MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 231 AM EDT SAT MAR 14 2015 VALID MAR 14/0000 UTC THRU MAR 17/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION WITH PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. EASTERN PACIFIC TROUGH MONDAY INTO TUESDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: CLOSE TO THE ECMWF CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 00Z GFS SPLITS THE ENERGY WITHIN THIS TROUGH, KEEPING THE NORTHERN STREAM SHORTWAVE FLATTER AT ITS BASE OFFSHORE OREGON WHEN COMPARED TO THE REMAINDER OF THE GUIDANCE. AS THE DOWNSTREAM RIDGE IS AMPLIFYING IN ADVANCE/DUE TO THIS FEATURE MONDAY INTO TUESDAY, BELIEVE A MORE CONSOLIDATED UPPER TROUGH MAKES SENSE HERE. A COMPROMISE OF THE REMAINING GUIDANCE, CLOSE TO THE 00Z ECMWF, IS PREFERRED WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE. INTERMEDIATE STREAM SHORTWAVE NEAR THE NORTHWEST SUN/MON ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NAM/UKMET/ECMWF/SREF MEAN COMPROMISE CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 00Z GFS/00Z CANADIAN SHOW A STRONGER SHORTWAVE MOVING NEAR THE REGION THAN SEEN IN THE OTHER GUIDANCE, WHICH LEADS TO A STRONGER SURFACE LO. THE PARENT SHORTWAVE LIES WITHIN AN INTERMEDIATE STREAM OF THE WESTERLIES, IMPLYING MINIMAL CHANCE OF AN AMPLIFIED LOOK. THE 12Z GLOBAL ENSEMBLE LOW CLUSTERING HINTS AT THIS, DISPLAYING A DISTRIBUTION TYPICAL OF A WEAK FRONTAL WAVE -- IN STARK CONTRAST TO THE GFS AND CANADIAN SOLUTIONS. A COMPROMISE OF THE 00Z NAM/00Z UKMET/00Z ECMWF/21Z SREF MEAN FITS THE IDEA OF A WEAK AND ELONGATED SHORTWAVE SLOWLY SHEARING OUT WITH A WEAK SURFACE LOW MOVING INTO THE NORTHWEST, WHICH BEST FITS CONCEPTUAL MODELS. THIS PREFERENCE IS MADE WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE. UPPER LOW WANDERING ACROSS NORTHWEST MEXICO ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-CANADIAN COMPROMISE CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 00Z CANADIAN IS THE QUICKEST TO ATTEMPT TO EJECT THIS SYSTEM NORTH TO NORTHEASTWARD TOWARDS THE SOUTHERN PLAINS/SOUTHERN ROCKIES WITHOUT A SIGNIFICANT KICKER UPSTREAM. PREFER THE SLOWER NON-CANADIAN COMPROMISE HERE WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE. SYSTEM MOVING THROUGH SOUTHEAST CANADA SUN/MON ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NAM/ECMWF/UKMET COMPROMISE CONFIDENCE: AVERAGE THE 00Z GFS/00Z CANADIAN ARE STRONGER/QUICKER TO MOVE A SLUG OF ENERGY THROUGH NEW ENGLAND THAN THE OTHER GUIDANCE. THE 12Z ECMWF/21Z SREF ENSEMBLE MEAN SOLUTIONS APPEAR SUPPORTIVE OF A SLOWER EVOLUTION, AS SEEN IN THE 00Z NAM/00Z ECMWF/00Z UKMET GUIDANCE. WILL FAVOR THE GUIDANCE SHOWING A SLOWER EVOLUTION HERE WITH AVERAGE CONFIDENCE. NORTHEAST CYCLONE SAT/SUN ~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: HIGH THE GUIDANCE SHOWS GOOD AGREEMENT WITH THIS SYSTEM. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ROTH