MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1210 AM EDT FRI MAR 17 2017 VALID MAR 17/0000 UTC THRU MAR 20/1200 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. FRONTAL ZONE MOVING THROUGH THE NORTHWEST/NORTHERN PLAINS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ THE GUIDANCE SHOWS GOOD AGREEMENT WITH THIS FEATURE AND THE LOW MOVING THROUGH SOUTHERN CANADA. A COMPROMISE OF THE AVAILABLE GUIDANCE, SIMILAR TO THE PARALLEL VERSION OF THE NATIONAL BLEND OF MODELS, IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE. SYSTEM LIFTING OUT OF THE NORTHEAST EARLY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-UKMET COMPROMISE CONFIDENCE: ABOVE AVERAGE THE 12Z UKMET LEAVES MORE ENERGY BEHIND ACROSS MAINE SATURDAY EVENING, SO MUCH SO THAT IT ENDS UP WITH A BONUS CLOSED LOW IN A VERY UNSTABLE POSITION WITHIN THE FLOW PATTERN. DUE TO THE UNUSUAL BEHAVIOR OF THE UKMET FEATURE, WILL PLAY THE ODDS AND PREFER A COMPROMISE OF THE 00Z GFS, 12Z CANADIAN, 00Z NAM, 12Z ECMWF, SIMILAR TO THE PARALLEL VERSION OF THE NATIONAL BLEND OF MODELS, WITH ABOVE AVERAGE CONFIDENCE. DEEP CYCLONE MOVING INTO THE NORTHWEST ATLANTIC LATE SUN ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GFS/NAM/UKMET COMPROMISE CONFIDENCE: ABOVE AVERAGE SMALL DIFFERENCES WITH THE BEHAVIOR OF THE SYSTEM MOVING THROUGH THE MID-ATLANTIC HAVE QPF CONSEQUENCES, PER COORDINATION WITH THE DAY 2/3 QPFer. THE 12Z ECMWF IS MORE SUPPRESSED THAN THE OTHER GUIDANCE WITH A BOUNDARY NEAR D.C., PERHAPS BECAUSE ITS SOLUTION AT 500 HPA IS MORE OPEN THAN THE REMAINDER OF THE GUIDANCE. THERE'S LITTLE REASON WHY IT SHOULDN'T BE CLOSED OFF ALOFT, SO PREFER A COMPROMISE OF THE 00Z GFS, 00Z NAM, 12Z UKMET WITH ABOVE AVERAGE CONFIDENCE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... Roth