MESOSCALE DISCUSSION 1770
   NWS STORM PREDICTION CENTER NORMAN OK
   1153 AM CDT SAT SEP 27 2014

   AREAS AFFECTED...AZ...UT

   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 

   VALID 271653Z - 271800Z

   PROBABILITY OF WATCH ISSUANCE...80 PERCENT

   SUMMARY...CHANCES FOR ORGANIZED THUNDERSTORMS POSING SOME RISK FOR
   HIGH WINDS AND HAIL SHOULD INCREASE INTO THE AFTERNOON HOURS ACROSS
   PARTS OF CENTRAL/NORTH-CENTRAL AZ AND SOUTH-CENTRAL UT.

   DISCUSSION...A BROKEN BAND OF VIGOROUS CONVECTION CONTINUES ACROSS
   WESTERN AZ INTO SOUTHWEST UT AHEAD OF A STRONG AND SLOW-MOVING UPPER
   TROUGH/LOW CENTERED OVER EASTERN CA/WESTERN NV. DEEP-LAYER ASCENT
   AIDED BY HEIGHT FALLS AND ENTRANCE REGION OF MID/UPPER JET ROUNDING
   THE EASTERN FLANK OF THE CA LOW WILL SPREAD GRADUALLY EAST ACROSS
   THE BULK OF CENTRAL AZ AND SOUTHERN UT THROUGH THE DAY. CONFLUENT
   LOW-LEVEL FLOW AND RESULTANT MASS AND MOISTURE FLUXES IN RESPONSE TO
   THE UPPER FORCING...IN ADDITION TO OROGRAPHIC
   ENHANCEMENT/LIFT...SHOULD CONTINUE TO SUPPORT THUNDERSTORM
   DEVELOPMENT AMIDST MODEST LAPSE RATES AND INSTABILITY BOOSTED BY
   POCKETS OF STRONGER INSOLATION.

   OVER THE LAST SEVERAL HOURS...OCCASIONALLY LONGER-LIVED CELLS WITHIN
   THE LARGER CONVECTIVE PLUME HAVE EXHIBITED ROTATION AND LEWP
   STRUCTURES INDICATIVE OF A CAPE/SHEAR ENVIRONMENT SUPPORTIVE OF
   SEVERE WEATHER IN THE FORM OF HAIL AND LOCALLY STRONG/DAMAGING
   WINDS. NOW THAT DIURNAL HEATING CYCLE IS UNDERWAY AND DEEP-LAYER
   WIND FIELDS SHOULD CONTINUE TO GRADUALLY STRENGTHEN AS THE TROUGH
   EDGES EAST...THE CHANCES FOR LINE SEGMENTS AND A FEW SUPERCELLS
   SHOULD INCREASE WITH EASTWARD EXTENT AND A NEW WATCH WILL BE NEEDED
   TO ACCOUNT FOR THIS EVOLUTION THROUGH THE AFTERNOON.

   ..CARBIN/MEAD.. 09/27/2014


   ATTN...WFO...GJT...FGZ...SLC...PSR...VEF...

   LAT...LON   37661314 38521261 38651223 38621118 37531061 35961040
               34261077 32721247 32521397 33311348 34411329 36471318
               37661314