MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1254 AM EDT WED AUG 13 2014 VALID AUG 13/0000 UTC THRU AUG 16/1200 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. ...ANOMALOUS CLOSED LOW AFFECTING THE NORTHEASTERN U.S. THROUGHOUT THE PERIOD... ...COASTAL SURFACE WAVE... PRELIMINARY PREFERENCE: BLEND OF THE 12Z CMC/ECMWF FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE AN UPPER PATTERN RESEMBLING SOMETHING MORE ALONG THE LINES OF AUTUMN FEATURES QUITE THE HEIGHT/TEMPERATURE ANOMALIES. THE 00Z NAM SUGGEST 500-MB HEIGHT ANOMALIES APPROACHING 2 TO 2.5 STANDARD DEVIATIONS BELOW AVERAGE. SUCH VALUES SHOULD PERSIST THROUGHOUT THE WORK WEEK BEFORE THE LOWER HEIGHTS BEGIN TO LIFT TOWARD QUEBEC. THE FIRST BATCH OF HEIGHT FALLS WILL TRACK ACROSS THE NORTHEASTERN U.S. THROUGH WEDNESDAY WHILE A CLOSED LOW DEVELOPS IN THE WAKE ACROSS THE GREAT LAKES. EXCEPT FOR THE 12Z UKMET WHICH IS A HAIR FASTER...THE MODELS FORM A DECENT CONSENSUS THROUGH THURSDAY EVENING. BEYOND THIS PERIOD THERE IS UNCERTAINTY WITH HOW QUICKLY THE VORTEX LIFTS TOWARD QUEBEC. THE 12Z ECMWF ENSEMBLE/21Z SREF MEANS BELIEVE THE SYSTEM WILL STAY FARTHER TO THE SOUTH WITH THE 12Z ECMWF/CMC AGREEING WITH THIS SOLUTION. THESE MEANS HAVE BEEN FAIRLY CONSISTENT THE PAST COUPLE RUNS SO WILL LEAN ON THEIR CONSENSUS. ...MID-LEVEL ENERGY LIFTING FROM AZ INTO THE CENTRAL ROCKIES THROUGH THURSDAY... PRELIMINARY PREFERENCE: BLEND OF THE 00Z NAM WITH THE 12Z ECMWF/UKMET FORECAST CONFIDENCE: BELOW AVERAGE SHORTWAVE ENERGY LIFTING THROUGH SOUTHERN AZ HAS BEEN A CULPRIT FOR WIDESPREAD AND SUSTAINED CONVECTION OVERNIGHT. THESE IMPULSES SHOULD MIGRATE NORTHWARD TOWARD THE CENTRAL ROCKIES DURING THE NEXT 36 HOURS. SOLUTIONS BEGIN TO VARY WITH HOW MUCH OF THIS ENERGY MOVES EASTWARD INTO THE CENTRAL PLAINS VERSUS UP INTO THE NORTHERN HIGH PLAINS. A BULK OF THE GUIDANCE SHOW A RATHER ROBUST SHORTWAVE EVOLVING ON FRIDAY ACROSS THE MIDDLE MS VALLEY WITH THE 00Z GFS/12Z DEPICTING A FASTER SOLUTION WHILE THE 00Z NAM/12Z ECMWF ARE NEARLY IN LINE WITH ONE ANOTHER. THE 12Z UKMET SUBTLY AGREES WITH THIS SLOWER IDEA AS WELL. GIVEN THE COMPLEX EVOLUTION...WOULD PREFER TO HEDGE SLOWER AND RECOMMEND A COMBINATION OF THE 00Z NAM AND 12Z ECMWF/UKMET. CONFIDENCE IS BELOW AVERAGE GIVEN HOW COMPLEX THE FLOW IS. ...STRONG CLOSED LOW OVER THE PACIFIC NORTHWEST... PRELIMINARY PREFERENCE: 00Z NAM/GFS AND 12Z ECMWF ARE USEFUL HERE FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE OTHER LARGELY NEGATIVE HEIGHT ANOMALY WILL ANCHOR THE NORTHWESTERN CONUS. HEIGHT FALLS CURRENTLY ADVANCING INLAND HAVE BEEN RESPONSIBLE FOR WIDESPREAD PRECIPITATION INLAND...ESPECIALLY ACROSS THE FAVORED TERRAIN. AS THIS SYSTEM ADVANCES INLAND IT WILL CLOSE OFF AND BECOME NEARLY STATIONARY ALONG THE WA/OR BORDER ON THURSDAY. THROUGH 60 HOURS/FRIDAY MORNING...ENSEMBLE MEANS AGREE QUITE WELL WITH ONLY THE 12Z CMC BEING THE OUTLIER OFF TO THE WEST. TOWARD THE END OF THE PERIOD THE 12Z UKMET DEPICTS ANOTHER BATCH OF ENERGY FROM THE SYSTEM ACROSS THE CENTRAL PLAINS DISTURBING THE HEIGHT FIELD ACROSS THE NORTHERN PLAINS. OVERALL...THE 00Z NAM/GFS AND 12Z ECMWF FOLLOW THE CLUSTERED MEANS WELL ENOUGH TO BE USEFUL IN THIS SECTOR OF THE COUNTRY. ...POSSIBLE SHORTWAVE REACHING THE CA COAST BY EARLY SATURDAY... PRELIMINARY PREFERENCE: A NON-12Z ECMWF SOLUTION FORECAST CONFIDENCE: AVERAGE BY EARLY SATURDAY...MODELS DEPICT A WEAK SHORTWAVE REACHING THE NORTHERN CA COAST. THE OUTLIER HERE IS THE 12Z ECMWF WHICH IS RATHER QUICK. WILL RECOMMEND A NON-12Z ECMWF SOLUTION IN THIS CASE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... RUBIN-OSTER