SPC discussion
Posted by JAC on 4/6/2011, 1:52 pm


ZCZC SPCSWOD48 ALL
  ACUS48 KWNS 060907
  SPC AC 060907
 
  DAY 4-8 CONVECTIVE OUTLOOK  
  NWS STORM PREDICTION CENTER NORMAN OK
  0407 AM CDT WED APR 06 2011
 
  VALID 091200Z - 141200Z
 
  ...DISCUSSION...
  COMPARISONS OF THE PAST 1-2 DAYS OF THE GFS AND ECMWF SHOWED LESS
  INTER- AND INTRA-MODEL SIMILARITIES...THOUGH THERE IS AGREEMENT THAT
  THE WRN U.S. TROUGH WILL PROGRESS EWD ACROSS THE CONUS MOVING INTO
  THE ERN STATES ON DAY 6 /MON APR 11/.  IN THE WEST ON DAY 6...THE
  NEXT UPSTREAM PACIFIC TROUGH IS EXPECTED TO MOVE INLAND WHILE
  TENDENCIES FOR A SPLIT FLOW REGIME PERSISTS ACROSS THIS REGION.
  MODELS DIFFER WITH THE EWD PROGRESSION OF A SYSTEM ALONG THE
  U.S./CANADIAN BORDER TOWARD THE UPPER GREAT LAKES DAY 7 /TUE APR 12/
  AND DAY 8 /WED APR 13/.  FARTHER S...THERE IS AGREEMENT THAT A
  PROGRESSIVE TROUGH SHOULD REACH THE SRN PLAINS ON DAY 8...BUT THE
  GFS/ECMWF DIVERGE IN THE STRENGTH OF THIS SYSTEM.
 
  ...DAY 4 /SAT APR 9/...
  ALTHOUGH MODELS DIFFER SOMEWHAT IN THE TIMING OF A SHORTWAVE TROUGH
  MOVING EWD ACROSS THE NRN PLAINS ON SATURDAY...THERE IS AGREEMENT IN
  THE LOW LEVELS SHOWING AN AREA OF LOW PRESSURE TRACKING FROM THE
  CENTRAL PLAINS TO WRN WI BY 12Z SUNDAY.  STRENGTHENING SSWLY LOW
  LEVEL WINDS FROM THE SRN/CENTRAL PLAINS TO THE UPPER MS VALLEY WILL
  ADVECT MOISTURE NWD BENEATH A PLUME OF STEEP LAPSE RATES.  MODERATE
  TO STRONG INSTABILITY AND INCREASING SWLY MIDLEVEL WINDS WILL
  SUPPORT ORGANIZED STORMS DEVELOPING OVER PORTIONS OF THE LOWER-MID
  MO VALLEY AND SPREADING NEWD INTO THE UPPER MS VALLEY.
 
  ...DAY 5 /SUN APR 10/...
  THE 00Z ECMWF SOLUTION FOR SUNDAY HAS DIVERGED FROM ITS EARLIER RUNS
  AND IS NOW INDICATING A CLOSED COMPACT LOW TRACKING ACROSS THE SRN
  PLAINS TO MID MS VALLEY.  MEANWHILE...THE GFS MAINTAINS MORE OF A
  OPEN LONGWAVE TROUGH MOVING FROM THE PLAINS REACHING THE GREAT LAKES
  TO LOWER MS VALLEY BY 12Z MONDAY.  DESPITE THESE DIFFERENCES...EACH
  MODEL SHOWS STRONG SWLY MIDLEVEL WINDS EXTENDING FROM TX TO THE
  MIDWEST/GREAT LAKES SUNDAY AFTERNOON.  THUS...CONFIDENCE REMAINS FOR
  A REGIONAL SEVERE WEATHER THREAT AREA MID MS/LOWER OH VALLEYS...WITH
  A W/SWWD EXTENSION ADDED AT THIS TIME DUE TO THE SLOWER 06/00Z
  ECMWF.
 
  ...DAY 6 /MON APR 11/...
  GIVEN THAT THE ECMWF AND GFS SOLUTIONS DIVERGE ON THE PORTION OF THE
  ERN HALF OF THE U.S. THAT WILL BE AFFECTED BY TSTMS ON MONDAY...A
  REGIONAL SEVERE WEATHER THREAT AREA WILL NOT BE INCLUDED AT THIS
  TIME.
 
  ..PETERS.. 04/06/2011



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