MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1133 PM EST SUN JAN 11 2015 VALID JAN 12/0000 UTC THRU JAN 15/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...TROUGH OVER TEXAS SHEARING ACROSS THE TENNESSEE VALLEY AND MID ATLANTIC... PREFERENCE: NON-NAM COMPROMISE CONFIDENCE: ABOVE AVERAGE OVERALL THE LATEST MODELS ARE IN GOOD AGREEMENT WITH THE MASS FIELD DETAILS OF THIS SYSTEM. THE 00Z NAM THOUGH IS MORE PRONOUNCED WITH THE SOUTHERN EXTENT OF THIS TROUGH AXIS OVER FLORIDA AT MID LEVELS. THEREFORE WE CONTINUE TO PREFER A NON-NAM COMPROMISE. ...NORTHERN STREAM TROUGH CROSSING THE UPPER MIDWEST TO NEW ENGLAND THROUGH TUESDAY... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE A SHORTWAVE TROUGH IS PROGGED TO SWING FROM THE UPPER MIDWEST THROUGH THE GREAT LAKES MONDAY AND THROUGH NEW ENGLAND BY TUESDAY MORNING. THE MODELS ARE NOW IN GOOD AGREEMENT WITH THE TIMING AND DEPTH OF THIS SYSTEM AND SO A GENERAL MODEL COMPROMISE IS PREFERRED. ...NORTHERN STREAM TROUGH ENTERING THE NORTHERN PLAINS/UPPER MIDWEST BY TUESDAY... PREFERENCE: BLEND OF THE 00Z GFS/12Z ECMWF CONFIDENCE: AVERAGE THE 12Z GEM BECOMES A DEEPER OUTLIER WITH THE TROUGH AXIS AND GRADUALLY THE 00Z NAM TENDS TO BECOME SHARPER THAN THE GLOBAL MODEL CONSENSUS AS THE ENERGY MOVES THROUGH THE LOWER GREAT LAKES AND INTO THE NORTHEAST WEDNESDAY AND THURSDAY. THE STRONGER CLUSTERING AND BETTER MODEL CONTINUITY RESIDE WITH THE 00Z GFS AND 12Z ECMWF...AND SO THIS BLEND WILL BE PREFERRED. ...SOUTHERN CALIFORNIA TROUGH ACCELERATING EASTWARD... PREFERENCE: BLEND OF THE 00Z GFS/12Z ECMWF CONFIDENCE: AVERAGE THIS FEATURE IS FORECAST TO OPEN UP AND DE-AMPLIFY AS IT MOVES EAST...REACHING THE GULF COAST STATES BY TUESDAY NIGHT. THE 00Z NAM IS THE STRONGEST SOLUTION AS THE ENERGY TRAVERSES THE SOUTH THROUGH THE PERIOD. THE 12Z GEM IS ALSO A BIT DEEPER THAN THE GLOBAL MODEL CONSENSUS BUT IS A BIT SLOWER. BETTER CONTINUITY IS FOUND WITH THE GFS AND ECMWF SOLUTIONS FOR THIS LOW AMPLITUDE FEATURE...AND SINCE THE FLOW DOWNSTREAM SHOULD BE MORE CONFLUENT...A RELATIVELY FLATTER SOLUTION WILL BE PREFERRED WHICH IS SUGGESTED BY THE 00Z GFS AND 12Z ECMWF. ...SHORTWAVE TROUGH OVER THE FOUR CORNERS REGION... PREFERENCE: 12Z ECMWF CONFIDENCE: SLIGHTLY BELOW AVERAGE THE MODELS ARE BEGINNING TO IMPROVE WITH THE DETAILS OF A TROUGH CROSSING THE NORTHWEST THAT IS FORECAST TO AMPLIFY OVER THE FOUR CORNERS REGION BEFORE EJECTING OUT OVER THE CENTRAL AND SOUTHERN PLAINS. THE 12Z ECMWF AND 12Z GEM ARE A LITTLE FASTER BY WEDNESDAY TO EJECT ENERGY OUT ACROSS THE PLAINS...WITH THE 12Z UKMET/12Z NAM AND ESP THE 12Z ECMWF A BIT SLOWER AND SUGGESTING THAT ENERGY HANGS BACK LONGER OVER THE FOUR CORNERS AREA. HOWEVER...BY THURSDAY THERE IS A BIT BETTER AGREEMENT AS ALL OF THE MODELS ADVANCE ENERGY EAST TOWARD THE LOWER MS VALLEY. THE 00Z NAM BY THAT TIME IS A BIT SHARPER AND SLOWER THAN THE MULTI-MODEL CONSENSUS. THE 12Z ECMWF TENDS TO CLUSTER REASONABLY WELL WITH THE 12Z GEM AND 12Z UKMET...WITH THE 00Z GFS A TAD SLOWER. STRONGER ENSEMBLE SUPPORT RESIDES WITH THE 12Z ECMWF...AND SO THAT WILL BE THE PREFERENCE AT THIS TIME. ...SHORTWAVE TROUGH ENTERING THE PACIFIC NORTHWEST BY EARLY THURSDAY... PREFERENCE: 12Z ECMWF CONFIDENCE: AVERAGE THE MODELS INDICATE A SHORTWAVE TROUGH ENTERING THE PACIFIC NORTHWEST BY EARLY THURSDAY. THE 00Z GFS AND TO A LESSER EXTENT THE 00Z NAM ARE STRONGER THE GLOBAL MODEL CONSENSUS. THE NON-NCEP MODELS INCLUDING THE 12Z ECMWF/12Z UKMET AND 12Z GEM ARE ALL A BIT FASTER AND NOTABLY FLATTER. A NON-NCEP CONSENSUS LED BY THE 12Z ECMWF WILL BE PREFERRED AS THE SHORTWAVE WILL BE ENCOUNTERING A STRENGTHENING RIDGE AXIS ALOFT OVER THE WESTERN U.S. BY THE END OF THE PERIOD WHICH WOULD FAVOR A WEAKENING SHORTWAVE. THE WEAKER NON-NCEP CAMP IS ALSO FAVORED BY THE 18Z GEFS MEAN AND 12Z ECENS MEAN. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON