379  
FXUS10 KWNH 031838  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
137 PM EST TUE DEC 03 2019  
 
VALID DEC 03/1200 UTC THRU DEC 07/0000 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: GENERAL MODEL BLEND, LESS WEIGHT ON 12Z GFS BY DAY 3  
CONFIDENCE: ABOVE AVERAGE  
 
---18Z UPDATE---  
NO CHANGE TO THE PRELIMINARY PREFERENCE AS MODELS REMAIN IN  
GENERALLY GOOD AGREEMENT OVERALL.  
 
---PREVIOUS DISCUSSION---  
DETERMINISTIC MODELS ARE GENERALLY IN GOOD AGREEMENT WITH THE  
SYNOPTIC PATTERN. IN THE 00Z ECMWF ENSEMBLE, THE 500MB SPREAD OVER  
THE VAST MAJORITY OF THE CONUS IS BELOW THE PREVIOUS 30-DAY  
AVERAGE. THIS SUGGESTS VERY GOOD MODEL SIMILARITY, AND THAT THE  
PRIMARY DIFFERENCES OVER THE NEXT FEW DAYS WILL BE WITH MESOSCALE  
DETAILS SUCH AS PLACEMENT OF INDIVIDUAL PRECIPITATION BANDS.  
 
THE MOST NOTABLE DIFFERENCES WERE WITH THE 12Z GFS. IT SHOWED A  
SHARPER SHORTWAVE TROUGH DIGGING INTO THE SOUTHERN PLAINS ON  
THURSDAY, WHICH IS IN CONTRAST TO MOST OTHER MODELS AND THE  
EXPECTED DEAMPLIFICATION AS IT PUSHES THROUGH A RIDGE AXIS.  
NEVERTHELESS, THIS DOESN'T APPEAR TO HAVE A SIGNIFICANT EFFECT ON  
THE QPF. THE GFS IS ALSO SLIGHTLY COLDER WITH LOW-LEVEL  
TEMPERATURES IN THE GREAT LAKES. THIS IS IN LINE WITH ITS USUAL  
BIAS, BUT THE MAGNITUDE OF THE DIFFERENCE IS SMALL IN THIS CASE.  
THEREFORE, SLIGHTLY LESS WEIGHT COULD BE PLACED ON THE GFS BY DAY  
3, BUT OVERALL THE PREFERENCE IS FOR A GENERAL MODEL BLEND.  
 
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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