MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 227 PM EDT SUN JUN 12 2016 VALID JUN 12/1200 UTC THRU JUN 16/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION WITH PREFERENCES AND FORECAST /CONFIDENCE INTERVALS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SYSTEMS MOVING THROUGH NEW ENGLAND SUN AND MONDAY NIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: OPERATIONAL MODEL BLEND CONFIDENCE: ABOVE AVERAGE THE 12Z NAM HAS TRENDED FASTER WITH THE SECONDARY S/W TROF PUSHING THROUGH NEW ENGLAND MONDAY NIGHT/TUESDAY MORNING THOUGH REMAINS A BIT SLOWER THAN THE BEST CONSENSUS. THE 00Z CMC IS ABOUT EQUAL/OPPOSITE ON THE FAST SIDE. BOTH ARE MINOR TO THE OVERALL SYSTEM AND SENSIBLE WEATHER TO SUPPORT AN OPERATIONAL MODEL BLEND AT ABOVE AVERAGE CONFIDENCE. 19Z UPDATE: NEARLY ALL SPREAD REMAINS WITH SECONDARY S/W TROF...AND WHILE THE 12Z CMC SLOWED TO BETTER MATCH THE ECMWF/12Z NAM...THE UKMET SHIFTED SLIGHTLY FASTER TOWARD THE SLIGHTLY FASTER GFS. STILL OVERALL SPREAD/EFFECTS TO SENSIBLE WEATHER SEEM TO BE SMALL ENOUGH TO CONTINUE AN OPERATIONAL BLEND AT ABOVE AVERAGE CONFIDENCE. WEAK UL SYSTEM MOVING FROM TX/OK THROUGH MS VALLEY/SOUTHEAST (TUES/WED) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: OPERATIONAL MODEL BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 12Z NAM AND 00Z CMC CONTINUE TO BE STRONGEST AND CONSOLIDATED WITH THIS WAVE'S ENERGY PARTICULARLY MONDAY INTO TUES ACROSS S AR THOUGH THEY MATCH GENERALLY WITH THE TIMING OF THE GFS/ECMWF AND ENSEMBLE MEANS. THE 00Z UKMET CONTINUES TO WASH OUT THE FEATURE AS A WHOLE. A GFS/ECMWF MAY BE BEST/MIDDLE GROUND BUT WILL INCLUDE THE NAM/CMC TO AID IN ANY MESOSCALE INTERACTIONS GROWING UPSCALE...WHICH SEEM PLAUSIBLE GIVEN INGREDIENTS. AS SUCH WILL FAVOR A NON-UKMET BLEND AT SLIGHTLY ABOVE AVERAGE CONFIDENCE. 19Z UPDATE: THE 12Z UKMET WAS A BIT MORE ROBUST...THOUGH STILL ON THE WEAKER SIDE AND NORTHERN SIDE OF THE BEST ALIGNED GUIDANCE...THE CHANGES ARE SUFFICIENT FOR MORE INCLUSION. AS SUCH AN OPERATIONAL MODEL BLEND IS SUPPORTED NOW WITH THE 12Z DETERMINISTIC RUNS. SURFACE WAVE MOVING THROUGH DAKOTAS/UPPER MS VALLEY BEFORE WEAKENING MON NIGHT/TUES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: OPERATIONAL MODEL BLEND CONFIDENCE: ABOVE AVERAGE MODELS ARE IN STRONG AGREEMENT WITH THIS SFC TROF AS WELL AS PLACEMENT OF THE SURFACE LOW THROUGH TUESDAY BEFORE IT WEAKENS ACROSS THE SW GREAT LAKES REGION. ABOVE AVERAGE CONFIDENCE IN AN OPERATIONAL MODEL BLEND IS PREFERRED. SYSTEM MOVING FROM THE SOUTHWEST INTO THE NORTHERN PLAINS WITH SURFACE LOW MOVING INTO UPPER MS VALLEY BY WED ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-UKMET BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE MODELS CONTINUE TO BE WELL ALIGNED IN TIMING WITH THE SYSTEM LIFTING OUT OF THE SOUTHWEST INTO THE CENTRAL PLAINS TUE/WED...INCLUDING THE PRECURSORY CONVECTIVE COMPLEX THAT HAS SOME UPSCALE GROWTH ON MONDAY NIGHT. DIFFERENCES SEEM TO BE RESOLVED IN THE STRENGTH OF THE WAVE AS WELL PLACEMENT NW OR SE WITHIN THE WAVE AXIS (INFLUENCE OF THE NORTHERN STREAM). THE 00Z CMC IS MOST OUT OF PHASE WITH LITTLE INTERACTION WITH THE NORTHERN STREAM ALLOWING FOR A STRONG CONSOLIDATED LOW AND SURFACE REFLECTION BEST NOTED ON THE 7H MASS FIELD. THE 00Z UKMET IS FURTHEST NW INTERACTING WITH THE NORTHERN STREAM AND DEVELOPS A VERY DEEP SURFACE LOW ON THE NW SIDE OF THE ENSEMBLE CLUSTER. THE NAM WAS SIMILAR TO THE UKMET BUT THE 12Z RUN TRENDED MORE CENTRALLY TOWARD THE GEFS/ECENS MEAN. WITH LITTLE CHANGE TO THE 12Z GFS A BLEND OF THE 12Z NAM/GFS AND 00Z ECMWF WILL BEST REPRESENT THE ENSEMBLE AS WELL AS THE MIDDLE GROUND. CONFIDENCE REMAINS SLIGHTLY ABOVE AVERAGE. 19Z UPDATE: THE 12Z CMC CAME INTO LINE WITH THE 12Z GFS/NAM PLACING IT INTO BETTER OVERALL AGREEMENT WITHIN THE ENSEMBLE SUITE THOUGH ON THE STRONGER SIDE OF GUIDANCE. THIS LEAVES THE 12Z UKMET AS THE REMAINING OUTLIER AS IT CONTINUES TO FAVOR A NORTHWARD TRACK AND DEEPER SFC LOW WED. AS SUCH THE UKMET RESOLVES A MORE AMPLIFIED RIDGE AXIS AND IS SLOW TO HAVE THE WAVE OVER-TOP THE RIDGE AT THE END OF THE PERIOD. AS SUCH WILL NOW FAVOR A NON-UKMET BLEND AT SLIGHTLY ABOVE AVERAGE CONFIDENCE. BROAD UPPER LOW MOVING INTO THE WESTERN US/WESTERN CANADA TUES TO WED ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z GFS/ECMWF/CMC BLEND CONFIDENCE: AVERAGE THE MODELS ARE IN FAIRLY STRONG AGREEMENT WITH THE UL DIGGING INTO THE PAC NW BY TUES AND TRANSITIONING THE STRONG LEAD WAVE INTO ALBERTA BY WED MORNING WHILE THE WESTERN PORTION OF THE BROAD UL BEINGS TO DIG SOUTHWARD OFFSHORE. MODELS GENERALLY AGREE TO A SPLITTING OF THESE PINCHING THROUGH THE WEAKNESS NEAR VANCOUVER ISLAND/SW BC BY THE END OF THE FORECAST PERIOD WITH ONE EXCEPTION... THE 12Z NAM WHICH SWINGS AN EMBEDDED SHORTWAVE THROUGH N CA/OR SLOWER AND STRONGER AT THE END OF DAY 3; TYPICAL OF A DAY 3 NAM BIAS. UPSTREAM DIFFERENCES IN THE WESTERN SECTION OF THE UL CONTINUE TO INCREASE A BIT IN THE TIMING/PHASING OF SHORTWAVE ENERGY INJECTED FROM THE ARCTIC STREAM IN W AK ON TUES NIGHT/WED MORNING. THE 00Z UKMET REMAINS STRONGER AND SLOWER THOUGH THE 00Z ECMWF ALSO TRENDED A BIT DEEPER SLOWER THOUGH NOT AS DRAMATIC AS THE UK EVEN LAGGING THE ECENS MEAN. STILL THE 12Z GFS/06Z GEFS/09Z SREF CMC ARE QUICKER HERE THAN THE ECENS MEAN. WILL SUGGEST NON-NAM FOR LEAD WAVE AND NON-UKMET FOR THE WESTERN PORTION OF THE UPPER LOW AT AVERAGE CONFIDENCE THROUGHOUT IN A 00Z CMC/ECMWF AND 12Z GFS BLEND TO BEST REPRESENT THE ENSEMBLE SPREAD. 19Z UPDATE: THE 12Z UKMET CONTINUES TO BE AN OUTLIER WITH LITTLE CONSISTENCY AS IT NOW FAVORS AMPLIFYING AN INTERNAL S/W ACROSS N CA/W NV BY WED AFTERNOON WHILE ALSO REMAINING SLOWER WITH THE SHORTWAVE PHASING OUT OF W AK INTO THE GULF OF ALASKA WED AS WELL. THE 12Z CMC/ECMWF REMAIN SLOWER ON THE WESTERN TROF MATCHING THE 00Z ECENS MEAN WHILE THE 12Z GEFS AS EXPECTED MATCHES THE SLIGHTLY FASTER 12Z GFS. AS SUCH WILL CONTINUE A BLEND OF THE 12Z GFS/ECMWF/CMC AT AVERAGE CONFIDENCE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... GALLINA