MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1232 AM EDT TUE AUG 12 2014 VALID AUG 12/0000 UTC THRU AUG 15/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ...AN EVALUATION OF THE 00Z NAM/GFS ALONG WITH PRELIMINARY PREFERENCES/FORECAST CONFIDENCE... THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE 00Z NAM/GFS DEEMED SIGNIFICANT ENOUGH TO IMPACT THEIR FORECASTS. ...BATCH OF ENERGY LIFTING FROM NORTHERN MEXICO INTO THE FOUR CORNERS REGION MID-WEEK... PRELIMINARY PREFERENCE: BLEND OF THE 00Z GFS/12Z ECMWF FORECAST CONFIDENCE: AVERAGE THERE IS A STRONG SIGNAL IN THE GUIDANCE THAT A RATHER IMPRESSIVE SHORTWAVE EMERGES FROM NORTHERN MEXICO AND CROSSES THE AZ BORDER BY TUESDAY EVENING. THE LARGEST UNCERTAINTY BY MID-WEEK IS WITH HOW QUICKLY THIS ENERGY LIFTS NORTHWARD AND BECOMES EMBEDDED WITH A BROAD LONGWAVE TROF ACROSS THE WESTERN U.S. THE 00Z NAM AND 18Z GEFS/21Z SREF MEANS ARE QUICKER WITH THE EVOLUTION OF THIS SYSTEM WHILE THE 00Z GFS AND 12Z ECMWF/ECMWF ENSEMBLE MEAN CLUSTER ON THE SLOWER END. WILL STICK WITH SOMETHING CLOSER WHICH IS MORE ALONG THE LINES OF THE 00Z GFS/12Z ECMWF. ...CUT-OFF LOW INITIALLY OFF OF NORTHERN CA... ...ANOMALOUS CLOSED LOW ANCHORING THE PACIFIC NORTHWEST... PRELIMINARY PREFERENCE: SOME COMBINATION OF THE 00Z GFS AND 12Z ECMWF/UKMET FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE WATER VAPOR IMAGERY SHOWED A CUT-OFF LOW SPINNING OFF THE NORTHERN CA COAST WITH THIS FEATURE EVENTUALLY EVOLVING INTO AN OPEN WAVE. THIS SYSTEM WILL LIFT NORTH AND EAST AHEAD OF A WELL DEVELOPED UPPER TROF ADVANCING TOWARD THE PACIFIC NORTHWEST COAST. THROUGH WEDNESDAY EVENING...IT APPEARS THE ENSEMBLE MEANS HAVE A STABLE HANDLE ON THE CLOSED LOW POSITION. DIVERGING FROM THESE SOLUTIONS ARE THE 00Z NAM AND 12Z CMC WITH THE NAM BEING QUICKER AND THE CMC OFF TOWARD THE SOUTH WITH CORE OF LOWER HEIGHTS. OVERALL THE 00Z GFS AND 12Z ECMWF/UKMET HAVE USEFUL COMPONENTS TO THEIR FORECASTS AND WILL BE RECOMMENDED IN THE PREFERENCE. ...BROAD VORTEX SETTING UP ACROSS THE GREAT LAKES/NORTHEASTERN U.S. WEDNESDAY THROUGH FRIDAY... ...PAIR OF SURFACE LOWS AFFECTING ONTARIO AND THE EAST COAST RESPECTIVELY... PRELIMINARY PREFERENCE: THROUGH WEDNESDAY: GENERAL MODEL COMPROMISE...FOLLOWED BY A NON-00Z NAM SOLUTION FORECAST CONFIDENCE: ABOVE AVERAGE AN AREA OF HEIGHT FALLS ADVANCING THROUGH THE GREAT LAKES WILL HELP LIFT A STRONG SURFACE WAVE FROM THE LOWER GREAT LAKES INTO SOUTHERN ONTARIO. THIS IS WELL HANDLED BY THE GUIDANCE EARLY IN THE PERIOD WITH THE SYSTEM EVENTUALLY TRANSITIONING INTO MORE OF AN UPPER LOW BY MID-WEEK. THROUGH 14/0000Z THE MODELS ARE IN RATHER REMARKABLE AGREEMENT WITH ONLY MINOR DIFFERENCES NOTED IN THE SURFACE LOW TRACK. WILL RECOMMEND A GENERAL MODEL COMPROMISE THROUGH WEDNESDAY BEFORE THE 00Z NAM STARTS TO LEAVE THE STRONGER CLUSTERING. WILL RECOMMEND A NON-00Z NAM SOLUTION THEREAFTER. OF COURSE SUBTLE DIFFERENCES IN THIS SYSTEM WILL HAVE LARGE IMPLICATIONS ON THE AXIS OF HEAVY RAINFALL WHICH IS EXPECTED TO AFFECT THE NORTHEASTERN U.S. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... RUBIN-OSTER