MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1134 PM EST TUE FEB 17 2015 VALID FEB 18/0000 UTC THRU FEB 21/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...SHORTWAVE TROUGH DIGGING THROUGH THE INTERMOUNTAIN WEST... ...SURFACE LOW PRESSURE DEVELOPING OVER THE SOUTHERN PLAINS BY FRI... PREFERENCE: BLEND OF THE 12Z ECMWF/12Z ECENS MEAN AND 18Z GEFS MEAN CONFIDENCE: BELOW AVERAGE THE 12Z UKMET AND TO A SLIGHTLY LESSER EXTENT THE 12Z GEM ARE THE FASTEST SOLUTIONS TO PROGRESS THIS ENERGY DOWN THROUGH THE INTERMOUNTAIN WEST AND OUT INTO THE SOUTHERN PLAINS. CONSEQUENTLY...THE UKMET AND GEM ARE FASTER TO ADVANCE DEVELOPING SURFACE LOW PRESSURE EAST ACROSS THE SOUTHERN PLAINS AND TOWARD THE LOWER MS VALLEY BY THE END OF THE PERIOD. THE 00Z NAM/00Z GFS AND 12Z ECMWF ARE SLOWER...WITH THE 00Z GFS BY FAR THE SLOWEST AND STRONGEST SOLUTION WHICH INCLUDES A TREND IN THE 18Z AND 00Z RUNS TOWARD A MORE AMPLIFIED SOLUTION. THE ENSEMBLE MEANS LED BY THE 18Z GEFS MEAN AND 12Z ECENS MEAN TEND TO FAVOR A RELATIVELY FLATTER EVOLUTION WITH TIMING THAT IS CLOSE TO THAT OF THE 12Z ECMWF. CONFIDENCE IS VERY LIMITED GIVEN THE SPREAD IN GUIDANCE BY THE END OF THE PERIOD...BUT FOR A CONSENSUS OF THE 12Z ECMWF/12Z ECENS MEAN AND 18Z GEFS MEAN WILL BE PREFERRED. ...DEEP TROUGH/VORTEX MOVING ACROSS THE GREAT LAKES AND NORTHEAST... ...NORLUN TROUGH/SURFACE LOW IMPACTING EASTERN NEW ENGLAND... PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF CONFIDENCE: AVERAGE THE 12Z UKMET MOVES ITS DEVELOPING LOW CENTER NEAR EASTERN NEW ENGLAND FARTHER EAST THAN THE MULTI-MODEL CONSENSUS. MEANWHILE...THE 12Z GEM IS OVERALL THE WEAKEST SOLUTION WITH THE DEEP TROUGH/VORTEX THAT PIVOTS DOWN THROUGH THE GREAT LAKES AND INTO THE NORTHEAST. THE 00Z GFS AND 12Z ECMWF CLUSTER VERY WELL WITH THEIR SOLUTIONS AND HAVE SOLID SUPPORT FROM THE GEFS MEAN AND ECENS MEAN. THE 00Z NAM IS CLOSE TO THE GFS/ECMWF CAMP REGARDING SURFACE LOW EVOLUTION BUT IS A LITTLE WEAKER WITH ITS 700 MB REFLECTION AND TENDS TO LIFT SOME OF THE ENERGY A LITTLE QUICKER TO THE NORTH THROUGH NEW ENGLAND VERSUS THE GFS/ECMWF SOLUTIONS. A BLEND OF THE GFS AND ECMWF WILL BE PREFERRED. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON