MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 137 AM EST TUE NOV 17 2015 VALID NOV 17/0000 UTC THRU NOV 20/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION WITH PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ GFS/NAM INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. SYSTEM OFFSHORE THE NORTHWEST FRIDAY MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GFS/NAM CONSENSUS CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE GUIDANCE HAS SHOWN INCREASED SPREAD IN THEIR 00Z RUNS, WITH THE 00Z UKMET/00Z ECMWF THE STRONGEST/SLOWEST AND THE 00Z CANADIAN THE FLATTEST. AS A MID-LEVEL RIDGE IS MOVING OVER THE TOP OF THE SYSTEM, THERE IS OPPORTUNITY FOR THE SYSTEM TO ATTEMPT TO BRIEFLY CLOSE OFF. FOR NOW THOUGH, PREFER THE MIDDLE-OF-THE-ROAD 00Z GFS/00Z NAM WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE. SHORTWAVE/LOW APPROACHING THE NORTHWEST WED NIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NAM/ECMWF/UKMET COMPROMISE CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE GUIDANCE IS SHOWING SOME CONVERGENCE HERE IN THEIR 00Z RUNS. HOWEVER, THE 00Z GFS REMAINS STRONGER ALOFT WITH THIS SYSTEM, THOUGH IT HAS TRENDED WEAKER OVER ITS PAST DAY OF RUNS. THE 00Z CANADIAN IS THE SLOWEST TO MOVE THE WAVE INTO THE NORTHWEST -- ITS USUAL BIAS. PREFER THE 00Z NAM/00Z UKMET/00Z ECMWF CONSENSUS HERE WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE. CYCLONE MOVING THROUGH THE PLAINS TUE/WED RESULTANT MERGED CYCLONE MOVING ACROSS ONTARIO FRONT PUSHING THROUGH THE EAST THU/FRI MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-GFS COMPROMISE CONFIDENCE: ABOVE AVERAGE THE 00Z GFS EXHIBITS CONVECTIVE FEEDBACK WITHIN THE SYSTEM'S COMMA HEAD, WHICH ACTS TO SLOW DOWN ITS MID-LEVEL CYCLONE PROGRESSION MORE THAN THE OTHER GUIDANCE THROUGH WEDNESDAY. LIKE YESTERDAY, THIS REMAINS UNPREFERRED. ON THURSDAY, ITS SPEED UP TO THE NORTHEAST OF THE REMAINING GUIDANCE, WHICH IS ALSO UNIQUE. A COMPROMISE OF THE 00Z NAM/00Z UKMET/00Z ECMWF/00Z CANADIAN IS BEST HERE WITH ABOVE AVERAGE CONFIDENCE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ROTH