MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 228 PM EDT WED JUL 13 2016 VALID JUL 13/1200 UTC THRU JUL 17/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE ...CLOSED MID LEVEL LOW TRACKING FROM THE NORTHERN PLAINS INTO ONTARIO THROUGH THU... ...COLD FRONT MOVING ACROSS THE PLAINS TO THE NORTHERN EAST COAST THU PREFERENCE: OPERATIONAL MODEL BLEND CONFIDENCE: ABOVE AVERAGE MODELS CONTINUE TO TIGHTEN ALIGNMENT AS THE CLOSED UPPER LEVEL LOW SHEARS INTO A DEVELOPING LARGER SCALE TROF THAT WILL DOMINATE THE NORTHEAST QUADRANT OF THE CONTINENT. LIKEWISE THE SURFACE LOW ACROSS THE GREAT LAKES/ONTARIO WILL ELONGATE NW-SE BUT CONTINUE TO PRESS THE FRONTAL ZONE ACROSS THE EASTERN LAKES ACROSS THE EAST COAST...WITH GOOD TIMING/STRENGTH. THE 12Z NAM/GFS BOTH REMAIN ON THE STRONGER SIDE OF GUIDANCE AS THE SYSTEM WEAKENS BUT DOES NOT SEEM TO AFFECT MUCH OVERALL TO SUPPORT AN OPERATIONAL MODEL BLEND AT ABOVE AVERAGE CONFIDENCE. 19Z UPDATE: LITTLE CHANGES WITH THE NON-NCEP SUITE AND THE 12Z GEFS MIRRORS THE 12Z GFS QUITE TIGHTLY TO CONTINUE INITIAL PREFERENCE/CONFIDENCE ...SHORT WAVE DROPPING INTO THE UPPER GREAT LAKES FRI... ...COLD FRONT CROSSING THE UPPER GREAT LAKES INTO NEW ENGLAND... PREFERENCE: OPERATIONAL MODEL BLEND CONFIDENCE: AVERAGE LINGERING SHORTWAVE ENERGY FROM SHEARING TROF AS WELL AS ADDITIONAL SPEED SHEAR FROM WESTERN CANADA SUPPORT A WEAK AMPLIFICATION OF THE 5H PATTERN ACROSS THE GREAT LAKES ON FRIDAY. MODELS CONTINUE TO VARY/WAVER IN LOCATION, TIMING AND AMPLITUDE FROM RUN TO RUN GIVEN THE SMALL BUT IMPORTANT INFLUENCES OF ALL STREAMS WITHIN A BROAD CYCLONIC GLOBAL TROF... THE 12Z GFS REMAINS MOST AMPLIFIED BUT HAS BACKED OFF TOWARD THE 06Z GEFS. THE 12Z NAM IS SOUTH OF THE MAIN CLUSTER WITH RESPECT TO THE SHORTWAVE BUT ALSO REMAINS SLOW TO THE OVERALL GUIDANCE MINUS THE 00Z CMC WHICH IS TYPICAL OF ITS BIAS. THIS SPREAD SEEMS GREAT BUT HAS VERY LITTLE INFLUENCE TO THE SURFACE FRONT/TROF ACROSS THE GREAT LAKES IN TIME/SPACE/QPF...TO FAVOR ONE SOLUTION OVER ANOTHER...FAVORING TOWARD AN OVERALL BLEND OR SOMETHING CLOSER TO THE BLEND OF THE ENSEMBLE MEANS. AS SUCH WILL FAVOR AN OPERATIONAL MODEL BLEND FOR THIS WAVE; HOWEVER CONFIDENCE IS JUST AVERAGE GIVEN THE SPREAD IS LARGE ALOFT BUT NOT TOO BAD BELOW 7H. 19Z UPDATE: SMALL PERTURBATIONS CROSSING THE GREAT LAKES FRI/SAT CONTINUE WITH RUN TO RUN VARIATION. THE 12Z ECMWF DID TRENDED TOWARD THE TIMING/DEPTH OF THE GFS WHILE THE CMC/UKMET WERE GENERALLY FLATTER; THIS MADE THE 12Z NAM STAND OUT FOR ITS SLOWNESS AT 3H-7H. OVERALL AN OPERATIONAL MODEL BLEND SHOULD CONTINUE TO BE SUFFICE TO HELP TAMP OUT THE LOW PREDICTABILITY SHORTWAVE NOISE. ...CLOSED MID LEVEL LOW CROSSING THE PACIFIC NORTHWEST AND NORTHERN ROCKIES FRI/FRI NIGHT... PREFERENCE: OPERATIONAL MODEL BLEND UNTIL 16/12Z...NON-NAM THEREAFTER CONFIDENCE: ABOVE AVERAGE UNTIL 16/12Z...AVERAGE AFTERWARD ISSUES SEEN WITH A FASTER 00/06Z GFS ARE BETTER ALIGNED TO THE REST OF THE GUIDANCE SUITE WITH RESPECT TO THE CLOSED UPPER LOW ACROSS THE NORTHERN US ROCKIES BY SAT FOR THE 12Z RUN EVEN THOUGH IT REMAINS THE EASTERN SIDE OF THE ANALYSIS SUITE. OVERALL THE CLUSTER IS STRONG ENOUGH TO SUPPORT AN OPERATIONAL MODEL BLEND FOR THIS PORTION OF THE TROF AT ABOVE AVERAGE CONFIDENCE THROUGH 16/12Z. AFTER 12Z ON SAT...MODEL SPREAD IS LARGER WITH RESPECT TO THE ENERGY THAT WILL DESCEND ON THE EASTERN SIDE OF THE PACIFIC TROF TO CARVE OUT A DEEPER CLOSED LOW INTO SUNDAY. THE 12Z NAM SEEMS A BIT WEAK AND EAST WHILE THE 12Z GFS SEEMS FAST TO THE OVERALL GUIDANCE SUITE. THE 00Z ECMWF IS THE MIDDLE GROUND SOLUTION IN AMPLIFICATION AND SPEED AS THE 00Z UKMET AND CMC LAG SLOWER RESPECTFULLY. ONLY THE NAM DOES NOT SUGGEST THE DEEPER SOLUTION...AND AS SUCH PREFERENCE IS NON-NAM AFTER 12Z ON THE 16TH...SPREAD AT THIS TIME ALSO MAKES THE CONFIDENCE JUST AVERAGE FOR THE END OF DAY 3. 19Z UPDATE: THE SLOWER 00Z ECMWF TRENDED A BIT FASTER TOWARD THE 12Z GFS WHILE THE UKMET/CMC REMAINED ALIGNED WITH THE GFS PRIOR TO 16/12Z. THIS WAS ALSO TRUE FOR THE UPSTREAM DIGGING TROF WEST OF VANCOUVER ISLAND AT THE END OF DAY THREE; ALL IN ALL CONTINUING TO PUSH THE 12Z NAM FURTHER FROM TIGHTER CONSENSUS. NO CHANGE IN INITIAL PREFERENCE/CONFIDENCES. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... GALLINA