MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1254 AM EDT MON OCT 03 2016 VALID OCT 03/0000 UTC THRU OCT 06/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...UPPER LOW/TROUGH CROSSING THE NORTHEAST... PREFERENCE: BLEND OF THE 00Z GFS/12Z ECMWF CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE LARGE UPPER LOW THAT HAS BEEN IMPACTING THE OH VALLEY AND GREAT LAKES REGION WILL FINALLY MOVE EAST ACROSS THE NORTHEAST THROUGH MONDAY. IT IS FORECAST TO EVOLVE INTO AN OPEN TROUGH BY THE TIME IT REACHES THE NEW ENGLAND COAST BY TUESDAY AND THEN SHEAR OUT. THE 12Z UKMET IS A TAD FASTER THAN THE MODEL CONSENSUS WITH THIS...WITH THE 00Z NAM ON THE SLOWER SIDE. THE 00Z GFS AND 12Z ECMWF SPLIT THE DIFFERENCE BETWEEN CAMPS...AND A BLEND OF THESE SOLUTIONS WILL BE PREFERRED. ...UPPER TROUGH DEVELOPING OVER THE GULF OF MEXICO... ...SUBTROPICAL RIDGE OFF THE EAST COAST... PREFERENCE: BLEND OF THE 00Z GFS/12Z ECMWF CONFIDENCE: AVERAGE SHORTWAVE ENERGY DIGGING SOUTHEAST THROUGH THE GULF COAST STATES WILL HELP REINFORCE THE BROAD WEAKNESS THAT IS ALREADY IN PLACE ACROSS THE GULF OF MEXICO. THE REINFORCING UPPER TROUGH HERE ALONG WITH PROXIMITY OF THE SUBTROPICAL RIDGE FARTHER EAST OFF THE EAST COAST IS EXPECTED TO HELP STEER POWERFUL HURRICANE MATTHEW OVER THE CENTRAL CARIBBEAN SEA TO THE NORTH OVER THE NEXT COUPLE OF DAYS. THE GUIDANCE THOUGH INDICATES SOME BUILDING/STRENGTHENING OF THIS RIDGE TOP THE NORTH OF MATTHEW BY THE MIDDLE OF THE WEEK AND AS THE WEAKNESS OVER THE GULF OF MEXICO SHIFTS FARTHER SOUTH. THIS ALLOWS THE GUIDANCE TO GENERALLY AGREE IN BENDING THE TRACK OF MATTHEW BACK TO THE NORTHWEST. THE 12Z UKMET WAS BY FAR THE STRONGEST WITH THE RIDGING NORTH OF MATTHEW...WITH THE 12Z CMC THE WEAKEST. THE 00Z NAM/00Z GFS AND 12Z ECMWF ALL CLUSTER IN BETWEEN THE UKMET AND CMC SOLUTIONS. THE 00Z NAM THOUGH IS STRONGEST WITH THE TROUGHING OVER THE GULF OF MEXICO. WILL SUGGEST A BLEND OF THE 00Z GFS AND 12Z ECMWF WITH RESPECT TO THE UPPER TROUGH OVER THE GULF OF MEXICO AND WITH THE SUBTROPICAL RIDGE NORTH OF MATTHEW. PLEASE CONSULT THE LATEST NHC FORECAST ADVISORY FOR MORE DETAILS ON MATTHEW. ...DEEP UPPER TROUGH/CLOSED LOW CROSSING THE INTERMOUNTAIN WEST... ...ENERGY AMPLIFYING WHILE CROSSING THE NORTHERN HIGH PLAINS... PREFERENCE: NON-NAM CONSENSUS CONFIDENCE: SLIGHTLY ABOVE AVERAGE A STRONG UPPER TROUGH AND ASSOCIATED CLOSED LOW MOVING INTO THE WEST WILL TRAVERSE THE INTERMOUNTAIN WEST WHILE BECOMING NEGATIVELY TILTED THROUGH MONDAY. THE GUIDANCE SHOWS A DEEPENING LOW AND MID LEVEL LOW CENTER CROSSING EASTERN MT MONDAY NIGHT AND TUESDAY...AND THE GUIDANCE SHOWS REASONABLY GOOD AGREEMENT WITH THIS EVOLUTION THOUGH TUESDAY. ON WEDNESDAY AS THE HEIGHT FALLS ADVANCE EAST...THE 00Z NAM TENDS TO SHOW MORE TROUGHING LINGERING DOWN OVER THE NORTHERN PLAINS GIVEN A SLOWER AND FARTHER SOUTH EJECTION OF THE UPPER LOW. WILL PREFER A NON-NAM CONSENSUS FOR THE MODEL MASS FIELDS AT THIS TIME. ...UPPER TROUGH/SURFACE LOW MOVING INTO THE PACIFIC NORTHWEST ON TUESDAY... ...ENERGY THEN DIGGING INTO THE FOUR CORNERS ON WEDNESDAY... ...SURFACE LOW DEVELOPMENT OVER THE CENTRAL PLAINS ON THURSDAY... PREFERENCE: BLEND OF THE 00Z GFS/12Z UKMET/12Z ECMWF CONFIDENCE: AVERAGE THE NEXT UPPER TROUGH DIGGING DOWN FROM THE GULF OF ALASKA IS EXPECTED TO BE OFFSHORE BRITISH COLUMBIA BY MONDAY NIGHT AND APPROACHING THE PACIFIC NORTHWEST ALONG WITH A WELL-DEFINED SURFACE LOW AND FRONT. AFTER CROSSING THE PACIFIC NORTHWEST...THE GUIDANCE SHOWS THIS ENERGY QUICKLY DIGGING TOWARD THE FOUR CORNERS REGION BY WEDNESDAY WITH SOME EVIDENCE OF TROUGH AMPLIFICATION BY THURSDAY. THIS WILL ALLOW A WAVE OF LOW PRESSURE TO DEVELOP IN THE LEE OF THE ROCKIES ALONG A FRONT OVER THE CENTRAL PLAINS BY THURSDAY. WITH THE EXCEPTION OF THE SLOWER 12Z CMC...THE GUIDANCE IS IN GOOD AGREEMENT WITH THE INITIAL ARRIVAL OF THE UPPER TROUGH AND SURFACE LOW ACROSS THE PACIFIC NORTHWEST. THEREAFTER...THE 00Z GFS HAS TRENDED A BIT STRONGER/SHARPER WITH THE TROUGHING ADVANCING INTO THE INTERIOR AND TENDS TO BE A LITTLE STRONGER THAN THE MODEL CONSENSUS. THE 00Z NAM AND 12Z CMC APPEAR A LITTLE TOO BROAD WITH THE TROUGH WHICH ALLOWS FOR THE HEIGHT FALLS TO SPREAD INTO THE HIGH PLAINS A LITTLE FASTER. THIS IN TURN ALLOWS THE NAM AND CMC TO HAVE SOMEWHAT MORE PROGRESSIVE SURFACE LOWS DEVELOPING AND MOVING THROUGH THE CENTRAL PLAINS. THE 12Z UKMET AND 12Z ECMWF SUPPORT THE 00Z GFS BUT ARE JUST NOT QUITE AS DEEP. WILL PREFER A BLEND OF THE GFS/UKMET/ECMWF SOLUTIONS FOR NOW. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON