674  
FXUS10 KWNH 131619  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1119 AM EST SAT JAN 13 2018  
 
VALID JAN 13/1200 UTC THRU JAN 17/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z GFS/NAM EVALUATION WITH PRELIMINARY MODEL PREFERENCES  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT  
RANGE FORECASTS.  
 
SYSTEM MOVING INTO THE NORTHWEST TUESDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
THE GUIDANCE LOOKS REASONABLE IN THIS AREA, WITH ANY NOTICEABLE  
DIFFERENCES (SUCH AS THE SHARPNESS OF THE MID-LEVEL TROUGH) WELL  
WITHIN THE ERROR/POSSIBLE ENVELOPE OF SOLUTIONS. A COMPROMISE OF  
THE 12Z NAM, 12Z GFS, 00Z CANADIAN, 00Z UKMET, AND 00Z ECMWF IS  
PREFERRED WITH ABOVE AVERAGE CONFIDENCE.  
 
AMPLIFYING UPPER TROUGH/LOW IN THE GREAT LAKES/EAST  
AND ASSOCIATED SYSTEMS ROTATING AROUND ITS PERIPHERY  
CYCLONE EJECTING THROUGH ATLANTIC CANADA TODAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-UKMET BLEND; CONFIDENCE ABOVE AVERAGE  
 
ON THE WHOLE, THE GUIDANCE SHOWS VERY GOOD AGREEMENT WITH THE  
DETAILS OF THE SHORTWAVES MOVING AROUND THE FORMING CLOSED LOW.  
THE MAIN PROBLEM IS WITH THE DEEP LAYER CYCLONE ITSELF, WHICH THE  
00Z UKMET BECOMES MORE SOUTHERLY WITH ON MONDAY AND MORE EASTERLY  
ON TUESDAY. SINCE THE 00Z ECMWF/06Z GEFS MEAN FAVOR THE CONSENSUS  
WE WILL AS WELL -- A COMPROMISE OF THE 12Z GFS, 12Z NAM, 00Z  
ECMWF, AND 00Z CANADIAN COMPROMISE WITH ABOVE AVERAGE CONFIDENCE.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
ROTH  

 
 
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