MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1130 AM EST MON FEB 29 2016 VALID FEB 29/1200 UTC THRU MAR 04/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...ARCTIC COLD FRONT CROSSING THE LOWER GREAT LAKES/NORTHEAST... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS SHOW AN ARCTIC COLD FRONT SETTLING SOUTHEAST ACROSS THE LOWER GREAT LAKES REGION AND THE NORTHEAST TONIGHT THROUGH EARLY TUES IN THE WAKE OF THE DEPARTING NORTHERN NEW ENGLAND CYCLONE TODAY. ONLY MINOR TIMING DIFFERENCES EXIST WITH THE TIMING OF THE ARCTIC BOUNDARY...SO A GENERAL MODEL COMPROMISE WILL BE PREFERRED WITH THIS. ...SURFACE LOW CROSSING THE MIDWEST TONIGHT... ...AMPLIFYING ACROSS THE OH VALLEY/NORTHEAST BY WED... PREFERENCE: BLEND OF THE 12Z NAM/00Z ECENS MEAN CONFIDENCE: AVERAGE THE MODELS STILL SHOW RELATIVELY SIGNIFICANT SPREAD WITH THE EVOLUTION OF THE LOW CENTER OUT OF THE MIDWEST AND INTO THE OH VALLEY THROUGH TUES...WITH THE SPREAD BECOMING EVEN GREATER AS THE SYSTEM LIFTS INTO THE NORTHEAST ON WED. THE 00Z UKMET AGAIN IS THE NORTHERN MOST SOLUTION WITH THE WAVE TRACK BY 36 HOURS...AND IT TRACKS THE LOW WELL LEFT OF THE MULTI-MODEL CONSENSUS AS THE SYSTEM CROSSES THE NORTHEAST. THE 00Z UKMET ALSO BECOMES THE DEEPEST SOLUTION. THE 12Z GFS WHICH OVER THE PAST WEEKEND WAS THE SLOWEST SOLUTION...HAS NOW BECOME THE MOST PROGRESSIVE. THE 12Z NAM/00Z CMC AND 00Z ECMWF ARE ALL SLOWER...BUT THE 00Z ECMWF BECOMES THE SLOWEST SOLUTION AS IT REACHES THE NORTHEAST...AND THE 00Z CMC TENDS TO BE A TAD NORTHWEST OF THE OVERALL CONSENSUS. THE 12Z NAM ACTUALLY APPEARS TO BE A REASONABLE COMPROMISE SOLUTION AT THIS TIME WHICH MOST CLOSELY REFLECTS THE MODEL CONSENSUS...AND SPLITS THE DIFFERENCE EFFECTIVELY BETWEEN THE GFS AND ECMWF. THE 12Z NAM ALSO HAS EXCELLENT SUPPORT FROM THE 00Z ECENS MEAN. THEREFORE...WILL LEAN TOWARD A CONSENSUS OF THESE TWO SOLUTIONS FOR THE TIME BEING. ...SHORTWAVE CROSSING THE NORTHWEST AND MOVING INTO THE PLAINS BY WED... ...ENERGY/SURFACE LOW CROSSING THE MID MS/TN VALLEYS BY THURS... PREFERENCE: BLEND OF THE 12Z GFS/00Z ECMWF...THROUGH 60 HOURS BLEND OF THE 06Z GEFS MEAN/00Z ECENS MEAN...AFTER 60 HOURS CONFIDENCE: BELOW AVERAGE THE 00Z UKMET IS A BIT MORE AMPLIFIED WITH THE SHORTWAVE/SURFACE LOW IMPACTING THE PACIFIC NORTHWEST THROUGH ABOUT 36 HOURS...WITH THE REMAINING MODELS CLUSTERED AROUND A SOMEWHAT WEAKER SOLUTION. THE ENERGY WILL EJECT SOUTHEAST ACROSS THE HIGH PLAINS AND TOWARD THE MID MS/TN VALLEYS ON THURS...AND THE 12Z GFS AND 00Z ECMWF GENERALLY HAVE THE BETTER MODEL CLUSTERING THROUGH ABOUT 60 HOURS. THEREAFTER..THE 12Z GFS BECOMES A BIT MORE AMPLIFIED WITH THE SURFACE LOW COMPARED TO THE GLOBAL MODEL CONSENSUS. THE 12Z NAM BECOMES THE WEAKEST SOLUTION WITH ITS INITIAL LOW ARRIVING ACROSS THE PLAINS AND TOWARD THE LOWER OH VALLEY...BUT IT DOES FAVOR A STRONGER SECONDARY REFLECTION FARTHER SOUTH TOWARD THE GULF COAST BY LATE THURS AS STRONGER ENERGY DIGS FARTHER SOUTH. THE 00Z UKMET IS RATHER WEAK AS WELL AND IS A BIT MORE PROGRESSIVE. THE 00Z CMC BECOMES THE SLOWEST SOLUTION...WITH THE 00Z ECMWF THE MOST SUPPRESSED. THE ENSEMBLE MEANS DO NOT QUITE FAVOR THE MORE AMPLIFIED GFS AS THE ENERGY APPROACHES THE TN VALLEY ON THURS. SO...WILL PREFER A GFS/ECMWF BLEND THROUGH ABOUT 60 HOURS...AND THEN LEAN TOWARD A CONSENSUS OF THE LATEST GEFS MEAN AND ECENS MEAN THEREAFTER. GIVEN THE DETERMINISTIC MODEL SPREAD...CONFIDENCE IS LIMITED. ...SHORTWAVE/FRONT APPROACHING THE PACIFIC NORTHWEST EARLY THURS... PREFERENCE: NON-UKMET CONSENSUS CONFIDENCE: ABOVE AVERAGE THE 00Z UKMET IS A BIT OF A FAST OUTLIER WITH THIS SYSTEM AS IT ARRIVES ACROSS THE PACIFIC NORTHWEST ON THURS. THE REMAINING MODELS ARE REASONABLY WELL CLUSTERED WITH THEIR TIMING...AND SO WILL PREFER A NON-UKMET CONSENSUS. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON