MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 239 AM EDT WED MAY 25 2016 VALID MAY 25/0000 UTC THRU MAY 28/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ WEAKENING UPPER LOW IN NORTHEAST WED ALONG WITH KICKER SHORTWAVE ACROSS NORTHEAST WITH ASSOCIATED SURFACE LOW AND FRONT WED/EARLY THURS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: OPERATIONAL MODEL BLEND CONFIDENCE: ABOVE AVERAGE A KICKER WAVE IN CENTRAL ONTARIO IS DRIFTING EAST AND WILL BEGIN TO AMPLIFY AND HELP TO LIFT/ACCURATE THE CLOSED LOW CURRENTLY OVER NEW ENGLAND INTO THE NORTHERN STREAM. DURING THE KICKER'S DIGGING...SURFACE CYCLOGENESIS TRACKS A SURFACE WAVE THROUGH SE QUEBEC TO NEW BRUNSWICK DRAPING A FRONT PASSAGE THROUGH NEW ENGLAND WED INTO THURS. THE MODELS ARE A BIT SPREAD ON EXACT POSITION OF THE SFC LOW WITH THE 00Z GFS CONTINUING A FAVORED NORTHERN TRACK NEVER REACHING NB...WHILE THE EC/UKMET ARE A ON THE SOUTHERN TRACK CLOSE TO N ME. OVERALL THIS IS FAIRLY SMALL TO SUPPORT AN OPERATIONAL MODEL BLEND AT ABOVE AVERAGE CONFIDENCE. QUASI-STATIONARY CLOSED UPPER LOW EAST OF SOUTHERN CANADIAN ROCKIES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS/ECMWF/CMC BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE MODELS CONTINUE FAIRLY STRONG AGREEMENT OVERALL WITH PLACEMENT OF THE REMNANTS OF THE CENTROID OF THE UPPER LOW ACROSS S SASK/NE MT THOUGH INFLUENCES FROM THE SHORTWAVE MOVING OUT OF THE CENT ROCKIES WED/THURS INDUCE SPREAD MAINLY DEPENDENT ON PROXIMITY TO THIS FEATURE. THE 00Z NAM IS WELL PLACED BUT IS TYPICAL OF BIAS IS QUITE STRONG/SLOW TO SPIN DOWN BECOMING EVEN SLOWER THAN THE 12Z ECMWF/CMC ON FRI/SAT WHEN LIFTING N/NW AS IT WEAKENS. THE 12Z UKMET IS A BIT FARTHER NORTH INITIALLY AND MAY BE A BIT QUICK TO LIFT NORTH AND DISSIPATE LATE FRI/SAT. THE 00Z GFS TRENDED A BIT WEAKER OVERALL FOR BEST ALIGNMENT IN PLACEMENT/TIMING/STRENGTH OF THE 12Z ECMWF MATCHING THE ENSEMBLE MEANS AS WELL TO SUPPORT A 00Z GFS/12Z ECMWF BLEND. GIVEN PROBABILITY OF RUN TO RUN VARIABILITY WITH RESPECT TO A WEAKENING SYSTEM INFLUENCED BY OTHER LARGER SYSTEMS...CONFIDENCE IN THIS BLEND IS HIGH GIVEN THE CIRCUMSTANCES BUT ONLY AVERAGE OVERALL. 07Z: THE 00Z UKMET REMAINS WEST OF THE MAIN SOLUTION CLUSTER IN E MT BY FRI AND GIVEN THE STRONGER AGREEMENT OF THE 00Z CMC/ECMWF AND 00Z GFS WILL ONLY ADD THE CMC TO THE PREFERRED BLEND OF THE GFS/ECMWF TO STRENGTHEN CONFIDENCE TO SLIGHTLY ABOVE AVERAGE. SHORTWAVES MOVING OUT OF CENT. ROCKIES SOUTHWEST FLOW AMPLIFY WED/THUR OVER N. HIGH PLAINS AND SHIFTS INTO ONTARIO BY FRI ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z ECMWF/CMC/UKMET BLEND