MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 233 AM EDT SAT MAY 23 2015 VALID MAY 23/0000 UTC THRU MAY 26/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION WITH PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ GFS/NAM INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. UPPER LOW DRIFTING ACROSS THE PACIFIC NORTHWEST ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE GUIDANCE IS IN GOOD AGREEMENT WITH THIS SYSTEM. CLOSED LOW MOVING THROUGH THE NORTHERN PLAINS MONDAY PAIR OF SURFACE WAVES MOVING INTO SOUTHERN CANADA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-UKMET COMPROMISE CONFIDENCE: AVERAGE OTHER THAN THE 00Z UKMET LYING SOUTH OF THE OTHER GUIDANCE ON MONDAY/TUESDAY, THERE WAS A DEFINITE TREND SEEN IN THE 00Z GUIDANCE TOWARDS THE 00Z NAM/00Z GFS. A COMPROMISE OF THE 00Z CANADIAN/00Z ECMWF/00Z GFS/00Z NAM IS PREFERRED WITH AVERAGE CONFIDENCE. SYSTEM MOVING INTO THE SOUTHERN PLAINS MON/TUE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-CANADIAN COMPROMISE CONFIDENCE: SLIGHTLY BELOW AVERAGE THE 00Z GUIDANCE, OUTSIDE THE CANADIAN, HAS TRENDED TOWARDS A QUICKER SOLUTION HERE, SIMILAR TO THE 00Z GFS/00Z NAM. SINCE THE CANADIAN CAN HAVE A SLOW BIAS WITH SYSTEMS MOVING THROUGH THE WESTERLIES, PREFER A NON-CANADIAN COMPROMISE WITH SLIGHTLY BELOW AVERAGE CONFIDENCE DUE TO THE SIGNIFICANT MODEL SHIFT IN THIS REGION. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ROTH