MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1159 PM EDT FRI JUL 18 2014 VALID JUL 19/0000 UTC THRU JUL 22/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...SHORTWAVE TROUGH LIFTING THROUGH THE TN/OH VALLEYS INTO THE NORTHEAST... ...WEAK MID-LEVEL DISTURBANCE LEFT BEHIND OVER THE DEEP SOUTH... PREFERENCE: NON-NAM CONSENSUS CONFIDENCE: ABOVE AVERAGE THE MID LEVEL SHORTWAVE OVER THE OH/TN VLYS ATTM WILL LIFT INTO THE NORTHEAST THIS WEEKEND...ALTHOUGH THERE IS EXPECTED TO BE A BROAD AND WEAK TROUGH LEFT BEHIND IN ITS WAKE OVER THE TN VLY AND MUCH OF THE SOUTHEAST SUN THROUGH TUES. MOST OF THE MODELS ARE IN VERY GOOD AGREEMENT WITH THE TIMING AND DEPTH OF EVOLVING MASS FIELDS...BUT THE 00Z NAM WAS NOTED TO BE A LITTLE WEAKER THAN THE GLOBAL MODEL CONSENSUS WITH THE INITIAL SHORTWAVE THAT DEPARTS THROUGH THE NORTHEAST...AND THE 00Z NAM ALSO APPEARS TO BE A LITTLE STRONGER THAN THE GLOBAL MODELS WITH THE LINGERING ENERGY OVER THE SOUTHEAST. WILL PREFER A NON-NAM CONSENSUS. ...INITIAL SHORTWAVE TROUGH/FRONT CLIPPING THE UPPER MIDWEST SAT... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS ARE GENERALLY IN VERY GOOD AGREEMENT MASS FIELD WISE WITH THIS SYS...SO A GENERAL MODEL COMPROMISE WILL BE PREFERRED. ...UPPER TROUGH/COLD FRONT CLIPPING THE NORTHERN U.S SUN AND MON... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS ARE GOOD AGREEMENT AT LEAST ON THE LARGER SCALE WITH THIS SYS...SO A GENERAL MODEL COMPROMISE WILL BE PREFERRED TO RESOLVE THE SMALLER SCALE DIFFS. ...DEEP UPPER TROUGH/CLOSED LOW DEVELOPING OVER THE GULF OF AK AND IMPACTING THE NORTHWEST... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE ON THE LARGER SCALE...THE MODELS AGREE WITH THE DETAILS OF A DEVELOPING DEEP UPR TROUGH AND THEN A CLOSED LOW OVER THE GULF OF AK...WITH HEIGHT FALLS ADVANCING DOWNSTREAM INTO THE NORTHWEST U.S. OVER THE NEXT FEW DAYS. OVERALL THERE IS REASONABLY GOOD MASS FIELD AGREEMENT AND SO A GENERAL MODEL COMPROMISE WILL BE PREFERRED ATTM TO RESOLVE THE SMALLER SCALE DIFFS. ...SURFACE LOW DEVELOPING OVER THE NORTHERN PLAINS/UPPER MIDWEST BY MON AND TUES... PREFERENCE: 12Z ECMWF CONFIDENCE: AVERAGE THE MODELS SHOW A LEAD SHORTWAVE TROUGH CROSSING THE PAC NORTHWEST AND EJECTING EAST ACROSS THE NRN PLAINS AND THE UPR MIDWEST BY EARLY NEXT WEEK AND THIS SHOULD INITIATE A WEAK AREA OF LOW PRESSURE IN THE LEE OF THE NRN ROCKIES THAT WILL LIFT INTO THE UPR MIDWEST BY TUES. THE 00Z NAM/12Z UKMET AND 12Z GEM ARE ALL FASTER WITH THE TIMING OF THE LOW CENTER. THE 00Z GFS IS THE SLOWEST WITH THE 12Z ECMWF IN BETWEEN THE FASTER AND SLOWER CAMPS. THE 18Z GEFS MEAN FAVORS THE SLOWER 00Z GFS...WITH THE 12Z ECENS MEAN AND 21Z SREF MEAN FAVORING THE 12Z ECMWF. BASED ON THE MODEL SPREAD AND OVERALL BETTER ENSEMBLE SUPPORT...WILL FAVOR THE 12Z ECMWF WITH THIS SYS. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON