MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1251 AM EDT FRI JUN 20 2014 VALID JUN 20/0000 UTC THRU JUN 23/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ================================================== 00Z NAM/GFS EVALUATION AND PRELIMINARY PREFERENCES ================================================== NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO SIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT. ================================================== ...CENTRAL U.S... PREFERENCE: BLEND OF 00Z NAM WITH 12Z ECMWF/UKMET DURING THE SHORT RANGE A CYCLONE WILL SLOWLY SPIN DOWN AND OPEN UP ACROSS SOUTHERN CANADA. A PRONOUNCED SHORTWAVE TROUGH WILL PROGRESS UNDERNEATH THIS...THROUGH THE ROCKIES AND INTO THE CENTRAL PLAINS STATES BY DAY 3...SUNDAY. THERE ARE NO STRONG OUTLIERS...BUT OUR PREFERENCE IS BASED UPON THE BEST CLUSTERING WITH RESPECT TO UPPER AIR...SURFACE...AND PRECIPITATION. THE ECMWF DID APPEAR SLIGHTLY FAST WITH THE SURFACE FRONT ON DAY 3 IN THE LOWER MISSOURI VALLEY...BUT ITS PRECIPITATION OUTPUT WAS NOT FAR OFF FROM CONSENSUS. THE GFS SEEMS TO OPEN THE CANADIAN CYCLONE EARLY...AS THAT MODEL IS PRONE TO PHASING FEATURES PREMATURELY. THIS LEAVES THE REMNANT TROUGH BACK TO THE WEST OF CONSENSUS. THIS RUN OF THE GFS ALSO APPEARS PRONE TO SOME CONVECTIVE FEEDBACK...WITH LOCAL INTENSE RAINFALL MAXIMA ON DAYS 1 AND 3 THAT ARE DISPLACED FROM THE ENSEMBLE CONSENSUS PRECIPITATION SWATHS. ...EASTERN U.S... PREFERENCE: BLEND OF 00Z GFS WITH 12Z ECMWF/UKMET THE GFS/ECMWF/UKMET HAVE SHOWN REASONABLE RUN TO RUN CONTINUITY REGARDING A SHORTWAVE THAT ROTATES THROUGH THE BASE OF THE NORTHEAST U.S. MEAN TROUGH ON DAYS 2 AND 3. THE NAM IS SLOW AND FALLS OUT OF PHASE WITH THE MULTI-RUN CONSENSUS BY DAY 2...ESPECIALLY OVER THE MID ATLANTIC AND APPALACHIANS. ...SOUTHERN / SOUTHWESTERN U.S... PREFERENCE: BLEND OF THE OPERATIONAL MODELS...EXCLUDING THE 12Z CANADIAN ON DAY 3 HERE THE MODELS GENERALLY AGREE AS TO THE PROGRESSION OF AN INVERTED TROUGH MOVING UP THE RIO GRANDE VALLEY...AND INTRODUCTION OF A PACIFIC SHORTWAVE TROUGH INTO THE DESERT SOUTHWEST. THE 12Z CANADIAN LEANED TOWARD A FLAT...LESSER DEFINED FLOW PATTERN BY DAY 3. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... BURKE