MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 312 AM EDT SAT OCT 24 2015 VALID OCT 24/0000 UTC THRU OCT 27/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION WITH FINAL FORECAST PREFERENCE AND CONFIDENCE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ TROUGH OVER THE CENTRAL/NORTHERN PLAINS MERGES WITH NORTHERN STREAM TROUGH LOW PRESSURE TRACKING TO THE GREAT LAKES SAT AND COLD FRONTAL PASSAGE THRU NEW ENGLAND/MID-ATLANTIC SUNDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: MODEL CONSENSUS CONFIDENCE: ABOVE AVERAGE IN GENERAL THE MASS FIELDS REMAIN CONGRUENT WITHIN THE DETERMINISTIC AND ENSEMBLE MEANS WITH THE UPPER LOW AND SURFACE REFLECTION AS IT MOVES INTO THE GREAT LAKES. MINOR DIFFERENCES OCCUR FURTHER NORTH INTO CANADA WITH THE CMC AND GFS BEING A BIT FURTHER NORTH A BIT DEEPER WITH THE SURFACE LOW AS WELL AS MAKING THE LOW A BIT SLOWER. BUT ALL IN ALL...A BLEND OF THE DETERMINISTIC MODELS WILL CONTINUE TO BE PREFERRED AT ABOVE AVERAGE CONFIDENCE. KICKER WAVE CROSSING THE NORTHERN TIER INTO THE WESTERN GREAT LAKES MONDAY INTO NORTHERN NEW ENGLAND BY TUESDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF 00Z NAM/ECMWF CONFIDENCE: AVERAGE SHORTWAVE ENERGY PULLED OVER THE WESTERN CANADIAN RIDGE QUICKLY DROPS SOUTHWEST INTO MN BY MONDAY IN FAIRLY STRONG AGREEMENT WITHIN THE MODEL SUITE INCLUDING THE ENSEMBLE MEANS. AS THE FEATURE ROUNDS THE BASE OF THE MAIN GLOBAL UPPER LOW IN THE GREAT LAKES...THE 00Z UKMET/GFS AND NOW 00Z CMC BECOMING INCREASINGLY FAST WHILE SHEARING THE ENERGY OUT. THE 00Z NAM/ECMWF REMAIN A BIT MORE AMPLIFIED THOUGH DIFFERENCES IN TIMING INCREASE TOWARD THE END OF THE PERIOD WITH THE ECMWF LEADING THE NAM LAGGING A BIT. GIVEN THE HIGHER TRANSLATIONAL SPEEDS AND LIMITED SENSIBLE WEATHER DIFFERENCES WILL CONTINUE A BLEND OF THE 00Z NAM/ECMWF AS PREFERENCE AT AVERAGE CONFIDENCE. LONG WAVE TROUGH ENTERING THE PACIFIC NORTHWEST SAT CROSSING THE ROCKIES AND EJECTING INTO CENTRAL PLAINS BY TUES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF 00Z UKMET/CMC/ECMWF CONFIDENCE: SLIGHTLY BELOW AVERAGE THREE SIGNIFICANT FEATURES INTERACT TOWARD THE DEVELOPMENT OF AN AMPLIFIED LONG WAVE TROUGH ENTERING THE PACIFIC COAST SATURDAY...THE MAIN FEATURE BEING THE TIGHTLY WRAPPED UP CYCLONE NEAR 43N 140W. FURTHER NORTH ENERGY FROM A SHORTWAVE OVER THE GULF OF ALASKA CROSSES THE NORTHERN CANADIAN ROCKIES AND OVER TOPS THE UPPER LEVEL RIDGE ON THE LEE OF THE MOUNTAINS. TO COMPLICATE THE EVOLUTION FURTHER...LOOSELY DEFINED SHORTWAVE ENERGY SHED FROM TWO SOURCES IN THE SUBTROPICAL EASTERN PACIFIC; THE LEADING ENERGY SHED FROM OUTFLOW OF HURRICANE OLAF...THE LAGGING ENERGY FROM S/W NEAR 31N145W. OVERALL...THERE IS STRONG AGREEMENT WITH THE GLOBAL MODELS AND THEIR ENSEMBLE FORECASTS THROUGH LANDFALL OF THE SURFACE CYCLONE ON MONDAY. AFTER THIS TIME...THE 00Z NAM REMAINS VERY STRONG WITH THE NORTHERN STREAM ENERGY BEING QUITE CONSOLIDATED AND DEVELOPS A STRONG SURFACE REFLECTION WELL INTO CANADA AS IT REMAINS THE MOST DRAMATIC OUTLIER BY THE END OF THE FORECAST PERIOD. THE 00Z GFS ALSO APPEARS TO BE AN OUTLIER MAINLY IN THE EVOLUTION OF THE ENTIRE TROF... BEING MOST ELONGATED AND AMPLIFIED WITH GENERAL EQUAL CONTRIBUTIONS WITHIN THE TROF AS A WHOLE...BUT ALSO ON THE FAST SIDE OF THE SOLUTIONS. THE MAIN DEPARTURE APPEARS TO BE IN THE HANDLING OF THE SOUTHERN SUBTROPICAL ENERGY...BRINGING IT ASHORE INTO SOUTHERN CALIFORNIA FASTER THAN THE REST OF THE GUIDANCE AS WELL AS THE GEFS ENSEMBLE MEAN. THE 00Z UKMET/CMC/ECMWF SEEM TO HANDLE THE SUBTROPICAL FEATURE SIMILARLY AND LESS PROGRESSIVE AS THE 00Z GFS...THOUGH THE ECMWF IS A BIT DEEPER AND HENCE SLOWER BY THE END OF DAY 3. FARTHER NORTH THE 00Z UKMET/CMC/ECMWF ALL APPEAR TO EVOLVE SIMILARLY WITH A STRONGER UPPER LOW/CUT-OFF ALONG THE ALBERTA/SASKATCHEWAN/U.S. BOARDER BY TUESDAY WITH SMALL DIFFERENCES IN PLACEMENT OF INNER CORE MESOSCALE WAVES. WILL CONTINUE AN OVERALL A BLEND OF THE 00Z UKMET/CMC/ECMWF AS PREFERENCE AT SLIGHTLY BELOW AVERAGE CONFIDENCE GIVEN THE OVERALL COMPLEXITIES AND SPREAD IN SOLUTIONS. SHORTWAVE CROSSING THE U.S. SOUTHWEST/NW MEXICO AND ENERGY FROM TROPICAL CYCLONE PATRICIA INTO THE WESTERN GULF COAST REGION SAT INTO MON ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GEFS OR BLEND OF 00Z NAM/CMC/UKMET CONFIDENCE: AVERAGE THE NEW 00Z GUIDANCE (NAM/GFS) HAS ONCE AGAIN TRENDED FASTER THAN THE 12Z GUIDANCE WHICH HAS TRENDED CORRECTLY OVER THE LAST DAY OR SO...BUT AROUND MONDAY NIGHT/TUESDAY. THE 00Z GFS IS VERY QUICK IN LIFTING AND WEAKENING THE ENERGY OUT OF THE GULF INTO THE LOWER MISSISSIPPI RIVER VALLEY AHEAD OF THE APPROACHING DEEP LAYERED TROF EJECTING IN THE GREAT PLAINS ON TUES. THOUGH THIS DEPARTS FROM BETTER CLUSTERING OF THE PRIOR ENSEMBLES INCLUDING THE 12Z/18Z GEFS AND 12Z ECENS MEAN AND 21Z SREF...OTHER DETERMINISTIC AND NEWER 00Z GEFS HAVE ALSO TRENDED TOWARD THIS FASTER...NEARLY NORTHWARD MOTION OF THE SURFACE CYCLONE ACROSS THE MISSISSIPPI RIVER VALLEY. THOUGH THE OPERATIONAL 00Z GFS MAY BE A BIT TOO AGGRESSIVE DUE TO UPSTREAM INFLUENCES EJECTING OUT OF THE SUBTROPICAL PACIFIC TO FULLY INCORPORATE IT IN THE BLEND AT THIS TIME. THE 00Z UKMET AND 00Z ECMWF ARE THE SLOWER MEMBERS OF THE GLOBAL DETERMINISTIC MODELS REMAINING FURTHER SOUTH AND MORE CONSOLIDATED ALONG THE GULF COAST LONGER BEFORE MAKING THE NORTHWARD MIGRATION. IN FACT...THERE IS STRONG AGREEMENT EVEN AT THE END OF THE PERIOD AT 7H...WITH ONLY THE 00Z ECMWF LAGGING MOST DRAMATICALLY. SO WILL FAVOR A BIT STRONGER WEIGHTING TO THE FASTER CAMP. THIS IS REPRESENTED WELL BY THE 00Z GEFS OR NON-ECMWF BLEND. PLEASE NOTE THE 00Z GFS QPF PATTERN MAY BE A BIT TOO FAST AND ROBUST WITH THE COMMA HEAD PRECIPITATION...ADDITIONALLY FAVORING THE 00Z GEFS IN ITS STEAD. WHILE THE 00Z ECMWF QPF MAY BE SERVICEABLE. OVERALL CONFIDENCE IS STRONG UNTIL MIDDAY MONDAY WHEN THE MODEL CAMPS START TO DIVERGE WHEN IT BECOMES MUCH LESS SO. AS A RESULT OVERALL CONFIDENCE IN THE 00Z GEFS/NAM/UKMET/CMC BLEND IS AVERAGE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... GALLINA