MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1227 AM EDT WED MAR 22 2017 VALID MAR 22/0000 UTC THRU MAR 25/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ...PLEASE NOTE THAT THE NAM WAS UPGRADED TO A NEW VERSION 21/12Z CYCLE... 00Z NAM/GFS EVALUATION WITH PRELIMINARY MODEL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ GFS/NAM INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. SYSTEM MOVING INTO THE WEST FRIDAY NIGHT UPPER LOW CLOSING OFF IN THE BAHAMAS UPPER TROUGH LEAVING NEW ENGLAND TODAY SHORTWAVE STREAKING THROUGH SOUTHEAST CANADA FRONT MOVING INTO THE NORTHEAST SATURDAY MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ THE GUIDANCE SHOWS GOOD AGREEMENT WITH THESE SYSTEMS. A COMPROMISE OF THE AVAILABLE GUIDANCE, SIMILAR TO THE PARALLEL VERSION OF THE NATIONAL BLEND OF MODELS, IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE. DEEP CYCLONE MOVING THROUGH THE SOUTHERN PLAINS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: COMPROMISE OF THE AVAILABLE GUIDANCE CONFIDENCE: AVERAGE THE 12Z ECMWF/ITS ENSEMBLE MEAN REMAIN NORTHEAST OF THE OTHER GUIDANCE WITH THIS SYSTEM. IT APPEARS THIS IS DUE TO A SLIGHTLY MORE PROGRESSIVE TROUGH/RIDGE COUPLET OUT WEST AND SLIGHTLY MORE TROUGHING ALOFT NEAR MICHIGAN. THE RIDGE MOVING OVER THE TOP OF THE SYSTEM SHOULD SLOW ITS PROGRESSION, AND FOR NOW, THE ECMWF AND ENSEMBLE MEAN PROGRESSION IN THE WEST SLIGHTLY EXCEEDS THE REST OF THE GUIDANCE. PREFER A COMPROMISE OF THE AVAILABLE GUIDANCE -- SIMILAR TO THE PARALLEL VERSION OF THE NATIONAL BLEND OF MODELS -- WHICH IS A SOLUTION WEIGHTED SLOWER THAN THE 12Z ECMWF. CONFIDENCE IS AVERAGE IN THIS CHOICE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... Roth