MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 300 AM EDT TUE AUG 30 2016 VALID AUG 30/0000 UTC THRU SEP 02/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/CMC AND ECMWF ...UPPER TROUGH TRACKING ACROSS SOUTHERN CANADA THROUGH MID-WEEK... ...TROUGH AMPLIFICATION INTO THE EASTERN U.S.... ...ATTENDANT COLD FRONT PROGRESSION... PREFERENCE: BLEND OF THE 00Z GFS AND 00Z ECMWF CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 00Z NAM IS A TAD SLOWER AND DEEPER THAN THE MULTI-MODEL CONSENSUS WITH THE LARGE SCALE TROUGH AMPLIFYING SOUTHEAST FROM SOUTHERN CANADA AND INTO THE EASTERN U.S. OVER THE NEXT FEW DAYS. THE GLOBAL MODELS ARE REASONABLY WELL CLUSTERED THEIR MASS FIELD EVOLUTION...AND FOR NOW WILL MAINTAIN CONTINUITY AND CONTINUE TO LEAD TOWARD A GFS/ECMWF BLEND. ...UPPER LOW/TROUGH DIGGING SOUTH OFFSHORE BRITISH COLUMBIA... ...ENERGY PIVOTING INTO THE WEST COAST BY LATE TUES/WED... ...LEAD SHORTWAVE CROSSING NORTHERN CA ON TUES... PREFERENCE: BLEND OF THE 00Z GFS/00Z UKMET AND 00Z ECMWF CONFIDENCE: AVERAGE THE GUIDANCE IS IN GOOD AGREEMENT ON THE DEPTH AND TIMING OF A LEAD SHORTWAVE IMPULSE THAT ARRIVES ACROSS NORTHERN CA ON TUES OUT AHEAD OF A LARGER SCALE DEEP TROUGH AND CLOSED LOW THAT ADVANCES SOUTH FROM OFFSHORE BRITISH COLUMBIA AND THEN BEGINS DIGGING INTO THE NORTHWEST U.S. THURS AND FRI. THE 00Z NAM AND 00Z CMC BOTH GRADUALLY BECOME THE SLOWEST SOLUTIONS TO ADVANCE THE HEIGHT FALLS INTO PACIFIC NORTHWEST. THE 00Z GFS/00Z UKMET AND 00Z ECMWF CLUSTER TOGETHER REASONABLY WITH TAD MORE PROGRESSION. HOWEVER...THE 00Z GFS IS ACTUALLY THE STRONGEST WITH ITS HEIGHT FALLS. SINCE THE LATEST GEFS MEAN TENDS TO SUPPORT THE SLIGHTLY STRONGER DETERMINISTIC GFS...WILL SUGGEST A MULTI-MODEL CONSENSUS HERE...WITH A BLEND OF THE 00Z GFS/00Z UKMET AND 00Z ECMWF. ...MID-UPPER LEVEL TROUGH OVER THE SOUTHWEST... ...ENERGY WEAKENING TOWARD THE HIGH PLAINS THROUGH WED... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE MODELS ARE IN REASONABLY GOOD AGREEMENT ON THE EVOLUTION OF THIS GRADUALLY WEAKENING SYSTEM. ...WEAK MID LEVEL LOW OVER THE WESTERN GULF COAST... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THIS SYSTEM IS EXPECTED TO GRADUALLY WEAKEN AS IT DRIFTS SOUTHWEST...WITH THE GUIDANCE SHOWING RELATIVELY MINOR DIFFERENCES. ...WAVE DEVELOPING ALONG THE SOUTHEAST COAST WED-THU... PREFERENCE: 00Z GFS CONFIDENCE: BELOW AVERAGE WHILE MOST MODELS ARE INDICATING SOME LOW LEVEL/SURFACE WAVE DEVELOPMENT OVER NORTHERN FL AND THEN NORTHEAST ALONG A COASTAL TROUGH POSITIONED ALONG THE GA/SC COAST...THERE IS LARGE SPREAD WITH RESPECT TO THE TIMING AND AMPLITUDE OF THIS FEATURE. ALL OF THE GUIDANCE SHOWS THIS LOW CENTER LIFTING NORTHEAST ON THE HEELS OF T.D. NINE WHICH WILL EXITING AWAY FROM THE EAST COAST. THE 00Z CMC IS A STRONG OUTLIER SOLUTION. THE 00Z NAM/00Z GFS AND 00Z UKMET ARE ALL WEAKER...BUT WITH THE 00Z GFS BEING NOTABLY MORE PROGRESSIVE. THE 00Z ECMWF IS THE WEAKEST SOLUTION OF ALL AND IS A LITTLE SLOW THAN THE GFS. THE DYNAMICAL SUPPORT FOR THIS LOW WILL BE A MID/UPPER LEVEL LOW WHICH IS CURRENTLY OFF THE SOUTHEAST COAST AND EXPECTED TO DRIFT INLAND OVER THE COASTAL PLAIN BEFORE THEN LIFTING NORTHEAST AHEAD OF THE STRONGER UPPER TROUGH DIGGING INTO THE EASTERN U.S. THROUGH THE END OF THE WEEK. WILL LEAN TOWARD THE WEAKER CONSENSUS AT THIS POINT...BUT THE CURRENT THINKING IS THAT THE ECMWF IS TOO WEAK...AND THUS WILL LEAN TOWARD THE 00Z GFS AS A COMPROMISE. CONFIDENCE IS LIMITED GIVEN THE MODEL SPREAD. ...T.D. EIGHT MOVING TOWARD THE MID-ATLANTIC COAST... PREFERENCE: PLEASE CONSULT THE LATEST NHC FORECAST ADVISORY THE 00Z NAM AND 00Z CMC TAKE T.D. EIGHT A BIT FARTHER WEST THAN THE MULTI-MODEL CONSENSUS AND THE LATEST NHC TRACK. THE 00Z GFS AND 00Z ECMWF ARE CLOSEST TO THE NHC TRACK THROUGH WED. THE 00Z UKMET IS AGAIN A DEEPER OUTLIER. ALL OF THE MODELS INDICATE RECURVATURE OF T.D. EIGHT BEGINNING ON WED. PLEASE CONSULT THE LATEST NHC FORECAST ADVISORY FOR MORE INFORMATION. ...T.D. NINE MOVING INTO THE GULF OF MEXICO... PREFERENCE: PLEASE CONSULT THE LATEST NHC FORECAST ADVISORY A CONSENSUS OF THE 00Z NAM AND 00Z ECMWF ARE THE CLOSEST TO THE LATEST NHC TRACK WITH T.D. NINE THIS PERIOD. THE 00Z GFS IS A LITTLE SLOWER AND ALSO WEAKER WITH THIS SYSTEM BY COMPARISON. THE 00Z UKMET AND 00Z CMC ARE THE SLOWEST SOLUTIONS RELATIVE TO THE NHC TRACK. PLEASE CONSULT THE LATEST NHC FORECAST ADVISORY FOR MORE INFORMATION ON T.D. NINE. ORRISON www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...