MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1229 PM EDT THU JUN 19 2014 VALID JUN 19/1200 UTC THRU JUN 23/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z NAM/GFS EVALUATION AND PRELIMINARY PREFERENCES ...CLOSED LOW OVER THE NORTHERN ROCKIES... PREFERENCE: EQUAL BLEND GFS/ECMWF CONFIDENCE: ABOVE AVERAGE OTHER THAN THE NAM AND A HANDFUL OF ENSEMBLE MEMBERS...MODELS CLUSTER QUITE WELL IN DEPICTING SLOWER AND MORE NORTHWARD PROGRESSION OF THE MID-LEVEL CENTER INTO CANADA. GIVEN THIS AGREEMENT AND THAT THE LOW REMAINS CUTOFF FROM THE WESTERLIES...RECOMMEND DISCOUNTING THE NAM IN FAVOR A COMPROMISE OF THE SLOWER GFS/ECMWF TO ADDRESS ANY LINGERING UNCERTAINTIES. ...FRONTAL SYSTEM EXTENDING FROM THE N. PLAINS/UPPER MIDWEST INTO THE OH VALLEY... PREFERENCE: BEFORE 00Z SUN...EQUAL BLEND GFS/ECMWF AFTER 00Z SUN...ENSEMBLE MEANS CONFIDENCE: AVERAGE THE ORIENTATION OF THIS FRONT DEPENDS ON THE POSITION AND AMPLIFICATION OF THE BASE OF THE CLOSED LOW SLOWLY EXITING THE NORTHERN ROCKIES...AS WELL AS THE PERSISTENT SHORTWAVE TROUGH OVER NEW ENGLAND...AND ANY MESOSCALE INFLUENCES RESULTING FROM CONVECTION. GIVEN THE SHORTENING WAVELENGTH OF THE PREVAILING PATTERN ALONG WITH RISING HEIGHTS ACROSS THE SOUTH RESULTING IN WEAKENING FLOW...THE OVERALL RECOMMENDATION IS FOR AN INTERMEDIATE SOLUTION BETWEEN THE GFS/ECMWF THROUGH 00Z SUNDAY...BEFORE DEFERRING TO THE ENSEMBLE MEANS AS THE SPREAD INCREASES. THE NAM GENERALLY STRAYS TOO FAR FROM THE CONSENSUS ACROSS THE OHIO VALLEY LATE FRIDAY TO BE CONSIDERED A LEADING SOLUTION FROM 00Z SUNDAY ONWARD. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... JAMES