MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1245 AM EDT SUN MAY 25 2014 VALID MAY 25/0000 UTC THRU MAY 28/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ISSUES DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. UPPER TROUGH IMPACTING THE PACIFIC NORTHWEST THROUGH MID-WEEK ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE THROUGH 00Z/27 NON 12Z UKMET COMPROMISE AFTER 00Z/27 CONFIDENCE: ABOVE AVERAGE THE GUIDANCE IS IN GOOD AGREMENT OUTSIDE OF THE FASTER UKMET BY ABOUT 00Z/27 REGARDING AN APPROACHING CLOSED MID-LEVEL LOW. THERE IS STRONG AGREEMENT FROM THE ENSEMBLE MEANS SUPPORTING A NON-UKMET COMPROMISE OF THE REMAINING MODELS WHICH SHOW REASONABLE RUN TO RUN CONTINUITY. CLOSED LOW MOVING INTO THE CENTRAL AND SOUTHERN PLAINS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON 00Z NAM COMPROMISE CONFIDENCE: ABOVE AVERAGE THE NAM ENDS UP PROGRESSING THE UPPER TROUGH MUCH MORE QUICKLY THROUGH THE CENTRAL/SOUTHERN PLAINS COMPARED TO THE REMAINING DETERMINISTIC AND ENSEMBLE GUIDANCE. THIS DIFFERENCE BEGINS TO SHOW UP DURING THE DAY ON MONDAY OVER TEXAS AND OKLAHOMA AT 500 MB...WITH THE NAM A BIT SOUTH AND EAST OF THE REMAINING DETERMINISTIC MODELS WHICH SHOW VERY GOOD AGREEMENT ALOFT. MID-LEVEL SHORTWAVE AND SURFACE FRONT AFFECTING THE NORTHEAST ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS / 18Z GEFS MEAN COMPROMISE CONFIDENCE: AVERAGE THE 00Z GFS AND 12Z ECMWF HAVE BOTH TRENDED FASTER WITH A CLOSED MID-LEVEL LOW THAT CLIPS NRN NEW ENGLAND MON NIGHT COMPARED TO YESTERDAY. HOWEVER...THE ENSEMBLE MEANS SHOW VERY GOOD AGREEMENT FOR A TRACK A BIT SLOWER THAN THE GFS/ECWMF. NO SINGLE DETERMINISTIC MODEL APPEARS THE RIGHT WAY TO GO AT THE MOMENT...SO WILL PREFER A BLEND OF THE GFS WITH THE SLOWER GEFS MEAN...WHILE NOTING THAT THE EC MEAN IS ALSO VERY SIMILAR TO THE GEFS...AND THE 12Z ECMWF IS SLIGHTLY FASTER THAN THE GFS. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO