MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 105 PM EDT FRI OCT 03 2014 VALID OCT 03/1200 UTC THRU OCT 07/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ...AN EVALUATION OF THE 12Z NAM/GFS ALONG WITH PRELIMINARY PREFERENCES/FORECAST CONFIDENCE... THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE 12Z NAM/GFS DEEMED SIGNIFICANT ENOUGH TO IMPACT THEIR FORECASTS. ...FULL LATITUDE TROF ANCHORING THE EASTERN HALF OF THE CONUS... ...ASSOCIATED SURFACE LOWS/BAROCLINIC ZONE... PRELIMINARY PREFERENCE: THROUGH MONDAY MORNING: BLEND OF THE 12Z GFS/00Z ECMWF...THEREAFTER: BLEND OF THE 06Z GEFS/00Z ECMWF ENSEMBLE MEANS FORECAST CONFIDENCE: AVERAGE A VERY AMPLIFIED MID-LATITUDE PATTERN IS IN PLACE FEATURING A BROAD NEGATIVE HEIGHT ANOMALY ACROSS MUCH OF THE NORTHERN TO NORTHEASTERN U.S. A BUILDING RIDGE DOWNSTREAM WILL HELP CONFINE THE BROAD UPPER VORTEX TO THE NORTHEASTERN SECTOR OF NORTH AMERICA THROUGH THE END OF THE PERIOD. THROUGH SATURDAY EVENING...THE ONLY DIFFERENCES NOTED WITH THE TROF ARE THE 00Z UKMET IS QUICKER CARRYING HEIGHT FALLS INTO THE LOWER MID-ATLANTIC WHILE THE 12Z NAM IS SLOWER WITH THE BACK END OF THE TROF. FARTHER TO THE NORTH...THERE IS SOME VARIABILITY WITH WHERE MODELS PLACE THE CORE OF THE LOWER HEIGHTS WITH THE 00Z ECMWF ENSEMBLE/09Z SREF MEANS MORE SUPPORTIVE OF THE 00Z ECMWF. TOWARD THE EARLY PART OF NEXT WEEK...THE ENSEMBLE MEANS VARY SLIGHTLY WITH THE 09Z SREF MEAN SUPPORTING A QUICKER SOLUTION THAN THE 06Z GEFS/00Z ECMWF ENSEMBLE MEANS. THE SPREAD IS NOT THAT SIGNIFICANT GIVEN THE REASONABLE CLUSTERING SEEN IN THE SPAGHETTI PLOTS. HOWEVER...THE DETERMINISTIC MODELS DO SHOW MORE VARIABILITY WITH THE 00Z ECMWF MORE AMPLIFIED WITH SHORTWAVE ENERGY CROSSING THE CENTRAL U.S. BY MONDAY. WILL RECOMMEND A BLEND OF THE 12Z GFS/00Z ECMWF THROUGH 06/1200Z BUT THEN UTILIZE THE ENSEMBLE MEANS FOR THE LAST 12 HOURS TO ACCOUNT FOR GROWING SPREAD WITHIN THE BACK SIDE OF THE TROF. ...TROPICAL STORM SIMON... PRELIMINARY PREFERENCE: BLEND OF THE 12Z GFS/00Z CMC FORECAST CONFIDENCE: ----- THIS TROPICAL CYCLONE IS EXPECTED TO CROSS INTO THE MAP DOMAIN BY EARLY SUNDAY MORNING...LIKELY AS A HURRICANE ACCORDING TO THE LATEST FORECAST. THE 12Z NAM APPEARS TO BE WELL EAST OF THE NHC TRACK WHILE THE 00Z ECMWF BECOMES INCREASINGLY WEST OF THE TRACK. WHILE THE 00Z UKMET IS IN LINE WITH THE FORECAST...IT IS A TAD QUICK. THE BEST COMPROMISE TO THE NHC FORECAST IS A BLEND OF THE 12Z GFS/00Z CMC. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... RUBIN-OSTER