MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1159 AM EST SAT NOV 12 2016 VALID NOV 12/1200 UTC THRU NOV 16/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z NAM/GFS EVALUATION INCLUDING PRELIMINARY PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ MID-LEVEL LOW CLOSING OFF IN THE SOUTHEAST BY SUNDAY SHIFTING NEWD SUPPORTING SURFACE LOW DEVELOPMENT MONDAY ALONG EAST COAST ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z ECMWF/ECMWF MEAN BLEND CONFIDENCE: AVERAGE ENSEMBLE SPAGHETTI PLOTS SHOW MODERATE SPREAD WITH THIS SYSTEM WHICH LEADS TO ONLY AVERAGE CONFIDENCE. TRENDS IN THE ENSEMBLE SCATTER LOW PLOTS SUPPORT A NORTHWARD ADJUSTMENT OVER THE PAST FEW RUNS VALID TUE NEAR THE EAST COAST. HOWEVER...THE 12Z GFS APPEARS ON THE NRN EDGE OF THE BETTER ENSEMBLE CLUSTERING...WITH THE 00Z ECMWF NEXT CLOSEST TO THE CENTER OF THE ENSEMBLE CLUSTERING. GOING OFF OF THE ENSEMBLE HEIGHT/SURFACE LOW DISTRIBUTIONS AND TRENDS...A BLEND OF THE 00Z ECMWF/00Z ECMWF MEAN APPEARS CLOSEST...WHILE THE 00Z UKMET/CMC AND 12Z NAM HAVE LITTLE SUPPORT. SHORTWAVE TROUGH OVER THE NORTHWEST THIS MORNING...TRANSLATING EAST TOWARD THE GREAT LAKES SUN NIGHT MID-LEVEL ENERGY DIVING INTO THE SOUTHEAST U.S. TUE MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON 12Z NAM BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE RELATIVELY MINOR DIFFERENCES EXIST WITH THIS SYSTEM...WITH THE 12Z GFS A BIT DEEPER/STRONGER WITH THE TROUGH AMPLIFYING INTO THE SOUTHEAST. HOWEVER...BY 00Z/16 THEY ALL SHOW SIMILAR AGREEMENT...WITH ONLY THE NAM DIFFERING DUE TO A FLATTER SHORTWAVE TROUGH CROSSING THE MID-MISS VALLEY MON NIGHT. LEAD SHORTWAVE ENERGY INTO BRITISH COLUMBIA SUN...WITH ASSOCIATED COLD FRONT ACROSS THE DAKOTAS BY TUESDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z GFS...00Z ECMWF...00Z UKMET BLEND CONFIDENCE: AVERAGE DIFFERENCES IN THE 12Z NAM UPSTREAM IMPACT THE FLOW DOWNSTREAM ACROSS THE NRN TIER...MAINLY REGARDING THE TIMING AND AMPLITUDE SEEN IN THE NAM. THE NAM STANDS OUT FROM THE REMAINING WELL CLUSTERED DETERMINISTIC CONSENSUS STARTING SUN NIGHT. A BLEND OF THE GFS/ECMWF/UKMET SHOWS THE MOST REPRESENTATIVE SOLUTION OF THE LATEST ENSEMBLE CLUSTERING...AVERAGING OUT THE MINOR AMPLITUDE DIFFERENCES SEEN IN THESE MODELS. SECONDARY SHORTWAVE IN ZONAL FLOW INTO PACIFIC NORTHWEST WITH SURFACE WAVE APPROACHING MONDAY EVENING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z ECMWF/12Z NAM BLEND CONFIDENCE: SLIGHTLY BELOW AVERAGE MODELS CONTINUE TO SHOW CONSIDERABLE RUN-TO RUN VARIABILITY GIVEN THE STRONG ZONAL NATURE OF THE FLOW. THE ECMWF/UKMET TRENDED FASTER TUE EVENING WITH THEIR 00Z RUNS...WHILE THE 00Z CMC REMAINED SIMILAR TO ITS PRIOR RUN. THE 12Z GFS HAS BEEN STEADILY TRENDING FLATTER AND FASTER ACROSS THE WEST COAST...AND LIES ON THE WEAKER SIDE OF THE LATEST ENSEMBLE SPREAD. GIVEN THE AGREEMENT SEEN BY THE ECMWF/NAM...THEY ARE PREFERRED AT THIS TIME BUT THE 00Z UKMET/CMC ARE SECONDARY OPTIONS AS WELL. GIVEN THE VOLATILITY SEEN IN THE GUIDANCE...CONFIDENCE IS A BIT BELOW AVERAGE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO