MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1113 AM EST THU DEC 22 2016 VALID DEC 22/1200 UTC THRU DEC 26/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z NAM/GFS MODEL EVALUATION WITH PRELIMINARY MODEL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ISSUES DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. DEEP CYCLONE MOVING OFFSHORE CA SUNDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-GFS COMPROMISE CONFIDENCE: ABOVE AVERAGE THIS SYSTEM IS EXPECTED TO DROP SOUTH TO THE EAST OF ANOMALOUSLY STRONG BUT BROAD RIDGING IN THE EASTERN PACIFIC. NORMALLY IN THIS SYNOPTIC PATTERN, THE MORE SOUTHERLY GUIDANCE IS ATTRACTIVE, WHICH RULES OUT THE 06Z GEFS AND 12Z GFS FROM CONSIDERATION. A COMPROMISE OF THE 12Z NAM, 00Z CANADIAN, 00Z UKMET, AND 00Z ECMWF IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE. TROUGH DIGGING INTO THE WEST CYCLONE MOVING INTO SD LATE SUNDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-NAM COMPROMISE CONFIDENCE: ABOVE AVERAGE THE 12Z NAM IS EAST AND DEEPER (ITS USUAL BIAS) THAN THE REMAINDER OF THE GUIDANCE WITH THIS SYSTEM. SINCE THE GUIDANCE IS OTHERWISE IN VERY GOOD AGREEMENT, A COMPROMISE OF THE 00Z CANADIAN, 00Z UKMET, 00Z ECMWF, AND 12Z GFS IS PREFERRED WITH ABOVE AVERAGE. SHORTWAVE MOVING FROM THE PLAINS/OH VLY/NORTHEAST FRI-SAT PROGRESSIVE SHORTWAVE MOVING ACROSS THE NORTHEAST TODAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ THE GUIDANCE SHOWS REASONABLY GOOD AGREEMENT WITH THESE SYSTEMS, SO A COMPROMISE OF THE AVAILABLE GUIDANCE IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ROTH