CONFIDENCE: AVERAGE ALL MODELS ARE GENERALLY IN THE SAME PLACE IN TIMING OF THE INITIAL WAVE AS WELL AS SECONDARY WESTERN S/W LIFTING OUT OF THE CENTRAL ROCKIES THURS...HOWEVER PROXIMITY TO THE QUASI-STATIONARY UL IN NE MT...HELPS INCREASE SPREAD DUE TO INFLUENCE AS WELL AS THE RELATIVE STRENGTH OF THE SHORTWAVE FEATURES THEMSELVES. THE 12Z UKMET REMAINS A DEEP OUTLIER WITH THE INITIAL WAVE MOST NOTICEABLE AT 7H. 00Z NAM CONTINUES TO BE WEST OF THE CLUSTER EJECTING THE INITIAL WAVE AND WITH A DEEP QUASI-STATIONARY UL AS WELL...SEEMS TO DOUBLE DOWN ON A STRONGER SOLUTION WHICH HAS NOT BEEN THE TREND. THE 00Z GFS BROKE WITH FAIRLY GOOD CONTINUITY WITH A FASTER EJECTION OF THE LEAD WAVE/SURFACE LOW THAT GRAVITATES WEST FOR THE SECOND WAVE ON THURS...SHIFTING THE OVERALL PATTERN WEST AS WELL. THE 12Z CMC/ECMWF HAVE THEIR OWN FAULTS BEING ON THE EASTERN SIDE OF THE BEST PACKING SEEN IN THE GEFS/ECENS SURFACE CLUSTER...AND THOUGH SUPPORTED BY GOOD ALIGNMENT OF THE UKMET MAY BE A BIT TOO FAR EAST. AS A COMPROMISE WILL SUPPORT A 18Z GEFS TO REPLACE THE GFS ALONG WITH THE 12Z ECMWF/CMC IN A BLEND AT AVERAGE CONFIDENCE. 07Z UPDATE: A SLIGHT WESTWARD SHIFT IN BOTH THE 00Z ECMWF/CMC TOWARD THE 18Z/00Z GEFS AND 12Z ECENS MEAN BRINGS MORE CONFIDENCE TOWARD THIS MIDDLE GROUND SOLUTION...STILL THE GFS AND 00Z GEFS REMAIN SLOWER TO TRANSLATE INTO CANADA MAKING THEM LESS LIKELY GIVEN PERSISTENCE OF THE NON-NCEP SUITE INCLUDING THEIR ENSEMBLES. THE 00Z UKMET HAS ALSO RESOLVED SOME OF ITS OVER AMPLIFICATION TOWARD THE ECMWF/CMC TO INCLUDE IT AS WELL. AS SUCH WILL SUPPORT A NON-NCEP BLEND (ECMWF/CMC/UKMET). CLOSED LOW NEARING S CA TRANSLATES ACROSS SOUTHWEST THURS AND EJECTS INTO CENTRAL PLAINS FRI/SAT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-CMC BLEND CONFIDENCE: AVERAGE STRONG AGREEMENT EXISTS PRIOR TO THE WAVE EJECTING INTO THE PLAINS 27/12Z...AT THIS POINT THE 00Z NAM/GFS AND 12Z UKMET ARE A BIT MORE PROGRESSIVE AND LIFT NORTHWARD FASTER WHICH MAY BE A SHADE TOO FAST GIVEN THE 21Z SREF/18Z GEFS. THE 12Z ECENS SHOWS A LARGE VARIATION PARTICULARLY IN THE SURFACE CLUSTER WHILE THE CMCE/GEFS MEMBERS WERE TIGHTER INTERNAL TO THEIR BLEND...GIVEN THE 12Z ECMWF IS MUCH WEAKER WITH THE WAVE OVERALL AND EVEN SLOWER THAN THE ECENS MEAN...THERE IS SOME QUESTION TO IT. THE 12Z CMC IS MOST OUT OF PHASE EJECTING SLOWER AND MORE BROADLY OVERALL TO BE MISSHAPED TO THE REST OF THE GUIDANCE TO SUPPORT IT. TO ENCOMPASS THE MOST LIKELY SCENARIO WILL FAVOR A NON-CMC BLEND AS OVERALL SHAPE/TIMING PLACEMENT IS MODERATE...THOUGH WOULD FAVOR WEIGHTING TOWARD THE 00Z GFS...AS MOST CENTRAL REPRESENTATIVE. 07Z UPDATE: 00Z ECMWF IS A BIT MORE ROBUST AND THOUGH NOT AS FAST AS THE GFS/NAM (MAY STILL BE TOO FAST) IT ALIGNS WELL. LIKEWISE THE 00Z CMC IS ALIGNING TOO BUT STILL THE SLOWEST...THOUGH OF MORE CONCERN IS THE STRONG RESPONSE OVER THE OZARKS/CENTRAL MS RIVER VALLEY BY SAT...THIS IS BEST SEEN AT 7H. THE 00Z UKMET LOOKS GENERALLY IDEAL AS A BLEND OF THE NAM/GFS AND ECMWF SPEEDS. ALL CONSIDERED WILL KEEP A NON-CMC BLEND AT AVERAGE CONFIDENCE. UPPER LEVEL LOW/TROF DESCENDING INTO PAC NW LATE THUR...STALLS IN THE VICINITY THROUGH SAT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS/ECMWF/CMC CONFIDENCE: AVERAGE THE 12Z ECWMF SUITE IS A BIT STRONGER BRING MORE ENERGY TO REINFORCE THE STALLING TROF ACROSS THE PAC NW BY FRI EVENING/SAT MORNING...THIS APPEARS EVEN A BIT DEEP COMPARED TO AN OTHERWISE FAIRLY TIGHT DETERMINISTIC AND NAEFS ENSEMBLE CLUSTER WITH ONLY THE 00Z NAM UNDER INFLUENCES OF A STRONGER QUASI-STATIONARY UL LIFTING BACK N/NW IN ALBERTA...DRAWS FALLING HEIGHTS ON SAT FURTHER EAST. AS SUCH WILL SUPPORT A 00Z GFS AND 12Z UKMET/CMC BLEND AT AVERAGE CONFIDENCE FOR THIS SYSTEM. 07Z UPDATE: THE 00Z ECMWF TRENDED BETTER AND LESS DEEP BY FRI/SAT ACROSS THE PAC NW... BUT THE 00Z UKMET HAS TRENDED EVEN FASTER THAN THE 00Z NAM. AS SUCH WILL SWAP THE ECMWF FOR THE UKMET IN A 00Z GFS/ECMWF/CMC BLEND AT AVERAGE CONFIDENCE. UPPER LOW DRIFTING E OF FLORIDA WITH APPROACHING SURFACE WAVE TRACKING N OF BAHAMAS FRI/SAT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-CMC BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE DETERMINISTIC AND ENSEMBLE SUITE IS FAIRLY CONFIDENT IN MODESTLY DEEP SYSTEM TRACKING NORTH OF THE BAHAMAS THUR/FRI WITH THE MAIN AXIS JUST OFF THE FL COAST BY 12Z SAT WITH EXCELLENT AGREEMENT IN TIMING OVERALL. THE 00Z NAM IS A BIT MORE AGGRESSIVE (STRONG) AS THE ONLY DETERMINISTIC RUN TO CLOSE OFF 1012MB SURFACE ISOBAR AND MAINTAIN IT; THOUGH THIS IS A DOWNWARD SHIFT IN INTENSITY CLOSER TO THE PACK. ALSO THE 12Z CMC IS GENERALLY SOUTH OF THE CONSENSUS AND THE 00Z GFS/18Z GEFS ARE A BIT FURTHER NORTH. GIVEN THE SPREAD IS NOT TERRIBLY LARGE...SUPPORT AN OPERATIONAL MODEL BLEND AT AVERAGE CONFIDENCE ATTM. 07Z UPDATE: THE CMC HAS SHIFTED FROM A SOUTHERN MEMBER OF THE CLUSTER TO A MUCH FURTHER NORTH MEMBER...THE ECMWF TRENDED A BIT DEEPER TO CLOSE A 1012MB LOW BY SAT OFF THE FL COAST IN SUPPORT OF THE 00Z NAM. AND UKMET IS A BIT WEAKER AND SLOWER IN SUPPORT OF THE GFS SOLUTION... AS SUCH WILL SUPPORT A NON-CMC BLEND AT SLIGHTLY ABOVE AVERAGE CONFIDENCE GIVEN BUILDING CONTINUITY AND MODERATE CLUSTERING. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... GALLINA