MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1221 AM EDT MON AUG 18 2014 VALID AUG 18/0000 UTC THRU AUG 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 DID NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. CLOSED LOW DROPPING OFFSHORE CALIFORNIA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z ECMWF CONFIDENCE: SLIGHTLY ABOVE AVERAGE WITH THE CLOSED LOW DROPPING THROUGH CA, THE NON-GFS DROPS THE SYSTEM THROUGH THE COL IN THE MID-LEVEL PATTERN, WHICH ALLOWS IT TO CONTINUE ALONG ITS MERRY WAY INTO THE SUBTROPICAL PACIFIC. THE 00Z GFS DOES NOT QUITE GET THE SYSTEM PAST THE COL, SO IT SWEEPS THE SYSTEM INTO THE SOUTHEAST. THE 12Z ECMWF/18Z GEFS MEAN SOLUTIONS DO NOT FAVOR THE EASTWARD-MOVING GFS. A COMPROMISE OF THE REMAINDER OF THE GUIDANCE, CLOSEST TO THE 12Z ECMWF, APPEARS BEST HERE. FOR FORECASTS/MODEL PREFERENCES PREFERRED WITH THE SYSTEM IT INTERACTS WITH -- CURRENTLY TROPICAL DEPRESSION 12-E, SEE THE LATEST FORECASTS FROM THE NATIONAL HURRICANE CENTER. TROUGH BROADENING ACROSS THE NORTHERN ROCKIES ENERGY SHIFTING INTO THE DAKOTAS WED/THU ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-CANADIAN COMPROMISE CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE NON-CANADIAN GUIDANCE HANDLES THE DEGREE OF TROUGHING ACROSS THE NORTHWEST/NORTHERN ROCKIES SIMILARLY. A SHORTWAVE BEING FLUNG OUT OF THE EASTERN PERIPHERY OF THE UPPER TROUGH SHOWS AMPLITUDE ISSUES, WITH THE 12Z CANADIAN THE STRONGEST -- ITS USUAL BIAS. FOR THIS PORTION OF THE FORECAST, A NON-CANADIAN COMPROMISE IS BEST, WHICH IS PREFERRED WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE. SYSTEM MOVING OVER THE GREAT LAKES INTO THE NORTHEAST ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-CANADIAN COMPROMISE CONFIDENCE: ABOVE AVERAGE THE 12Z CANADIAN STARTS OFF STRONGER THAN THE OTHER GUIDANCE -- ITS USUAL BIAS -- THEN BECOMES BROADER/QUICKER WITH ITS ASSOCIATED UPPER LEVEL TROUGH. SINCE THE REMAINDER OF THE DETERMINISTIC GUIDANCE IS SIMILAR TO THE 12Z ECMWF/18Z GEFS MEANS, PREFER A NON-CANADIAN COMPROMISE WITH ABOVE AVERAGE CONFIDENCE. ...MODEL TREND GRAPHICS AT www.wpc.ncep.noaa.gov/html/model2.shtml... ...500 HPA FORECASTS AT www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ROTH