MESOSCALE DISCUSSION 2180
   NWS STORM PREDICTION CENTER NORMAN OK
   0240 PM CDT MON AUG 18 2003
   
   AREAS AFFECTED...NERN CO
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL 
   
   VALID 181940Z - 182145Z
   
   ISOLATED LARGE HAIL/DAMAGING WINDS WILL BE POSSIBLE THIS AFTERNOON
   INTO EARLY EVENING WITH THE STRONGEST CELLS. A WW WILL BE ISSUED
   SHORTLY.
   
   RECENT TRENDS IN REGIONAL RADAR IMAGERY SHOWS TSTMS INCREASING IN
   COVERAGE AND INTENSITY LARIMER COUNTY SWD ALONG THE I-25 CORRIDOR
   INTO EL PASO COUNTY. STEEP MID-LEVEL LAPSE RATES OVERSPREADING THE
   AREA FROM THE W COUPLED WITH SURFACE TEMPERATURES NOW WARMING INTO
   THE 80S HAS ALLOWED THE AIRMASS TO THE E OF THESE STORMS TO BECOME
   SLIGHTLY UNSTABLE WITH MLCAPES OF 500-1000 J/KG. FORCING FOR ASCENT
   AHEAD OF SHORTWAVE TROUGH/VORTICITY MAX ROTATING AROUND PRIMARY
   MID-LEVEL CIRCULATION CENTER APPEARS TO BE LARGELY RESPONSIBLE FOR
   THE CURRENT INCREASE ON ACTIVITY OVER THE PAST HOUR OR SO. 
   
   ONGOING STORMS SHOULD CONTINUE TO INTENSIFY THROUGH THE REMAINDER OF
   THE AFTERNOON AS THEY MOVE EWD INTO INSTABILITY AXIS DEVELOPING OVER
   THE LOWER ELEVATIONS. MODESTLY STRONG MID-LEVEL FLOW /30-35KTS AT
   500MB/ ATOP LOW-LEVEL ELY/NELY WINDS IS RESULTING IN 35-40KTS OF
   DEEP-LAYER SHEAR. ALTHOUGH THE INSTABILITY IS SOMEWHAT LIMITED...THE
   FAVORABLE SHEAR SUGGESTS THE POTENTIAL FOR SUPERCELLS WITH LARGE
   HAIL BEING THE PRIMARY SEVERE WEATHER THREAT. 
   
   A WW WILL BE ISSUED SHORTLY FOR THE AREA.
   
   ..MEAD.. 08/18/2003
   
   
   ATTN...WFO...GLD...PUB...BOU...CYS...
   
   39660506 40770502 41370442 41150301 40310209 38660238
   38500452