MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 232 AM EDT SAT APR 18 2015 VALID APR 18/0000 UTC THRU APR 21/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION WITH PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. UPPER LOW CLOSING OFF IN NORTHERN MN EARLY MONDAY CYCLONE MOVING THROUGH THE MS VALLEY/GREAT LAKES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-NAM COMPROMISE CONFIDENCE: AVERAGE THE 00Z NAM WAS ON THE EASTERN/DEEP SIDE OF THE SPREAD AT THE SURFACE AND ALOFT. THE ECMWF/CANADIAN SOLUTIONS TRENDED A LITTLE SLOWER, WHILE THE UKMET PICKED UP THE PACE, LEADING TO CONVERGENCE AMONGST THE NON-NCEP GUIDANCE. THE 12Z GLOBAL ENSEMBLE CLUSTERING MOST FAVORED A COMPROMISE OF THE NON-NAM GUIDANCE. TO ACCOUNT FOR RECENT TRENDS AMONGST THE NON-NCEP GUIDANCE, PREFER A COMPROMISE OF THE 00Z GFS/00Z CANADIAN/00Z UKMET/00Z ECMWF WITH LOWERED/AVERAGE CONFIDENCE CONSIDERING THE CHANGES SEEN IN THE NON-NCEP GUIDANCE. SYSTEM SLIPPING THROUGH NEW ENGLAND SATURDAY ENERGY DROPPING SOUTHWARD OFFSHORE CALIFORNIA FRONT APPROACHING THE PACIFIC NORTHWEST EARLY TUE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE GUIDANCE IS IN GOOD AGREEMENT WITH THESE SYSTEMS. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ROTH