MESOSCALE DISCUSSION 0688
   NWS STORM PREDICTION CENTER NORMAN OK
   0806 PM CDT FRI MAY 04 2007
   
   AREAS AFFECTED...LOW ROLLING PLAINS...ERN PNHDL TX...WRN OK...OK
   PNHDL...SWRN/CNTRL KS
   
   CONCERNING...TORNADO WATCH 227...
   
   VALID 050106Z - 050230Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 227 CONTINUES.
   
   TSTM THAT DEVELOPED ALONG THE DRYLINE OVER THE ERN TX PNHDL
   EVENTUALLY ROOTED INTO THE STRONGER INSTABILITY AXIS OVER FAR NW OK
   AND DEVELOPED INTO A TORNADIC SUPERCELL.  ORIGINAL CELL HAS WEAKENED
   SOMEWHAT OVER WOODWARD COUNTY...BUT A SERIES OF LEFT-SPLITS WERE
   MOVING QUICKLY NWD INTO SWRN KS.  THESE STORMS HAVE HAD A HISTORY OF
   LARGE HAIL.
   
   LATEST VSBL SATL PHOTOS INDICATED THAT CU STREETS WHICH WERE
   PROMINENT EARLIER FROM THE LOW ROLLING PLAINS NWD INTO PARTS OF SWRN
   KS HAVE DIMINISHED.  BUT...MOISTURE WAS BEGINNING TO SURGE BACK WWD
   OWING TO UPSTREAM LARGE SCALE HEIGHT FALLS ASSOCD WITH NEXT IMPULSE
   ROTATING NEWD TOWARD THE HIGH PLAINS.  WATER VAPOR IMAGERY HINTS
   THAT SRN EDGE OF THE HEIGHT FALLS WILL SKIRT BY AT LEAST THE
   LATITUDE OF KLBB-KCDS.  GIVEN THE LARGE SCALE SUPPORT AND LOW-LEVEL
   MOISTURE ADVECTING UPSLOPE...OTHER STORMS MAY TRY TO FORM ACROSS THE
   TX/OK PORTION OF THE TORNADO WATCH YET THIS EVENING.  HIGHER
   PROBABILITIES FOR STORMS WILL EXIST FARTHER N OVER KS AS PRIMARY
   MOISTURE CONVERGENCE FOCUSES NEAR/N OF KDDC.
   
   LOW-LEVEL HODOGRAPHS AND AMPLY MOIST BOUNDARY LAYER ARE QUITE
   FAVORABLE FOR TORNADOES AND STEEP LAPSE RATES ALOFT WILL YIELD LARGE
   HAIL WITH ANY SUSTAINED STORMS.
   
   ..RACY.. 05/05/2007
   
   
   ATTN...WFO...ICT...OUN...DDC...LUB...AMA...
   
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