MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1250 AM EDT SUN JUN 29 2014 VALID JUN 29/0000 UTC THRU JUL 02/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. SURFACE LOW LINGERING OFF OF THE SERN U.S. COAST ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z ECMWF...12Z UKMET COMPROMISE THE NATIONAL HURRICANE CENTER (NHC) GIVES THIS SYSTEM A 40 PERCENT CHANCE TO DEVELOP INTO A TROPICAL CYCLONE OVER THE NEXT FEW DAYS. THE GUIDANCE THAT IS CLOSEST TO THE NHC AND WPC MEDIUM RANGE COORDINATED POINTS...WHICH IS IN LINE WITH THE LATEST ENSEMBLE SCATTER LOW PLOTS AND ENSEMBLE MEANS IS A BLEND OF THE 12Z ECMWF AND 12Z UKMET. THE 00Z NAM IS CLOSE TO THIS CONSENSUS...BUT THE NAM ALSO THE STRONGEST WITH THE SURFACE LOW AND SHOWS SEVERAL VORTICITY MAXIMA ALOFT COMPARED TO THE MORE FOCUSED ECMWF/UKMET. SEE NHC FOR THE LATEST INFORMATION ON TROPICAL DEVELOPMENT OF THIS SYSTEM. CLOSED LOW OVER S-CNTRL CANADA TODAY...OPENING UP INTO UPPER TROUGH TO CROSS THE GREAT LAKES TUE NIGHT WITH ASSOCIATED COLD FRONT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z NAM...12Z ECMWF COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS ARE IN REASONABLE AGREEMENT WITH THE SYNOPTIC EVOLUTION OF THIS SYSTEM BUT DIFFER WHEN IT COMES TO A POTENTIAL MCS ACROSS THE UPPER MIDWEST MON EVENING/NIGHT. THE 00Z GFS APPEARS TO HAVE SOME FEEDBACK...SHOWING A LARGE/ROUNDED QPF MAXIMA OVER WISCONSIN FOR THE 24 HR PERIOD ENDING 12Z/01 AND IS THEREFORE NOT PREFERRED. REGARDING A SECONDARY MID-LEVEL SHORTWAVE AXIS MOVING THROUGH THE MIDWEST WED MORNING...SOUTH OF THE MAIN UPPER TROUGH CENTERED OVER HUDSON BAY...THE NAM APPEARS TO SHOW THE BEST AGREEMENT TO THE CURRENT SET OF ENSEMBLE MEANS WITH SECONDARY AGREEMENT FROM THE 12Z ECMWF. WEAK SHORTWAVE TROUGH REACHING CALIFORNIA TUESDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE MODELS SHOW GOOD AGREEMENT WITH THIS SYSTEM...SO PREFER A GENERAL COMPROMISE AT THE MOMENT HERE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ROTH