MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1140 AM EST TUE NOV 18 2014 VALID NOV 18/1200 UTC THRU NOV 22/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ================================================== 12Z NAM/GFS EVALUATION AND PRELIMINARY PREFERENCES ================================================== NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO SIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT. ================================================== ...STRONG WESTERLY JET REACHING THE PACIFIC NORTHWEST FRIDAY... PREFERENCE: BLEND OF 12Z NAM/GFS WITH 00Z ECMWF OVER THE NEXT FEW DAYS A BROAD TROUGH IN THE NORTHERN PACIFIC WILL IMPINGE UPON THE PERSISTENT RIDGE IN WESTERN CANADA. BY FRIDAY THIS WILL BRING A 130 KNOT JET AT 250 MB TOWARD THE PACIFIC NORTHWEST COAST...ACCOMPANIED BY INCREASING ONSHORE FLOW AT LOW LEVELS. THE MODEL SPREAD IS RELATIVELY NARROW. THE GFS AND ECMWF CONTINUE TO LOOK REPRESENTATIVE OF CONSENSUS...AND THE 12Z NAM IS VERY SIMILAR AS WELL. THE 00Z UKMET AND CANADIAN WERE NOT OUTLIERS...BUT THEY WERE SLIGHTLY FAST AND SLIGHTLY SLOW...RESPECTIVELY. ...SOUTHERN STORM TRACK FROM CALIFORNIA TO THE SOUTHERN PLAINS... PREFERENCE: BLEND OF THE OPERATIONAL MODELS...EXCLUDING THE CANADIAN A LEAD SHORTWAVE TROUGH WILL ENTER CALIFORNIA TUESDAY EVENING AND TRACK TOWARD THE SOUTHERN PLAINS BEFORE DAMPENING. A STRONGER TROUGH ON ITS HEELS WILL ARRIVE IN CALIFORNIA ON THURSDAY AND DIG INTO THE DESERT SOUTHWEST. AGAIN THE MODELS SHOW VERY SIMILAR SOLUTIONS IN THIS REGION. THE 00Z CANADIAN IS TOO SLOW IN THE EARLY HOURS OF THE FORECAST...ALTHOUGH IT NEARLY CATCHES UP TO CONSENSUS TOWARD FRIDAY EVENING...22/00Z. ...EASTERN U.S. / GREAT LAKES... PREFERENCE: BLEND OF 12Z NAM/GFS WITH 00Z ECMWF THERE IS GENERALLY GOOD LARGE SCALE AGREEMENT HERE. THE 00Z UKMET WAS MORE OF AN OUTLIER WITH ITS DEEP AND SLOW MOVING SHORTWAVE TROUGH. OTHER MODELS AGREE THAT THIS SHORTWAVE WILL SWING THROUGH MICHIGAN ON THURSDAY...ROTATING QUICKLY THROUGH THE BASE OF THE LARGER TROUGH. THE NAM/GFS/ECMWF HAVE NOW SHOWN SOME RUN TO RUN CONTINUITY...AND FIT WELL WITH THE ENSEMBLE MEANS. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... BURKE