MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 249 PM EDT TUE OCT 04 2016 VALID OCT 04/1200 UTC THRU OCT 08/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING FINAL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...NOTE THAT THE ARRIVAL OF THE 12Z ECMWF WAS SIGNIFICANTLY DELAYED TODAY AND IS THEREFORE NOT INCLUDED IN THIS DISCUSSION... UPPER LOW/TROUGH DEPARTING FROM THE NORTHEAST TONIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON 12Z NAM BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE OUTSIDE OF THE FASTER NAM...THE MODELS HANDLE THIS SYSTEM SIMILARLY OVER THE NEXT COUPLE OF DAYS. WHILE THERE IS ROOM IN THE ENSEMBLE GUIDANCE TO BE A LITTLE FASTER THAN THE NON-NAM CONSENSUS...THE NAM STILL STANDS OUT AS A QUICK OUTLIER. HURRICANE MATTHEW UPPER TROUGH OVER THE GULF OF MEXICO SUBTROPICAL RIDGE OFF THE EAST COAST ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF THE 12Z GFS/00Z ECMWF CONFIDENCE: AVERAGE THE COMBINATION OF THE STRENGTH OF A MID-LEVEL RIDGE OVER THE WRN ATLANTIC AND AN ADVANCING TROUGH MOVING THROUGH THE CNTRL PLAINS WILL HELP TO INFLUENCE THE TRACK OF HURRICANE MATTHEW. THE 15Z NHC ADVISORY SUPPORTS A TRACK SIMILAR TO THE 12Z GFS AND 00Z ECMWF THROUGH ABOUT 12Z ON THE 7TH...AT WHICH POINT THE GFS/ECMWF LAG THE NHC SPEED FOR MATTHEW. THE 12Z UKMET IS SLOWER THAN THE NHC ADVISORY WHILE THE 12Z CMC IS FASTER. THE LATEST ENSEMBLE SPAGHETTI HEIGHTS CONTINUE TO SHOW A WIDE RANGE OF POSSIBILITIES REGARDING THE STRENGTH OF THE WRN ATLANTIC RIDGE WITH THE LATEST 00Z/04 ENSEMBLE SUITE SHOWING THE GFS AND ECMWF TO BE WEAKER WITH THE RIDGE COMPARED TO THE EC MEAN AND 12Z UKMET. UPSTREAM...THE 00Z ECMWF AND ITS MEAN SHOW A FLATTER/BROADER UPPER TROUGH MOVING THROUGH THE PLAINS COMPARED TO THE 12Z NAM/GFS BUT HAVE GAINED SUPPORT FROM THE 12Z UKMET/CMC. PLEASE CONSULT THE LATEST NHC FORECAST ADVISORY FOR MORE DETAILS ON MATTHEW. CLOSED UPPER LOW OVER MT LIFTING INTO SRN CANADA WEDNESDAY COLD FRONT CROSSING THE GREAT LAKES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE MODELS SHOW GOOD AGREEMENT WITH THIS SYSTEM AS THE UPPER TROUGH AXIS AND SURFACE COLD FRONT MOVE INTO CANADA. THE SRN END OF THE FRONT IS INFLUENCED BY THE NEXT UPPER TROUGH ADVANCING THROUGH THE WEST ON THU...DESCRIBED IN THE SECTION BELOW. UPPER TROUGH/SURFACE LOW MOVING INTO THE PACIFIC NORTHWEST TODAY ENERGY DIGGING INTO THE FOUR CORNERS THROUGH THURSDAY SURFACE LOW DEVELOPMENT OVER THE CENTRAL PLAINS ON THURSDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF THE 12Z GFS/00Z UKMET CONFIDENCE: SLIGHTLY BELOW AVERAGE THE 00Z ECMWF REMAINS CONSISTENTLY DIFFERENT FROM THE REMAINING DETERMINISTIC AND ENSEMBLE CONSENSUS REGARDING HEIGHTS ACROSS THE WRN CONUS. THIS IS DUE TO FLATTER RIDGING IN THE ECMWF ACROSS THE ERN PACIFIC. GIVEN CONTINUITY AND THE BETTER MODEL SUPPORT FOR A NON ECMWF SOLUTION OUT WEST...AND GIVEN SIMILARITY IN THE GFS/UKMET...THESE TWO MODELS ARE PREFERRED AT THIS TIME. HOWEVER...THE ECMWF IS TYPICALLY A BETTER PERFORMING MODEL...AND THE POTENTIAL FOR FUTURE ADJUSTMENTS IS PRESENT...HENCE THE BELOW AVERAGE CONFIDENCE. 19Z UPDATE...THE 12Z UKMET/CMC HAVE BOTH CHANGED SIGNIFICANTLY TO BE SIMILAR TO THE 00Z ECMWF IN SHOWING A FLATTER E-PAC RIDGE AND MORE PROGRESSIVE AND FLATTER CNTRL PLAINS TROUGH. GRANTED...THE 12Z GFS HAS BEEN TRENDING FLATTER WITH THE PLAINS TROUGH BUT GIVEN THE LACK OF THE 12Z ECMWF FOR THIS DISCUSSION UPDATE AND THE CHANGE IN CONTINUITY SEEN IN THE UKMET/CMC...WILL NOT JUMP ON BOARD THE 12Z UKMET/CMC JUST YET PENDING THE ARRIVAL OF THE 12Z ECMWF AND ANY POTENTIAL CHANGES SEEN IN FUTURE GFS RUNS. UPPER TROUGH APPROACHING THE PACIFIC NORTHWEST ON FRIDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON 12Z GFS BLEND CONFIDENCE: BELOW AVERAGE THE LATEST MODEL CONSENSUS SHOWS A SIMILAR STRENGTH TO THIS FEATURE...BUT THE 12Z GFS IS FASTER WITH THE POSITION OF A SHORTWAVE TROUGH NEARING THE PACIFIC NORTHWEST FRI EVENING. WHILE CONFIDENCE IS LOW IN THESE DETAILS...IT APPEARS THE GFS IS UNSUPPORTED AT THIS TIME...EVEN WHEN CONSIDERING THE 12Z UKMET/CMC. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO