MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 238 PM EDT MON JUN 13 2016 VALID JUN 13/1200 UTC THRU JUN 17/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION WITH FINAL PREFERENCES AND FORECAST CONFIDENCE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SYSTEMS MOVING THROUGH NEW ENGLAND MON INTO TUE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL BLEND CONFIDENCE: ABOVE AVERAGE THE 12Z NAM CONTINUES TO BE A SLIGHT BIT DEEPER AND THEREFORE EAST BY TUESDAY CROSSING NOVA SCOTIA AND THE 00Z CMC IS A BIT SLOW WITH THE SECONDARY CONSOLIDATED SHORTWAVE SWINGING THROUGH NEW ENGLAND TONIGHT INTO TUESDAY MORNING...BUT OVERALL THE PLACEMENT/TIMING AND STRENGTH OF THE DEEP CYCLONE REMAIN TIGHT ENOUGH TO SUPPORT A GENERAL MODEL BLEND AT ABOVE AVERAGE CONFIDENCE. LONG WAVE TROUGH CROSSING THE LOWER MS VALLEY/SOUTHEAST STATES MON THROUGH WED ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL BLEND CONFIDENCE: ABOVE AVERAGE THE 12Z NAM CONTINUES ITS TREND OF SLIGHTLY DEEPER EMBEDDED SHORTWAVE TRACKING TROUGH THE LOWER MS VALLEY AND GULF REGION BEFORE ELONGATING ACROSS SW-NE AND PHASING WITH NORTHERN STREAM ENERGY TOWARD FRI. THE 00Z ECMWF EVENTUALLY IS WEAKER OVERALL ACROSS N FL/SW GA BY THURSDAY EVENING. ALL IN ALL THIS IS FAIRLY MINOR THAT AN GENERAL MODEL BLEND IS PREFERRED AT ABOVE AVERAGE CONFIDENCE. 19Z UPDATE: THE 12Z ECMWF IS A BIT MORE ROBUST WITH THE WAVE ACROSS THE SOUTHEAST MATCHING WITH THE 12Z UKMET/CMC THAN THE SLIGHTLY DEEPER NAM/GFS. THOUGH DIFFERENCES ARE SMALL ENOUGH TO BLEND WITH HIGH CONFIDENCE. SHORTWAVE IN SOUTHWEST EVOLVING INTO A CLOSED MID LEVEL SYSTEM IN THE UPPER MS VALLEY MON NIGHT/TUE ROLLING OVER TOP THE RIDGE INTO GREAT LAKES BY THURS WITH ASSOCIATED SURFACE LOW ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z GFS/ECMWF BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 12Z NAM IS ROBUST IN AMPLIFYING THE EJECTING SW WAVE INTO THE PLAINS WITH A CONSOLIDATED FEATURE WITH A STRONG SURFACE RESPONSE THAT BENDS WEST AND THEN NORTH ACROSS THE UPPER MS VALLEY BY WED OUT OF PHASE WITH THE ENSEMBLE SUITE. THE 00Z UKMET IS LIKEWISE A BIT MORE WRAPPED UP LEFT OF CONSENSUS AND SHEARS MORE OF ITS ENERGY INTO THE NORTHERN STREAM. AS THE SYSTEM OVER TOPS THE AMPLIFYING CENTRAL RIDGE...THE REMAINING ENERGY OF THE NAM/UKMET CROSS INTO THE GREAT LAKES TOWARD DAY 3 MORE IN LINE IN PLACEMENT/STRENGTH AND TIMING WITH THE WELL CLUSTERED GEFS/ECENS MEANS ODDLY ALLOWING FOR SOME UTILITY AFTER MIDDAY WED. ON THE OTHER SIDE OF THE SPECTRUM...THE 00Z CMC IS CENTERED WELL WITH THE ENSEMBLES UNTIL ABOUT 16/12Z THURS WHEN A SLOWER/DEEPER S/W OUT OF THE NORTHERN STREAM IN QUEBEC AMPLIFIES AND DRAWS THE GREAT LAKES WAVE OUT FASTER EVENTUALLY DEVELOPING THE SURFACE LOW OFF THE CAROLINA COAST EARLIER AND WELL EAST OF THE CLUSTER. THE 12Z GFS REMAINS IN LINE WITH THE 00/06Z GFS AND IS SLIGHTLY FASTER THAN THE 00Z ECMWF VERY NEAR THE ENSEMBLE MEANS. THIS IS A TYPICAL SETUP FOR ENHANCED CONFIDENCE OVERALL. THOUGH THERE ARE DIFFERENCES ON THE EAST SIDE OF THE RIDGE LIKELY DUE TO DIFFERENCES IN MAGNITUDE/INTERACTION WITH THE GULF/SE STATES BROAD WAVE. STRONGER WAVE IN THE GFS...MORE INTERACTION AND DRAWS SOUTH...OPPOSED TO THE WASHED OUT ECMWF...ALLOWING FOR A NORTHERN TRACK. A BLEND OF THE TWO WILL LIKELY RESOLVE A BEST PREDICTABILITY AT THIS POINT AND AS SUCH WILL BLEND THE 12Z GFS/00Z ECMWF AT SLIGHTLY ABOVE AVERAGE CONFIDENCE. THOUGH DO NOTE: THE CMC COULD BE ADDED THROUGH THE WESTERN GREAT LAKES UNTIL THURS AND THE 12Z NAM/00Z UKMET MAY HAVE UTILITY AFTERWARD FOR SOME ADDITIONAL BLENDING SUPPORT IF SO DESIRED. 19Z UPDATE: THE 12Z UKMET LIKE THE 12Z NAM HAVE TRENDED TOWARD THE BETTER CLUSTER BUT BEING LEFT OF THE CLUSTER RESULTS IN A STRONGER SURFACE LOW ACROSS MN AND THEREFORE IS A BIT SLOWER EAST OF THE RIDGE INTO THE GREAT LAKES/OH VALLEY BY DAY 3. THE 12Z CMC ALSO REMAINS FAST AND NORTHEAST AFTER OVER TOPPING THE RIDGE BUT LESSER SO THAN THE 00Z RUN SHOWING BETTER AGREEMENT THE PRIOR PREFERENCE. THE 12Z ECMWF TRENDED A BIT FASTER TOWARD BETTER TIMING OF THE 12Z GFS AS WELL AS TRENDING SOUTH AND WEST WITH THE SURFACE LOW AND QPF SWATH THOUGH STILL A NORTHEAST MEMBER OF THE SUITE. WILL CONTINUE TO FAVOR A 12Z GFS/ECMWF BLEND AT SLIGHTLY ABOVE AVERAGE CONFIDENCE. EASTERN PORTION OF BROAD UPPER LOW THAT CUTS OFF AND LIFTS FROM PAC NW INTO W CANADA MON TO WED ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-NAM BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 12Z NAM IS A BIT SLOWER THAN THE REST OF THE GUIDANCE WITH THE LEAD SHORTWAVE TUES MORNING IN THE PAC NW...AND REMAINS SO INTO SW CANADA WHICH KEEPS INTERACTION/CONNECTIVITY TO THE WESTERN PORTION OF THE WAVE GREATER THAN OTHER GUIDANCE SUGGESTS MAKING IT THE GREATEST OUTLIER FOR BOTH PORTIONS OF THE LOW. OTHERWISE...A SLIGHT ADJUSTMENT EAST WITH THE 12Z GFS ACROSS ALBERTA BRINGS BETTER OVERALL AGREEMENT WITH THIS PORTION OF THE BROAD UPPER LOW... THROUGH THURSDAY EVENING. AS SUCH A NON-NAM BLEND IS PREFERRED AT SLIGHTLY ABOVE AVERAGE CONFIDENCE. 19Z UPDATE: LITTLE CHANGE WITH THE 12Z NON-NCEP SUITE TO CHANGE INITIAL PREFERENCES OF NON-NAM BLEND AT SLIGHTLY ABOVE AVERAGE CONFIDENCE. WESTERN PORTION OF BROAD UPPER LOW THAT CUTS OFF JUST OFFSHORE OR LATE WED BECOMING GENERALLY STATIONARY THRU THURS NIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z ECMWF/CMC/GEFS MEAN CONFIDENCE: AVERAGE AS MENTIONED ABOVE...THE 12Z NAM REMAINS IN CLOSER PROXIMITY WITH THE LEAD WAVE LEADING TO NORTHERN BIAS THROUGHOUT THE EVOLUTION THOUGH THE TIMING/SHAPE OF THE INTERNAL WAVES AND THE LARGER UL AS A WHOLE SEEM TO BE A NORTHERN REPRESENTATION OF THE 00Z ECENS MEAN/ECMWF/UKMET/CMC THE STRONG AGREEMENT OF THE 00Z GEFS AND ECENS MEAN HAS BECOME A BIT DISPLACED AS THE 06Z/12Z GFS AND 06Z GEFS HAVE SHOWN A TENDENCY FOR A FASTER INTERNAL S/W ENTERING CENTRAL CA WED EVENING WITH CONTINUED AMPLIFICATION ACROSS THE ID INTO SW CANADA BY THURS AND AS SUCH IS ALSO PROGRESSIVE WITH THE BASE OF THE TROF NEARING CENTRAL CA BY 19/00Z. IT IS POSSIBLE THE GFS IS ONTO A TREND BUT GIVEN THE CHANGES FIT WITH A TYPICAL DAY 3 BIAS AND THE 12Z NAM EVOLUTION IS CLOSER TO A WELL PACKED 00Z ECENS MEAN/ECMWF/CMC AND UKMET WILL RESERVE SOME HESITATION FOR ITS INCLUSION INTO THE PREFERENCE AT THIS TIME. CONFIDENCE IS REDUCED A BIT BUT REMAINS AVERAGE GIVEN THE SPREAD IS NOT TOO DRAMATIC FOR DAY 3. 19Z UPDATE: THE 12Z UKMET/CMC AND ECMWF ALL TRENDED TOWARD THE 12Z GFS WITH THE LEAD SHORTWAVE MOVING FROM N CA 16/00Z AND AMPLIFYING ACROSS ID INTO S ALBERTA BY 17/00Z. THE CMC/ECMWF ARE GENERALLY WEAKER THAN THE GFS WHILE THE 12Z UKMET SIGNIFICANTLY WRAPS UP THE WAVE ACROSS W MT INTO ALBERTA WELL OUT OF PHASE EVEN FROM THE 12Z GEFS...AND AS SUCH SHOULD BE REJECTED ON THURS. AS FOR THE BASE OF THE TROF NEARING THE WEST COAST AT THE END OF THE FORECAST PERIOD: THE 12Z GEFS REMAINS SIMILAR TO THE 06Z ENSEMBLE MEAN AND WELL SLOWER THAN THE 12Z GFS...KEEPING IT OUT OF THE PREFERENCE. THOUGH THE 12Z CMC TRENDED FASTER THE ECMWF IS VERY STABLE AS THE SLOWEST MEMBER BUT WELL ALIGNED WITH THE 00Z ECENS MEAN. AS SUCH WILL FAVOR A 12Z GEFS/CMC/ECMWF BLEND TO BEST ENCOMPASS THE SPREAD AND OVERALL SUITE'S TREND. CONFIDENCE REMAINS AVERAGE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... GALLINA