MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1254 PM EDT THU SEP 08 2016 VALID SEP 08/1200 UTC THRU SEP 12/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ...AN EVALUATION OF THE 12Z NAM/GFS WITH PRELIMINARY PREFERENCES/FORECAST CONFIDENCE... ...MID/UPPER LEVEL TROUGH AMPLIFYING OVER THE NORTHERN/CENTRAL PLAINS LATE FRI/EARLY SAT... ...SURFACE LOW DEVELOPING OVER THE UPPER GREAT LAKES EARLY SAT... PREFERENCE: GFS/00Z ECMWF COMPROMISE...WITH MORE WEIGHT GIVEN TO THE GFS LATE IN THE PERIOD CONFIDENCE: AVERAGE OVERALL THE 12Z NAM/GFS AND THE OVERNIGHT GUIDANCE ARE IN GOOD AGREEMENT THROUGH EARLY SAT. THEN AS THE UPPER TROUGH SWINGS FURTHER TO THE EAST ACROSS THE GREAT LAKES AND THE SURFACE LOW TRACKS TO THE NORTHEAST INTO EASTERN CANADA...THE NAM BECOMES A NOTABLY SLOW OUTLIER IN COMPARISON TO THE OTHER DETERMINISTIC GUIDANCE. THE GFS/00Z ECMWF ARE MORE SIMILARLY TIMED UNTIL LATE SAT WHEN THEN GFS MOVES TO THE LEADING EDGE OF THE DETERMINISTIC SOLUTIONS. HOWEVER ENSEMBLE GUIDANCE FROM OVERNIGHT...INCLUDING THE 00Z EC ENSEMBLE MEAN...SUGGESTS THE 00Z ECMWF MAY BE TOO SLOW. THEREFORE...WILL RECOMMEND A COMPROMISE BETWEEN THE GFS/00Z ECMWF BUT WITH MORE WEIGHT GIVEN TO THE GFS LATE IN THE PERIOD. ...UPPER TROUGH DIGGING SOUTHEAST ACROSS WESTERN CANADA INTO THE NORTHWESTERN U.S. SAT-SUN... PREFERENCE: GFS/00Z ECMWF CONFIDENCE: AVERAGE THE DETERMINISTIC CONSENSUS...INCLUDING THE 12Z GFS/UKMET...SUPPORTS A SOLUTION THAT IS SLOWER THAN THE NAM AS THE TROUGH DIGS INTO THE NORTHWESTERN U.S. ON SUN. ...MID LEVEL SHORTWAVE ASSOCIATED WITH THE REMNANTS OF T.C. NEWTON... PREFERENCE: NAM/GFS/00Z ECMWF CONFIDENCE: AVERAGE OVERALL THE 12Z NAM/GFS AND THE 00Z ECMWF ARE IN GOOD AGREEMENT WITH THIS SYSTEM...SHOWING A WEAK MID LEVEL SHORTWAVE MOVING SLOWLY TO THE EAST INTO THE SOUTHERN HIGH PLAINS BY LATE FRI...BEFORE BEING CAPTURED IN PART BY THE AFOREMENTIONED TROUGH AMPLIFYING OVER THE PLAINS...WITH SOME WEAK ENERGY LINGERING ACROSS TX INTO SUN. ...UPPER LOW LIFTING TO THE NORTH ALONG THE SOUTHERN CA COAST... PREFERENCE: NAM/GFS/00Z ECMWF CONFIDENCE: AVERAGE OVERALL THE 12Z NAM/GFS AND THE 00Z ECMWF ARE IN GOOD AGREEMENT WITH THIS SYSTEM...SHOWING THIS SYSTEM DRIFTING SLOWLY TO THE NORTH ALONG THE COAST THIS PERIOD. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... PEREIRA