MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 302 PM EDT WED JUN 17 2015 VALID JUN 17/1200 UTC THRU JUN 21/0000 UTC ...12Z CANADIAN WAS NOT AVAILABLE FOR THIS DISCUSSION... ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION WITH PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. CLOSED LOW OPENING UP AS IT MOVES ACROSS SOUTHWEST CANADA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: ECMWF/GFS COMPROMISE CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 00Z CANADIAN WAS SLOWER THAN THE OTHER GUIDANCE, WHICH ALLOWED FOR IT TO ADVERTISE A COHESIVE UPPER LEVEL DISTURBANCE RATHER THAN TWO -- ONE MOVING ACROSS SOUTHERN CANADA AND THE OTHER CLOSING OFF NEAR THE WEST COAST OF CANADA. SINCE THE GUIDANCE CAN BE QUICK TO PHASE SYSTEMS, PREFER A COMPROMISE OF THE REMAINING GUIDANCE, WHICH IS CLOSE TO A 12Z ECMWF/12Z GFS COMPROMISE, WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE. LOW MOVING THROUGH SOUTH-CENTRAL CANADA THIS WEEKEND ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: ECMWF/UKMET COMPROMISE CONFIDENCE: AVERAGE A 12Z ECMWF/12Z UKMET SPLITS THE DIFFERENCE IN THE GUIDANCE AND BRINGS US CLOSER TO THE 00Z GLOBAL ENSEMBLE CLUSTERING. THIS SOLUTION IS PREFERRED WITH AVERAGE CONFIDENCE. TROPICAL DEPRESSION BILL ~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GFS/ECMWF/UKMET COMPROMISE CONFIDENCE: AVERAGE/SEE LATEST WPC ADVISORY THE 12Z NAM WAS A CLEAR SLOW/WEST OUTLIER WITH THE TROPICAL DEPRESSION, LYING ON THE SLOW SIDE OF THE 00Z GLOBAL ENSEMBLE MEMBERS AND NOT HAVING ENOUGH SUPPORT BY FRIDAY MORNING. THE 00Z CANADIAN LOOKS REASONABLE INTO FRIDAY NIGHT BEFORE DEPARTING TO THE NORTH -- ONE OF ITS OLD BIASES WITH TROPICAL CYCLONES. CONSIDERING THE OVERALL FLOW PATTERN, BELIEVE A COMPROMISE OF THE 12Z GFS/12Z ECMWF/12Z UKMET LOOKS BEST WITH BILL. SEE THE LATEST WPC ADVISORY FOR THE FRESHEST INFORMATION, INCLUDING STORM TOTALS, RELATING TO BILL. FRONT MOVING THROUGH THE NORTHEAST FRIDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE GUIDANCE SHOWED GOOD AGREEMENT WITH THIS SYSTEM. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ROTH