MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1216 AM EDT MON MAY 19 2014 VALID MAY 19/0000 UTC THRU MAY 22/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ================================================== 00Z NAM/GFS EVALUATION AND PRELIMINARY PREFERENCES ================================================== NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO SIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT. ================================================== ...DEEP TROUGH SETTLING INTO THE SOUTHWEST STATES... PREFERENCE: OPERATIONAL MODEL CONSENSUS MODELS HAVE SHOWN STRONG AGREEMENT AND ONLY MINOR RUN TO RUN VARIABILITY HERE. THE 00Z NAM POSITIONS THE TROUGH AXIS JUST VERY SLIGHTLY EAST OF THE GLOBAL MODEL CONSENSUS ON DAY 3. THE DIFFERENCE AS MEASURED AT 700-500 MB IS ONLY ABOUT 85 MILES. ...SYSTEM CROSSING THE NORTHERN PLAINS AND GREAT LAKES... PREFERENCE: BLEND OF 00Z GFS WITH 12Z ECMWF/UKMET THE GFS...BUT ESPECIALLY THE NAM...HAVE SHOWN MORE RUN TO RUN VARIABILITY HERE COMPARED TO THE ECMWF. ENCOURAGINGLY...THE 00Z GFS TRENDED INTO FAIRLY STRONG AGREEMENT WITH THE 12Z ECMWF/UKMET REGARDING TIMING AND DEPTH. THE 12Z CANADIAN AND 00Z NAM WERE FLAT ALOFT ON DAY 2. THE NAM TRIES TO RECOVER INTO A DEEPER SOLUTION BY DAY 3 OVER THE EASTERN GREAT LAKES...BUT BOTH THE NAM AND CANADIAN PREDICT A POORLY DEFINED SURFACE REFLECTION COMPARED TO THE GFS/ECMWF/UKMET. ENSEMBLE INFORMATION SUPPORTS THE GLOBAL MODEL CLUSTER INDICATED IN OUR PREFERENCE. ...CLOSED LOW DRIFTING OFFSHORE OF NEW ENGLAND... PREFERENCE: BLEND OF THE OPERATIONAL MODELS...EXCLUDING THE 12Z UKMET THE 12Z UKMET CLOSES THE UPPER LOW NEARER TO THE COAST OF MAINE ON DAY 2 WHILE THE OPERATIONAL MODEL CONSENSUS IS FOR SOMETHING FARTHER SOUTH TOWARD 38 DEG NORTH / 64 DEG WEST WEDNESDAY MORNING. THIS TROUGH WILL WEAKEN AND LIFT OVER THE NORTH ATLANTIC ON DAY 3 WHILE A MEAN TROUGH POSITION ALONG THE EAST COAST OF NORTH AMERICA IS RELOADED BY THE SYSTEM APPROACHING THROUGH THE GREAT LAKES. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... BURKE