790  
FXUS10 KWNH 200424  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1124 PM EST THU DEC 19 2019  
 
VALID DEC 20/0000 UTC THRU DEC 23/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION WITH PREFERENCE AND FORECAST CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..OVERALL PATTERN ACROSS THE CONUS  
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 00Z GFS, 12Z ECMWF, 12Z ECMWF ENSEMBLE MEAN  
CONFIDENCE: AVERAGE  
 
THE 00Z GFS HAS SHOWN SOME IMPORTANT TRENDS TOWARD A SLOWER  
PROGRESSION OF THE LARGE SCALE WAVES ACROSS THE CONUS OVER THE  
NEXT FEW DAYS. IT NOW SHOWS VERY CLOSE ALIGNMENT TO THE 12Z ECMWF  
WITH THE STRONG CLOSED LOW ALONG THE GULF COAST. ALTHOUGH IT STILL  
PUSHES HEIGHT FALLS EASTWARD THROUGH THE INTERMOUNTAIN WEST AND  
ROCKIES FASTER IN ADVANCE OF THE WEST COAST TROUGH, THE STRUCTURE  
OF THE TROUGH AND POSITION OF EMBEDDED WAVES IS NOW VERY CLOSE TO  
THE ECMWF. THIS STILL DOES YIELD SLIGHTLY FASTER FRONTAL TIMING ON  
THE WEST COAST IN THE GFS, AND FOR DETAILS LIKE THIS THE  
PREFERENCE WOULD BE A SLIGHT LEAN TOWARD THE ECMWF AND ECMWF  
ENSEMBLE MEAN.  
 
GLOBAL MODELS SHOW RELATIVELY GOOD CONSISTENCY WITH THE QPF  
PATTERNS IN THE WEST DESPITE SOME SMALL DIFFERENCES IN THE TIMING  
AND AMPLITUDE OF THE APPROACHING TROUGH. THEREFORE, THE 12Z CMC  
AND 12Z UKMET SEEM TO OFFER REASONABLE FORECASTS IN ADDITION TO  
THE ECMWF AND GFS IN THIS REGION.  
 
THE 00Z NAM IS NOW SLOWER THAN THE CONSENSUS WITH THE GULF COAST  
SYSTEM, AND PROGRESSES THE SURFACE LOW FURTHER INLAND ACROSS  
GEORGIA. THE 12Z CMC AND UKMET ALSO PROGRESS THE SURFACE LOW  
FURTHER INLAND THAN THE GFS AND ECMWF, AND THIS AFFECTS THE QPF  
DISTRIBUTION IN THOSE MODELS. THIS HAS SOME ENSEMBLE SUPPORT, BUT  
FAR LESS THAN THE GFS AND ECMWF.  
 
CONSIDERING ALL THESE FACTORS, THE MODEL PREFERENCE IS FOR A BLEND  
OF THE GFS, ECMWF AND ECMWF ENSEMBLE MEAN, WHICH WILL PROVIDE GOOD  
CONSISTENCY WITH THE PREVIOUS PREFERENCE FOR MOST AREAS OF THE  
CONUS, AND HAS THE GREATEST ENSEMBLE SUPPORT AT THE MOMENT.  
 
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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