Thursday, August 1, 2013

New Tornado Watch Coming for Parts of Nebraska, South Dakota

  MD 1581 graphic

MESOSCALE DISCUSSION 1581
   NWS STORM PREDICTION CENTER NORMAN OK
   1253 PM CDT THU AUG 01 2013

   AREAS AFFECTED...NEB...SWRN SD

   CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY 

   VALID 011753Z - 012000Z

   PROBABILITY OF WATCH ISSUANCE...95 PERCENT

   SUMMARY...ISOLATED TO SCATTERED SUPERCELLS WILL FORM BY
   MID-AFTERNOON WITH INITIAL PRIMARY RISKS OF VERY LARGE HAIL AND A
   FEW TORNADOES. A WW WILL BE ISSUED WITHIN THE HOUR...WITH MODERATE
   UNCERTAINTY OVER THE SPATIAL EXTENT OF AN INITIAL WW.

   DISCUSSION...17Z SURFACE ANALYSIS PLACED A 1012 MB CYCLONE NEAR
   BFF...WITH A QUASI-STATIONARY FRONT EXTENDING NEWD AND THEN E ACROSS
   SRN SD. SURFACE-BASED CB/S HAVE FORMED ALONG THIS FRONT IN
   SHANNON/BENNETT COUNTIES SD. ADDITIONAL CU DEVELOPMENT HAS BEEN
   NOTED ALONG RESIDUAL OUTFLOW IN CNTRL NEB /CENTERED OVER VALLEY
   COUNTY/. ALTHOUGH LARGE-SCALE FOR ASCENT IS NEBULOUS...CONTINUED
   SURFACE HEATING WILL YIELD INCREASING DESTABILIZATION AND MINIMAL
   CAPPING WITH SUSTAINED SURFACE-BASED TSTMS EXPECTED DURING THE
   AFTERNOON /SUPPORTED BY RECENT HRRR RUNS/. STRONG DEEP-LAYER SHEAR
   AND STEEP MID-LEVEL LAPSE RATES WILL BE QUITE FAVORABLE FOR
   SUPERCELLS PRODUCING LARGE HAIL /SOME SIGNIFICANT/. VEERING OF THE
   LOW-LEVEL WIND PROFILE ALONG WITH THE PRESENCE OF THE BOUNDARIES
   WILL SUPPORT A RISK FOR A COUPLE OF TORNADOES AS WELL.

   ..GRAMS/MEAD.. 08/01/2013


   ATTN...WFO...FSD...OAX...TOP...GID...LBF...UNR...GLD...BOU...
   CYS...

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