MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1205 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 NAM/GFS EVALUATION WITH PRELIMINARY MODEL 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: GFS/ECMWF/CANADIAN COMPROMISE CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 00Z NAM WAS ON THE EASTERN/DEEP SIDE OF THE SPREAD ALOFT WHILE THE 12Z UKMET WAS SLOW AND ON THE WEST SIDE OF THE GUIDANCE. THE 12Z GLOBAL ENSEMBLE CLUSTERING MOST FAVORED A COMPROMISE OF THE 00Z GFS/12Z ECMWF/12Z CANADIAN, WHICH IS PREFERRED WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE. 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