MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1128 PM EST SAT NOV 14 2015 VALID NOV 15/0000 UTC THRU NOV 18/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z NAM/GFS EVALUATION WITH PRELIMINARY MODEL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. SYSTEM MOVING THROUGH SOUTHWEST CANADA TUE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GFS/UKMET/CANADIAN COMPROMISE CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 00Z NAM WAS THE SLOWEST WITH THIS SYSTEM -- ITS USUAL BIAS. OTHERWISE, THE OTHER DETERMINISTIC GUIDANCE SHOWED SOME LATITUDE ISSUES WITH THE SURFACE LOW NEAR THE US/CANADIAN BORDER, WITH THE 12Z ECMWF SOUTH OF THE BORDER AND THE OTHER GUIDANCE NORTH OF THE BORDER. THIS DIFFERENCE APPEARS TO BE RELATED TO THE SHARPNESS OF THE UPPER SHORTWAVE SPAWNING THE LOW. SINCE THE SYSTEM IS UNDERCUTTING A BROAD UPPER LOW ACROSS WEST-CENTRAL CANADA, BELIEVE A LESS SHARP SOLUTION HAS A BETTER CHANCE OF VERIFYING. THIS FAVORS A COMPROMISE OF THE 00Z GFS/12Z UKMET/12Z CANADIAN GUIDANCE, WHICH IS PREFERRED WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE. CYCLONE ALOFT MOVING FROM SOUTHWEST INTO THE MS VALLEY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GFS/UKMET COMPROMISE CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 00Z NAM/21Z SREF MEAN ARE THE SLOWEST WITH THIS SYSTEMS PROGRESSION -- THEIR USUAL BIAS -- WHILE THE 12Z CANADIAN/12Z ECMWF ARE THE QUICKEST. THIS LEAVES THE 12Z UKMET/00Z GFS AS THE INTERMEDIATE SOLUTIONS, WHICH SPLIT THE DIFFERENCE BETWEEN THE 18Z GEFS AND 12Z ECMWF ENSEMBLE MEAN SOLUTIONS. AS THE SYSTEM IS BEING KICKED OUT AHEAD OF A DECENT STRENGTH SHORTWAVE/CYCLONE MOVING NEAR THE US/CANADIAN BORDER, THE SLOWER NAM/SREF MEAN SOLUTIONS HAVE BEEN DISCOUNTED. FOR THE TIME BEING, A COMPROMISE OF THE 12Z UKMET/00Z GFS ARE PREFERRED WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE. SHORTWAVE MOVING THROUGH SOUTHWEST CANADA MON/TUE SHORTWAVE SWINGING BY NEW ENGLAND MONDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE GUIDANCE IS IN GOOD AGREEMENT WITH THESE SYSTEMS. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ROTH