MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 239 AM EDT THU APR 03 2014 VALID APR 03/0000 UTC THRU APR 06/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/GEM GLOBAL AND THE ECMWF ...NRN STREAM UPPER TROUGH REACHING THE NORTHWEST THURS NIGHT/FRI... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS SHOW SIMILAR EVOLUTION WITH HEIGHT FALLS ENTERING THE NORTHWEST U.S. LATER IN THE WEEK. REGARDING THE SHORTWAVE TRACKING THROUGH WRN CANADA ON FRI...THE 00Z MODELS SHOW REASONABLY GOOD AGREEMENT THAT A GENERAL MODEL COMPROMISE SHOULD SUFFICE. ...SRN STREAM SYSTEM MOVING INTO THE SOUTHWEST SAT MORNING... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS SHOW GOOD AGREEMENT WITH THIS SYSTEM AND A GENERAL MODEL COMPROMISE WILL BE FAVORED ATTM TO RESOLVE ANY SMALLER SCALE DIFFS THAT REMAIN. ...UPPER TROUGH TRACKING FROM THE SOUTHWEST TO THE GREAT LAKES... ...ACCOMPANYING SURFACE LOW AND COLD FRONT THROUGH THE MIDWEST/GREAT LAKES... ...TRIPLE POINT LOW DEVELOPING OVER THE MID-ATLANTIC AND CROSSING COASTAL NEW ENGLAND... PREFERENCE: 00Z GFS/00Z GEM COMPROMISE...WITH MIDWEST/GREAT LAKES TROUGH/LOW CENTER 00Z GFS/00Z ECMWF COMPROMISE...WITH THE TRIPLE POINT LOW IMPACTING THE NORTHEAST CONFIDENCE: AVERAGE THE 00Z NAM AGAIN APPEARS TO BE THE STRONGEST OF THE DETERMINISTIC GUIDANCE WITH THE LOW-MID LEVEL LOW CENTER AND DEEP LYR TROUGH ADVANCING UP THROUGH THE MIDWEST AND GREAT LAKES REGION FOR THURS AND FRI. IT GRADUALLY BECOMES ONE OF THE SLOWER MODELS IN EXITING ITS SFC LOW PRESSURE OUT OF THE UPPER GREAT LAKES AND INTO SERN CANADA. THE 00Z GEM REGIONAL/GLOBAL AND 00Z GFS ARE A LITTLE WEAKER THAN THE NAM AND HAVE THEIR LOW TRACKS SLIGHTLY FARTHER EAST. THE 00Z UKMET IS RATHER CLOSE TO THE 00Z GFS SOLN WITH RESPECT TO LOW TRACK AND DEPTH UNTIL ABOUT 48 HRS WHEN IT BECOMES A LITTLE MORE PROGRESSIVE THAN THE GFS/GEM SOLNS. THE 12Z ECMWF EARLY IN THE PERIOD THROUGH THURS HAD BECOME THE WEAKEST AND MOST PROGRESSIVE SOLN WITH A LOW TRACK THAT WAS FARTHEST SOUTHEAST. THE 00Z ECMWF HAS TRENDED BACK TO THE LEFT WITH ITS LOW TRACK...BUT IT IS STILL THE WEAKEST SOLN SFC AND ALOFT AND APPEARING TOO PROGRESSIVE UNTIL ABOUT 48 HOURS OUT WHEN IT COMES INTO SUBSTANTIALLY BETTER AGREEMENT WITH THE GLOBAL MODELS AND OF COURSE MINUS THE NAM SOLN WHICH LOOKS TOO STRONG/SLOW. THE LATEST GEFS MEAN STRONGLY SUPPORTS A SOLN WEIGHTED TWD A GFS/GEM BLEND AND THAT WILL BE THE PREFERENCE ATTM. ACROSS THE NORTHEAST...ALL OFF THE MODELS SUPPORT THE IDEA OF A TRIPLE POINT LOW DEVELOPING INVOF THE MID-ATLANTIC COASTAL PLAIN LATE FRI AND THEN LIFTING NEWD JUST OFFSHORE NEW ENGLAND ON SAT. THE 00Z NAM AND TO AN EXTENT THE 00Z UKMET ARE WEAK OUTLIERS WITH THIS LOW DEVELOPMENT. WOULD PREFER TO LEAN TWD THE MORE DEVELOPED GFS/ECMWF SOLNS WHICH ALSO HAVE SUPPORT FROM THE GEM GLOBAL WITH THIS FEATURE. ...UPPER TROUGH CLIPPING NEW ENGLAND THROUGH THURS... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THERE IS VERY LITTLE SPREAD IN THE GUIDANCE WITH THIS SYS...AND SO WILL PREFER A GENERAL MODEL COMPROMISE TO DEAL WITH ANY LINGERING DETAIL ISSUES. www.wpc.ncep.noaa.gov/html/model2.shtml... ORRISON