MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1220 AM EDT FRI OCT 16 2015 VALID OCT 16/0000 UTC THRU OCT 19/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...SOUTHWEST U.S. UPPER LEVEL LOW... PREFERENCE: NON-UKMET CONSENSUS CONFIDENCE: SLIGHTLY ABOVE AVERAGE A WELL DEVELOPED UPPER LEVEL LOW CURRENTLY NEAR THE CENTRAL CALIFORNIA COASTLINE WILL BE THE MAIN WEATHER MAKER ACROSS THE SOUTHWESTERN U.S. THROUGH THE SHORT TERM FORECAST PERIOD. GOOD AGREEMENT CONTINUES AMONG THE MODELS IN TAKING THIS SYSTEM GRADUALLY INLAND ACROSS CALIFORNIA THROUGH FRIDAY AND THEN EAST ACROSS ARIZONA FRIDAY NIGHT WHILE GRADUALLY TRANSITIONING INTO AN OPEN WAVE FEATURE BY SATURDAY MORNING. THE 12Z UKMET APPEARS TO BE THE QUICKEST IN WEAKENING THE SYSTEM BY 36 HOURS AND BEYOND...WITH THE REMAINING MODELS WELL CLUSTERED AT THIS POINT WITH TIMING AND DEPTH. A NON-UKMET CONSENSUS WILL BE PREFERRED AT THIS POINT. ...UPPER TROUGH INFLUENCING THE WEST COAST THIS WEEKEND... PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF CONFIDENCE: AVERAGE ANOTHER PRONOUNCED UPPER LEVEL TROUGH AND SHORTWAVE IS PROGGED TO REACH THE WEST COAST BY THIS WEEKEND...WITH THE TROUGH AXIS EXPECTED TO REACH THE COAST SAT NIGHT. SINCE LAST NIGHT...THE GUIDANCE HAS COME INTO BETTER AGREEMENT IN DEPICTING ENERGY IN THE BASE OF THIS TROUGH AMPLIFYING INTO A CLOSED LOW AND SEPARATING AWAY FROM THE MAIN BELT OF THE WESTERLIES TO THE NORTH. THE 12Z ECMWF/12Z CMC AND 12Z UKMET ARE A LITTLE SLOWER WITH THE EVOLUTION OF THE HEIGHT FALLS AS THEY EJECT INTO THE GREAT BASIN VERSUS THE 00Z NAM AND TO A LESSER EXTENT THE 00Z GFS. THE NAM AND GFS TEND TO FOCUS THEIR ENERGY A LITTLE FARTHER NORTH VERSUS THE NON-NCEP GUIDANCE...ALTHOUGH THE ECMWF IN ON THE NORTH SIDE OF THE NON-NCEP ENVELOPE BY MON WITH THE POSITION OF ITS CLOSED LOW CENTER. A COMPROMISE BETWEEN THE 00Z GFS AND 12Z ECMWF WILL BE PREFERRED AT THIS POINT GIVEN OVERALL BETTER CLUSTERING AND ENSEMBLE SUPPORT. ...SURFACE LOW PRESSURE AND SHORT WAVE CROSSING THE GREAT LAKES AND NORTHEAST THROUGH FRIDAY... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS ARE IN VERY GOOD AGREEMENT WITH THE MASS FIELDS DETAILS OF THIS SYSTEM AS IT CROSSES NORTHERN NEW ENGLAND ON FRI. THUS A GENERAL MODEL COMPROMISE WILL BE PREFERRED. ...SECOND LOW PRESSURE WAVE CROSSING NORTHERN NEW ENGLAND ON SATURDAY... PREFERENCE: NON-NAM CONSENSUS CONFIDENCE: ABOVE AVERAGE THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THIS NEXT SHORTWAVE IMPULSE AND ASSOCIATED SURFACE WAVE THAT CROSSES NORTHERN NEW ENGLAND EARLY ON SATURDAY. THE 12Z CMC HAS COME INTO BETTER AGREEMENT WITH THE OVERALL PATTERN COMPARED TO ITS EARLIER RUN. THE 12Z ECMWF HAS ALSO TRENDED TOWARD THE MULTI-MODEL CONSENSUS. HOWEVER...THE 00Z NAM IS A TAD SLOWER THAN THE MULTI-MODEL CONSENSUS...AND SO AS A RESULT WILL PREFER A NON-NAM CONSENSUS. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON