912   
FXUS10 KWNH 071634  
PMDHMD  
  
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1133 AM EST SAT DEC 07 2019  
  
VALID DEC 07/1200 UTC THRU DEC 11/0000 UTC  
  
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
  
12Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..OVERALL PATTERN ACROSS THE CONUS  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 00Z GFS, ECMWF, ECMWF ENSEMBLE MEAN  
CONFIDENCE: AVERAGE   
  
MODELS ARE SHOWING SOME MORE SUBSTANTIAL DIFFERENCES BEYOND 09.06Z  
(SUNDAY NIGHT), PARTICULARLY WITH HOW THEY HANDLE A SOUTHERN  
STREAM WAVE DIGGING THROUGH THE SOUTHWEST, AND HOW THAT EVENTUALLY  
PHASES WITH A LARGER, AMPLIFYING TROUGH OVER THE CENTRAL U.S. THIS  
IS MOST NOTABLE IN A RELATIVELY LARGE SPREAD IN TIMING CENTERED  
AROUND 10.00Z (MONDAY EVENING) OVER THE SOUTHWEST. OVER THE PAST  
FEW MODEL CYCLES, THE ECMWF AND ECMWF ENSEMBLE MEAN HAVE GRADUALLY  
CONVERGED AROUND THEIR POSITIONS DEPICTED ON THE 00Z RUNS. OTHER  
MODELS HAVE BEEN LESS CONSISTENT, WITH THE UKMET TRENDING FASTER  
AND LESS AMPLIFIED, AND THE GFS TRENDING SLOWER.  
  
THE PREFERENCE WILL BE TO LEAN TOWARD THE 00Z ECMWF AND 00Z ECMWF  
ENSEMBLE MEAN, GIVEN THE MULTI-RUN CONSISTENCY THEY HAVE SHOWN,  
AND THE 00Z GFS GIVEN ITS RELATIVELY GOOD ALIGNMENT WITH THE ECMWF  
ENSEMBLE ENVELOPE. CONCEPTUALLY, THE ECMWF ALSO MAKES SENSE AS THE  
SOUTHERN STREAM WAVE MAY HAVE A TENDENCY TO DEAMPLIFY AND  
ACCELERATE AS IT IS OVERWHELMED BY LARGER HEIGHT FALLS FROM THE  
LONGWAVE TROUGH EXPANDING OVER THE CENTRAL U.S. THE 00Z CMC AND  
MANY 00Z NAEFS MEMBERS HANG THE SOUTHERN STREAM WAVE BACK MORE  
OVER THE SOUTHWEST, AND THE 12Z GFS HAS JOINED THAT CLUSTER. THIS  
CAN'T BE COMPLETELY DISCOUNTED, BUT THERE IS A LACK OF SUPPORT  
FROM OTHER GLOBAL MODELS.  
  
FINALLY, A PREFERENCE CENTERED AROUND THE 00Z GFS AND ECMWF WILL  
PROVIDE CONSISTENCY WITH THE PREVIOUS FORECAST, AS THAT WAS THE  
PREFERRED MODEL BLEND OVERNIGHT AS WELL.  
  
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
  
LAMERS  
  
  
 
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