MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 251 PM EDT TUE OCT 14 2014 VALID OCT 14/1200 UTC THRU OCT 18/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ============================================== 12Z MODEL EVALUATION AND PREFERENCES ============================================== NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO SIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT. ============================================== ...BROAD AND DEEP CYCLONE AFFECTING THE CENTRAL AND EASTERN U.S... PREFERENCE: BLEND OF 12Z GFS/ECMWF/CANADIAN CONFIDENCE: AVERAGE THE EFFECTS OF INDIVIDUAL SHORTWAVES WILL CAUSE THIS CLOSED CYCLONE TO WIGGLE ITS WAY EASTWARD THROUGH 17/00Z. THEN ON DAY 3 A KICKER SYSTEM ARRIVES FROM THE NORTHERN PLAINS/UPPER MIDWEST TO SET THE EASTERN U.S. SYSTEM INTO A PROCESS OF OPENING AND LIFTING. THE GFS/ECMWF/CANADIAN HAVE BEEN STABLE NOW OVER MULTIPLE MODEL CYCLES...WITH THE EXCEPTION OF SMALL SCALE VARIATION IN HANDLING THE UPSTREAM KICKER. THE NAM AND SREF...MEANWHILE...HAVE TRIED TO SIGNAL A TREND TOWARD A SLOWER SOLUTION. THIS IS LESS PRONOUNCED ON DAYS 1-2 WHEN THE NAM KEEPS LOWER HEIGHTS FARTHER SOUTH THAN CONSENSUS. ON DAY 3 THIS DELAYS INTERACTION WITH THE UPSTREAM KICKER...AND THE OPENING/LIFTING PROCESS TAKES ALMOST 12 HOURS LONGER IN THE NAM. THE 06Z GEFS MEMBERS AND THEIR MEAN OFFERED SOME SUPPORT FOR THE SLOWER SOLUTION...BUT THE 12Z GEFS JUMPED BACK TO A QUICKER SOLUTION THAT IS MORE SUPPORTIVE OF THE NON-NAM CLUSTER OF GLOBAL MODELS. ...DEEP TROUGH IMPACTING THE NORTHWEST AND EJECTING TO THE NORTHERN PLAINS... PREFERENCE: BLEND OF 12Z ECMWF/CANADIAN CONFIDENCE: AVERAGE WHEN THIS SYSTEM REACHES THE PLAINS AND DEVELOPS A CLOSED 500 MB CONTOUR CONSECUTIVE UKMET RUNS HAVE BEEN SOUTHERLY OUTLIERS AND CONSECUTIVE NAM RUNS HAVE DEFINED THE NORTHERN EDGE OF THE OPERATIONAL MODEL SPREAD. IN TERMS OF TIMING...ALL THE MODELS REACH THE SAME LONGITUDE...ROUGHLY WESTERN MINNESOTA BY 18/00Z. THE EXCEPTION IS THE GFS AND GEFS WHICH HAVE BEEN SYSTEMATICALLY JUST A LITTLE FASTER...ALTHOUGH THEIR DEPICTIONS OF THE SYSTEM CHARACTER AND INTENSITY LOOK REASONABLE. GIVEN THE GFS TENDENCY TO BE TOO FAST...WE FAVOR THE ECMWF/CANADIAN. ...NEXT PACIFIC SYSTEM APPROACHING BY FRIDAY... PREFERENCE: BLEND OF THE OPERATIONAL MODELS CONFIDENCE: AVERAGE THE OPERATIONAL MODELS SHOW STRONG SIMILARITY AT THE SURFACE AND ALOFT AS THIS SYSTEM NEARS THE WEST COAST OF THE U.S. ON DAY 3. MODEL SPREAD HAS INCREASED REGARDING A LEAD SHORTWAVE IN THE SOUTHERN STREAM WHICH IS PICKED UP INTO THE SOUTHWEST U.S. THIS SYSTEM...HOWEVER...SHOULD HAVE LITTLE SENSIBLE WEATHER IMPACT. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... BURKE