MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1218 PM EDT TUE MAR 22 2016 VALID MAR 22/1200 UTC THRU MAR 26/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...SURFACE WAVE MOVING THROUGH THE NORTHERN/CENTRAL PLAINS TODAY... ...ENERGY/COLD FRONT REACHING NEW ENGLAND ON WED... PREFERENCE: GENERAL MODEL BLEND CONFIDENCE: ABOVE AVERAGE THERE REMAINS SOME MINOR PLACEMENT DIFFERENCES WITH A WEAK SURFACE LOW EXPECTED TO TRACK THROUGH THE GREAT LAKES LATER TODAY AND ALONG A FRONTAL ZONE DROPPING DOWN INTO NEW ENGLAND EARLY WED. THE GUIDANCE IS IN REASONABLE GOOD AGREEMENT WITH THE MASS FIELD DETAILS..SO A GENERAL MODEL BLEND WILL BE PREFERRED. ...UPPER TROUGH ENTERING THE INTERMOUNTAIN WEST... ...EJECTING INTO THE PLAINS WED AND LIFTING INTO THE GREAT LAKES THURS... ...ASSOCIATED DEEP SURFACE LOW... PREFERENCE: HALFWAY BETWEEN THE 12Z GFS AND 00Z ECMWF...AND CLOSE TO THE 12Z NAM CONFIDENCE: AVERAGE NO MAJOR CHANGES TO THE PREVIOUS THINKING. OVERALL...WPC IS FAVORING A MIDDLE GROUND SOLUTION BETWEEN THE DISTINCT DIFFERENCES BETWEEN THE FASTER/NORTHERN GFS/GEFS CAMP AND SLOWER/SOUTHWEST ECMWF/ECENS MEAN SOLUTIONS. THE DIFFERENCES AGAIN APPEAR TO BE TIED HEAVILY TO INTERACTION WITH NORTHERN STREAM AMPLIFICATION AND/OR SOME ENERGY LINGERING DOWNSTREAM OF THIS IN THE APEX OF SOME SHORTWAVE RIDGING. HOWEVER...THERE HAS BEEN SOME GRADUAL TREND OVER THE LAST DAY OR SO FOR SOME CONVERGENCE IN CAMPS...WITH THE GFS TRENDING A BIT SLOWER AND THE ECMWF A BIT FASTER. INTERESTINGLY THE OPERATIONAL VERSIONS OF THE GFS AND ECMWF REMAIN GENERALLY ON THE EDGES OF THEIR ENSEMBLE SUITES...WITH THE 12Z GFS WITHIN THE NORTHERN CAMP OF THE 00Z GEFS MEMBERS...AND THE 00Z ECMWF AT LEAST WITHIN THE SOUTHERN CAMP OF 00Z ECENS MEMBERS AFTER 72 HOURS. THE 12Z NAM AND 00Z CMC SPLIT THE DIFFERENCE BETWEEN THE FASTER/NORTHERLY GFS AND SLOWER/SOUTHERLY ECMWF CAMPS. THE 00Z UKMET GRADUALLY BECOMES THE MOST PROGRESSIVE SOLUTION AND ESPECIALLY BY THE END OF THE PERIOD. WILL LEAN TOWARD A COMPROMISE IN BETWEEN THE GFS AND ECMWF....WITH A SOLUTION CLOSE TO THE 12Z NAM. ...UPPER LOW SHEDDING ENERGY INTO THE PACIFIC NORTHWEST WED NIGHT/THURS... ...ASSOCIATED COLD FRONT MOVING INLAND AND REACHING THE HIGH PLAINS FRI... ...SURFACE CYCLOGENSIS OVER THE NORTHERN HIGH PLAINS... PREFERENCE: 00Z ECMWF CONFIDENCE: AVERAGE MODELS ARE IN FAIRLY STRONG AGREEMENT WITH THE OVERALL SHAPE/STRENGTH OF THE UPPER LOW APPROACHING THE ALASKAN PANHANDLE BY EARLY THURS. SHEDDING FORCES ALLOW FOR AN ELONGATION ALONG THE SEABOARD OF BC WITH THE SE PORTION OF THE WAVE SHEARING OFF INTO VANCOUVER ISLAND BY THURS MORNING AND CROSSING THE NW US/CANADA BOARDER AHEAD OF THE REST OF THE UPPER LOW ENERGY. THE SHORTWAVE ENERGY CROSSING THE NORTHWEST WILL BE ACCOMPANIED BY A COLD FRONT...AND BY LATE IN THE PERIOD...THIS FRONT ALONG WITH AN AREA OF LEE-SIDE CYCLOGENESIS WILL EJECT ACROSS THE NORTHERN PLAINS. THERE REMAINS SMALL TIMING AND STRENGTH DIFFERENCES TO THE LEAD PIECE OF ENERGY THAT REACHES THE HIGH PLAINS LATE THURS INTO FRI WITH THE LARGEST DIFFERENCES SEEN MAINLY WITH THE PLACEMENT/STRENGTH OF THE SURFACE LOW AND ORIENTATION OF THE FRONT. THE 12Z GFS AND 00Z UKMET BECOME THE MOST PROGRESSIVE...WITH THE 12Z NAM/00Z CMC AND 00Z ECMWF ALL SLOWER. THE 12Z NAM OVERALL IS THE SLOWEST. THE 00Z ECMWF IS A REASONABLE COMPROMISE SOLUTION AT THIS TIME AND DOES TEND TO HAVE SUPPORT FROM THE 00Z CMC AND THE 00Z ECENS MEAN. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON