MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1227 AM EDT FRI JUL 15 2016 VALID JUL 15/0000 UTC THRU JUL 18/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ MID-UPPER TROUGH ACROSS THE GREAT LAKES...OH VALLEY AND NORTHEAST ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-NAM MODEL/ENSEMBLE MEAN BLEND CONFIDENCE: ABOVE AVERAGE EARLIER CYCLE CONSENSUS WITH RESPECT TO THE UPPER LEVEL TROUGH AND SURFACE REFLECTION THAT WILL DEAMPLIFY INTO A LOWER AMPLITUDE SYSTEM AND THEN MOVE INTO THE NORTHEAST IS STILL ON TRACK. THE 21Z SREF MEAN IS IN BETTER AGREEMENT WITH THE 12Z ECMWF/12Z UKMET/18Z GFS/18Z GEFS MEAN ON LOWER AMPLITUDE AND SLIGHTLY FASTER TIMING WITH 500 MB WAVES VS THE 00Z NAM. DUE TO GOOD CLUSTERING OF THE NON-NAM CLUSTER...A BLEND OF THESE SOLUTIONS IS PREFERRED. CLOSED 700 MB LOW NEAR WA/ID BORDER WITH BRITISH COLUMBIA TODAY MOVING EAST OVER THE WEEKEND AND WEAKENING OVER THE NORTHERN PLAINS SAT-GREAT LAKES SUN ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-OPERATIONAL NAM MODEL/ENSEMBLE MEAN BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE MODELS SHOW A 700 MB CLOSED LOW MOVING SLOWLY EAST ACROSS THE US BORDER WITH SOUTHWEST CANADA AND A SHORTWAVE EJECTING EAST ACROSS THE PLAINS OF EASTERN MT FRI NIGHT/SAT MORNING...WHERE THE NAM IS FASTER WITH THE WAVE AND LOWERING HEIGHTS INTO ND EARLY SAT...WITH THE SREF MEAN IN BETTER AGREEMENT TIMING WISE WITH THE UKMET/GFS/GEFS MEAN. THE 12Z ECMWF WAS A LITTLE FASTER DEAMPLIFYING THE WAVE THAN THE UKMET/GFS/NAM...SO A SPREAD REMAINS IN PLACE. THE NAM REMAINS WITH A HIGHER AMPLITUDE WAVE CROSSING THE UPPER MS VALLEY SUN...WHEREAS THE ECMWF/GFS/21Z SREF MEAN ARE FLATTER WITHIN THE CONFLUENT FLOW ACROSS THE REGION. GOOD CLUSTERING AMONG THE 21Z SREF MEAN/12Z ECMWF/00Z GFS SUPPORTS A BLEND AT SLIGHTLY ABOVE AVERAGE CONFIDENCE FOR THIS SYSTEM. DEVELOPING CLOSED LOW OFF WA/OR COAST SUN NIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GFS/18Z GEFS MEAN/12Z ECMWF/12Z UKMET BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE BY SAT NIGHT/SUN MORNING SHORTWAVE ENERGY AMPLIFYING ALONG THE PACIFIC NORTHWEST COAST SUPPORTS A CLOSED LOW DEVELOPING AROUND 12Z SUN. THE 00Z NAM AND 21Z SREF MEAN ARE ON THE NORTHERN EDGE OF THE SUITE OF SOLUTIONS WHILE THE 12Z ECMWF/UKMET/00Z GFS/18Z GEFS MEAN CLUSTER WELL WITH THE LOW DRIFTING SOUTH ALONG THE WA/OR BORDER SUN. LATER IN THE FORECAST THE GFS/UKMET/ECMWF STALL OUT THE LOW AND BY 12Z MON THE NAM AND SREF MEAN MOVE THE LOW SOUTH TO JOIN THE MAJORITY CLUSTER. THE GOOD AGREEMENT IN THE 00Z GFS/18Z GEFS MEAN/12Z ECMWF/12Z UKMET SUGGESTS A CONSENSUS OF THESE SOLUTIONS BE USED. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... PETERSEN