MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1152 PM EST THU NOV 17 2016 VALID NOV 18/0000 UTC THRU NOV 21/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ DEEP LAYER CYCLONE IN THE EASTERN PACIFIC...WEAKENING INTO THE PACIFIC NORTHWEST ON SUN ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL BLEND CONFIDENCE: ABOVE AVERAGE MINOR DIFFERENCES CONTINUE TO EXIST WITH THE EXACT TIMING/TRACK OF THE LOW...BUT IN GENERAL MODEL CLUSTERING IS CLOSE ENOUGH TO PREFER A GENERAL MODEL BLEND FOR THIS SYSTEM. THE GREATEST DIFFERENCE WAS WITH THE 00Z GFS...LIKELY HOLDING ON A BIT TOO LONG WITH A LOW-MID LEVEL LOW NEAR THE PACIFIC NORTHWEST COAST ON SUN. OUTSIDE OF THIS RELATIVELY SHORT TERM DIFFERENCE...THE MODELS SHOW SIMILARLY. TROUGH AND SHORTWAVE ENERGY APPROACHING CA AND WEST COAST ON SUNDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON 12Z CMC BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE DETAIL DIFFERENCES WITH MINOR PERTURBATIONS WITHIN THE LARGER SCALE TROUGH APPROACHING CALIFORNIA ON SUN EXIST...BUT THEY DO NOT LAST FOR AN EXTENDED PERIOD OF TIME. OVERALL...THE MODELS HAVE COME INTO BETTER AGREEMENT COMPARED TO THE GUIDANCE FROM 12-24 HOURS AGO WITH FASTER TRENDS. THE LATEST ENSEMBLE SPAGHETTI HEIGHTS SHOW ONLY THE 12Z GEFS AS SLOW OFF OF THE CA COAST MON MORNING. GIVEN THE 18Z GEFS AND 18Z/00Z GFS HAVE JOINED THE PACK...CONFIDENCE HAS INCREASED SOME AGAINST THE SLOWER TRACK. THE ONE MODEL THAT STANDS OUT MORE SIGNIFICANTLY FROM THE REST IS THE 12Z CMC...WITH A SLOWER AND MORE COMPACT VORT MAX WITHIN THE BASE OF THE TROUGH APPROACHING CA SUN EVENING. THEREFORE...A NON 12Z CMC BLEND IS PREFERRED. UPPER TROUGH MOVING FROM THE PLAINS THROUGH THE GREAT LAKES TODAY CLOSED LOW OVER THE NORTHEAST SUN NIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z NAM...00Z GFS...12Z ECMWF BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 12Z UKMET STANDS OUT DISPLACED FROM THE REMAINING...WELL CLUSTERED MODELS REGARDING THE SURFACE LOW TRACK ACROSS THE GREAT LAKES FRI NIGHT TOWARD THE NORTHEAST. THE 12Z UKMET IS ALSO A BIT WEAKER AT 850 MB WITH THE LOW CENTER AND SO THERE IS ENOUGH OF A DIFFERENCE FROM THE 12Z UKMET TO GO AGAINST IT. THE 12Z CMC HAS A BETTER POSITION BUT IS WEAKER 850 MB SLOW CENTER LIKE THE 12Z UKMET. THE 00Z NAM...00Z GFS AND 12Z ECMWF FORM A MORE PREFERABLE COMPROMISE. MINOR DIFFERENCES AMONG THE NAM/GFS/ECMWF CONTINUE AS THE STORM SYSTEM APPROACHES THE NORTHEAST BUT THEY LIE WITHIN THE RELATIVELY TIGHT ENSEMBLE SPREAD SEEN BY 12Z/20. THE NAM/GFS/ECMWF SHOW SIMILAR STRENGTH 850 MB LOW AND TRACK. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO