776  
FXUS10 KWNH 061640  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1139 AM EST FRI DEC 06 2019  
 
VALID DEC 06/1200 UTC THRU DEC 10/0000 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: NON-NAM BLEND  
CONFIDENCE: AVERAGE  
 
THE SYNOPTIC PATTERN OVER THE CONUS WILL UNDERGO CONSIDERABLE  
AMPLIFICATION OVER THE NEXT FEW DAYS WITH A TROUGH BUILDING INTO  
THE CENTRAL U.S. AND A RIDGE BUILDING ALONG THE PACIFIC COAST.  
MODELS ARE IN GOOD AGREEMENT WITH SOME MINOR TIMING OR AMPLITUDE  
VARIATIONS. THROUGH THE FIRST THREE DAYS OF THE FORECAST, GLOBAL  
MODELS GENERALLY PLACE QPF IN THE SAME AREAS AND MASS FIELD SPREAD  
IN THE ENSEMBLES IS SOMEWHAT LIMITED IN THE SAME TIME FRAME.  
THEREFORE, A GENERAL MODEL BLEND IS THE PREFERENCE, WITH SLIGHTLY  
LESS WEIGHT PLACED ON THE 12Z GFS DUE TO A TENDENCY TOWARD LOWER  
HEIGHTS IN THE SOUTHERN STREAM AND SLIGHTLY FASTER PROGRESSION OF  
A SHORTWAVE TROUGH IN THE SOUTHWEST ON MONDAY (CONTRARY TO  
CONSENSUS AND ITS ENSEMBLE MEAN).  
 
THE ONE EXCEPTION WILL BE THE 12Z NAM, WHICH IS NOT INCLUDED IN  
THE PREFERENCE. THE NAM SHOWS A MUCH STRONGER SHORTWAVE DIGGING  
SOUTH ALONG THE WEST COAST AND EVENTUALLY ARRIVING IN THE  
SOUTHWEST, WHICH IS ONLY MARGINALLY SUPPORTED BY THE 00Z UKMET.  
ADDITIONALLY, DESPITE A SIMILAR EVOLUTION OF THE TROUGH AND  
SURFACE LOW TRACK OVER THE EASTERN HALF OF THE COUNTRY, IT  
CONCENTRATES MUCH OF ITS HEAVIER QPF ALONG THE ATLANTIC COAST ON  
SUNDAY NIGHT AND MONDAY, WITH MUCH LOWER QPF FURTHER INLAND IN THE  
OHIO VALLEY AND GREAT LAKES. THIS IS IN CONTRAST TO ALL OF THE  
GLOBAL MODELS, AND THE PREFERENCE IS TO LEAN TOWARD THE GLOBAL  
MODELS WHICH HAVE MUCH STRONGER ENSEMBLE SUPPORT.  
 
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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