MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 246 AM EDT FRI SEP 12 2014 VALID SEP 12/0000 UTC THRU SEP 15/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ...AN EVALUATION OF THE 00Z CMC/UKMET/ECMWF ALONG WITH FINAL PREFERENCES/FORECAST CONFIDENCE... THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE 00Z NAM/GFS DEEMED SIGNIFICANT ENOUGH TO IMPACT THEIR FORECASTS. ...STRONG UPPER TROF SWINGING FROM THE CENTRAL U.S. TOWARD THE LOWER GREAT LAKES... ...COOLER THICKNESSES ADVANCING THROUGH THE CONUS... FINAL PREFERENCE: BLEND OF THE 00Z NAM/ECMWF FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE A FULL LATITUDE TROF ADVANCING THROUGH THE MIDDLE OF THE NATION WILL REMAIN PROGRESSIVE IN NATURE REACHING THE GREAT LAKES REGION BY EARLY SATURDAY. AS HAS BEEN THE THEME IN RECENT DAYS...THE 00Z GFS REMAINS FASTER THAN THE OTHER MODELS ALTHOUGH THE 00Z UKMET DOES APPEAR TO JOIN ITS SOLUTION FAIRLY QUICKLY. BY 14/0000Z...THE 00Z GFS/UKMET CONTINUE TO BE QUICKER WHICH KEEPS IT AWAY FROM THE SLOWER/MORE CLUSTERED ENSEMBLE MEANS. MEANWHILE...THE 00Z NAM WHICH ONCE APPEARED A BIT SLOW HAS BEEN JOINED BY THE 00Z CMC/ECMWF WHICH HAVE SEEMINGLY TRENDED TOWARD IT. WILL SHIFT THE PREFERENCE SLIGHTLY FROM EARLIER AND FAVOR A COMBINATION OF THE 00Z NAM/ECMWF. ...SECONDARY ENERGY CROSSING THE NORTHERN TIER STATES SATURDAY THROUGH MONDAY... ...ACCOMPANYING WEAK SURFACE WAVE... FINAL PREFERENCE: BLEND OF THE 00Z GFS/ECMWF FORECAST CONFIDENCE: AVERAGE ON THE WINGS OF THE INITIAL SHORTWAVE ADVANCING ACROSS THE CONUS...ANOTHER SYSTEM WILL AMPLIFY OVER THE NORTHERN TIER STATES BY THIS WEEKEND. THIS WILL COME IN THE FORM OF A SERIES OF SHORTWAVES WHICH HELP MAINTAIN A MEAN TROF OVER THE REGION. AMONG THE AVAILABLE MODELS...THE 00Z UKMET IS THE MOST AMPLIFIED/PROGRESSIVE SOLUTION COME EARLY SUNDAY ACROSS THE UPPER MIDWEST. THE ENSEMBLE MEANS ARE FAIRLY CLOSE TO ONE ANOTHER...PARTICULARLY THE 18Z GEFS/12Z ECMWF ENSEMBLE MEANS. THE 00Z NAM IS QUITE A BIT SLOWER WITH THE EVOLUTION RELATIVE TO THESE ENSEMBLES. THE 564-DM SPAGHETTI PLOT SUGGESTS THE 00Z UKMET IS INDEED TOO AMPLIFIED WHILE THE 00Z NAM IS SLOWER THAN THE CONSENSUS NOTED IN THE CONTOURS. WILL LEAN ON THE 00Z GFS/ECMWF GIVEN THE AFOREMENTIONED ASSESSMENT OF THE OTHER MODELS. ...DISTURBANCE EMERGING FROM THE YUCATAN PENINSULA REACHING EASTERN MEXICO... FINAL PREFERENCE: NON-00Z ECMWF FOR THE INITIAL WAVE...THEREAFTER THE 00Z GFS FORECAST CONFIDENCE: BELOW AVERAGE UNDERNEATH A BROAD RIDGE EXTENDING FROM THE SOUTHERN PLAINS EASTWARD TO THE SOUTHEASTERN CONUS WILL BE A SERIES OF DISTURBANCES MIGRATING FROM THE YUCATAN PENINSULA TOWARD FAR EASTERN MEXICO/EXTREME SOUTH TX. WITH THE EXCEPTION OF THE ECMWF SUITE...ALL MODELS SHOW ENERGY MOVING TOWARD EASTERN MEXICO LATE FRIDAY. LATER ON...ANOTHER DEFINED WAVE WILL APPROACH A SIMILAR REGION WITH THE 00Z UKMET BEING THE MOST AGGRESSIVE WITH ITS SOLUTION CARRYING A WELL DEFINED IMPULSE ALONG THE RIO GRANDE. OVERALL...WOULD PREFER TO NOT USE THE 00Z ECMWF EARLY ON AS IT LACKS AN INITIAL WAVE WHICH IS SHOWN IN ALL OF THE MODELS. THIS LEADS TO LARGE SCALE DIFFERENCES IN THE QPF DISTRIBUTION INLAND. THEREAFTER...WILL LEAN ON THE 00Z GFS AS IT SEEMS TO PROVIDE A SOLUTION CONSISTENT WITH THE MEANS. CONFIDENCE WILL BE BELOW AVERAGE GIVEN THE UNCERTAINTY PRESENT. ...EASTERLY WAVE TRACKING FROM SOUTH FL TOWARD THE CENTRAL GULF OF MEXICO... FINAL PREFERENCE: BLEND OF THE 00Z NAM/ECMWF FORECAST CONFIDENCE: AVERAGE A PRONOUNCED EASTERLY WAVE WILL MIGRATE FROM SOUTH FL TOWARD THE MIDDLE OF THE GULF OF MEXICO BY EARLY NEXT WEEK. THE NCEP GUIDANCE IS A TAD FASTER THAN THE 00Z ECMWF INITIALLY WHILE THE 00Z CMC INDICATES A MORE DEVELOPED MID-LEVEL CIRCULATION CENTER. WHILE THE 00Z CMC IS A BIT NORTH OF THE SURFACE LOW TRACK...IT DEFINITELY HAS COME SOUTHWARD RELATIVE TO ITS PREVIOUS RUN. THE WPC PREFERENCE WILL IGNORE THE SOMEWHAT OUTLYING 00Z CMC AND STAY CLOSER TO THE PREVIOUS SOLUTION WHILE INCORPORATING THE NEWER RUN OF THE ECMWF. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... RUBIN-OSTER