MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1111 PM EST TUE MAR 01 2016 VALID MAR 02/0000 UTC THRU MAR 05/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z GFS/NAM EVALUATION WITH PRELIMINARY MODEL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. WEAK UPPER TROUGH SPLITTING AS IT ENTERS THE WEST FRI/SAT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-UKMET COMPROMISE CONFIDENCE: ABOVE AVERAGE THE 12Z UKMET IS QUICKER -- ITS USUAL BIAS -- AND STRONGER WITH THIS SYSTEM MOVING INTO THE WEST. AS IT IS MOVING THROUGH QUICK FLOW ON THE EAST SIDE OF A BROAD UPPER TROUGH, A WEAKER SOLUTION ALOFT IS MORE PROBABLE. A COMPROMISE OF THE 00Z GFS/00Z NAM/12Z CANADIAN/12Z ECMWF IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE. SYSTEM DIVING THROUGH THE PLAINS FRIDAY/SAT MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GFS/ECMWF COMPROMISE CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 00Z NAM WAS QUITE TO THE NORTH WITH THE ASSOCIATED SURFACE LOW DUE TO A SHARPER UPPER LEVEL SYSTEM. MEANWHILE, THE 12Z UKMET WAS SURPRISINGLY SLOW ALOFT, EVEN THOUGH ITS PRESSURE PATTERN GENERALLY KEPT PACE WITH THE OTHER GUIDANCE. A COMPROMISE OF THE 00Z GFS/12Z ECMWF FITS THE 12Z ECMWF/18Z GEFS MEANS THE BEST AND IS PREFERRED WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE. SYSTEM MOVING THROUGH THE PLAINS/SOUTHWEST WED-FRI ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-UKMET COMPROMISE CONFIDENCE: ABOVE AVERAGE THE 12Z UKMET IS FASTER -- ONE OF ITS USUAL BIASES -- AND MORE NORTHERLY WITH THE LOW APPROACHING THE APPALACHIANS. THE REST OF THE GUIDANCE, INCLUDING THE ENSEMBLE MEANS, SHOWS GOOD AGREEMENT. A COMPROMISE OF THE 00Z GFS/12Z ECMWF/12Z CANADIAN/00Z NAM IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE TO DEAL WITH LINGERING DETAIL ISSUES. SYSTEM MOVING BY THE EASTERN SEABOARD WEDNESDAY MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ THE GUIDANCE SHOWS EXCELLENT AGREEMENT WITH THIS SYSTEM, SO A GENERAL MODEL COMPROMISE IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ROTH