MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 245 AM EDT SAT OCT 11 2014 VALID OCT 11/0000 UTC THRU OCT 14/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING FINAL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ UPPER TROUGH SHEARING ENEWD FROM THE SRN PLAINS TODAY/TONIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE MODELS SHOW SIMILARLY WITH THIS SYSTEM. SHORTWAVE CROSSING THE GREAT LAKES/NORTHEAST WITH SURFACE LOW TO TRACK SOUTH OF LONG ISLAND LATER TODAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE MODELS SHOW SIMILARLY WITH THIS SYSTEM. LARGE UPPER TROUGH AMPLIFYING OVER THE PLAINS/MS VALLEY SUN AND MON ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF THE 00Z UKMET AND 12Z CMC CONFIDENCE: A LITTLE BELOW AVERAGE DIFFERENCES WITH A DEEP/POWERFUL UPPER TROUGH FORECAST TO AMPLIFY AND LIKELY CLOSE OFF OVER THE MISSISSIPPI VALLEY ON MON/TUE ARE GREATEST TOWARD THE END OF THE SHORT RANGE PERIOD. ALL OF THE MODELS AGREE WITH A NEGATIVELY TILTED TROUGH AXIS...BUT STRENGTH AND TIMING ARE NOT SO CLEAR. THE ENSEMBLES SHOW A BI-MODEL DISTRIBUTION WITH THE EC MEMBERS SLOWER/DEEPER WITH THE UPPER TROUGH WHILE THE GEFS MEMBERS ARE MORE PROGRESSIVE BY 12Z/14. THE CMC MEMBERS SHOW NO CLEAR CONSENSUS FOR ONE CAMP OR THE OTHER. TRENDS OVER THE PAST 24 HOURS IN THE ENSEMBLES AND DETERMINISTIC MODELS SHOW SOME CONVERGENCE...AND THE BEST WAY TO GO FOR NOW IS TOWARD THE MIDDLE WHICH IS SLOWER THAN THE GFS AND NAM BUT NOT QUITE AS DEEP AS THE ECMWF. THE 00Z UKMET AND ECMWF REMAIN SIMILAR TO THEIR PREVIOUS RUNS BUT THE 00Z CMC ADJUSTED FASTER THAN THE 00Z GFS. PREFER TO STAY CONSISTENT WITH THE PREFERENCE AT THIS TIME GIVEN THE UNCERTAINTTY...WITH THE 00Z UKMET AND 12Z CMC REPRESENTING THE BEST REPRESENTATION WITH THE UPPER TROUGH...SURFACE LOW...AND CORRESPONDING COLD FRONT AT THIS TIME. CONFIDENCE IS REDUCED GIVEN THE LARGE MODEL SPREAD AND EXTENDED TIME RANGE. UPPER TROUGH / PACIFIC COLD FRONT CROSSING INTO THE PAC NW ON TUE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: AVERAGE THE MODELS SHOW SURPRISINGLY LITTLE DIFFERENCE FOR AN 84 HOUR FORECAST...WITH THE NAM/GFS/ECMWF/UKMET/CMC AND ENSEMBLES SHOWING REASONABLE AGREEMENT ON THE STRENGTH AND TIMING OF THIS UPPER TROUGH AND RELATED COLD FRONT. IF A BLEND WAS TO BE CHOSEN...THE GFS/ECMWF WOULD LIKELY BE THE BEST MIDDLE GROUND WITHIN THE LATEST SPREAD. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO