MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 120 AM EDT TUE OCT 04 2016 VALID OCT 04/0000 UTC THRU OCT 07/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/CMC/ECMWF ...UPPER LOW/TROUGH CROSSING THE NORTHEAST... PREFERENCE: BLEND OF THE 00Z GFS/12Z UKMET/12Z ECMWF CONFIDENCE: AVERAGE THE MODELS HANDLE THIS SYSTEM SIMILARLY OVER THE NEXT COUPLE OF DAYS...BUT GRADUALLY THE 00Z NAM AND 12Z CMC BECOME A LITTLE QUICKER TO ADVANCE THIS ENERGY DOWNSTREAM BY WEDNESDAY AND THURSDAY. WILL PREFER A BLEND OF THE MODESTLY SLOWER AND WELL CLUSTERED 00Z GFS/12Z UKMET AND 12Z ECMWF WHICH ALL HAVE BETTER ENSEMBLE SUPPORT AS WELL. ...HURRICANE MATTHEW... ...UPPER TROUGH OVER THE GULF OF MEXICO... ...SUBTROPICAL RIDGE OFF THE EAST COAST... PREFERENCE: BLEND OF THE 00Z GFS/12Z ECMWF CONFIDENCE: AVERAGE SHORTWAVE ENERGY DIGGING SOUTH FROM THE GULF COAST STATES WILL BE REINFORCING THE BROAD WEAKNESS/UPPER TROUGH 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 WILL STEER POWERFUL HURRICANE MATTHEW OVER THE CENTRAL CARIBBEAN SEA TO THE NORTH OVER THE NEXT DAY OR SO. THE GUIDANCE THOUGH CONTINUES TO TREND TOWARD A BUILDING/STRENGTHENING SUBTROPICAL RIDGE TO THE NORTH OF MATTHEW BY WEDNESDAY AS THE WEAKNESS OVER THE GULF OF MEXICO SHIFTS FARTHER SOUTH. THIS IS ALLOWS THE GUIDANCE TO GENERALLY AGREE IN BENDING THE TRACK OF MATTHEW BACK TO THE NORTHWEST AFTER 36 HOURS AND THROUGH THE SHORT RANGE PERIOD. THE MODELS HAVE BEEN COLLECTIVELY TRENDING FARTHER LEFT WITH THE TRACK OF MATTHEW ONCE IT REACHES THE BAHAMAS...AND THIS IS MORE SPECIFICALLY A REFLECTION OF THE EXPANSION OF THE SUBTROPICAL RIDGE WESTWARD BACK INTO THE MID-ATLANTIC STATES IN THE WAKE OF THE WEAKENING UPPER LOW/TROUGH THAT IS EXITING THE NORTHEAST. THE 12Z UKMET REMAINS GENERALLY THE STRONGEST WITH THE RIDGING...BUT THE 00Z NAM/00Z GFS/12Z CMC AND 12Z ECMWF ARE ALL ONLY MODESTLY WEAKER. BY THURSDAY AND FRIDAY...THE 12Z CMC APPEARS TO BE A BIT FASTER THAN THE MODEL CONSENSUS IN SHIFTING THE RIDGE BACK EAST WHICH ALLOWS FOR MATTHEW TO THEN TURN BACK NORTH AT A FASTER RATE OF SPEED...BUT THE REMAINING MODELS ARE CLUSTERED A BIT SLOWER. WILL PREFER A BLEND OF THE GFS AND ECMWF WITH THE MASS FIELDS CONCERNING THE ENVIRONMENT AROUND MATTHEW. THE 03Z NHC TRACK OF MATTHEW IS GENERALLY CLOSE TO A BLEND OF THE 00Z GFS AND THE 12Z ECMWF...WITH THE LATEST GFS A TAD LEFT AND FASTER THAN THE NHC TRACK...AND THE ECMWF A TAD SLOWER AND A LITTLE TO THE RIGHT. PLEASE CONSULT THE LATEST NHC FORECAST ADVISORY FOR MORE DETAILS ON MATTHEW. ...DEEP UPPER TROUGH/CLOSED LOW CROSSING THE NORTHERN PLAINS TUESDAY... ...SURFACE LOW PRESSURE/FRONT ADVANCING EAST... PREFERENCE: BLEND OF THE 00Z GFS/12Z ECMWF CONFIDENCE: AVERAGE THE DEEP UPPER TROUGH/CLOSED LOW EJECTING OUT OF THE NORTHERN ROCKIES WILL CROSS THE NORTHERN HIGH PLAINS TUESDAY ALONG WITH A STRONG AREA OF LOW PRESSURE AND