MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1144 PM EST THU JAN 07 2016 ...CORRECTION FOR REMOVAL OF EXTRA TEXT IN 4TH SECTION... VALID JAN 08/0000 UTC THRU JAN 11/1200 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 APPEAR TO DEGRADE THEIR SHORT RANGE FORECASTS. UPPER TROUGH AXIS NEARING THE WEST COAST MON MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON 00Z GFS BLEND CONFIDENCE: AVERAGE THE 00Z GFS SHOWS UP AS FAST COMPARED TO THE LATEST ENSEMBLE MEMBERS AND DETERMINISTIC GUIDANCE. SOME DEPTH DIFFERENCES REMAIN WITH THE NON GFS GUIDANCE...BUT A BLEND OF THESE MINOR DEPTH DIFFERENCES SHOULD SUFFICE WITH THIS SYSTEM THROUGH 12Z/11. ELONGATED UPPER TROUGH AXIS REACHING THE WEST COAST ON SAT SUBSEQUENT SHORTWAVE ENERGY DIVING THROUGH THE SOUTHWEST ON SUN ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS/12Z ECMWF MEAN COMPROMISE CONFIDENCE: AVERAGE THE 00Z NAM CONTINUES TO APPEAR SLOW WITH THE PIECE OF AN UPPER TROUGH FORECAST TO DIVE SEWD FROM THE CNTRL WEST COAST...WHILE THE 12Z ECMWF HAS BEEN ERRATIC WITH RUN TO RUN...MAKING CHANGES TO HOW THE TROUGH EVLOVES AS IT REACHES PAST THE WEST COAST OF THE CONUS. THE ENSEMBLE MEANS SHOW GOOD AGREEMENT BUT COULD BE BLENDING OUT ALL OF THE DETAILS. REGARDLESS...THE 00Z GFS HAS BEEN THE MOST CONSISTENT FROM RUN TO RUN...AND MATCHES THE ENSEMBLE MEANS...WHILE ALSO FALLING IN THE MIDDLE OF THE LATEST DETERMINISTIC SPREAD. ELONGATED UPPER TROUGH MOVING ACROSS THE NRN PLAINS SAT MORNING AND GREAT LAKES LATE SUN ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z NAM/12Z ECMWF COMPROMISE CONFIDENCE: AVERAGE THERE ARE ONLY MINOR DIFFERENCES WITH THIS SYSTEM...BUT THE 00Z NAM AND 12Z ECMWF ARE IN THE MIDDLE OF THE LATEST SPREAD. UPPER TROUGH REACHING THE LOWER OHIO VALLEY SAT NIGHT SURFACE LOW DEVELOPING EAST OF THE MISSISSIPPI THIS WEEKEND ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z NAM / 12Z ECMWF BLEND THROUGH 12Z/10 12Z ECMWF FROM 12Z/10 - 12Z/11 CONFIDENCE: AVERAGE THE NAM/GFS HAVE BEEN TRENDING NORTH/WEAKER WITH A LOW-MID LEVEL LOW VALID 12Z/09 OVER THE TEXAS/OKLAHOMA BORDER WHILE THE ECMWF/UKMET/CMC HAVE BEEN TRENDING SOUTH/MORE SEPARATED FROM A NRN STREAM FEATURE ACROSS THE N-CNTRL CONUS. REGARDLESS OF POSITION...THE 00Z GFS APPEARS TOO WEAK WITH THIS FEATURE AS IT IS THE WEAKEST OF THE LATEST DETERMINISTIC/ENSEMBLE GUIDANCE. THE LATEST ENSEMBLE SPAGHETTI HEIGHTS AT 546 DAM DO NOT OFFER MUCH HELP AS THERE ARE ENSEMBLE CLUSTERS SUPPORTING BOTH THE NCEP AND NON NCEP IDEAS...BUT THERE DOES APPEAR MORE OF AN ENSEMBLE TREND TOWARD A SMALL/SEPARATE CLOSED LOW OVER THE ERN TEXAS/OKLAHOMA BORDER BY 12Z/09. BY 00Z/10...THE 00Z NAM GETS ON THE FAST SIDE OF THE GUIDANCE WITH THE 500 MB WAVE...ALTHOUGH IS MATCHED BY THE 12Z ECMWF WITH THE SURFACE LOW...BOTH THE NAM/ECMWF RESIDING IN THE MIDDLE OF THE STRONGEST CLUSTERED ENSEMBLE LOW PLOTS. THE 12Z UKMET/CMC APPEAR TO BE TOO FAR REMOVED FROM THE BETTER MODEL CONSENSUS REGARDING THE 500 MB LOW CENTER CROSSING THE MISSISSIPPI VALLEY. COMPACT CLOSED LOW WEAKENING ACROSS THE GREAT LAKES FRI NIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON 12Z CMC COMPROMISE CONFIDENCE: ABOVE AVERAGE ONLY THE 12Z CMC DIFFERS FROM THE REMAINING MODEL CONSENSUS IN BEING A BIT SOUTH WITH THE SURFACE LOW TRACK AS IT REACHES THE UPPER MIDWEST. IN ADDITION...THE 12 HOUR FORECAST FROM THE 12Z CMC IS WEST OF THE OBSERVED CLOSED LOW POSITION ALONG THE KS/OK BORDER...REINFORCING A NON CMC BLEND FOR THIS FEATURE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO