MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 303 PM EDT FRI SEP 02 2016 VALID SEP 02/1200 UTC THRU SEP 06/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z FINAL MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ TROPICAL CYCLONE HERMINE AND FRONTAL/TROUGH INTERACTION ACROSS THE EAST ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: PLEASE REFER TO LATEST NHC FORECAST ADVISORY THE GFS/ECMWF AND UKMET ALL SHOW HERMINE INTERACTING WITH A POTENT UPPER LEVEL SHORTWAVE TROUGH...ESPECIALLY ON DAYS 2/3. REFER TO THE NHC TROPICAL CYCLONE DISCUSSION FOR MORE DETAILS ABOUT MODEL PREFERENCE. FIRST UPPER LOW/TROUGH DIGGING SOUTH OFFSHORE BRITISH COLUMBIA WITH HEIGHT FALLS ADVANCING ACROSS THE NORTHWEST THROUGH FRIDAY AND CENTRAL CANADA BY SAT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL BLEND CONFIDENCE: AVERAGE MODELS REMAIN IN GOOD ALIGNMENT WITH THE EVOLUTION OF THE UPPER LOW AS IT SHIFTS INTO CANADA ON SATURDAY. AT THAT POINT...THE SPREAD BEGINS TO OPEN SATURDAY NIGHT AND SUNDAY BUT THOSE DIFFERENCES OCCUR WELL NORTH OF THE BORDER WITH MINIMAL IMPACT ACROSS THE LOWER 48. THE 12Z ECMWF AND THE UKMET RUNS WERE PRETTY CLOSE AT THE MID LEVELS TO THEIR PREVIOUS RUNS. GIVEN NO SIGNIFICANT TREND ONE WAY OR ANOTHER IN THE MODELS...WILL CONTINUE TO RECOMMEND A GENERAL MODEL BLEND. TRAILING SHORTWAVE REINFORCING THE TROUGH OVER THE WEST THIS WEEKEND. HEIGHT FALLS MOVING TOWARDS THE PLAINS SUNDAY WITH CONSOLIDATING SURFACE WAVE IN SD BY MON MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-NAM/CMC BLEND CONFIDENCE: AVERAGE THE TRAILING SHORTWAVE WHICH SKIMS THE BC COAST TONIGHT AND SATURDAY BEFORE REINFORCING THE TROF OVER THE WESTERN US ON SUNDAY IS HANDLED SIMILARLY BY THE 12Z MODELS. THE 12Z RUNS OF THE CMC AND NAM WERE STILL THE MOST OUT OF PHASE WITH OTHER MODELS IN TERMS OF TIMING AND THE NAM WAS A STRONG OUTLIER. WHILE SOME RUN TO RUN DIFFERENCES EXISTED IN OTHER MODELS...THE DIFFERENCES TENDED TO BE FAIRLY SMALL WHILE THE NAM/CMC DIFFERENCES GO BACK SEVERAL RUNS. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... BANN