779  
FXUS10 KWNH 120636  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
236 AM EDT THU OCT 12 2017  
 
VALID OCT 12/0000 UTC THRU OCT 15/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL PREFERENCES WITH CONFIDENCE INTERVALS  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT  
RANGE FORECASTS.  
 
SYSTEM MOVING FROM THE PACIFIC NW INTO THE UPPER MIDWEST  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-NAM COMPROMISE; CONFIDENCE SLIGHTLY BELOW AVE  
 
STARTING SATURDAY MORNING, DIFFERENCES EMERGE WITH THIS SYSTEM.  
MODEL TRENDS IN THE 00Z CYCLE ARE QUICKER/STRONGER/MORE NORTHERLY,  
NO LONGER MAKING THE 00Z GFS LOOK LIKE A SIGNIFICANT OUTLIER. THE  
00Z ECMWF IS THE FARTHEST NORTHEAST, THE 00Z UKMET THE MOST  
EASTERLY, AND THE 00Z NAM THE SLOWEST. MODEL TRENDS SUGGEST THE  
00Z NAM IS TOO SLOW, SO WILL EXCLUDE IT FROM THE CHOICE. A  
COMPROMISE OF THE 00Z CANADIAN, 00Z GFS, 00Z ECMWF, AND 00Z UKMET  
IS ADVISED WITH SLIGHTLY BELOW AVERAGE CONFIDENCE CONSIDERING THE  
RECENT SHIFTS SEEN IN THEIR SOLUTIONS.  
 
SYSTEM MOVING THROUGH THE NORTHEAST THURSDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-CANADIAN BLEND; CONFIDENCE ABOVE AVERAGE  
 
THE 00Z CANADIAN IS WEAKER/SOMEWHAT QUICKER THAN THE REST OF THE  
GUIDANCE WITH THIS SYSTEM. WHILE IT IS EXPECTED TO SHEAR OUT  
WITHIN A QUASI-ZONAL FLOW REGIME, EVEN THE 00Z GEFS MEAN/12Z ECMWF  
ENSEMBLE MEAN SHOW GREATER AMPLITUDE. A COMPROMISE OF THE 00Z  
UKMET, 00Z ECMWF, 00Z NAM, AND 00Z GFS IS PREFERRED WITH ABOVE  
AVERAGE CONFIDENCE.  
 
FRONT MOVING INTO THE GREAT LAKES/NORTHEAST FRIDAY/SATURDAY  
TROPICAL WAVE/UPPER LOW MOVING THROUGH THE FL STRAITS FRIDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
THE GUIDANCE SHOWS GOOD AGREEMENT WITH THESE SYSTEMS. PREFER A  
COMPROMISE OF THE 00Z ECMWF, 00Z CANADIAN, 00Z UKMET, 00Z NAM, AND  
00Z GFS TO IRON OUT ANY LINGERING DETAIL ISSUES WITH ABOVE AVERAGE  
CONFIDENCE.  
 
WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
ROTH  

 
 
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