MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 239 AM EDT SUN OCT 02 2016 VALID OCT 02/0000 UTC THRU OCT 05/1200 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 MOVING INTO THE NORTHEAST... PREFERENCE: BLEND OF THE 00Z GFS/00Z ECMWF CONFIDENCE: AVERAGE THE UPPER LOW MOVING BACK INTO THE LOWER GREAT LAKES REGION WILL MOVE EAST OVER THE NEXT COUPLE OF DAYS INTO THE NORTHEAST AND THEN OFFSHORE NEW ENGLAND ON TUESDAY. THE SYSTEM WILL BE WEAKENING THROUGH THE PERIOD. AT THIS POINT...THE 00Z UKMET IS JUST A TAD MORE PROGRESSIVE THAN THE 00Z NAM/00Z GFS AND 00Z CMC AS ENERGY SHEARS OFFSHORE NEW ENGLAND. THE 00Z ECMWF HAS TRENDED A LITTLE SLOWER AND IS NOW VERY CLOSE TO THE GFS SOLUTION. REGARDLESS...ALL OF THE MODELS SHOW AT LEAST SOME VORT ENERGY NEAR THE BASE OF THE WEAKENING UPPER LOW/TROUGH SEPARATING OUT AND BECOMING LEFT BEHIND NEAR THE CENTRAL MID-ATLANTIC REGION ON WEDNESDAY. THE NAM AND CMC BOTH APPEAR TO STILL HAVE A LITTLE TOO MUCH ENERGY CUTTING OFF NEAR THE MID-ATLANTIC. BASED ON THE LATEST CLUSTERING BETWEEN THE GFS AND ECMWF...A BLEND OF THESE SOLUTIONS WILL BE PREFERRED. ...UPPER TROUGH DEVELOPING OVER THE GULF OF MEXICO... PREFERENCE: BLEND OF THE 00Z GFS/00Z ECMWF CONFIDENCE: AVERAGE SHORTWAVE ENERGY DIGGING SOUTHEAST INTO THE GULF COAST STATES WILL YIELD DEVELOPMENT AND PLACEMENT OF AN UPPER LEVEL TROUGH OVER THE GULF OF MEXICO BY MONDAY AND TUESDAY. THIS COUPLED WITH THE GRADUAL WEAKENING AND RETREAT OF THE SUBTROPICAL RIDGE OVER THE WESTERN ATLANTIC OCEAN IS EXPECTED TO ALLOW POWERFUL HURRICANE MATTHEW OVER THE SOUTHERN CARIBBEAN SEA TURN GRADUALLY TO NORTHWEST AND THEN NORTH OVER THE NEXT FEW DAYS. REGARDING THE UPPER TROUGH OVER THE GULF OF MEXICO...THE 00Z NAM APPEARS AGAIN TO BE TOO STRONG WITH IT. THE 00Z UKMET GRADUALLY APPEARS TO BE TOO WEAK AND ALSO SUGGESTS MORE RIDGING NORTH OF MATTHEW NEAR AND OFFSHORE THE SOUTHEAST U.S. BY WEDNESDAY. WILL FAVOR A BLEND OF THE 00Z GFS AND 00Z ECMWF FOR THE TIME BEING. PLEASE CONSULT THE LATEST NHC FORECAST ADVISORY FOR MORE INFORMATION ON HURRICANE MATTHEW. ...DEEP UPPER TROUGH/CLOSED LOW AFFECTING THE WEST COAST BY SUNDAY... ...ENERGY ADVANCING TOWARDS THE PLAINS TUESDAY... PREFERENCE: BLEND OF THE 00Z GFS/00Z ECMWF CONFIDENCE: SLIGHTLY ABOVE AVERAGE ON THE HEELS OF THE INITIAL SHORTWAVE MOVING THROUGH THE NORTHWEST...A MUCH STRONGER UPPER TROUGH AND CLOSED LOW IS EXPECTED TO DROP DOWN ALONG THE WEST COAST BEFORE CROSSING INLAND ON SUNDAY AND THEN ADVANCING ACROSS THE INTERMOUNTAIN WEST ON MONDAY AND TOWARDS THE PLAINS ON TUESDAY. OVERALL THERE IS GOOD AGREEMENT THROUGH EARLY TUESDAY WITH REGARDS TO THE EVOLUTION OF THIS UPPER LOW/TROUGH AND THE TRACK OF THE RESULTANT SURFACE LOW PRESSURE NEAR EASTERN MT AND WESTERN ND MONDAY INTO TUESDAY. THEREAFTER...THE MODELS SHOW UPSTREAM SHORTWAVE ENERGY DIGGING INTO THE BASE OF THE UPPER TROUGH WHICH MAY IMPACT THE EVOLUTION OF THE CLOSED LOW A BIT. BY WEDNESDAY...THE ADDITIONAL ENERGY RESULTS IN THE 00Z NAM BECOMING SLOWER THAN THE MODEL CONSENSUS. THE 00Z CMC ACTUALLY IS A STRONG OUTLIER WITH THE UPSTREAM ENERGY. BY WEDNESDAY...THE STRONGER MODEL CLUSTERING AND ENSEMBLE SUPPORT FAVORS THE 00Z GFS AND 00Z ECMWF...SO A BLEND OF THESE SOLUTIONS WILL BE PREFERRED. ...UPPER TROUGH APPROACHING THE PACIFIC NORTHWEST ON TUESDAY... PREFERENCE: NON-CMC CONSENSUS CONFIDENCE: AVERAGE THE NEXT UPPER TROUGH DIGGING DOWN FROM THE GULF OF AK WILL BE OFFSHORE BRITISH COLUMBIA ON MONDAY AND APPROACHING THE PACIFIC NORTHWEST ON TUESDAY. MEANWHILE ADDITIONAL SHORTWAVE ENERGY AT THE BASE OF THIS TROUGH APPEARS TO MOVE INTO THE PACIFIC NORTHWEST ON TUESDAY. THE 00Z CMC IS A TAD WEAKER WITH THIS SYSTEM AND DOES NOT DIG AS MUCH ENERGY INTO THE WESTERN U.S BY WEDNESDAY...BUT IT HAS BEEN TRENDING TOWARD THE MODEL CONSENSUS. GIVEN THE LEVEL OF AGREEMENT SEEM IN THE NON-CMC GUIDANCE...A NON-CMC CONSENSUS WILL STILL BE PREFERRED FOR NOW. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON