MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1207 PM EDT MON JUN 20 2016 VALID JUN 20/1200 UTC THRU JUN 24/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z NAM/GFS EVALUATION WITH PRELIMINARY MODEL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ THE HIGHLY VARIABLE GPS PRECIPITABLE WATER VALUE ISSUE WAS RESOLVED BY 1415Z. THIS RESOLUTION WAS NOT IN TIME FOR THE 12Z GFS OR RUNS PRIOR TO 14Z OF THE RAP/HRRR GUIDANCE, SO USE THOSE PIECES OF GUIDANCE WITH GREATER CAUTION THAN USUAL. SYSTEM MOVING INTO THE NORTHWEST THURSDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GFS/ECMWF/CANADIAN COMPROMISE CONFIDENCE: ABOVE AVERAGE THE 12Z NAM/00Z UKMET ARE QUICKER TO MOVE THIS SYSTEM EASTWARD ALOFT. AS THE SYSTEM IS DIGGING DOWNSTREAM OF RIDGING ACROSS THE NORTHEAST PACIFIC/GULF OF AK, PREFER A SLOWER SOLUTION HERE, WHICH IS ALSO FAVORED BY THE 00Z ECMWF/06Z GEFS ENSEMBLE MEAN SOLUTIONS. A COMPROMISE OF THE 12Z GFS/00Z ECMWF/00Z CANADIAN IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE. GREAT LAKES-NRN MID ATL STATES LOW & SHORTWAVE WED/THU ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: ECMWF/UKMET COMPROMISE CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 12Z GFS IS THE MOST AMPLIFIED/STRONGEST SOLUTION ALOFT WHICH ALLOWS ITS SURFACE CYCLONE TRACK TO MOVE NORTH OF THE REMAINDER OF THE GUIDANCE BY LATE WEDNESDAY. THE 12Z NAM IS THE QUICKEST. THIS SYSTEM IS EMBEDDED WITHIN QUASI-ZONAL FLOW MOVING OVER THE TOP OF BROAD RIDGING BEFORE MOVING UNDER THE BASE OF A RETREATING/NORTHWARD-MOVING VORTEX IN NORTHERN QUEBEC. THE FLOW PATTERN FAVORS A WEAKER SOLUTION ALOFT/FLATTER LOW TRACK AT THE SURFACE, WHICH IS ALSO SUPPORTED BY THE 00Z GLOBAL ENSEMBLE GUIDANCE. A COMPROMISE OF THE 12Z UKMET/12Z ECMWF LOOKS BEST HERE, WHICH IS PREFERRED WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE. FRONT MOVING THROUGH THE NORTHEAST TUE/WED ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ THE GUIDANCE SHOWS EXCELLENT AGREEMENT WITH THIS SYSTEM, SO PREFER A GENERAL MODEL COMPROMISE TO DEAL WITH ANY LINGERING DETAIL ISSUES WITH ABOVE AVERAGE CONFIDENCE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ROTH