245  
FXUS10 KWNH 221818  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
117 PM EST SUN DEC 22 2019  
 
VALID DEC 22/1200 UTC THRU DEC 26/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION WITH PREFERENCES & FORECAST CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
ANY NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR  
SHORT RANGE FORECASTS.  
 
LOWER 48 AND VICINITY  
~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
MODELS HAVE CONTINUED TO CONVERGE ON RELATIVELY SIMILAR FORECASTS  
AND SHOW GOOD AGREEMENT OVERALL OVER THE NEXT FEW DAYS. THE  
BIGGEST DIFFERENCES APPEAR TO BE ASSOCIATED WITH DETAILS SUCH AS  
HOW THE DEEP LAYER CYCLONE NEAR THE SOUTHEAST EJECTS  
EAST-SOUTHEAST OVER THE ATLANTIC, WHERE THE NON-NAM GUIDANCE HAS  
SHOWN A LONG TERM SLOWING TREND DUE TO A CORRESPONDING SLOWING OF  
THE NORTHERN STREAM SHORTWAVE NEAR THE US/CANADIAN BORDER, AND A  
SECONDARY SHORTWAVE/POSSIBLE DEEP LAYER CYCLONE NEAR CALIFORNIA ON  
WEDNESDAY. THE PREFERENCE WAS TO LEAN TOWARD A BROAD-BASED MODEL  
BLEND TO DEAL WITH LINGERING DETAIL DIFFERENCES WITH SLIGHTLY  
ABOVE AVERAGE CONFIDENCE.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
ROTH  
 

 
 
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