MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1240 PM EDT WED AUG 27 2014 VALID AUG 27/1200 UTC THRU AUG 31/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z NAM/GFS MODEL EVALUATION...INCLUDING PRELIMINARY PREFERENCES ...UPPER TROUGH AND ASSOCIATED COLD FRONT CROSSING THE NORTHEAST... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: AVERAGE OVERALL...THE 12Z NAM/GFS ARE IN GOOD AGREEMENT WITH THE 00Z ECMWF/UKMET/CANADIAN GLOBAL WITH RESPECT TO THE TIMING/AMPLITUDE OF THE 500 MB TROUGH AND ASSOCIATED SURFACE FRONT. ...UPPER-LEVEL TROUGH/LOW MOVING FROM THE ROCKIES IN THE PLAINS... ...SURFACE COLD FRONT DEVELOPING LATE WED IN THE LEE OF THE CENTRAL ROCKIES... ...SURFACE LOW LIFTING INTO THE MIDWEST... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: AVERAGE THERE ARE NO SIGNIFICANT OUTLIERS AMONGST THE 12Z NAM/GFS AND THE 00Z ECMWF/UKMET/ECMWF WITH THE AFOREMENTIONED FEATURES. ...SHORTWAVE IMPULSE MOVING FROM THE PAC NW FRI MORNING TO THE UPPER MIDWEST BY SAT EVENING... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: BELOW AVERAGE MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THIS FEATURE WITH SOME MINOR TIMING/AMPLITUDE DIFFERENCES NEAR THE END OF THE PERIOD. ...EASTERLY WAVE ADVANCING WEST ALONG THE GULF COAST... PREFERENCE: NON-NAM COMPROMISE CONFIDENCE: AVERAGE AS NOTED IN PREVIOUS RUNS...THE NAM IS MORE AMPLIFIED THAN THE MODEL CONSENSUS AS THIS SYSTEM MOVES INTO SOUTH TX/NORTHERN MEX. ...WAVE LIFTING FROM THE CENTRAL GULF INTO THE LOWER MS VALLEY... PREFERENCE: GFS/00Z ECMWF COMPROMISE CONFIDENCE: BELOW AVERAGE THE 00Z UKMET IS AMONG THE MORE AMPLIFIED MODELS AS THIS SYSTEM LIFTS ALONG THE WESTERN EDGE OF THE RIDGE FROM THE CENTRAL GULF COAST INTO THE LOWER MS VALLEY. IT ALONG WITH THE 00Z CANADIAN GLOBAL ALSO LIFTS THE SYSTEM FURTHER TO THE NORTH LATE IN THE PERIOD. IN CONTRAST...THE NAM OFFERS LITTLE EVIDENCE OF THIS FEATURE AT ALL. THE 00Z ECMWF IS A LITTLE MORE AMPLIFIED THAN THE GFS...BUT BOTH SHOW THIS FEATURE LIFTING ACROSS THE CENTRAL GULF COAST INTO THE LOWER MS VALLEY LATE IN THE PERIOD. ...DEEP TROUGH DIGGING INTO THE NORTHWEST BY FRI AND SAT... ...COLD FRONT PUSHING THROUGH THE NORTHWEST... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: AVERAGE THERE ARE NO SIGNIFICANT OUTLIERS AMONGST THE 12Z NAM/GFS AND THE 00Z ECMWF/UKMET/CANADIAN GLOBAL WITH THESE FEATURES. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... PEREIRA