MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1154 PM EST SAT NOV 15 2014 VALID NOV 16/0000 UTC THRU NOV 19/1200 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 DO NOT APPEAR TO DEGRADE THEIR SHORT RANGE FORECASTS. UPPER TROUGH SLOWLY APPROACHING CALIFORNIA TUE/WED ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 70% 00Z GFS...30% 12Z ECMWF BLEND CONFIDENCE: SLIGHTLY BELOW AVERAGE THE 12Z ECMWF...SIMILAR TO ITS 12Z ENSEMBLE MEAN...IS A BIT FARTHER NORTH WITH A CYCLONE CLOSING OFF OFFSHORE OF THE WEST COAST. THERE IS SIGNIFICANT SPREAD AMONGST THE 12Z ENSEMBLE GUIDANCE WHICH LOWERS CONFIDENCE. DIFFERENCES COME FROM THE DEGREE OF INTERACTION BETWEEN A CLOSED LOW WEST OF CALIFORNIA...NEAR NEAR 140 W...AND THE SRN INFLUENCE OF A CLOSED LOW CENTERED OVER THE BERING SEA. THE 12Z UKMET/CMC AND 00Z NAM SUPPORT THE GFS...BUT GIVEN THE ENSEMBLE SPREAD AND TIME FRAME IN THE FORECAST...WILL ONLY LEAN TOWARD THE GFS SOLUTION...WITH SOME WEIGHT GIVEN TO THE 12Z ECMWF. SHORTWAVE INVADING THE NORTHERN PLAINS LATE TUE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z NAM / 12Z ECMWF BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE GIVEN THE FAST MID-LEVEL FLOW FROM THE NORTH INTO THE NRN PLAINS BY LATE TUE...SLOWER SOLUTIONS LIKE THE 00Z GFS AND 12Z UKMET ARE LESS LIKELY TO VERIFY REGARDING THE MID LEVEL VORT CENTER. THERE ARE NO CLEAR TRENDS IN THE GUIDANCE...BUT THERE IS GOOD AGREEMENT IN THE ENSEMBLE MEANS SUPPORTING TIMING/STRENGTH CLOSE TO THE 00Z NAM AND 12Z ECMWF. LARGE UPPER LEVEL TROUGH SWINGING ACROSS THE ERN U.S. THROUGH TUE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z ECMWF/UKMET BLEND CONFIDENCE: AVERAGE THE LATEST GUIDANCE IS IN DECENT AGREEMENT WITH SOME MINOR TIMING DIFFERENCES STILL IN PLACE. THE 00Z NAM IS ON THE SLOWER END AND 00Z GFS CONTINUING TO BE TOWARD THE QUICKER END OF THE GUIDANCE. A MIDDLE OF THE ROAD APPROACH AND ENSEMBLE MEANS SUPPORT THE 12Z ECMWF/UKMET. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO