MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1254 AM EDT WED JUL 09 2014 VALID JUL 09/0000 UTC THRU JUL 12/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ...AN EVALUATION OF THE 00Z NAM/GFS ALONG WITH PRELIMINARY PREFERENCES/FORECAST CONFIDENCE... THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE 00Z NAM/GFS DEEMED SIGNIFICANT ENOUGH TO IMPACT THEIR FORECASTS. ...UPPER TROF ANCHORING NORTHEASTERN NORTH AMERICA... ...SURFACE BOUNDARY EXITING THE NORTHEASTERN U.S... PRELIMINARY PREFERENCE: A NON-12Z CMC MODEL COMPROMISE FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE A DEEP AND ANOMALOUS TROF WILL BE FEATURED ACROSS NORTHEASTERN NORTH AMERICA FOR MUCH OF THE WEEK. A SERIES OF SHORTWAVES ARE FORECAST TO TRAVERSE ABOUT THE BASE OF TROF WITH THE MEAN NEGATIVE ANOMALY SHIFTING EASTWARD IN TIME. THROUGH 48 HOURS...11/0000Z...THE MODELS ARE IN REASONABLE AGREEMENT WITH THE FORECAST EVOLUTION. ONE MINOR EXCEPTION IS THE 12Z CMC WHICH IS FARTHER EAST WITH THE PLACEMENT OF THE SURFACE BOUNDARY ALONG THE OFFSHORE WATERS OF NEW ENGLAND. THE 500-MB HEIGHT PATTERN OVER THE NORTHEASTERN U.S. IS NOT TERRIBLY DIFFERENT ACROSS THE BOARD WITH MORE OF THE UNCERTAINTY WITH THE CORE OF LOWER HEIGHTS UP IN QUEBEC. GIVEN THE EASTERN NATURE OF THE 12Z CMC SOLUTION...WILL FAVOR A NON-12Z CMC MODEL COMPROMISE HERE. ...BROAD UPPER TROF MOVING ACROSS WESTERN/CENTRAL CANADA... ...SHORTWAVE SLIDING THROUGH THE NORTHERN PLAINS/UPPER MIDWEST ON THURSDAY... PRELIMINARY PREFERENCE: BLEND OF THE 00Z GFS/12Z ECMWF FORECAST CONFIDENCE: AVERAGE MODELS DEPICT A SYSTEM EVOLVING OUT OF THE GULF OF AK WITH HEIGHT FALLS SPREADING INLAND ACROSS WESTERN U.S. BY MID-WEEK. THE CORRIDOR OF STRONGEST HEIGHT FALLS APPEAR TO BE CONFINED TO CANADA WITH QUASI-ZONAL FLOW PREVAILING FROM THE PACIFIC NORTHWEST INTO THE NORTHERN PLAINS. MORE OF THE CONUS FOCUS WILL BE ON A SHORTWAVE SWINGING THROUGH THE NORTH-CENTRAL U.S. ON THURSDAY BEFORE MIGRATING INTO THE UPPER GREAT LAKES BY THE FOLLOWING DAY. THERE APPEAR TO BE TWO CAMPS WITH A SLOWER/MORE NORTHERN GROUPING FEATURING THE 00Z NAM/GFS AND 12Z UKMET. FURTHER DOWNSTREAM THERE IS MORE AGREEMENT BETWEEN THE 12Z CMC/ECMWF. SOME DIFFERENCES OCCUR LATER ON WITH REGARD TO HOW QUICKLY TO SHEAR THE SHORTWAVE. ENSEMBLES SUGGEST MORE AMPLITUDE THAN THE 12Z CMC/UKMET ARE PROVIDING SO WILL LEAN TOWARD A MORE DEFINED WAVE FOLLOWING IN LINE WITH THE 00Z GFS/12Z ECMWF. ...WEAK TROF OFFSHORE OF THE WEST COAST LATE IN THE PERIOD... PRELIMINARY PREFERENCE: BLEND OF THE 00Z NAM/GFS WITH THE 12Z ECMWF FORECAST CONFIDENCE: SLIGHTLY BELOW AVERAGE TOWARD THE END OF THE WORK WEEK AND INTO THE EARLY PORTION OF THE UPCOMING WEEKEND...THE GUIDANCE SHOWS AN ELONGATED UPPER TROF SITTING JUST OFFSHORE OF THE WESTERN U.S. THE 00Z NAM/GFS AND 12Z ECMWF AGREE WITH THE ENSEMBLE MEANS IN DEPICTING A PAIR OF DEFINED SHORTWAVES. MEANWHILE...THE 12Z CMC/UKMET ARE FARTHER TO THE WEST WITH ONLY ONE DISTINCT WAVE NOTED. WHILE THE 00Z NAM/GFS AND 12Z ECMWF GROUP EXHIBIT DIFFERENCES IN POSITION...FEEL COMFORTABLE UTILIZING THESE MODELS AS THEY SUPPORT THE PATTERN THE ENSEMBLES ARE SUGGESTING. CONFIDENCE WILL BE SLIGHTLY REDUCED GIVEN THE SPREAD. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... RUBIN-OSTER