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Mesoscale Discussion 1692
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   MESOSCALE DISCUSSION 1692
   NWS STORM PREDICTION CENTER NORMAN OK
   0342 AM CDT MON SEP 08 2014

   AREAS AFFECTED...SOUTH-CENTRAL TO SERN SD/FAR NERN NEB INTO NWRN IA

   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

   VALID 080842Z - 081115Z

   PROBABILITY OF WATCH ISSUANCE...5 PERCENT

   SUMMARY...THUNDERSTORMS WILL CONTINUE TO DEVELOP OVER PART OF
   SOUTH-CENTRAL INTO SERN SD DURING THE LATE OVERNIGHT/EARLY MORNING
   HOURS /THROUGH AT LEAST 12Z/.  STORMS SHOULD MOVE TO THE E/SE AND
   BEGIN TO SHIFT INTO FAR NERN NEB AND NWRN IA BY DAYBREAK. HAIL WILL
   BE POSSIBLE WITH THE STRONGER/SUSTAINED CORES...BUT SHOULD REMAIN
   GENERALLY SUB-SEVERE...GIVEN A TENDENCY FOR CLUSTERED/BANDED STORM
   MODES.  STORM DEVELOPMENT OVER NERN SD MAY TEND TO REMAIN MORE
   ISOLATED...GIVEN A WEAKER INFLUX OF MOISTURE/INSTABILITY.

   DISCUSSION...TRENDS IN MOSAIC RADAR IMAGERY HAVE SHOWN CONTINUED
   TSTM DEVELOPMENT ACROSS MAINLY SOUTH-CENTRAL/SERN SD...WITH THE MORE
   PERSISTENT/SUSTAINED UPDRAFTS BEING ON THE WRN FLANK OF AN ONGOING
   CLUSTER OF STORMS THAT EXTENDED FROM BRULE TO HUTCHINSON COUNTIES SD
   AT 0805Z.  WSR-88D VWPS INDICATED A 35-45 KT LLJ HAS VEERED SINCE
   SUNDAY EVENING TO SWLY AND IS SUSTAINING AN INFLUX OF MOISTURE AND
   MODERATE ELEVATED INSTABILITY INTO THE SERN SD TSTM CLUSTER. 
   LOW-LEVEL WAA WITHIN THE NOSE OF THE LLJ COUPLED WITH DCVA ACROSS
   ERN SD...AT THIS TIME...ATTENDANT TO A LEAD MIDLEVEL IMPULSE IN ERN
   SD/SWRN MN WILL CONTINUE TO PROVIDE DEEP-LAYER ASCENT ACROSS THE
   DISCUSSION AREA FOR ADDITIONAL TSTM FORMATION ALONG THE ERN
   PERIPHERY OF THE EML.  WATER-VAPOR IMAGERY ALSO SHOWED ANOTHER
   MIDLEVEL IMPULSE...IMMEDIATELY UPSTREAM...MOVING EWD THROUGH WRN SD.
   ASCENT ATTENDANT TO THIS LATTER IMPULSE SHOULD TEND TO FAVOR
   CONTINUED NEW STORM DEVELOPMENT ON THE WRN FLANK OF THE SERN SD
   CLUSTER...AS THE LEAD IMPULSE DEPARTS THE DISCUSSION AREA.

   GIVEN THE PRESENCE OF 30-40 KT OF EFFECTIVE BULK SHEAR...STEEP
   700-500-MB LAPSE RATES AND MODERATE INSTABILITY...LARGE HAIL CANNOT
   BE RULED OUT.  THIS OCCURRENCE IS DEPENDENT ON A STORM HAVING
   UNIMPEDED INFLOW AND BEING DISCRETE.  THUS FAR...TRENDS IN RADAR
   IMAGERY ARE TENDING TO FAVOR CLUSTERS AND BANDS OF STORMS WITH HAIL
   SIZE GENERALLY BEING SUB-SEVERE PER WDSS-II DATA.  AS THE WRN SD
   IMPULSE TRACKS EWD INTO THE EARLY MORNING...THE ONGOING CLUSTER OF
   STORMS SHOULD ALSO DEVELOP E/SEWD INTO MORE OF SERN SD TO NWRN IA
   AND PERHAPS NERN NEBRASKA THROUGH DAYBREAK.

   ..PETERS/EDWARDS.. 09/08/2014


   ATTN...WFO...DMX...FSD...OAX...ABR...LBF...

   LAT...LON   42809760 43009870 43639930 44239886 43939745 43559657
               43259538 42819484 42339491 42099549 42309673 42649768
               42809760 

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Page last modified: September 08, 2014
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