MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1210 PM EDT MON JUN 16 2014 VALID JUN 16/1200 UTC THRU JUN 20/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z NAM/GFS EVALUATION INCLUDING PRELIMINARY MODEL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. DEEP CYCLONE APPROACHING VANCOUVER LATE THURSDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: ECMWF/GFS/UKMET COMPROMISE CONFIDENCE: ABOVE AVERAGE THE 00Z CANADIAN IS THE SLOWEST/DEEPEST/FARTHEST SOUTH; ITS USUAL BIAS. THE NAM IS A LITTLE SHARPER ALOFT WITH ITS UPPER TROUGH/SHORTWAVE THAN THE REMAINING GUIDANCE -- ONE OF ITS USUAL BIASES -- WHICH LED TO A MORE SOUTHERLY SOLUTION WITH ITS SURFACE LOW (THOUGH NORTH OF THE CANADIAN). THE REMAINDER OF THE GUIDANCE FITS IN WELL WITH THE ENSEMBLE MEANS, SHOWING A MORE NORTHERLY SYSTEM MOVING INTO VANCOUVER. A COMPROMISE OF THE 00Z ECMWF/12Z GFS/00Z UKMET IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE CONSIDERING THE BIASES OF THE NAM AND CANADIAN. DEEP CYCLONE EMERGING INTO THE NORTHERN PLAINS LATE THU ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: CLOSE TO THE GFS CONFIDENCE: AVERAGE THE GUIDANCE SHOWS A BIT OF SPREAD ALOFT WITH THIS SYSTEM, AS THE ECMWF HAS A TWO-FOR-ONE SPECIAL, USING ENERGY ROUNDING ITS BASE TO DEVELOP ANOTHER 500 HPA CLOSED LOW; THIS TYPE OF SOLUTION RARELY VERIFIES. THE 00Z CANADIAN IS THE SLOWEST/DEEPEST/FARTHEST SOUTH; ITS USUAL BIAS. THE 12Z NAM WAS THE STRONGEST; ITS USUAL BIAS. THE 12Z GFS HAS THE BEST SUPPORT OF THE 06Z GEFS/00Z ECMWF ENSEMBLE MEAN SOLUTIONS, AND IS PREFERRED WITH AVERAGE CONFIDENCE CONSIDERING THE EXISTING MODEL SPREAD. TUTT CELL RETROGRADING PAST FL WED/THU ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: ECMWF/GFS/UKMET COMPROMISE CONFIDENCE: AVERAGE THE 12Z NAM/00Z CANADIAN ARE QUICKER TO RETROGRADE THIS SYSTEM WESTWARD INTO THE GULF OF MEXICO THAN THE OTHER DETERMINISTIC/ENSEMBLE MEAN GUIDANCE. USING THE ENSEMBLE MEAN SUPPORT AND THE ONGOING CONSENSUS AS A GUIDE, PREFER A COMPROMISE OF THE 00Z ECMWF/12Z GFS/00Z UKMET WITH CONFIDENCE NO BETTER THAN AVERAGE SINCE THE GUIDANCE DOES NOT HANDLE RETROGRADING UPPER LOWS ESPECIALLY WELL. DEEP CYCLONE IN EASTERN CANADA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-NAM COMPROMISE CONFIDENCE: ABOVE AVERAGE THE 12Z NAM IS DEEPER ALOFT WHICH LEADS TO A MORE NORTHERN SURFACE LOW TRACK; THIS SOLUTION ENJOYS ZERO SUPPORT AMONGST THE 00Z GLOBAL ENSEMBLE MEMBERS AND DISPLAYS ON OF THE NAM'S KNOWN BIASES. A NON-NAM COMPROMISE IS PREFERRED HERE WITH ABOVE AVERAGE CONFIDENCE CONSIDERING NAM BIASES. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ROTH