTERNOON WITH DAMAGING WINDS AND HAIL BEING THE PRIMARY THREATS.
   
   DISCUSSION...TRENDS IN LATE MORNING-EARLY AFTERNOON SURFACE ANALYSES
   ACROSS THE OH VALLEY SHOWED A COLD FRONT ADVANCING EWD INTO NORTH
   CENTRAL TO WEST CENTRAL OH...AND FAR SWRN IND. THE TRAILING PORTION
   OF THIS BOUNDARY HAD REMAINED GENERALLY QUASI-STATIONARY FROM FAR
   SRN IL THROUGH NWRN AR AND SOUTH CENTRAL OK.  OBJECTIVE ANALYSES
   INDICATED DESTABILIZATION UNDERWAY ACROSS THE WARM SECTOR WHICH
   EXTENDED INTO THE MIDDLE AND UPPER PORTIONS OF THE OH VALLEY WITH
   SURFACE DEWPOINTS INTO THE LOWER 60S BENEATH THE ERN EXTENT OF THE
   STEEPER MIDLEVEL LAPSE RATES /7-7.5 C PER KM/. DESPITE GRADUAL
   HEIGHT RISES AND SOME MIDLEVEL WARMING...FURTHER LOW LEVEL
   MOISTENING SHOULD PROVE SUFFICIENT IN SUPPORTING A MODERATELY
   UNSTABLE ENVIRONMENT ACROSS MOST OF THE DISCUSSION AREA BY PEAK
   HEATING FOR STORMS TO BECOME SURFACE BASED.
   
   MEANWHILE...A CLUSTER OF PERSISTENT TSTMS UPSTREAM OVER CENTRAL
   IND...CENTRAL IL TO FAR EAST CENTRAL MO IS LOCATED N OF THE SURFACE
   FRONT AND LIKELY ROOTED AROUND 850 MB PER RECENT RAP SOUNDINGS. THIS
   ACTIVITY APPEARS TO BE SUPPORTED BY LOW LEVEL WAA AND ASCENT
   ATTENDANT TO A SUBTLE MIDLEVEL IMPULSE. 
   
   TRENDS IN THE HRRR THIS MORNING AND THE 12Z 4 KM WRF-NSSL...DESPITE
   TIMING DIFFERENCES IN THE LATTER MODEL...SUGGEST THE IND/IL STORMS
   COULD DEVELOP A COLD POOL AS THIS ACTIVITY REACHES SERN IND INTO SRN
   OH. ALTHOUGH LOW LEVEL WINDS ARE WEAKENING IN THE DISCUSSION
   AREA...50 KT WLY MIDLEVEL WINDS WILL MAINTAIN SUFFICIENT BULK SHEAR
   FOR STORMS TO BECOME ORGANIZED WITH ACTIVITY EVENTUALLY TRACKING
   TOWARD THE ESE PRODUCING A THREAT FOR PRIMARILY DAMAGING WINDS AND
   HAIL.
   
   ..PETERS/KERR.. 04/16/2013
   
   
   ATTN...WFO...PBZ...RLX...CLE...JKL...ILN...LMK...IND...
   
   LAT...LON   39168572 39928454 40688239 40518121 39578055 38818121
               38158229 38188357 38388531 39168572