MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 159 AM EST THU NOV 19 2015 VALID NOV 19/0000 UTC THRU NOV 22/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/CMC AND ECMWF ...WEAKENING CLOSED LOW EXITING THE UPPER GREAT LAKES... ...DEEP PHASED CYCLONE MOVING ACROSS ONTARIO... ...COLD FRONT PUSHING THROUGH THE EAST THURS AND FRI... ...SURFACE WAVE IMPACTING SOUTHERN NEW ENGLAND ON FRI PREFERENCE: GENERAL MODEL COMPROMISE...THROUGH 48 HOURS NON-NAM CONSENSUS...AFTER 48 HOURS CONFIDENCE: ABOVE AVERAGE...BECOMING AVERAGE AFTER 48 HOURS THE LATEST MODELS ARE IN EXCELLENT AGREEMENT WITH THE DETAILS OF THE EXITING MID LEVEL CLOSED LOW OVER THE UPPER GREAT LAKES REGION AND THE DEEP PHASED CYCLONE THAT EVOLVES OVER ONTARIO BEFORE THEN LIFTING UP OVER HUDSON BAY BY SAT. THE GUIDANCE ALSO SHOWS GOOD AGREEMENT WITH THE TIMING OF THE COLD FRONT MOVING THROUGH THE EASTERN U.S. AND ALSO WITH THE FRONTAL WAVE THAT IMPACTS SOUTHERN NEW ENGLAND ON FRI. DIFFERENCES THOUGH BEGIN BY SAT WITH THE DETAILS OF HOW THIS WAVE PUSHES EAST OF NEW ENGLAND. STRONGER MODEL CLUSTERING FAVORS A CONSENSUS OF THE 00Z GFS/00Z UKMET/00Z CMC AND 00Z ECMWF...WITH THE 00Z NAM PROBABLY A TAD TOO STRONG WITH ITS LOW CENTER. SO...WILL PREFER A GENERAL MODEL COMPROMISE THROUGH 48 HOURS...AND THEN A NON-NAM CONSENSUS THEREAFTER. ...SURFACE LOW APPROACHING THE PACIFIC NORTHWEST... ...ENERGY TRAVERSING THE INTERMOUNTAIN WEST THROUGH THURS... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE GUIDANCE SHOWS GOOD AGREEMENT WITH THE DETAILS OF THE SURFACE LOW MOVING INTO WESTERN ORE EARLY THURS AND THEN THROUGH THE INTERMOUNTAIN REGION BY LATE THURS. WILL PREFER A GENERAL MODEL COMPROMISE ACROSS THIS REGION AS A RESULT. ...DEEPENING SURFACE LOW/UPPER TROUGH OVER THE PLAINS/MIDWEST/GREAT LAKES... PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF CONFIDENCE: SLIGHTLY BELOW AVERAGE THE LOW CENTER MOVING THROUGH THE INTERMOUNTAIN WEST ON THURS WILL BE REDEVELOPING AND DEEPENING OUT ACROSS THE CENTRAL HIGH PLAINS BY EARLY FRI AS ROBUST NORTHERN STREAM SHORTWAVE ENERGY DIVES SOUTHEAST ACROSS THE NORTHERN AND CENTRAL ROCKIES. THIS WILL LEAD TO AN AMPLIFYING UPPER TROUGH ACROSS THE PLAINS AND MIDWEST FRI AND SAT WHICH WILL DRIVE SURFACE LOW PRESSURE EAST ACROSS THE CENTRAL PLAINS...MID MS VALLEY AND THEN NORTHEAST TOWARD THE LOWER GREAT LAKES REGION SAT NIGH AND SUN. THE 00Z GFS HAS TRENDED A BIT SLOWER AND DEEPER WITH THE STRENGTHENING LOW CENTER AND IS JUST A TAD FASTER THAN THE 12Z ECMWF SAT AND SUN AS IT EJECTS ACROSS THE MID MS VALLEY AND LOWER GREAT LAKES. THE 00Z ECMWF HOWEVER HAS TRENDED A BIT FARTHER SOUTH WITH ITS LOW TRACK AND IS SOUTH OF THE CONSENSUS AS IT MOVES THROUGH THE MIDWEST. THE 00Z GFS BECOMES THE MOST AMPLIFIED SOLUTION...WITH THE 00Z NAM AND TO A LESSER EXTENT THE 00Z CMC THE WEAKEST SOLUTIONS. THE LATEST ENSEMBLE GUIDANCE TENDS TO SUPPORT A MORE AMPLIFIED SOLUTION...AND THIS IS FAVORED BY THE 00Z UKMET. SINCE THE 00Z GFS TRENDED STRONGER...IT WILL NOT BE DISCOUNTED. HOWEVER...THERE IS SOME POTENTIAL FOR IT TO BE A BIT TOO AMPLIFIED ON SUN. THUS...WILL TEMPER IT BY RECOMMENDING A BLEND OF THE 00Z GFS AND 12Z ECMWF...AND THUS NOT PLACING ANY TRUST JUST YET ON THE 00Z ECMWF WITH ITS SOUTHWARD TREND. ...WARM FRONT EJECTING OUT INTO THE NORTHERN HIGH PLAINS ON SUN... PREFERENCE: 00Z ECMWF CONFIDENCE: AVERAGE THE MODELS SHOW A VERY DEEP LOW CENTER MOVING THROUGH CENTRAL CANADA BY EARLY SUN...AND THIS WILL ALLOW A WARM FRONT TO BEGIN IMPACTING THE NORTHERN HIGH PLAINS. THE MASS FIELD SPREAD WITH THE LOW CENTER IS RATHER MINIMAL...BUT THE 00Z ECMWF SEEMS TO BE RESOLVING THE SURFACE PRESSURE FIELDS INVOLVING THE HIGH PLAINS AND ADJACENT TERRAIN A BIT BETTER. THUS...WILL PREFER THE 00Z ECMWF WITH THIS SYSTEM FOR NOW. ...WAVE ACTIVITY OVER THE EASTERN GULF OF MEXICO/SOUTHEAST COASTLINE... PREFERENCE: BLEND OF THE 00Z GEFS MEAN AND 12Z ECENS MEAN CONFIDENCE: BELOW AVERAGE THERE IS SUGGESTION MAINLY FROM THE 00Z ECMWF AND 00Z UKMET FOR A WAVE OF LOW PRESSURE TO DEVELOP OVER THE EASTERN GULF OF MEXICO AND ALONG THE TAIL END OF A FRONT. THE 00Z GFS/00Z NAM AND 00Z CMC ARE MUCH WEAKER WITH THIS DEVELOPMENT. ADDITIONALLY THERE IS SUGGESTION TOO OF A WAVE FORMING JUST OFF THE SOUTHEAST COASTLINE ALONG THE SAME FRONT...BUT THE 00Z CMC IS THE MOST EMPHATIC ABOUT THAT WAVE...WITH THE REMAINING GUIDANCE WEAKER/FLATTER. CONFIDENCE IS LIMITED BUT AT THIS POINT WILL PREFER TO GO WITH THE ENSEMBLE MEANS...AND THIS A BLEND OF THE 00Z GEFS MEAN AND 12Z ECENS MEAN. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON