MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 248 AM EDT THU MAR 19 2015 VALID MAR 19/0000 UTC THRU MAR 22/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...UPPER TROUGH MOVING INTO THE NORTHWEST FRI NIGHT/SAT... PREFERENCE: BLEND OF THE 00Z GFS AND 00Z ECMWF CONFIDENCE: AVERAGE ALL OF THE MODELS SHOW AN UPPER TROUGH AND AN ASSOCIATED SURFACE LOW MOVING INTO THE PACIFIC NORTHWEST BY FRI NIGHT WITH THE ENERGY CROSSING INTO THE NORTHERN ROCKIES ON SAT. THE 00Z NAM AND 00Z GEM BOTH SUGGEST A STRONGER TROUGH MOVING ACROSS THE REGION VERSUS THE 00Z GFS/00Z ECMWF AND 00Z UKMET. THE 00Z UKMET IS THE WEAKEST WITH THE ENERGY. AT THE SURFACE...THE 00Z ECMWF AND 00Z GEM HAVE BOTH TRENDED WEAKER AND SUPPORT THE WEAKER CONSENSUS OF THE 00Z NAM/00Z GFS/00Z GEM AND 00Z UKMET. THIS LATEST GEFS MEAN AND ECENS MEAN SUPPORT THIS AS WELL. ALTHOUGH THE 00Z NAM APPEARS TO BE A BIT TOO FAR SOUTH WITH ITS WAVE TRACK. BASED ON THE LATEST MODEL TRENDS...A BLEND OF THE 00Z GFS AND 00Z ECMWF WILL BE PREFERRED BASED ON CLUSTERING AND ENSEMBLE SUPPORT. ...UPPER TROUGH/CLOSED LOW PROGRESSING EASTWARD OUT OF NORTHERN MEXICO... PREFERENCE: NON-UKMET CONSENSUS CONFIDENCE: AVERAGE THE MODELS SHOW A CLOSED LOW EVOLVING OVER THE BAJA PENINSULA THAT WILL GRADUALLY ADVANCE EAST AND BEGIN TO SHEAR OUT TOWARD THE SOUTHERN PLAINS AND LOWER MS VALLEY BY SAT NIGHT AND SUN. THERE IS NOT MUCH IN THE WAY OF SPREAD WITH THE MASS FIELDS FOR MOST OF THE PERIOD...ALTHOUGH THE 00Z UKMET TENDS TO HANG ONTO A STRONGER UPPER TROUGH OVER THE SOUTHERN PLAINS ON SUN VERSUS THE MULTI-MODEL CONSENSUS. WILL LEAN TOWARD A NON-UKMET CONSENSUS AS A RESULT. ...SHORTWAVE TRACKING FROM THE MIDWEST TO THE MID-ATLANTIC BY FRI... ...SURFACE LOW NEAR THE MID-ATLANTIC COAST FRI... PREFERENCE: 00Z ECMWF...THROUGH 48 HOURS BLEND OF THE 00Z ECMWF/00Z GEFS MEAN AND 12Z ECENS MEAN...AFTER 48 HOURS CONFIDENCE: BELOW AVERAGE THE 00Z GFS HAS COME INTO A BIT BETTER AGREEMENT WITH THE GLOBAL MODEL CONSENSUS CONCERNING THE SHORTWAVE ENERGY THAT DIGS SOUTHEAST FROM THE MIDWEST AND INTO THE MID-ATLANTIC REGION THURS AND FRI. HOWEVER...THE GFS OVERALL STILL TENDS TO HAVE A SLIGHTLY STRONGER SURFACE LOW REFLECTION OVER THE OH VALLEY AND ALSO ALONG THE MID-ATLANTIC COAST LATE THURS THROUGH FRI. THE LOW ALONG THE MID-ATLANTIC COAST BECOMES THE DOMINANT LOW AND IS EXPECTED TO MOVE EAST OF NEW ENGLAND ON SAT. THE 00Z GFS AND 00Z UKMET ARE THE STRONGEST SOLUTIONS WITH RESPECT TO THE SURFACE LOW EVOLUTION THROUGH SAT...HOWEVER THE 00Z GFS IS MUCH FARTHER OFFSHORE THE EAST COAST WITH ITS LOW TRACK AND APPEARS TO ALSO BE SUFFERING FROM SOME CONVECTIVE FEEDBACK PROBLEMS. THE 00Z UKMET IS NOW THE SOLUTION CLOSEST TO NEW ENGLAND. THE 00Z ECMWF/00Z GEM AND 00Z NAM ARE ALL SPREAD IN BETWEEN THE UKMET AND GFS TRACKS...WITH THE ECMWF FARTHER LEFT AND THE NAM FARTHER RIGHT BY COMPARISON. THE LATEST GEFS MEAN SUGGESTS THE 00Z GFS IS A LITTLE TOO FAR OFFSHORE AND TOO DEEP BY 72 HOURS. THE LATEST ECENS MEAN GIVES MUCH MORE SUPPORT FOR A COMPROMISE BETWEEN THE 00Z UKMET AND 00Z ECMWF. THE 00Z ECMWF WILL NOW BE THE PREFERENCE THROUGH ABOUT 48 HOURS...WITH A BLEND OF THE 00Z ECMWF/00Z GEFS MEAN AND 12Z ECENS MEAN FAVORED THEREAFTER TO ACCOUNT FOR THE MODEL SPREAD EAST OF NEW ENGLAND. CONFIDENCE IS LIMITED. ...CLOSED LOW DROPPING SOUTH FROM HUDSON BAY TOWARD END OF WEEK... PREFERENCE: BLEND OF THE 00Z GFS AND 00Z ECMWF CONFIDENCE: ABOVE AVERAGE THE MODELS SHOW PRETTY GOOD AGREEMENT WITH THE EVOLUTION OF THE LARGER SCALE UPPER TROUGH AND DEEP CLOSED LOW THAT DROPS ACROSS SOUTHEAST CANADA AND NEAR THE NORTHEAST THROUGH THE SHORT RANGE. HOWEVER...BY 72 HOURS AND BEYOND...THE 00Z UKMET SHOWS STRONGER HEIGHT FALLS FARTHER SOUTH VERSUS THE MULTI-MODEL CONSENSUS IMPACTING NEW ENGLAND. THE 00Z NAM ON THE OTHER HAND IS FARTHEST NORTH WITH THE CORE OF ITS HEIGHT FALLS. THE 00Z GFS/00Z ECMWF AND 00Z GEM SPLIT THE DIFFERENCE. THE STRONGER MODEL CLUSTERING FAVORS A BLEND OF THE GFS AND ECMWF...AND THAT WILL BE THE PREFERENCE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON