Sep 20, 2014 0600 UTC Day 1 Convective Outlook

DAY 1 CONVECTIVE OUTLOOK  

   NWS STORM PREDICTION CENTER NORMAN OK
   1229 AM CDT SAT SEP 20 2014

   VALID 201200Z - 211200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE UPPER MS VALLEY...

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM LOWER MI TO NRN MO...

   ...SUMMARY...
   SCATTERED SEVERE THUNDERSTORMS ARE EXPECTED SATURDAY FROM
   SOUTHWESTERN LOWER MICHIGAN TO NORTHERN MISSOURI. LARGE HAIL AND
   STRONG WINDS WILL BE POSSIBLE. SEVERE WIND AND MARGINALLY SEVERE
   HAIL ARE ALSO LIKELY ACROSS MUCH OF NORTHERN MINNESOTA AND VICINITY.
   A LOWER THREAT OF SEVERE WEATHER EXISTS ACROSS NEVADA AND WESTERN
   UTAH.

   ...UPPER MS VALLEY...

   EARLY MORNING WV IMAGERY CLEARLY DEPICTS A STRONG SHORT-WAVE TROUGH
   OVER CNTRL AB...DIGGING SEWD IN LINE WITH LATEST MODEL GUIDANCE. 
   00Z GUIDANCE SUGGEST 80KT+ 500MB SPEED MAX WILL TRANSLATE INTO WRN
   ND BY 18Z...THEN INTO SWRN MN BY EARLY EVENING.  EXIT REGION OF THIS
   FEATURE WILL ENHANCE UVV ACROSS THE RED RIVER VALLEY REGION AND A
   STRONGLY FORCED SECONDARY COLD FRONT SHOULD ADVANCE TO A POSITION
   OVER ERN ND BY 18Z.  DESPITE THE SOMEWHAT MARGINAL MOISTURE IN PLACE
   AHEAD OF THIS SYSTEM...COOLING PROFILES AND STRONG FORCING SHOULD
   ENCOURAGE A BAND OF CONVECTION TO DEVELOP ALONG WIND SHIFT BY EARLY
   AFTERNOON.  THIS ACTIVITY WILL THEN SPREAD SEWD ACROSS MN AS EXIT
   REGION OF JET ADVANCES DOWNSTREAM.  DAMAGING WINDS ARE POSSIBLE WITH
   THIS ACTIVITY...ESPECIALLY IF LINEAR MCS EVOLVES AS A FEW HIGH RES
   MODELS SUGGEST.  MARGINALLY SEVERE HAIL COULD ALSO ACCOMPANY THE
   MORE ROBUST UPDRAFTS.


   ...MID MS VALLEY TO LOWER MI...

   BAND OF STRONG THUNDERSTORMS HAS EVOLVED FROM NERN NEB INTO SERN MN
   AT 05Z.  THIS ACTIVITY APPEARS TO BE AIDED IN PART BY ENTRANCE
   REGION OF EJECTING SPEED MAX THAT WILL TRANSLATE INTO SERN CANADA
   DURING THE DAY.  WHILE CONVECTION MAY BE ONGOING AT THE BEGINNING OF
   THE PERIOD OVER PORTIONS OF NRN LOWER MI...MORE SIGNIFICANT
   CONVECTION IS POSSIBLE LATER IN THE DAY AS BOUNDARY LAYER WARMS.  AS
   MID-LEVEL SPEED MAX EJECTS INTO SERN CANADA LOW-LEVEL FLOW SHOULD
   VEER ACROSS THE MIDWEST AND A CONFLUENCE ZONE SHOULD ESTABLISH
   ITSELF FROM EXTREME SERN WI...SWWD INTO NRN MO.  GREATEST BUOYANCY
   IS EXPECTED ACROSS THE MID MS VALLEY WHERE SBCAPE COULD APPROACH
   3000 J/KG.  AS TEMPERATURES WARM INTO THE MID 80S CINH SHOULD WEAKEN
   SUFFICIENTLY FOR SCT TSTMS...LIKELY BY 22Z.  THIS ACTIVITY IS
   EXPECTED TO DEVELOP WITHIN INCREASINGLY SHEARED NWLY FLOW REGIME. 
   LARGE HAIL AND DAMAGING WINDS ARE POSSIBLE WITH ORGANIZED MULTI-CELL
   CLUSTERS AND ISOLATED SUPERCELLS.


   ...GREAT BASIN...

   UPPER LOW OFF THE SRN CA COAST IS EXPECTED TO EJECT NEWD ACROSS CA
   INTO NV BY THE END OF THE PERIOD.  MID-LEVEL FLOW WILL INCREASE
   ACROSS THE LOWER CO RIVER VALLEY INTO THE GREAT BASIN BY AFTERNOON
   AND HIGH-BASED CONVECTION THAT EVOLVES ACROSS THIS REGION MAY
   ORGANIZE WITHIN DEEP SELY FLOW.  FORECAST SOUNDINGS SUGGEST
   ORGANIZED ROTATING UPDRAFTS ARE POSSIBLE BUT PW VALUES ARE NOT
   PARTICULARLY HIGH.  GIVEN THE WEAK INSTABILITY WILL MAINTAIN 5
   PERCENT SEVERE FOR ISOLATED SEVERE WIND GUSTS AND MARGINALLY SEVERE
   HAIL.

   ..DARROW/COHEN.. 09/20/2014