MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 229 AM EDT WED MAR 25 2015 VALID MAR 25/0000 UTC THRU MAR 28/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/GEM AND ECMWF ...NEGATIVELY TILTED SHORTWAVE LIFTING THROUGH THE GREAT LAKES... ...ASSOCIATED SURFACE LOW CROSSING THE MIDWEST... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS TAKE A NEGATIVELY TILTING SHORTWAVE ACROSS THE MIDWEST AND THROUGH THE GREAT LAKES REGION ON WED. THE 00Z GFS IS STILL A TAD FASTER THAN THE MULTI-MODEL CONSENSUS...WITH THE 12Z ECMWF A LITTLE SLOWER. HOWEVER...THERE IS SUFFICIENT LARGER SCALE AGREEMENT WITH THE MODELS THAT A GENERAL MODEL COMPROMISE CAN BE PREFERRED TO RESOLVE THE SMALL TIMING DIFFERENCES. ...NORTHERN STREAM TROUGH AMPLIFYING OVER THE PLAINS/MIDWEST... PREFERENCE: BLEND OF THE 00Z GFS AND 00Z ECMWF CONFIDENCE: AVERAGE MORE DOMINANT NORTHERN STREAM SHORTWAVE ENERGY IS EXPECTED TO AMPLIFY SOUTHEASTWARD OUT OF SOUTHWEST CANADA AND DIG ACROSS THE NORTHERN PLAINS AND MIDWEST WED AND THURS...WHILE LEADING THE WAY FOR A LARGER SCALE TROUGH TO AMPLIFY OVER ACROSS THE MS VALLEY THROUGH THURS. THIS TROUGH WILL DRIVE INTO THE EASTERN U.S. BY FRI. THERE IS REASONABLY GOOD MASS FIELD AGREEMENT WITH THE TROUGH DETAILS THROUGH THURS. BY FRI...THE 00Z UKMET AND 00Z GEM BOTH TEND TO BECOME A BIT SLOWER AND DEEPER THAN THE GLOBAL MODEL CONSENSUS. THERE IS STRONGER MODEL CLUSTERING AROUND A SLIGHTLY MORE PROGRESSIVE TROUGH AS PER THE 00Z NAM/00Z GFS AND 00Z ECMWF SOLUTIONS. THE LATEST GEFS MEAN AND ECENS MEAN FAVOR THIS CLUSTERING...AND SO WILL SUGGEST A BLEND OF THE 00Z GFS AND 00Z ECMWF. ...SURFACE WAVE LIFTING FROM THE OH VALLEY TO NEW ENGLAND... PREFERENCE: NON-NAM CONSENSUS CONFIDENCE: ABOVE AVERAGE THE MODELS SUGGEST A WAVE OF LOW PRESSURE DEVELOPING ALONG THE COLD FRONT PUSHING INTO THE EASTERN U.S. BY LATE WED AND THURS. THE LOW SHOULD DEVELOP OVER THE LOWER OH VALLEY AND LIFT QUICKLY NORTHEAST ACROSS THE LOWER GREAT LAKES AND NEW ENGLAND BY LATE THURS. THE 00Z NAM IS THE SLOWEST SOLUTION WITH THE WAVE AND TENDS TO BE MORE ILL-DEFINED WITH IT VERSUS THE 00Z GFS AND THE NON-NCEP SOLUTIONS WHICH ARE WELL CLUSTERED. WILL PREFER A NON-NAM CONSENSUS WITH THIS WAVE. ...SHORTWAVE TROUGH ENTERING THE PACIFIC NORTHWEST ON FRI... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE A SHORTWAVE TROUGH WILL ARRIVE ACROSS THE PACIFIC NORTHWEST ON FRI AND ADVANCE PROGRESSIVELY INLAND. THE 00Z MODELS HAVE COME INTO BETTER TIMING AGREEMENT WITH THIS SYSTEM...AS THE NON-NCEP MODELS ALL GENERALLY TRENDED TOWARD A SOMEWHAT SLOWER PROGRESSION COMPARED TO THEIR PREVIOUS RUN. OVERALL...THE 00Z GFS IS JUST A TAD FASTER THAN THE MULTI-MODEL CONSENSUS...BUT AT THIS POINT THERE IS SUFFICIENTLY SMALL ENOUGH SPREAD THAT A GENERAL MODEL COMPROMISE WILL SUFFICE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON