MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 232 PM EDT SUN OCT 18 2015 VALID OCT 18/1200 UTC THRU OCT 22/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING THE NAM/GFS/CMC/UKMET/ECMWF ...UPPER TROUGH/CLOSED LOW DIGGING INTO THE SOUTHWEST U.S THROUGH MIDWEEK... PREFERENCE: BLEND OF THE 12Z GFS...CMC...AND ECMWF CONFIDENCE: AVERAGE THE MODELS ARE IN GOOD AGREEMENT IN TAKING THE UPPER TROUGH/CLOSED LOW CURRENTLY DIGGING INTO CALIFORNIA GRADUALLY SOUTHEASTWARD OVER THE NEXT FEW DAYS...WITH A ROBUST CLOSED LOW FORECAST TO DIG DOWN THROUGH THE SOUTHWEST. THE 12Z NAM CONTINUES TO KEEP A PIECE OF SHORTWAVE ENERGY FARTHER NORTH OVER THE GREAT BASIN TOWARD THE END OF THE PERIOD (BY 00Z THU)...WHILE THE 12Z UKMET REMAINS WEAKEST WITH THE HEIGHT FALLS INTO THE SOUTHWEST. THE 12Z GFS AND 00Z CMC/ECMWF RUNS ALL SHOW BETTER AGREEMENT...AND GIVEN THE GOOD CLUSTERING AND GOOD ENSEMBLE SUPPORT FROM THE GEFS MEAN AND ECENS MEAN...A BLEND OF THESE SOLUTIONS WILL BE PREFERRED. ...SHORTWAVE TROUGH CROSSING THE NORTHWEST/NORTHERN ROCKIES/NORTHERN PLAINS/UPPER MISSISSIPPI VALLEY THROUGH TUESDAY... PREFERENCE: BLEND OF THE 12Z GFS AND ECMWF CONFIDENCE: AVERAGE A NORTHERN STREAM TROUGH WILL CROSS THE NORTHWEST U.S. ON MON...ADVANCE DOWNSTREAM ACROSS THE NORTHERN ROCKIES AND NORTHERN PLAINS THROUGH TUE...THEN MOVE ACROSS THE UPPER MIDWEST ON WED. THE 12Z NAM AND 00Z CMC CONTINUE TO BE SLOWER COMPARED TO THE CONSENSUS OF THE OTHER MODELS ALONG WITH THE 00Z GEFS/ECENS MEAN...WHILE THE 12Z UKMET IS ON THE FASTER EDGE OF THE GUIDANCE SPREAD. ...FLAT UPPER TROUGH/SURFACE COLD FRONT CROSSING THE NORTHERN PLAINS/UPPER MIDWEST/GREAT LAKES BY MON AND TUES... ...COLD FRONT CROSSING INTO THE NORTHEAST LATE TUES AND WED... PREFERENCE: MULTI-MODEL BLEND CONFIDENCE: ABOVE AVERAGE THE MODELS AGREE VERY WELL IN BRINGING A COLD FRONT ACROSS THE NORTHERN PLAINS AND THROUGH THE UPPER MIDWEST MON AND TUES...IN RESPONSE TO A FLAT UPPER TROUGH SCRAPING THE NORTHERN TIER STATES. THE GUIDANCE CONTINUES TO COME INTO BETTER AGREEMENT WITH THE TIMING OF THIS FRONT...AS A MULTI-MODEL BLEND OF THE LATEST NAM/GFS/UKMET/ECMWF CLUSTER WELL WITH THE SREF/GEFS/ECENS MEANS. ...UPPER TROUGH AND COLD FRONT APPROACHING THE NORTHWEST BY WED... PREFERENCE: NON-NAM/NON-CMC CONSENSUS CONFIDENCE: ABOVE AVERAGE THE MODELS SHOW A NEW PACIFIC UPPER TROUGH AND ASSOCIATED COLD FRONT APPROACHING THE NORTHWEST TUES NIGHT AND EARLY WED. THE 12Z NAM REMAINS TOO SLOW WITH THIS SYSTEM...AND ESPECIALLY WITH ITS COLD FRONT AS IT APPROACHES THE PACK NW. THE 12Z CMC IS ALSO SLOWER AND MORE AMPLIFIED COMPARED TO THE GFS/UKMET/ECMWF CONSENSUS...WHICH REMAIN A LITTLE MORE PROGRESSIVE AND REMAIN WELL CLUSTERED WITH EACH OTHER AND THE LATEST SREF/GEFS/ECENS MEANS. WILL THUS PREFER A NON-NAM/NON-CMC CONSENSUS AT THIS JUNCTURE WITH THE APPROACH OF THIS ENERGY. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... HURLEY