MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1242 AM EDT THU JUL 16 2015 VALID JUL 16/0000 UTC THRU JUL 19/1200 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 IMPACT THEIR SHORT TERM FORECASTS. DEEP UPPER LEVEL CYCLONE MOVING ACROSS SOUTHWEST CANADA DIGGING TROUGH IN THE WEST SATURDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~ PREFERENCE: 00Z GFS / 12Z ECMWF CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE ENSEMBLES DO NOT SUPPORT THE FASTER PROGRESSION SHOWN BY THE 12Z UKMET REGARDING THE UPPER TROUGH AXIS AS IT MOVES OVER S-CNTRL CANADA THIS WEEKEND. THE 00Z NAM IS SLOWEST...WHILE THE 12Z CMC IS LESS AMPLIFIED WITH THE 500 MB WAVE. THE GFS/ECMWF SHOW GOOD AGREEMENT UNTIL THE END OF THE SHORT RANGE PERIOD...12Z/19...AT WHICH POINT THE ECMWF EDGES FASTER THAN THE GFS. AT THIS POINT...GIVEN SOME OF THE OBSERVED SPREAD...A BLEND OF THE TWO MODELS SHOULD SUFFICE THROUGH 12Z/19. SURFACE LOW LIFTING NEWD FROM KANSAS THIS MORNING...TO THE GREAT LAKES BY FRI MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~ PREFERENCE: 00Z GFS / 12Z ECMWF COMPROMISE CONFIDENCE: SLIGHTLY ABOVE AVERAGE TRENDS WITH THIS LOW HAVE BEEN MIXED...WITH THE NAM/GFS TRENDING LESS DEFINED WITH THE LOW BY FRI MORNING OVER THE GREAT LAKES REGION...WHILE THE ECMWF/UKMET/CMC HAVE TRENDED TOWARD THE SOUTH AND/OR HAVE BECOME MORE DEFINED WITH THE FEATURE COMPARED TO THEIR PAST 2 CYCLES. THE GFS/ECMWF CURRENT FIT THE MIDDLE OF THE LATEST DETERMINISTIC/ENSEMBLE SPREAD AND FIT THE LATEST ENSEMBLE MEANS THE BEST. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO