MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1135 PM EST FRI FEB 26 2016 VALID FEB 27/0000 UTC THRU MAR 01/1200 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 SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. SYSTEM MOVING THROUGH THE NORTHWEST SUNDAY/MONDAY CYCLONE IN THE SOUTHERN PLAINS LATE MONDAY/TUESDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: CLOSEST TO THE NAM CONFIDENCE: AVERAGE THE 12Z ECMWF, DESPITE A MODEST, BROAD UPPER SHORTWAVE SLOWLY DEEPENING AS IT MOVES INTO THE PLAINS, DECIDED TO DEVELOP A MUCH STRONGER LOW NEAR THE AR/MO/KS/OK BORDER (QUAD STATE) AREA THAN THE OTHER GUIDANCE. THE 12Z GLOBAL ENSEMBLE LOW SPREAD IS SUBSTANTIAL ACROSS THE PLAINS/MIDWEST/GREAT LAKES, BUT IT APPEARS THAT IT IS INDICATING TWO POSSIBLE LOWS -- ONE UP NEAR MI AND THE OTHER SOMEWHERE NEAR THE QUAD STATE AREA. DUE TO THE BREADTH OF THE UPPER LEVEL SHORTWAVE WHICH IS DIGGING SOMEWHAT ACROSS THE PLAINS, BELIEVE A WEAKER SOLUTION MAKES MORE SENSE. OVERALL, THE 00Z NAM BEST FITS THE GLOBAL ENSEMBLE LOW SPREAD, WHICH ALSO DEPICTS THE FRONTAL POSITION RATHER WELL. IT IS PREFERRED WITH AVERAGE CONFIDENCE. SHORTWAVE MOVING THROUGH SOUTH-CENTRAL CANADA FRONT MOVING THROUGH THE NORTHERN PLAINS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GFS/NAM/ECMWF COMPROMISE CONFIDENCE: ABOVE AVERAGE THE 12Z UKMET IS MUCH SLOWER IN MOVING THE PARENT SHORTWAVE THROUGH SOUTH-CENTRAL AND SOUTHEAST CANADA THAN THE OTHER GUIDANCE, WHICH SLOWS DOWN ITS COLD FRONT MOVING INTO THE NORTHERN PLAINS AND YIELDS A WAVE THAT SAILS NORTH OF THE SUBSTANTIAL 12Z GLOBAL ENSEMBLE LOW ENVELOPE. WHILE THE 12Z CANADIAN DOES SOMETHING SIMILAR, ITS OVERALL TROUGH APPEARS TOO PHASED BETWEEN THE NORTHERN AND SOUTHERN STREAM PORTIONS. PREFER A COMPROMISE OF THE 00Z GFS/00Z NAM/12Z ECMWF HERE WITH ABOVE AVERAGE CONFIDENCE. SYSTEM NEARING THE PACIFIC NORTHWEST MON NIGHT/TUE AM SYSTEM MOVING THROUGH THE PLAINS/GREAT LAKES/NORTHEAST ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ THE GUIDANCE SHOWS REASONABLE AGREEMENT WITH THESE SYSTEMS, SO PREFER A GENERAL MODEL COMPROMISE WITH ABOVE AVERAGE CONFIDENCE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ROTH