608   
FXUS10 KWNH 280502  
PMDHMD  
  
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
101 AM EDT SAT SEP 28 2019  
  
VALID SEP 28/0000 UTC THRU OCT 01/1200 UTC  
  
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
  
00Z PRELIMINARY MODEL EVALUATION WITH PREFERENCES AND FORECAST  
CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..NORTHWEST  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND THROUGH 60 HOURS  
    ECMWF/ECENS/GEFS DAY 3  
CONFIDENCE: ABOVE AVERAGE  
  
THE GENERAL MODEL SPREAD THROUGH DAY 2 REMAINS QUITE MINIMAL WITH  
THE POSITION AND INTENSITY OF AN ANOMALOUS CLOSED LOW ACROSS  
WA/OR. AS THE LOW BEGINS TO EVOLVE BY OPENING AND EJECTING TO THE  
NORTHEAST, THE SPREAD INCREASES DRASTICALLY SUCH THAT BY THE END  
OF THE FORECAST PERIOD THERE IS QUITE A BIT OF SPATIAL  
UNCERTAINTY. THE GFS EJECTS THE CLOSED LOW MUCH FASTER THAN THE  
REMAINING GUIDANCE, WHICH IS BOTH NOT CONSISTENT WITH ITS ENSEMBLE  
MEAN, BUT ALSO UNLIKELY BASED ON THE STRENGTH OF THE PACIFIC JET  
STREAK DIGGING SOUTHWARD FROM ALASKA. THE CMC IS TOO QUICK TO PUSH  
THE ENTIRE TROUGH AXIS TO THE EAST AND TILT IT NEUTRAL, WELL OUT  
OF TOLERANCE WITH THE GLOBAL CONSENSUS KEEPING THE LONGWAVE TROUGH  
POSITIVELY TILTED AND HUNG BACK TOWARDS CALIFORNIA. THE ECMWF AND  
ITS MEAN SHOW THE MOST CONSISTENCY, AND ARE IN VERY GOOD AGREEMENT  
WITH THE GEFS MEAN. THIS SOLUTION ALSO SEEMS MORE REASONABLE THAN  
A FASTER PUSH OF THE TROUGH TO THE E/NE AS JET ENERGY CONTINUES TO  
DIG SOUTHWARDS OFF THE PACNW COAST.  
  
   
..REST OF CONUS  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND THROUGH 60 HOURS  
    GFS/NAM/GEFS DAY 3  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
  
THERE IS VERY GOOD MODEL AGREEMENT THROUGH 60 HOURS WITH AN  
EXPANSIVE RIDGE AMPLIFYING ACROSS THE EASTERN HALF OF THE CONUS  
AND A TROUGH IN THE SOUTHWEST. WHILE THE MAJORITY OF THIS AREA  
REMAINS IN GOOD AGREEMENT WITH THE EVOLUTION DURING D3, THERE ARE  
DISCREPANCIES BETWEEN THE NCEP AND NON-NCEP SUITE WITH A SHORTWAVE  
MOVING ACROSS NEW ENGLAND MONDAY NIGHT INTO TUESDAY. THE NCEP  
MEMBERS ARE GENERALLY WEAKER AND FURTHER NORTH WITH THE ENERGY  
WHILE THE NON-NCEP IS A BIT MORE ROBUST AND FURTHER SOUTH. THE  
STRENGTH OF THE RIDGE ACROSS THE SOUTHEAST AS WELL AS THE SPEED OF  
THE FLOW BETWEEN THIS RIDGE AND THE CLOSED LOWS IN THE NORTHWEST  
AND NEAR THE HUDSON BAY SUGGESTS A FASTER/WEAKER SOLUTION IS MORE  
LIKELY. ALTHOUGH THE LATITUDINAL DIFFERENCES ARE PRETTY SMALL, IT  
DOES IMPACT THE QPF FOOTPRINT ACROSS THE NORTHEAST, AND THUS THE  
NCEP BLEND IS PREFERRED FOR D3 ACROSS THE EAST.  
  
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
  
WEISS  
  
  
 
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