MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 252 AM EDT WED OCT 05 2016 VALID OCT 05/0000 UTC THRU OCT 08/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/CMC AND ECMWF ...UPPER LOW/TROUGH DEPARTING THE NORTHEAST... ...SURFACE LOW OFFSHORE NEW ENGLAND... PREFERENCE: GENERAL MODEL COMPROMISE...UPPER TROUGH BLEND OF THE 00Z UKMET/00Z ECMWF...SURFACE LOW CONFIDENCE: AVERAGE THE MODELS ARE IN GOOD AGREEMENT WITH THE DETAILS OF THE UPPER TROUGH EVOLUTION...BUT THE 00Z NAM AND 00Z GFS ARE SLOWER TO EXIT THE SURFACE LOW OFFSHORE COMPARED TO THE NON-NCEP GUIDANCE. THE 00Z ECMWF TRENDED WEAKER FROM ITS PREVIOUS RUN AND IS CLOSER TO THE NON-NCEP MODEL CONSENSUS. WILL FAVOR A BLEND OF THE 00Z UKMET AND 00Z ECMWF FOR NOW WITH THE SURFACE LOW. ...HURRICANE MATTHEW... PREFERENCE: BLEND OF THE 00Z GFS/00Z ECMWF CONFIDENCE: AVERAGE THE MODELS CONTINUE TO ADVERTISE THE STRENGTHENING AND WESTWARD EXPANSION OF THE SUBTROPICAL RIDGE OVER THE WESTERN ATLANTIC AND INTO THE MID-ATLANTIC REGION OVER THE NEXT COUPLE OF DAYS...AND THIS WILL FORCE HURRICANE MATTHEW TO TURN BACK TO THE NORTHWEST AS IT MOVES THROUGH THE BAHAMAS. THIS WILL ALLOW MATTHEW TO COME VERY CLOSE TO THE EAST COAST OF FL THURSDAY AND FRIDAY. ON FRIDAY...THE SUBTROPICAL RIDGE IS EXPECTED TO WEAKEN AND BEGIN RETREATING OFFSHORE IN RESPONSE TO AN UPPER TROUGH APPROACHING THE GREAT LAKES AND OH VALLEY WHICH SHOULD ALLOW MATTHEW TO SLOW DOWN AND TURN NORTH...FOLLOWED BY A GRADUAL RECURVATURE TO THE NORTHEAST NEAR THE SOUTHEAST U.S. COASTLINE THROUGH 84 HOURS. THE 03Z NHC FORECAST TRACK IS A TAD RIGHT AND PERHAPS A LITTLE FASTER THAN A CONSENSUS OF THE 00Z GFS AND 00Z ECMWF. IT SHOULD BE NOTED THAT THE 00Z GFS HAS TRENDED A BIT SLOWER THIS CYCLE WITH MATTHEW. MEANWHILE...THE 00Z NAM AND 00Z CMC GRADUALLY TRACK MATTHEW FASTER AND TO THE RIGHT OF THE MODEL CONSENSUS AND THE NHC TRACK. THE 00Z UKMET IS CLOSE TO THE 00Z GFS/00Z ECMWF CAMP EXCEPT JUST A TAD FASTER AND ESPECIALLY BY FRIDAY NIGHT AND SATURDAY. WITH THE MASS FIELD ENVIRONMENT SURROUNDING MATTHEW...THE PREFERENCE WILL BE TO LEAN TOWARD A GFS/ECMWF BLEND. PLEASE CONSULT THE LATEST NHC FORECAST ADVISORY FOR MORE INFORMATION ON MATTHEW. ...UPPER LOW/TROUGH CROSSING INTO SOUTHERN CANADA WEDNESDAY... ...COLD FRONT CROSSING THE GREAT LAKES... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS SHOW GOOD AGREEMENT WITH THIS SYSTEM AS THE UPPER TROUGH AXIS AND SURFACE COLD FRONT MOVE INTO CANADA THROUGH THURSDAY. THE SOUTHERN END OF THE FRONT DRAPING BACK DOWN OVER THE MIDWEST AND CENTRAL PLAINS HOWEVER WILL BE INFLUENCED BY THE ARRIVAL OF UPSTREAM TROUGHING...AND THE GUIDANCE SHOWS LOW PRESSURE DEVELOPING ALONG THE FRONT IN THE LEE OF THE ROCKIES BY THURSDAY MORNING. ...UPPER TROUGH CROSSING THE WEST THROUGH THURSDAY... ...MOVING INTO THE EASTERN U.S. BY SATURDAY... ...SURFACE LOW MOVING FROM THE CENTRAL PLAINS TO THE GREAT LAKES... PREFERENCE: BLEND OF THE 00Z UKMET/00Z ECMWF CONFIDENCE: AVERAGE ALL OF THE MODELS SHOW A TROUGH CROSSING THE PACIFIC NORTHWEST EARLY WEDNESDAY AND THEN DIGGING SOUTHEAST ACROSS THE INTERMOUNTAIN WEST THURSDAY. THEREAFTER...A PROGRESSIVE UPPER TROUGH AND ASSOCIATED COLD FRONT WILL MOVE INTO THE EASTERN STATES. THE 00Z ECMWF HAS COME INTO SOMEWHAT BETTER AGREEMENT NOW WITH THE 00Z GFS AND 00Z UKMET CONCERNING THE TROUGH EVOLUTION THROUGH FRIDAY AND SATURDAY. THE 00Z NAM OVERALL IS SLOWER AND DEEPER WITH THE TROUGH WITH THE 00Z CMC ALSO A LITTLE SLOWER THAN THE MODEL CONSENSUS. THE HEIGHT FALLS WILL DEVELOP AND AREA OF LOW PRESSURE IN THE LEE OF THE ROCKIES WHICH WILL LIFT QUICKLY NORTHEAST ACROSS THE MIDWEST AND THE UPPER GREAT LAKES REGION AS A TRAILING COLD FRONT ADVANCES EAST OF THE MS VALLEY AND INTO THE OH VALLEY BY SATURDAY. THE 00Z GFS AT THIS POINT APPEARS TO BE A BIT OF A WEAK OUTLIER...AND THE 00Z NAM IS TOO SLOW. THE 00Z ECMWF TRENDED WEAKER AND A LITTLE FASTER WITH THE WAVE AND IS CLOSE TO THE 00Z UKMET SOLUTION. BASED ON STRONGER MODEL CLUSTERING...A BLEND OF THE UKMET AND ECMWF SHOULD SUFFICE. ...UPPER TROUGH APPROACHING THE PACIFIC NORTHWEST ON FRIDAY... PREFERENCE: BLEND OF THE 00Z GFS/00Z UKMET/00Z ECMWF CONFIDENCE: SLIGHTLY ABOVE AVERAGE MUCH BETTER AGREEMENT IS SEEN NOW WITH MODELS CONCERNING THE ARRIVAL OF A SHORTWAVE AND ATTENDANT SURFACE LOW ACROSS THE PACIFIC NORTHWEST EARLY FRIDAY. THE 00Z NAM IS A LITTLE NORTH OF THE MODEL CONSENSUS...BUT THE 00Z UKMET AND 00Z ECMWF TRENDED A LITTLE FARTHER NORTH TOWARD THE 00Z GFS SOLUTION. THE 00Z CMC IS A WEAK OUTLIER. A BLEND OF THE GFS/UKMET AND ECMWF WILL BE PREFERRED BASED ON DECENT MODEL CLUSTERING. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON