MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 251 PM EDT WED OCT 08 2014 VALID OCT 08/1200 UTC THRU OCT 12/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/GEM AND THE ECMWF ...SOUTHWEST U.S. TO THE ROCKIES FRONT RANGE... PREFERENCE: 12Z ECMWF CONFIDENCE: AVERAGE A WEAK SHORTWAVE TROUGH NOW ABSORBING THE REMNANTS OF SIMON OVER THE SOUTHWEST WILL ADVANCE DOWNSTREAM ACROSS THE CNTRL/SRN ROCKIES AND OUT INTO THE HIGH PLAINS THROUGH FRI. THE MODELS SUGGEST THAT THIS ENERGY WILL INVOKE A WAVE OF LOW PRESSURE ALONG A FRONTAL ZONE OVER THE SRN HIGH PLAINS BY LATE THURS WHICH WILL BEGIN TO THEN SHEAR EASTWARD ON FRI. THE 12Z NAM AND 12Z UKMET ARE FASTER AND WEAKER WITH THE SHORTWAVE ENERGY ALOFT...WITH THE 12Z ECMWF AND 12Z GEM THE SLOWEST AND RELATIVELY STRONGER. THE 12Z GFS BASICALLY SPLITS THE DIFF BETWEEN THE WEAKER AND STRONGER CAMPS. THE GEFS MEAN AND ECENS MEAN FAVOR THE SLOWER AND SOMEWHAT STRONGER CONSENSUS. THE NEW PARALLEL VERSION OF THE GFS OR GFSP...ALSO SUPPORTS THE ECMWF-LED CLUSTER. BASED ON THIS...THE GFS/NAM AND UKMET ALL APPEAR TOO FAST. ...EAST/WEST FRONTAL ZONE FROM THE SOUTHERN PLAINS TO THE OHIO VALLEY/MID-ATLANTIC... ...WEAK SURFACE LOW SHEARING EAST ALONG THE FRONTAL ZONE... PREFERENCE: 12Z ECMWF CONFIDENCE: AVERAGE THE MODELS SHOW THE ENERGY OVER THE HIGH PLAINS ENTERING A LARGE SCALE CONFLUENCE ZONE ALOFT THAT WILL BE SITUATED OVER THE MID MS AND OH VLY REGION THURS THROUGH SAT. SFC HIGH PRESSURE AIDED BY THIS WILL NOSE SEWD ACROSS THE MIDWEST AND WILL HELP TO SUPPRESS A FRONTAL ZONE THAT WILL BE INITIALLY FOCUSED FROM THE SRN PLAINS NEWD INTO THE OH VLY. THE PORTION OVER THE OH/TN VLY REGION SHOULD TEND TO BECOME MORE SUPPRESSED WITH TIME AS THIS RIDGE SHIFTS EASTWARD TWD THE OH VLY. MEANWHILE...THE SFC LOW THAT WILL BE OVER THE SRN HIGH PLAINS ON FRI WILL SHEAR EASTWARD ALONG THIS FRONT. THE 12Z GFS/12Z UKMET AND TO A SOMEWHAT LESSER EXTENT THE 12Z NAM ARE VERY PROGRESSIVE AND SHEARED AND SUPPORT THE BULK OF THIS WAVE ADVANCING DOWNSTREAM ACROSS THE TN VLY AND THE MID-ATLANTIC REGION BY EARLY SAT. THE 12Z ECMWF AND 12Z GEM ARE SHEARED WITH THE SFC LOW APPEARANCE BUT THEY ARE MUCH SLOWER WITH THE MAIN SFC LOW WHICH OWES TO THE SLOWER EVOLUTION OF THE ENERGY ALOFT. BOTH OF THESE MODELS DO SUPPORT THE IDEA OF A VERY WEAK LEAD SFC LOW THAT DEVELOPS AND SHEARS DOWNSTREAM TWD THE MID-ATLANTIC AND OFFSHORE BY SAT...BUT THEY MAINTAIN A STRONGER AND MORE FOCUSED LOW OVER THE SRN PLAINS AND LWR MS VLY REGION. THE GEFS MEAN AND ECENS MEAN ALONG WITH THE GFSP SUPPORT THE SLOWER CONSENSUS AND CLUSTER BEST WITH THE ECMWF SOLN. THE ECMWF WILL AGAIN BE PREFERRED. ...SHORTWAVE CROSSING THE GREAT LAKES FRI AND SAT... PREFERENCE: BLEND OF 12Z GFS AND 12Z ECMWF CONFIDENCE: AVERAGE A SHORTWAVE WILL CROSS THE GRT LAKES REGION FRI AND SAT. THE 12Z UKMET IS THE MOST ROBUST WITH THIS ENERGY FOLLOWED BY THE 12Z NAM. THE 12Z GEM/12Z ECMWF AND 12Z GFS ARE A LITTLE WEAKER. THE STRONGER CLUSTERING FAVORS THE 12Z GFS/12Z ECMWF CAMP...AND THAT WILL BE THE PREFERENCE. ...PACIFIC NORTHWEST/NORTHERN HIGH PLAINS... PREFERENCE: BLEND OF 12Z GFS AND 12Z ECMWF CONFIDENCE: AVERAGE A SHORTWAVE EMBEDDED WITHIN FAST/ZONAL PAC FLOW AIMING INTO WRN NOAM FRI AND SAT WILL BEGIN TO DIG ACROSS THE PAC NORTHWEST AND SHOULD BEGIN AMPLIFYING OVER THE NRN HIGH PLAINS BY LATE SAT. THE STRONGEST MODEL CLUSTERING FAVORS A BLEND OF THE 12Z GFS AND THE 12Z ECMWF. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON