MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1203 PM EST WED JAN 11 2017 VALID JAN 11/1200 UTC THRU JAN 15/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z NAM/GFS EVALUATION INCLUDING PRELIMINARY PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ CYCLONIC FLOW/SHORTWAVES SINKING ACROSS NORTHERN PLAINS ASSOCIATED FLAT SURFACE WAVE ACROSS GREAT LAKES EARLY THURS SURFACE WAVE CURVING THROUGH THE CANADIAN PRAIRIES EARLY THURSDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: AVERAGE TODAYS 12Z GFS IS A BIT FASTER WITH THE SURFACE LOW ACROSS NEW ENGLAND ON THU...AND WHILE THIS WAS ALSO THE CASE YESTERDAY...TRENDS SINCE YESTERDAY HAVE EDGED FASTER TOWARD THE PREVIOUS GFS. ENSEMBLE TRENDS AND THE LATEST 12Z NAM/GFS ALSO HOLD ONTO A SECOND LOW WITH A DOUBLE BARREL FEATURE APPEARING BY 00Z/13 ACROSS FAR NRN NEW ENGLAND INTO THE CANADIAN MARITIMES. GIVEN THE SMALL SCALE DIFFERENCES...RECOMMEND TO GO WITH A GENERAL MODEL BLEND...WHICH WOULD SLOW DOWN THE 12Z GFS POSITION SOME BUT NOT TO THE SLOWER EDGE OF THE SPECTRUM. WEAK SHORTWAVE CROSSING THE PLAINS TONIGHT...EVENTUALLY REACHING THE OHIO VALLEY AND GREAT LAKES BY THU ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: AVERAGE ONLY MINOR DIFFERENCES WITH THIS FEATURE WERE NOTED...WITH A GENERAL MODEL COMPROMISE RECOMMENDED TO SMOOTH OUT THESE SMALLER SCALE DIFFERENCES. CLOSED LOW OVER THE SRN WEST COAST FOR THE END OF THE WEEK ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z GFS / 00Z UKMET BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE EARLY IN THE FORECAST...BY 12Z/12...THE 00Z ECMWF WAS NOTED TO BE SLIGHTLY WEAKER THAN THE DETERMINISTIC/ENSEMBLE CONSENSUS REGARDING LOW PRESSURE NEAR THE CNTRL CA COAST. THIS RESULTS IN SLIGHTLY WEAKER 850 MB FLOW INTO CA. THE 00Z CMC WAS ALSO DISPLACED SLIGHTLY NORTH OF THIS CONSENSUS. A BLEND OF THE 12Z NAM/GFS APPEARS MOST REASONABLE HERE FOR EARLY IN THE PERIOD. BEYOND THU NIGHT...OR 00Z/13...THE CLOSED LOW THAT FORMS AND BEGINS TO MOVE EASTWARD ACROSS THE SWRN U.S. SHOWS SOME SMALLER SCALE DIFFERENCES. THE 00Z ECMWF LOOKED WEAKER WITH LOW-MID LEVEL RIDGING CENTERED ACROSS THE SOUTHEAST COMPARED TO ITS MEAN...WHICH MAY ALLOW THE 00Z ECMWF TO ADVANCE THE CLOSED LOW QUICKER TOWARD THE EAST. THERE WAS RELATIVELY GOOD CONSENSUS AMONG THE MODELS...BUT A BLEND OF THE 12Z GFS AND 00Z UKMET APPEARED TO HAVE THE BEST HANDLE ON THE SITUATION GIVEN TRENDS IN THE ENSEMBLE SPAGHETTI HEIGHTS HAVE SHOWN SLOWER AND SLIGHTLY WEAKER WITH THE CLOSED LOW THROUGH FRI NIGHT. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO