MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1201 PM EST TUE NOV 08 2016 VALID NOV 08/1200 UTC THRU NOV 12/0000 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... ...UPPER TROUGH SPLITTING ACROSS THE EASTERN SEABOARD ON WEDNESDAY... ...AREA OF LOW PRESSURE EXITING THE NJ COAST... PRELIMINARY PREFERENCE: BLEND OF THE 00Z ECMWF/ECMWF ENSEMBLE MEAN FORECAST CONFIDENCE: SLIGHTLY BELOW AVERAGE A SHORTWAVE TROUGH CURRENTLY ACCELERATING ACROSS THE UPPER GREAT LAKES IS FORECAST TO EVENTUALLY SPLIT AS IT MIGRATES TOWARD THE EASTERN SEABOARD. THE SOUTHERN BAND OF MID-LEVEL ENERGY WILL CROSS THE MID-ATLANTIC BY MIDDAY WEDNESDAY WHICH SHOULD BE ACCOMPANIED BY AN INCREASE IN RAINFALL COVERAGE ACROSS THE REGION. TO THE NORTH...A MORE PROGRESSIVE BAND OF HEIGHT FALLS WILL EXIT DOWNEAST MAINE BY WEDNESDAY NIGHT WITH MOST MODELS AGREEING ON A DECENT SEPARATION BETWEEN THE TWO FEATURES. THE EXCEPTION TO THIS RULE WAS THE 12Z NAM WHICH KEPT THE TWO ENTITIES MUCH CLOSER TOGETHER OFF THE DELMARVA COAST. AS THE ENTIRE TROUGH EXITS THE EASTERN SEABOARD...MODELS SHOW AN AREA OF LOW PRESSURE EMERGING AND EXITING OFF THE MID-ATLANTIC COASTAL REGION. THE 12Z GFS TRENDED SOUTHWARD WHICH SEEMS TO BE ON THE FAR SOUTHERN END OF THE SPREAD CONSIDERING THE ENSEMBLE LOW PLOT. FURTHER DIFFERENCES EMERGE AS THE SYSTEM MIGRATES FURTHER INTO THE OPEN ATLANTIC. LOOKING ALOFT...THE 00Z CMC WAS RATHER QUICK ACROSS THE BOARD. CONSIDERING ALL THESE OBSERVATIONS...WILL LEAN TOWARD A BLEND OF THE 00Z ECMWF/ECMWF ENSEMBLE MEAN WHICH IS CLOSER TO THE CENTER OF THE SPREAD. ...CLOSED LOW RETROGRADING BACK TOWARD WEST TX AND INTO NORTHERN MX... PRELIMINARY PREFERENCE: BLEND OF THE 12Z NAM/00Z ECMWF WITH THE 00Z ECMWF ENSEMBLE MEAN FORECAST CONFIDENCE: AVERAGE WATER VAPOR IMAGERY INDICATED A BROAD REGION OF CYCLONIC FLOW IN THE VICINITY OF THE BIG BEND OF TX. TO ITS EAST...AMPLE MOISTURE LIFTING OUT OF THE WESTERN GULF OF MX WILL CONTINUE TO FOSTER THE DEVELOPMENT OF NUMEROUS SHOWERS/THUNDERSTORMS ALONG THE LOWER TX COAST. MODELS AGREE ON A RETROGRESSION TOWARD THE WEST MOVING TOWARD NORTH-CENTRAL MX BY 10/0000Z. THIS FORMS SOME FORM OF REX BLOCK GIVEN THE WEST-EAST RIDGE DEVELOPING TO ITS NORTH OVER THE DESERT SOUTHWEST INTO THE CENTRAL/NORTHERN PLAINS. OVERALL MODEL SPREAD IS NOT WORTH NOTING UNTIL AROUND FRIDAY MORNING WHEN ENSEMBLE SPAGHETTI PLOTS SHOW A SPLIT AMONG THE MODELS. COMPARING THE LAST FOUR MODEL CYCLES...ECMWF SOLUTIONS HAVE BEEN CONSISTENTLY DOWN IN NORTHERN MX EARLY FRIDAY WHILE MOST RECENT GFS RUNS HAVE TRENDED STRONGER AND NORTHEASTWARD. THE 00Z GEFS MEMBERS FINALLY HAVE BEEN DEPICTING CONTOURS ON THE 576-DM PLOT...THUS INDICATIVE OF A MORE PRONOUNCED SOLUTION. WOULD PREFER TO STICK WITH THE MORE STABLE ECMWF SUITE WITH THE 12Z NAM GENERALLY IN FAVOR OF THIS CAMP. ...INITIAL HEIGHT FALLS CROSSING THE PACIFIC NORTHWEST BY 09/1800Z... ...EVENTUAL SYNOPTIC-SCALE TROUGH TAKING SHAPE ACROSS THE NORTHEASTERN U.S. ON FRIDAY... ...ATTENDANT COLD FRONT SWEEPING THROUGH THE REGION... PRELIMINARY PREFERENCE: BLEND OF THE 12Z GFS/00Z ECMWF FORECAST CONFIDENCE: AVERAGE HIGH AMPLITUDE FLOW INITIALLY OVER THE EASTERN PACIFIC AND WESTERN THIRD OF THE U.S. WILL BE IN PLACE. AN EMBEDDED SHORTWAVE WITHIN THE BROAD NEGATIVE HEIGHT ANOMALY WEST OF 130W SHOULD PROGRESS EASTWARD REACHING THE PACIFIC NORTHWEST COAST BY WEDNESDAY MORNING. THE 00Z CMC WAS NOTABLY SLOWER EARLY IN THE PERIOD WHICH CONTINUED TO BE AN ISSUE FURTHER DOWNSTREAM. EVENTUALLY THIS SYSTEM SHOULD BECOME ABSORBED INTO A DEEP NORTHERN STREAM TROUGH DIGGING THROUGH SOUTH-CENTRAL CANADA EARLY THURSDAY. AT THIS POINT THE 12Z NAM BECOMES MORE PROGRESSIVE WITH THE PROGRESSION OF THIS UPPER TROUGH. ENSEMBLE SPAGHETTI PLOTS DEPICT ONLY A MODEST AMOUNT OF SPREAD SO CAN PRIMARILY UTILIZE DETERMINISTIC SOLUTIONS HERE. THE 00Z ECMWF IS A BIT QUICKER THAN THE 12Z GFS BUT FEEL A MIX OF THE TWO WILL SUFFICE. ...AMPLIFIED SHORTWAVE APPROACHING THE PACIFIC NORTHWEST COAST BY THE END OF THE WORK WEEK... PRELIMINARY PREFERENCE: A NON-00Z CMC MODEL COMPROMISE FORECAST CONFIDENCE: ABOVE AVERAGE TOWARD THE END OF THE PERIOD...ANOTHER SYSTEM IS EXPECTED TO APPROACH/REACH THE PACIFIC NORTHWEST REGION. THERE IS PRETTY GOOD MODEL AGREEMENT ALL THE WAY OUT TO 12/0000Z GIVEN STABLE ENSEMBLE SPAGHETTI PLOTS AND ONLY SMALL DIFFERENCES AMONG THE DETERMINISTIC SOLUTIONS. THE ONLY TRUE OUTLIER WAS THE 00Z CMC WHICH REMAINED QUICKER EJECTING HEIGHT FALLS INTO THE COASTAL BRITISH COLUMBIA. FEEL A CONSENSUS OF THE OTHER REMAINING SOLUTIONS WOULD BE A REASONABLE STARTING POINT HERE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... RUBIN-OSTER