MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 253 AM EDT WED AUG 12 2015 VALID AUG 12/0000 UTC THRU AUG 15/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/CMC AND ECMWF ...UPPER LOW/TROUGH OFF THE WEST COAST... PREFERENCE: BLEND OF THE 00Z GFS AND 00Z ECMWF CONFIDENCE: AVERAGE THE UPPER LOW OFF THE WEST COAST IS EXPECTED TO GRADUALLY SHIFT EAST INTO THE NORTHWEST U.S. BY THURS AND FRI. THE MODELS ARE RATHER WELL CLUSTERED WITH THE TIMING AND DEPTH OF THE ENERGY THROUGH ABOUT 48 HOURS...BUT THEN SOME NOTABLE DIFFERENCES SHOW UP THEREAFTER. THE 00Z NAM AND 00Z GFS ACCELERATE THE EASTWARD ADVANCE OF THE HEIGHT FALLS ACROSS THE NORTHERN ROCKIES AND INTO THE NORTHERN HIGH PLAINS FRI AND SAT. THE NON-NCEP MODELS LED BY THE 00Z ECMWF/00Z UKMET AND 00Z CMC ARE CLUSTERED ALL SLOWER...WITH THE 00Z UKMET BEING THE SLOWEST OVERALL. THE LATEST GEFS MEAN AND ECENS MEAN WOULD SUGGEST A SOLUTION GENERALLY IN BETWEEN CAMPS. THIS WOULD GENERALLY BE A BLEND OF THE 00Z GFS AND 00Z ECMWF AS IT RELATES ESPECIALLY TO TIMING...AND SINCE THEY AGREE WELL ON DEPTH...AND A BLEND OF THE 00Z GFS AND 00Z ECMWF WILL BE PREFERRED. ...VORT ENERGY LIFTING NORTH THROUGH THE GREAT BASIN... ...EJECTING EAST AROUND THE MID LEVEL RIDGE INTO THE PLAINS/MIDWEST... PREFERENCE: NON-NAM CONSENSUS CONFIDENCE: ABOVE AVERAGE A RATHER WELL-DEFINED VORT CENTER IS EXPECTED TO LIFT NORTH THROUGH THE GREAT BASIN TODAY AROUND THE WESTERN PERIPHERY OF THE MID LEVEL RIDGE AXIS ANCHORED OVER THE SOUTHERN HIGH PLAINS. THIS VORT WILL ROUND THE NORTH SIDE OF THE RIDE AND EJECT EAST OUT INTO THE NORTHERN PLAINS ON THURS BEFORE SHEARING SOUTHEAST ACROSS THE MIDWEST ON FRI. THE 00Z NAM IS A DEEPER OUTLIER WITH THIS SYS AS IT CROSSES THE NORTHERN PLAINS AND ALSO TRACKS ITS VORT NORTH OF THE GLOBAL CONSENSUS. A NON-NAM CONSENSUS WILL BE PREFERRED. ...UPPER TROUGH/SURFACE LOW CROSSING THROUGH THE NORTHEAST THROUGH THURS... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS ARE GENERALLY IN GOOD AGREEMENT ON THE LARGER SCALE WITH THE TROUGH EVOLUTION AND TIMING OF THE SURFACE WAVE THAT WILL BE LIFTING THROUGH THE NORTHEAST AND INTO SOUTHEAST CANADA OVER THE NEXT COUPLE OF DAYS. A GENERAL MODEL COMPROMISE WILL BE PREFERRED. ...NORTHERN STREAM TROUGH DIGGING TOWARD SOUTHEAST CANADA BY FRI... ...ENERGY APPROACHING THE NORTHERN NEW ENGLAND FRI NIGHT/SAT... PREFERENCE: NON-NAM CONSENSUS CONFIDENCE: ABOVE AVERAGE A NORTHERN STREAM SHORTWAVE TROUGH DIGGING SOUTHEAST OF HUDSON BAY BY THURS WILL MOVE INTO SOUTHEAST CANADA AND APPROACH THE NORTHEAST ON FRI. OVERALL THERE IS FAIRLY GOOD MASS FIELD AGREEMENT ALOFT WITH THE HEIGHT FALLS...BUT THE 00Z NAM IS NOW TENDING TO BE THE DEEPEST SOLUTION AS THE ENERGY MOVES INTO NORTHERN NEW ENGLAND BY FRI NIGHT/SAT. A NON-NAM CONSENSUS WILL BE PREFERRED. ...UPPER TROUGH OVER THE SOUTHEAST BY LATE THURS AND FRI... PREFERENCE: NON-NAM CONSENSUS CONFIDENCE: AVERAGE THE GUIDANCE INDICATES ENERGY SEPARATING AWAY FROM THE INITIAL TROUGH MOVING INTO THE NORTHEAST OVER THE NEXT COUPLE OF DAYS. THE RESULT WILL BE A TROUGH OVER THE SOUTHEAST WITH SOME AMPLIFICATION INDICATED IN THE MODELS. THE 00Z NAM IS A DEEPER OUTLIER SOLUTION WITH THE TROUGH. THE GLOBAL MODELS ARE NOW IN BETTER AGREEMENT COLLECTIVELY AND CLUSTER TOGETHER WELL WITH OVERALL DEPTH AND TROUGH PLACEMENT. THUS...A NON-NAM CONSENSUS WILL BE PREFERRED. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON