MODEL DIAGNOSTIC DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 137 PM EDT THU AUG 16 2012 VALID AUG 16/1200 UTC THRU AUG 20/0000 UTC ...SEE NOUS42 KWNO ADMNFD FOR THE STATUS OF THE UPPER AIR INGEST... FINAL 12Z MODEL EVALUATION ANY INITIALIZATION ERRORS IN THE NAM/GFS DO NOT APPEAR TO SIGNIFICANTLY IMPACT THEIR FORECASTS... ...LONGWAVE AND FRONT MIGRATING THROUGH THE MIDWEST AND NORTHEAST...DAYS 1-3 PREFERENCE: 12Z GFS-CANADIAN/00Z ECMWF BLEND CONFIDENCE: AVERAGE THE 12Z GFS AND 00Z ECMWF WERE TWO GOOD STARTING POINTS THIS MORNING THROUGH DAY 2. WITH THE 12Z CANADIAN AND UKMET IN...THE 12Z GFS CARRIES A SLIGHTLY FASTER/DEEPER SYSTEM ALONG 80W LONGITUDE BY EARLY DAY 3 VS THE OTHER 12Z SOLUTIONS IN HANDLING THE FRONTAL PROGRESSION THROUGH THE MIDWEST AND OHIO VALLEY DAY 1 THE MODELS WERE ROCK SOLID. THEN WITH THE SECONDARY IMPULSE TRACKING SOUTHEASTWARD FROM SOUTHERN CANADA INTO THE MISSOURI VALLEY BETWEEN DAY 2-3...THE CANADIAN AND GFS WOULD BE THE QUICKER SOLUTIONS ACROSS THE MID MISSOURI VALLEY. THE FINER DETAILS HAVE YET TO BE DETERMINED...BUT THE BLENDED MASS FIELDS OF THE SLIGHTLY FASTER 12Z GFS AND THE SLOWER 00Z ECMWF IS A GOOD PLACE TO START THROUGH DAY. DIFFERENCES CROP UP ALONG THE SOUTHERN END OF THE FRONT EARLY ON IN THE LATE DAY 1 PERIOD...SO BLENDING THE TWO WILL MITIGATE THESE DIFFERENCES. FOR DAYS 2-3...SOMETHING CLOSER TO THE 00Z ECMWF/12Z CANADIAN SEEMS TO HANDLE THE FASTER GFS SOLUTION BY THE END OF DAY 3. ...NEGATIVE TILT TROUGH MOVING ACROSS NEW ENGLAND...DAY 1 PREFERENCE: 12Z MODEL CONSENSUS AND 00Z ECMWF BLEND CONFIDENCE: ABOVE AVERAGE THE 12Z GUIDANCE OVERALL AGREES WITH THE MASS FIELD FORECAST FOR A TRACK THROUGH THE GULF OF MAINE DURING THE DAY 1 PERIOD. THE DIFFERENCES ARE TIED TO THE FINER DETAILS AND QPFS. HOWEVER...NOT ENOUGH OF A DIFFERENCE FOR WAVER FROM THE SOLID MODEL CONSENSUS. ...MODEL TREND GRAPHICS AT www.hpc.ncep.noaa.gov/html/model2.shtml ...500 MB FORECASTS AT www.hpc.ncep.noaa.gov/h5pref/h5pref.shtml VOJTESAK