MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 250 PM EDT THU MAY 14 2015 VALID MAY 14/1200 UTC THRU MAY 18/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ...AN EVALUATION OF THE 12Z MODEL GUIDANCE ALONG WITH FINAL PREFERENCES/FORECAST CONFIDENCE... THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE 12Z NAM/GFS DEEMED SIGNIFICANT ENOUGH TO IMPACT THEIR FORECASTS. ...BROAD LOW EJECTING FROM THE SOUTHWESTERN U.S. INTO GREAT PLAINS... FINAL PREFERENCE: GENERAL MODEL COMPROMISE FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE LATER OPERATIONAL MODELS 12Z UKMET/ECMWF/CMC HAVE FALLEN INTO LINE WITH THE PRIOR SUGGESTIONS OF THE 12Z GFS/00Z ECMWF SOLUTION....IN COMPARISON TO WATER VAPOR LOOP AND RECENT MODEL TRENDS...12Z GFS AND 00Z ECMWF APPEAR TO HAVE BEST SOLUTION OF INITIAL CONDITIONS...THE 12Z GFS CONTINUES TO HOLD MOST OF THE ENERGY BACK AND WITHIN THE BASE OF THE TROF...EJECTING IT LATER WITH A FURTHER SOUTH AND STRONGER SOLUTION. THIS IS MORE IN LINE WITH PREVIOUSLY PREFERRED 00Z ECMWF AND 00Z ECENS/GEFS EVEN THOUGH THE 12Z GFS IS A BIT STRONGER AND FURTHER SOUTH WOULD NOT BE SURPRISED TO SEE THE 12Z ECMWF COME IN STRONGER AS WELL. THE 00Z UKMET/CMC APPEAR TO STRONG WITH THE INITIAL NORTHERN SFC LOW AND OCCLUSION. REMARKABLE AGREEMENT NOW OCCURS THROUGH MOST OF THE PERIOD NOW THAT THE CMC/UKMET ARE IN LINE WITH THE OTHERS. SO HOLDING BACK ENERGY WITH THE 12Z-18Z EJECTION ON SATURDAY ...SHEARING OUT UPPER MIDWEST SHORTWAVE AND SYSTEM OVER SOUTHERN CANADIAN PRAIRIE... ...RESULTANT SHORTWAVE CROSSING THE GREAT LAKES DEEPENING ACROSS NEW BRUNSWICK BY SUN... FINAL PREFERENCE: GENERAL MODEL COMPROMISE FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE UPPER PLAINS/MIDWEST SHORTWAVE SHEARS OUT ACROSS GREAT LAKES BY FRIDAY NIGHT PULLING SMALL CLOSED LOW ACROSS SOUTHERN CANADIAN PLAINS ALONG WITH EVENTUALLY GOING NEG TILT AND BREAKING OFF ACROSS NORTHERN NEW ENGLAND/NEW BRUNSWICK BY SUNDAY. THE 12Z CMC/UKMET SOLIDIFYING ON THE UPSTREAM SOLUTION...THIS AREA APPEARS TO FALL IN LINE WITH THE 12Z NAM/GFS/00Z ECMWF. ...BROAD CYCLONIC CIRCULATION OFF THE WEST COAST LATE WEEKEND/MONDAY... FINAL PREFERENCE: GENERAL MODEL COMPROMISE FORECAST CONFIDENCE: ABOVE AVERAGE AT THE END PERIOD...ENHANCING CANADIAN REX BLOCK IN THE NORTHERN STREAM DEVELOPS AND DESCENDS AN JET STREAK/SPEED MAX ON THE BACK SIDE OF AN BROAD UPPER LOW OFF THE U.S. WEST COAST BY THE END OF THE WEEKEND IN PREPARATION OF ROUNDING THE BASE AND BETTER DEFINING THE LARGE SCALE TROF BY THE END OF THE DISCUSSION PERIOD. NEARLY ALL SOLUTIONS OF OPERATIONAL RUNS AND ENSEMBLE MASS FIELDS ARE IN REMARKABLE AGREEMENT. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... GALLINA