MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1232 PM EDT SUN MAR 16 2014 VALID MAR 16/1200 UTC THRU MAR 20/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z NAM/GFS EVALUATION WITH PRELIMINARY MODEL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. DEEP CYCLONE MOVING TOWARDS THE GREAT LAKES TUE NIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GFS/ECMWF/CANADIAN COMPROMISE CONFIDENCE: SLIGHTLY BELOW AVERAGE THE 12Z NAM IS COMPLETELY OUTSIDE THE 00Z GLOBAL ENSEMBLE SPREAD WITH ITS LOW TRACK, AND IS UNIQUELY DEEP ALOFT -- ITS TRADITIONAL BIAS. THE 09Z SREF MEAN IS UNIQUELY QUICK WITH THIS SYSTEM'S NORTHEAST PROGRESSION. NEITHER IS DEEMED USABLE. THE 00Z UKMET IS THE SLOWEST WITH THIS SYSTEM'S PROGRESSION. THE SYSTEM IS EMBEDDED WITHIN A PROGRESSIVE FLOW PATTERN WITH MODERATE AMPLITUDE, SO THE UKMET COULD BE SOMEWHAT SLOW. WHILE THE GFS HAS BEEN RELATIVELY CONSISTENT WITH THIS SYSTEM, IT HAS NUDGED IT SOUTHWARD ALOFT AND AT THE SURFACE, IN THE DIRECTION OF THE NON-NCEP GUIDANCE. A COMPROMISE OF THE 00Z CANADIAN/00Z ECMWF/12Z GFS WILL DEAL WITH LINGERING ISSUES HERE, WITH SLIGHTLY BELOW AVERAGE CONFIDENCE DUE TO THE GREATER THAN AVERAGE GUIDANCE SPREAD. SHORTWAVE MOVING BY THE OHIO VALLEY/NORTHEAST MONDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: AVERAGE MODELS HAVE CONVERGED ENOUGH SUCH THAT REMAINING DIFFERENCES CAN BE RESOLVED WITH A GENERAL MODEL COMPROMISE. UPPER TROUGH/LOW MOVING ALONG THE GULF/SOUTHEAST COASTS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: UKMET/ECMWF COMPROMISE CONFIDENCE: BELOW AVERAGE WELL ABOVE AVERAGE SPREAD CONTINUES WITH THIS SYSTEM, AS THE GFS IS TRENDING EVEN QUICKER WITH ITS PROGRESSION, LIKELY DUE TO PLENTY OF GRIDSCALE FEEDBACK. ITS MASS FIELDS ARE LIKELY TOO PROGRESSIVE. THE 12Z NAM/09Z SREF MEAN ARE THE SLOWEST -- THE USUAL NAM/WRF BIAS. WITH A STRONG UPSTREAM KICKER MOVING THROUGH THE ROCKIES/CENTRAL PLAINS, THIS SYSTEM SHOULD BE PROGRESSIVE. THE GUIDANCE CLOSEST TO THE 00Z ECMWF/06Z GEFS MEANS ARE THE 00Z ECMWF/00Z UKMET, A COMPROMISE OF WHICH IS PREFERRED WITH BELOW AVERAGE CONFIDENCE DUE TO THE LARGE SPREAD REMAINING AMONGST THE AVAILABLE GUIDANCE. SHORTWAVE/COLD FRONT APPROACHING THE PAC NW WED MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-UKMET COMPROMISE CONFIDENCE: AVERAGE THE 00Z UKMET IS THE QUICKEST OF THE GUIDANCE WITH THIS SYSTEM -- ONE OF ITS USUAL BIASES. SINCE THE SLOWER CONSENSUS IS AGREEABLE WITH THE 00Z ECMWF/06Z GEFS MEANS, PREFER A NON-UKMET COMPROMISE WITH AVERAGE CONFIDENCE DUE TO ITS PROGRESSIVE NATURE. www.wpc.ncep.noaa.gov/html/model2.shtml... ROTH