GFS: Negative. EURO: Neutral to Positive
Posted by JAC on 4/7/2011, 7:03 am



DAY 4-8 CONVECTIVE OUTLOOK  
  NWS STORM PREDICTION CENTER NORMAN OK
  0357 AM CDT THU APR 07 2011
 
  VALID 101200Z - 151200Z
 
  ...DISCUSSION...
  07/00Z GFS IS IN AGREEMENT WITH THE LAST THREE RUNS OF THE ECMWF
  SHOWING THE STRONGER FORCING FOR ASCENT WITH THE WRN TROUGH TRACKING
  THE SRN/CENTRAL ROCKIES AND REACHING THE MID SOUTH TO WRN GREAT
  LAKES BY THE END OF DAY 4 /12Z MON APR 11/.  WHILE EACH MODEL
  MAINTAINS THE PROGRESSIVENESS OF THIS SYSTEM ON DAY 5 /MON APR
  11/...THE GFS INDICATES THE TROUGH BECOMES NEGATIVELY TILTED MOVING
  INTO THE NERN STATES.  THE ECMWF DURING THIS SAME PERIOD IS SLOWER
  WITH EWD MOVEMENT WITH A MORE NEUTRAL TO POSITIVELY-TILTED TROUGH.
  THE DIFFERENT SOLUTIONS ATTENDANT TO THIS ERN TROUGH ON DAY 5 RESULT
  IN VARYING MAGNITUDES OF AN UPSTREAM RIDGE OVER THE CENTRAL
  STATES...AND THE SUBSEQUENT EWD MOVEMENT OF A PACIFIC TROUGH FROM
  THE WEST COAST TO MS VALLEY NEXT WEEK.
 
  ...DAY 4 /SUN APR 10/...
  THE POTENTIAL FOR A REGIONAL SEVERE THREAT EXTENDING FROM NRN LA TO
  IA AND EWD THROUGH THE TN/OH VALLEYS AND PART OF THE WRN GREAT LAKES
  FROM SUNDAY AFTERNOON THROUGH SUNDAY NIGHT/EARLY MONDAY MORNING
  REMAINS VERY LIKELY.  CONFIDENCE REMAINS HIGH FOR THIS SEVERE
  WEATHER EVENT WITH THE POTENTIAL FOR DAMAGING WINDS AND TORNADOES AS
  STRONG HEIGHT FALLS SPREAD ACROSS THE DAY 4 OUTLOOK AREA...
  ESPECIALLY DURING THE LATTER HALF OF THE FORECAST PERIOD.
 
  A SURFACE LOW ATTENDANT TO THE PROGRESSIVE MID-UPPER LEVEL TROUGH IS
  EXPECTED TO TRACK FROM WRN KS INTO IA BY LATE SUNDAY AFTERNOON AND
  REACH THE WRN GREAT LAKES BY 12Z MONDAY.  A TRAILING COLD FRONT IS
  EXPECTED TO OVERTAKE THE PLAINS DRY LINE WITH TSTMS DEVELOPING
  INITIALLY FROM ERN OK TO WRN IA.  SLY LOW LEVEL WINDS WILL MAINTAIN
  A MOIST AIR MASS ALREADY IN PLACE AT THE START OF DAY 4 AND SUPPORT
  A MODERATELY UNSTABLE WARM SECTOR.  STRENGTHENING DEEP LAYER WIND
  FIELDS ACROSS THE UNSTABLE AIR MASS WILL PROMOTE BOTH LINE SEGMENTS
  AND SUPERCELLS WITH THE INITIAL ACTIVITY SPREADING TO THE MS VALLEY.
  FOR SUNDAY NIGHT...THE SEVERE WEATHER THREAT SHOULD EVOLVE TO
  PRIMARILY DAMAGING WINDS AS A BROAD SWLY LLJ /50-70 KT/ DEVELOPS
  FROM THE MID SOUTH TO OH VALLEY AND A SQUALL LINE ADVANCES EWD FROM
  THE MS VALLEY.
 
  ...DAY 5 /MON APR 11/...
  GIVEN MODEL DIFFERENCES IN THE TIMING AND ORIENTATION OF THE DAY 4
  TROUGH AS IT MOVES EWD ON DAY 5 AND UNCERTAINTY IN THE DEGREE OF
  DESTABILIZATION WITH EWD EXTENT...A REGIONAL SEVERE WEATHER THREAT
  AREA WILL NOT BE INCLUDED FOR THIS PERIOD.
 
  ...BEYOND DAY 5...
  MODEL UNCERTAINTIES WITH THE TIMING OF A PACIFIC TROUGH REACHING THE
  PLAINS STATES NEXT WEEK PRECLUDES THE INCLUSION OF ANY THREAT AREAS
  FOR DAYS 7-8 /WED APR 13 THROUGH THU APR 14/.
 
  ..PETERS.. 04/07/2011







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Setup for this Weekends Severe Weather Event - JAC, 4/6/2011, 7:26 am
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