MESOSCALE DISCUSSION 1294
   NWS STORM PREDICTION CENTER NORMAN OK
   0713 PM CDT TUE JUN 23 2009
   
   AREAS AFFECTED...NERN CO / SERN WY / NEB PANHANDLE
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 502...
   
   VALID 240013Z - 240115Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 502
   CONTINUES.
   
   LARGE HAIL/DMGG WINDS WILL LIKELY REMAIN THE PRIMARY THREATS THROUGH
   THE EARLY EVENING HOURS.  AN ISOLD TORNADO IS POSSIBLE OVER THE NEB
   PANHANDLE.
   
   LATEST SINGLE SITE RADAR IMAGERY SHOWS SEVERAL SUPERCELLS NEAR AND N
   OF THE I-80 CORRIDOR MOVING GENERALLY EWD INTO MORE MOIST/ELY
   UPSLOPE FLOW.  LARGE HAIL ALONG WITH ISOLD DMGG WINDS WILL LIKELY BE
   THE MAIN HAZARDS ASSOCIATED WITH THESE STORMS.  HOWEVER...MODESTLY
   LOW SURFACE TEMP/DEWPOINT SPREADS /15-20 DEG F/ AND HIGHER QUALITY
   BOUNDARY LAYER MOISTURE OVER THE NEB PANHANDLE VICINITY IN
   COMBINATION WITH STRONG LOW LEVEL VEERING PROFILES ARE CONTRIBUTING
   TO POTENTIALLY SUPPORT AN ISOLD TORNADO IF STORMS CAN MAINTAIN A
   MORE DISCRETE MODE.
   
   VISIBLE SATELLITE/RADAR MOSAIC IMAGERY SHOW AN EXPANSIVE ANVIL
   SHIELD AND MORE WIDESPREAD PRECIP HAVE OVERSPREAD MUCH OF NERN CO
   THAN AREAS FURTHER N.  SOMEWHAT CHAOTIC SURFACE PATTERN IS
   DEVELOPING OVER THIS AREA DUE MAINLY TO SURGING OUTFLOW BOUNDARIES
   FROM PRIOR EXISTING AND ONGOING STORMS.
   
   WATER VAPOR IMAGERY DEPICTS A PLUME OF MID LEVEL MOISTURE AND
   IMPLIED ASCENT CONTINUING NEWD OVER THE AREA AHEAD OF A WEAK UPPER
   DISTURBANCE OVER NRN NM.  A GRADUAL INCREASE IN 1 KM SLY FLOW HAS
   BEEN OBSERVED AT GLD IN THE PAST FEW HOURS ACCORDING TO VAD DATA. 
   SHORT TERM MODEL GUIDANCE SUGGESTS THIS WILL CONTINUE TO INCREASE
   DURING THE EVENING HOURS IN RESPONSE TO THE WEAK APPROACHING
   WAVE...POTENTIALLY FAVORING UPSCALE GROWTH INTO ONE OR MORE MCS/S
   LATER THIS EVENING OVER ERN PORTIONS OF THE WW.
   
   ..SMITH.. 06/24/2009
   
   
   ATTN...WFO...LBF...GLD...BOU...CYS...
   
   LAT...LON   39170423 40330471 41920469 42380422 42420305 42140270
               40560268 39420273 39080327 38990360 39170423