MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 113 AM EDT MON MAR 14 2016 VALID MAR 14/0000 UTC THRU MAR 17/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE WEAKENING UPPER LOW AND SURFACE SYSTEM TRACKING ACROSS GREAT LAKES INTO E CANADA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: OPEATIONAL MODEL BLEND CONFIDENCE: ABOVE AVERAGE THE MODELS MASS FIELDS ARE GENERALLY IN GOOD AGREEMENT AS THE REMNANTS OF AN UPPER LOW CURRENTLY ACROSS THE LP OF MI CONTINUE TO LIFT NORTHEAST AND THOUGH THE TIMING OF THE LINGERING ENERGY/QPF ACROSS SE ONTARIO/S QUEBEC IS A BIT DIFFERENT WITH THE 12Z CMC FASTEST/QUICKEST TO REDUCE IT...VERSUS THE 12Z ECMWF LINGERING A BIT MORE. AS SUCH WILL SUPPORT AN OPERATIONAL MODEL BLEND FOR THE MASS AT ABOVE AVERAGE CONFIDENCE...PLEASE REFER TO WPC QPF GRAPHICS AND QPFPFD FOR ADDITIONAL INFO ON PRECIPITATION. UPPER LOW TRACKING INTO THE OH VALLEY/MID ATLANTIC MON...LEADING TO SURFACE DEVELOPMENT ALONG MID ATLANTIC COAST TUE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: OPERATIONAL MODEL BLEND UNTIL 16/00Z 12Z CMC/18Z GEFS MEAN AFTERWARD CONFIDENCE: ABOVE AVERAGE UNTIL 16/00Z AVERAGE AFTERWARD MODELS ARE IN FAIRLY STRONG AGREEMENT AS THE UPPER LOW SHIFTS INTO THE OH/TN VALLEY AND THE SURFACE WAVE LIFTS NORTHEAST BEFORE COASTAL DEVELOPMENT OFF THE MID-ATLANTIC TAKES OVER. IT IS AFTER THIS TIME PERIOD ABOUT 16/00Z WHERE MODELS START TO DIVERGE. THE 00Z NAM BROADENS THE WAVE AS CONVECTION DEVELOPS ALONG THE NORTH WALL OF THE GULF STREAM INTO A DEEP COMPLEX THAT LIFTS NORTH. THIS IS SUPPORTED BY THE 12Z UKMET AND 00Z GFS. THE TROF OVER QUEBEC SIMULTANEOUSLY AMPLIFIES INTO NEW ENGLAND AND STRONGLY DEEPENS THE SURFACE LOW...WHICH IS OUT OF PHASE TOWARD THE NE/STRONG SIDE OF THE GUIDANCE. THE 12Z ECMWF/CMC BECOME A BIT SLOWER WITH THE UPPER LOW EXITING THE MID-ATLANTIC...THE ECMWF MORE SO. AS SUCH THE ECMWF IS ON THE SOUTHERN EDGE OF THE GUIDANCE WITH A SURFACE LOW... INSTEAD OF THE BETTER ENSEMBLE CLUSTERING SOUTH OF LONG ISLAND AND NANTUCKET. THE 00Z GFS IS INITIALLY CLOSER TO THE NAM AND REMAINS ON THE NORTHERN SIDE OF THE BEST CLUSTER...MAYBE A BIT TOO FAR NORTH AFTER 16/00Z...AT LEAST THE DEPTH OF THE LOW IS MORE IN RANGE WITH THE REST OF THE GUIDANCE HAVING LESS INTERACTION WITH THE TROF OVER E CANADA. THE 12Z UKMET/CMC PROVIDE NICE SURFACE TRACK SIMILAR TO THE 18Z GEFS MEAN...BUT A MUCH FASTER UPSTREAM TROF INTERACTION BY LATE WED LAGS THE 12Z UKMET FOR FULL INCLUSION. THE 21Z SREF AND 12Z ECENS MEAN ALSO SUPPORT INCLUSION OF THE 12Z ECMWF. ALL CONSIDERED A BLEND OF THE 12Z CMC AND 18Z GEFS MAY BE MOST CONSISTENT AND CENTRAL SOLUTIONS AFTER 16/00Z... BUT CONFIDENCE IS REDUCED DUE TO THE INCREASED SPREAD. MULTIPLE WAVES ACROSS THE NORTHWEST U.S. EVOLVING INTO A BROAD CLOSED LOW OVER THE NORTHERN PLAINS TUE/WED. ASSOCIATED DEEP SURFACE LOW IN LEE OF ROCKIES MON/TUES...DEEPENING ACROSS THE GREAT LAKES WED AND STALLING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z ECENS MEAN/18Z GEFS/21Z SREF MEAN BLEND CONFIDENCE: BELOW AVERAGE THERE ARE TWO IMPORTANT SHORTWAVE FEATURES TO TRACK THE EVOLUTION OF THE DEVELOPING LARGE SCALE TROF/REX BLOCK PATTERN ACROSS THE NORTHERN PLAINS/MIDWEST BY THE END OF THE PERIOD. THE LEADING WAVE ENERGY OF WESTERLY ONSHORE FLOW OVER THE PAST FEW DAYS...HAS LIFTED INTO SE BC ATTM PER WV LOOP. THIS WILL DEVELOP THE CENTRAL HUB OR NORTHERN PORTION OF THE TROF ALONG THE US/CANADIAN BORDER INTO WED. THE SECOND PORTION OF ENERGY IS SHORTWAVE ENERGY CURRENTLY ENTERING N CA/S OR ATTM. THE SPACING BETWEEN AND THE RELATIVE STRENGTHS OF EACH FEATURE LEAD IN INITIAL CONDITIONS LEAD TO THE DIFFERENCES (SOMETIMES COOPERATIVE...OTHERS DIMINISHING). THE NCEP MODELS SEEM TO BE HANDLING THE NORTHERN PORTION OF THE INNER CORE A BIT MORE AMPLIFIED AND MORE CONSISTENT BUT ARE QUITE FAST/STRONG INTO THE MIDWEST/LOWER MICHIGAN WHICH SEEMS A BIT TOO FAST. WHILE THE ECMWF/CMC ARE SLOWER ACROSS THE CENTRAL PLAINS INTO THE GREAT LAKES WHILE THEIR ENSEMBLE MEANS HAVE BEEN BUILD STRONG CONTINUITY IN THE MIDWEST FOR THE LAST FEW DAYS PROVIDING CONFIDENCE TOWARD THAT SOLUTION. THOUGH THE NORTHERN STREAM EVOLUTION DOES NOT APPEAR AS PREFERABLE TO THE GFS/NAM SOLUTIONS. THE 12Z UKMET IS MOST AGGRESSIVE IN PROGRESSING THE OVERALL SYSTEM EVOLUTION...RAPIDLY KICKING EAST THE SOUTHERN STREAM ENERGY AS WELL AS ROTATING THE CLOSED UPPER LEVEL ANTICYCLONE ACROSS CANADA BACK SOUTH INTO THE NORTHERN U.S. PLAINS BY DAY 3...THIS SEEM MOST OUT OF PHASE FROM THE ENSEMBLE SETUP. THE 00Z NAM HAVING SPLIT THE DIFFERENCE BETWEEN THE ECMWF/GFS SOLUTIONS IN THE NORTHERN STREAM IS ALSO THE WEAKEST NORTH AND EAST WITH THE CUT-OFF UPPER RIDGE... EVEN MORE SO THAN ITS 21Z SREF MEAN. AS SUCH...THE 21Z SREF/12Z ECENS MEAN/18Z GEFS MEANS ALL ARE MORE CENTRAL TOWARD A CONSENSUS OF THE OVERALL PATTERN THAN THEIR OPERATIONAL COUNTERPARTS. AS SUCH FAVOR THESE IN A BLEND WITH A BIT MORE WEIGHTING TOWARD THE ECENS MEAN GIVEN ITS RUN TO RUN CONTINUITY...THOUGH CONFIDENCE IS BELOW AVERAGE BECAUSE OF THE SPREAD AND LACK OF OPERATIONAL REPRESENTATIVES TOWARD THIS MIDDLE GROUND SOLUTION. AMPLIFYING SHORTWAVE DROPPING OUT OF WESTERN CANADA THURSDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z NAM/GFS AND 12Z ECMWF BLEND CONFIDENCE: AVERAGE A FAIRLY WELL AGREED UPON WESTERN RIDGE DOMINATES THE NEAR COAST NORTHEAST PACIFIC. AS THE RIDGE AMPLIFIES THE SHORTWAVE ENERGY OVER N BC BEGINS TO DROP SOUTHWARD ALONG THE EAST SIDE OF THE RIDGE WHILE HERDED BY THE REX BLOCK OVER THE NORTHERN PORTION OF THE CONTINENT. PLACEMENT/TIMING IS FAIRLY WELL AGREED UPON WITH THE 00Z NAM/GFS AND 12Z ECMWF WHILE THE 00Z CMC IS A BIT SLOWER AND LESS AMPLIFIED AND THE UKMET IS WELL OUT OF PLACED DUE TO FASTER ROTATION OF THE CLOSED HIGH DROPPING THROUGH THE DAKOTAS. AS SUCH WILL FAVOR A 00Z NAM/GFS AND 12Z ECMWF BLEND AT AVERAGE CONFIDENCE FOR THIS FEATURE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... GALLINA