MESOSCALE DISCUSSION 0912
   NWS STORM PREDICTION CENTER NORMAN OK
   0740 PM CDT MON MAY 28 2007
   
   AREAS AFFECTED...PORTIONS NERN WY...WRN/NRN SD...S-CENTRAL/SWRN ND.
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 302...
   
   VALID 290040Z - 290245Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 302
   CONTINUES.
   
   SEVERAL STG-SVR TSTMS ARE EVIDENT ATTM ACROSS WRN PORTIONS WW --
   PRIMARILY SURROUNDING BLACK HILLS OVER SWRN SD AND WESTON COUNTY WY.
    ACTIVITY ACROSS WRN LAWRENCE COUNTY SD AS OF 0020Z HAS PRODUCED
   HAIL REPORTS UP TO 1.75 INCH DIAMETER IN CROOK COUNTY WY WITHIN PAST
   HOUR.  OTHER TSTMS OVER WRN MEADE COUNTY ARE ENLARGING IN COVERAGE
   AND BECOMING BETTER ORGANIZED ATTM. MEANWHILE OUTFLOW BOUNDARY FROM
   EARLIER ACTIVITY OVER NWRN NEB PANHANDLE IS INITIATING POTENTIALLY
   SVR TSTMS AS IT MOVES NWD INTO BLACK HILLS.
   
   SFC ANALYSIS SHOWS FRONTAL ZONE NEAR A DVL....MBG...PHP LINE THEN
   SWWD INTO OUTFLOW POOL EVIDENT OVER SWRN SD S OF BLACK HILLS.  FRONT
   SHOULD DRIFT SEWD...WITH FAVORABLY MOIST AND UNSTABLE AIR MASS
   PRESENT BEHIND IT.  DESPITE NLY/POSTFRONTAL WINDS...00Z UNR SOUNDING
   SAMPLED SFC-BASED EFFECTIVE INFLOW PARCELS WITH MLCAPES AROUND 1500
   J/KG FOR MID 50S F DEW POINTS.  MOIST AXIS APPEARS TO EXTEND NEWD
   PAST STATION D07 IN ZIEBACH COUNTY.  NLY FLOW ALSO ELONGATES LOW
   LEVEL HODOGRAPH...RESULTING IN 0-1 KM SRH NEAR 200 J/KG.  MODIFIED
   RAOB AND RUC/NAM-KF FCST SOUNDINGS SUGGEST PROSPECTIVE INFLOW LAYER
   WILL REMAIN VERY NEARLY SFC-BASED FOR ANOTHER COUPLE HOURS ACROSS
   W-CENTRAL SD.  PRIND ONGOING ACTIVITY WILL CONTINUE TO POSE SVR
   HAIL/GUST THREAT AS IT COALESCES INTO ONE OR TWO MESOBETA SCALE
   CONVECTIVE CLUSTERS...PERHAPS EVOLVING INTO EVEN LARGER MCS LATER
   THIS EVENING.  FARTHER NE...CAPPING HAS SUPPRESSED DEVELOPMENT INVOF
   FRONTAL ZONE OVER NRN SD AND SRN ND...HOWEVER AMBIENT BUOYANCY AND
   SHEAR REMAIN FAVORABLE FOR SVR SHOULD ANY TSTMS FORM.
   
   ..EDWARDS.. 05/29/2007
   
   
   ATTN...WFO...FGF...ABR...BIS...LBF...UNR...CYS...
   
   46599802 45259796 45269871 44869875 44879968 44529967
   44490060 44179983 44160101 43830103 43710126 43380121
   43400213 43000207 42970303 43510303 43450504 44510499
   45070372 45980254 46260215 47010204 46960081 47300073
   47269922 47599928 47609847 47139848 46639843