ATTENDANT FRONT. THIS WILL LIFT ACROSS SOUTHERN CANADA ON WEDNESDAY WHILE GRADUALLY SLOWING DOWN. THE ATTENDANT COLD FRONT WILL CROSS THE UPPER MS VALLEY ON WEDNESDAY. THE 12Z CMC PERIODICALLY APPEARS TO BE A TAD TOO DEEP WITH ITS CLOSED LOW...AND GRADUALLY THE 12Z UKMET BECOMES A LITTLE TOO WEAK IT APPEARS OVER SOUTHERN CANADA...AND ESPECIALLY BY THURSDAY AS THE UPPER TROUGH/CLOSED LOW SLOWS DOWN OVER SOUTHERN CANADA. WILL PREFER THE MASS FIELD CLUSTERING OF THE GFS/ECMWF SOLUTIONS AT THIS TIME. ...UPPER TROUGH/SURFACE LOW MOVING INTO THE PACIFIC NORTHWEST ON TUESDAY... ...ENERGY DIGGING INTO THE FOUR CORNERS THROUGH THURSDAY... ...SURFACE LOW DEVELOPMENT OVER THE CENTRAL PLAINS ON THURSDAY... PREFERENCE: BLEND OF THE 00Z GFS/12Z UKMET...UPPER TROUGH BLEND OF THE 00Z GFS/12Z ECMWF...SURFACE LOW CONFIDENCE: AVERAGE...BECOMING BELOW AVERAGE A ROBUST UPPER TROUGH AND CLOSED LOW CURRENTLY DROPPING SOUTH OFFSHORE BRITISH COLUMBIA WILL APPROACH THE PACIFIC NORTHWEST ON TUESDAY ALONG WITH A WELL-DEFINED SURFACE LOW AND FRONT. AFTER CROSSING THE PACIFIC NORTHWEST TUESDAY NIGHT AND WEDNESDAY...THE GUIDANCE SHOWS THIS ENERGY QUICKLY DIGGING INTO THE THE FOUR CORNERS REGION WITH SOME EXPECTATION 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. THE 12Z ECMWF GRADUALLY BECOMES THE WEAKEST SOLUTION WITH THE EVOLUTION OF THE HEIGHT FALLS AS IT HAS A FLATTER TROUGH EJECTING OUT INTO THE HIGH PLAINS BY EARLY FRIDAY. THE MODEL CONSENSUS IS FOR A SOMEWHAT SHARPER TROUGH...ALTHOUGH THE 00Z NAM LOOKS EVENTUALLY TO BE A TAD TOO DEEP AND TOO SLOW. WILL PREFER A BLEND OF THE 00Z GFS AND 12Z UKMET FOR THE DETAILS OF THE UPPER TROUGH EVOLUTION. REGARDING THE SURFACE LOW OVER THE CENTRAL PLAINS...THE 12Z UKMET APPEARS TO BE TOO PROGRESSIVE WITH THIS FEATURE...AND THE 12Z CMC IS TOO ILL-DEFINED. THE STRONGER MODEL CLUSTERING WITH THIS IS WITH THE 00Z NAM/00Z GFS AND 12Z ECMWF. A BLEND OF THE GFS AND ECMWF WILL BE PREFERRED WITH ALL OF THE SURFACE LOW DETAILS OF THIS SYSTEM. ...UPPER TROUGH APPROACHING THE PACIFIC NORTHWEST ON FRIDAY... PREFERENCE: BLEND OF THE 00Z GFS/12Z UKMET/12Z CMC CONFIDENCE: BELOW AVERAGE THE NEXT IN A SERIES OF UPPER TROUGHS WILL ENCROACH ON THE PACIFIC NORTHWEST ON FRIDAY. THERE IS SIGNIFICANT DISAGREEMENT AMONG THE MODELS ON THE INTERACTION OF ENERGY DROPPING SOUTH FROM THE GULF OF AK...AND WITH A FAST-MOVING UPSTREAM PACIFIC SHORTWAVE THAT ADVANCES RAPIDLY EAST AROUND THE BOTTOM OF THE GULF OF AK ENERGY. THE 12Z ECMWF IS GENERALLY OUT OF TOLERANCE WITH THE MULTI-MODEL CONSENSUS. STRONGER MODEL CLUSTERING TENDS TO RESIDE WITH THE 00Z GFS/12Z UKMET AND 12Z CMC...AND A BLEND OF THESE SOLUTIONS WILL BE PREFERRED. ENSEMBLE GUIDANCE SHOWS A FAIR AMOUNT OF SPREAD WITH THE DETAILS OF THE ATTENDANT SURFACE LOW EVOLUTION OFF THE NORTHWEST...AND SO CONFIDENCE IS LIMITED. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON