MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 240 AM EDT TUE MAY 09 2017 VALID MAY 09/0000 UTC THRU MAY 12/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION INCLUDING FINAL PREFERENCES AND FORECAST CONFIDENCE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...CLOSED LOW OVER THE NORTHEAST... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF THE 00Z GFS/00Z ECMWF CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 00Z NAM WAS CLOSE TO THE CONSENSUS WITH THE CLOSED MID LEVEL LOW FOR MUCH OF THE TIME... THOUGH IT IS FASTER THAN THE CONSENSUS THU WELL SOUTHEAST OF NOVA. ITS SURFACE LOW IS MUCH TOO DEEP AND SLOW...AND FOR THAT REASON THE 00Z NAM IS NOT INCLUDED IN THE MODEL PREFERENCES. THE 00Z GFS IS CLOSER TO THE CONSENSUS WITH THE TRACK OF THE MID LEVEL SYSTEM...AS WELL AS ITS SURFACE REFLECTION. IT REMAINS CLOSE TO THE 00Z ECMWF/12Z ECWMF ENSEMBLE MEAN. THE 00Z UKMET WAS CLOSE WITH THE MID LEVELS SYSTEM...BUT LIKE THE 00Z NAM IT WAS TOO SLOW WITH THE ATTENDANT SURFACE SYSTEM...WHILE THE 00Z CMC WAS TOO FAST WITH THE MID LEVEL SYSTEM. SINCE THE 00Z GFS/00Z ECMWF REMAIN CLOSE IN THEIR SOLUTIONS...THIS BLEND REMAINS THE PREFERRED SOLUTION. ...CLOSED LOW OVER THE NORTHERN BAJA TRACKS TO FOUR CORNERS TUE/WED...THEN SHEARS OUT INTO THE CENTRAL PLAINS THU... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF THE 00Z GFS/00Z UKMET/00Z CMC CONFIDENCE: AVERAGE THE DEEP CLOSED MID LEVEL LOW OVER THE NORTHERN BAJA PENINSULA EARLY TUE CROSSES THE SOUTHWEST STATES DURING WED...THEN SHEARS OUT AT IT CROSSES THE CENTRAL PLAINS AND LOWER MS VALLEY DURING THU. THE 00Z NAM AND 00Z GFS ARE CLOSE TO THE MODEL CONSENSUS WITHE THE TRACK AND STRENGTH OF THE SYSTEM (THOUGH THE 00Z NAM IS PROBABLY TOO FAR NORTH WITH ITS QPF MAXIMUM INTO THE COOLER AIR...A KNOWN MODEL BIAS). THE 00Z UKMET IS A BIT SLOWER THAN ITS PREDECESSOR (AS WELL AS THE CONSENSUS)...BUT NOT ENOUGH TO REMOVE FROM THE PREFERENCE. THE 00Z CMC WAS ALSO CLOSE WITH THE POSITION OF ITS CLOSED LOW BY EARLY FRI AM. THE 00Z ECMWF IS FASTER THAN THE CONSENSUS (AS WELL AS ITS 12Z ENSEMBLE MEAN)...AND BECAUSE OF THIS IS NOT INCLUDED IN THE MODEL PREFERENCE AT THIS TIME. ...SHORTWAVE OVER THE NORTHERN ROCKIES MERGING WITH A RETROGRADING UPPER LOW OVER CENTRAL CANADA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL BLEND CONFIDENCE: AVERAGE BOTH THE 00Z NAM/GFS WERE CLOSE TO THE CONSENSUS LIFTING SHORT WAVE ENERGY ACROSS THE NORTHERN ROCKIES EARLY TUE...BEFORE IT MERGES WITH A RETROGRADING UPPER LOW OVER CENTRAL CANADA WED INTO THU. THE 00Z NON-NCEP CAMP WAS ALSO SIMILAR WITH ITS SOLUTION. GIVEN THE RELATIVELY GOOD MODEL AGREEMENT WITH THESE FEATURES...A GENERAL MODEL BLEND IS PREFERRED. ...SURFACE LOW DROPPING SOUTHEAST THROUGH THE UPPER MIDWEST/OH VALLEY THROUGH TUE... ...SURFACE WAVES CROSSING THE OH VALLEY/MID ATLANTIC WED/THU... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE BOTH THE 00Z NAM/GFS WERE CLOSE TO THE CONSENSUS WITH THE TRACK OF THE SHORT WAVE AND SURFACE WAVES RIDING DOWN A FRONTAL BOUNDARY ACROSS THE OH VALLEY TUE...THEN INTO THE MID ATLANTIC STATES THU. THE 00Z CMC WAS CLOSER WITH IS SURFACE SOLUTION WITH THE WAVE CROSSING THE OH VALLEY WED/THU...SO IT WAS INCLUDED IN THE PREFERENCE. GIVEN THE GOOD MODEL AGREEMENT...A GENERAL MODEL BLEND WAS PREFERRED WITH THESE SYSTEMS. ...DEEP CLOSED LOW APPROACHING THE PACIFIC NORTHWEST THU... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE A CLOSED MID LEVEL LOW OVER THE NORTHERN GULF OF AK EARLY TUE TRACKS SOUTHEAST WED...REACHING A POSITION OFF THE PACIFIC NORTHWEST COAST BY EARLY FRI. THE 00Z NAM WAS A BIT SLOWER THAN THE CONSENSUS...WHILE THE 00Z GFS WAS A BIT FASTER (AS WAS THE 00Z ECMWF/12Z ECMWF ENSEMBLE MEAN). THESE DIFFERENCES ARE FAIRLY MINOR... CONSIDERING IT IS A DAY 3 FORECAST. WITH THIS IN MIND...A GENERAL MODEL BLEND IS PREFERRED WITH THIS SYSTEM. WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML... /ALL LOWER CASE/ WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML... /ALL LOWER CASE/ HAYES