MESOSCALE DISCUSSION 0638
   NWS STORM PREDICTION CENTER NORMAN OK
   0718 PM CDT MON MAY 13 2013
   
   AREAS AFFECTED...NRN/WRN MT...CENTRAL ID...FAR NERN ORE...AND FAR
   SERN WA
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 159...
   
   VALID 140018Z - 140145Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 159
   CONTINUES.
   
   SUMMARY...THE GREATEST SEVERE WEATHER THREAT ACROSS WW 159 INTO THE
   EVENING WILL BE IN CENTRAL ID TO WRN MT.  MEANWHILE...ADDITIONAL
   HIGH BASED STORMS HAVE DEVELOPED E OF WW 159...WITH THE POTENTIAL TO
   PRODUCE DAMAGING WINDS AND A HAIL THREAT.  THE OVERALL COVERAGE OF
   THIS LATTER AREA IS UNCERTAIN...AND PRECLUDES THE NEED FOR A NEW
   WATCH AT THIS TIME.
   
   DISCUSSION...A STRONG NEGATIVELY-TILTED SHORTWAVE TROUGH CONTINUES
   TO PROGRESS EWD ACROSS WA/ORE...WITH A FURTHER INCREASE IN
   DOWNSTREAM WSWLY MIDLEVEL WINDS EXPECTED ACROSS WW 159 INTO
   CENTRAL/ERN MT THIS EVENING. THIS WILL MAINTAIN STRONG BULK
   SHEAR...SUPPORTING STORM ORGANIZATION.  DESPITE RELATIVELY MODEST
   INSTABILITY /MUCAPE 500-1000 J PER KG/ TENDING TO LIMIT THE COVERAGE
   OF STRONGER CELLS THUS FAR...HEIGHT FALLS/ASCENT SPREADING ACROSS
   CENTRAL ID/WRN MT ARE EXPECTED TO COMPENSATE...RESULTING IN
   ADDITIONAL TSTM DEVELOPMENT.
   
   TO THE EAST OF WW 159...REGIONAL RADAR IMAGERY SHOWED A FEW STORMS
   HAVE DEVELOPED ALONG A ZONE OF LOW LEVEL CONVERGENCE AND WITHIN A
   DEEPLY MIXED BOUNDARY LAYER WHERE LOW LEVEL AND MID LEVEL LAPSE
   RATES ARE QUITE STEEP.  ONE PARTICULAR STORM IN FERGUS COUNTY MT /45
   NE KLWT/ HAS BECOME ROBUST WITH SUSTAINED REFLECTIVITY AT 7 KM AND 9
   KM PER WDSS-II CAPPI.  STEEP MIDLEVEL LAPSE RATES EXCEEDING 8
   C/KM...LARGE DEWPOINT DEPRESSIONS PER 00Z GTF/GGW SOUNDINGS AND
   STRENGTHENING BULK SHEAR SUGGEST DAMAGING WINDS AND HAIL WILL BE A
   THREAT WITH THIS STORM AND OTHERS THAT DEVELOP.  GIVEN DEWPOINTS
   ONLY IN THE LOWER 40S LIMITING STRONGER INSTABILITY...THE COVERAGE
   OF INTENSE STORMS SHOULD REMAIN LOW AND WILL LIKELY PRECLUDE THE
   NEED FOR A WATCH.
   
   ..PETERS.. 05/14/2013
   
   
   ATTN...WFO...BYZ...GGW...TFX...MSO...BOI...OTX...PDT...
   
   LAT...LON   45251861 45901788 46331730 46591658 46941594 46961545
               47211495 47371449 47671454 48041463 48781439 48581356
               48211299 48481214 48351158 48241085 48341012 48420851
               48420717 48300607 47500534 47020542 46610631 46570949
               46541003 46641036 46941137 46431178 46191249 45761313
               45131466 45101566 44471627 44611697 44291729 44301787
               44271848 45251861