MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 201 PM EST TUE NOV 22 2016 VALID NOV 22/1200 UTC THRU NOV 26/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION INCLUDING MODEL PREFERENCES AND FORECAST CONFIDENCE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ LOW PRESSURE OVER NEW ENGLAND...EXITING INTO THE ATLANTIC TODAY/WED ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL BLEND CONFIDENCE: ABOVE AVERAGE ONLY MINOR DIFFERENCES EXIST WITH THE LATEST GUIDANCE SUCH THAT A GENERAL MODEL BLEND IS PREFERRED TO SMOOTH OUT SMALLER SCALE DIFFERENCES. SHORTWAVE TROUGH ENTERING THE PLAINS TODAY WITH SURFACE LOW MOVING FROM THE PLAINS TO GREAT LAKES TUE-THU ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL BLEND CONFIDENCE: ABOVE AVERAGE WV LOOP INDICATES MATURE WAVE CROSSING THE CENTRAL PLAINS... MODELS ARE IN AGREEMENT OVERALL AS THE INNER CORE WEAKENS AN THE TROF UNFOLDS N-S. THE TROF EVENTUALLY SHEARS AS IT PIVOTS THROUGH THE GREAT LAKES THURSDAY WITH WEAK EXTENSION CROSSING THE SOUTHEAST. THERE ARE MINOR SMALLER SCALE DIFFERENCES WITHIN THE DETERMINISTIC SUITE BUT SEEM MINOR AND EQUALLY PLAUSIBLE. THE ONLY OUTLIER REMAINS THE 00Z CMC WHICH HAS A WEAKER REFLECTION THROUGH THE GREAT LAKES BUT SLOWER BUT MORE VIGOROUS BASE CROSSING THE SOUTHEAST. WOULD CONSIDER THIS RUN TO BE A BIT OUT OF SPEC WITH CURRENT ENSEMBLE SUITE TO INCLUDE IN A BLEND. CONFIDENCE IS SLIGHTLY ABOVE AVERAGE IN THIS NON-CMC BLEND. 19Z UPDATE: WHILE THE 12Z CMC REMAINS A BIT SLOWER IT IS NO LONGER SIGNIFICANTLY SO...SHOWING SIMILARITIES CLOSEST TO THE 12Z UKMET AND GFS. AS SUCH WILL SUPPORT A GENERAL MODEL BLEND AT ABOVE AVERAGE CONFIDENCE. UPPER TROUGH CROSSING THE WEST COAST TUE NIGHT REACHING THE CENTRAL PLAINS THURS AND BROADENING OVER THE GREAT LAKES BY LATE FRIDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL BLEND CONFIDENCE: AVERAGE THE TROF ENTERING THE WEST COAST AT PRESENT TRANSLATES ACROSS THE INTERMOUNTAIN WEST EXITING INTO THE CENTRAL PLAINS THURSDAY. THE 00Z CMC THOUGH TRENDING TOWARD OTHER GUIDANCE CONTINUES TO BE SLIGHTLY WEAKER MAKING IT ALSO A FASTER MEMBER OF THE GUIDANCE. THE 00Z UKMET ALSO CONTINUES TO PRODUCE A VERY SMALL BUT VIGOROUS BASE TO THE WAVE LEADING TO A DEEPER SLOWER REFLECTION CROSSING THE CENTRAL PLAINS. THE MODELS DRAW SHORTWAVE ENERGY OUT OF S CENTRAL CANADA TO HELP BROADEN THE TROF AS IT LIFTS INTO THE GREAT LAKES BY FRIDAY. THE 12Z NAM CONTINUES FROM PRIOR RUNS TO LIFT FASTER OUT OF THE CENTRAL PLAINS...THIS COMBINED WITH A DEEPER/CONSOLIDATED S/W OUT OF CANADA (A TYPICAL NEGATIVE BIAS BY DAY 3) LEADS TO SOME CONCERN/UNCERTAINTY BY THE END OF DAY 3. THE 12Z GFS DOES SHED SOME CREDENCE TOWARD THE NAM SOLUTION HOWEVER AS IT HAS TRENDED FASTER CROSSING THE CENTRAL PLAINS WITH THE LEAD WAVE AND INDICATES A STRONG/MORE CONSOLIDATED WAVE EMERGING OUT OF S CENTRAL CANADA TO SUPPORT A DEEPER/WEST AXIS OF THE TROF IN THE GREAT LAKES TRENDING AWAY FROM 00Z/06Z GEFS AND 00Z ECENS MEANS. THE 00Z ECMWF IS FURTHER SOUTH INITIALLY WITH THE NORTHERN STREAM SHORTWAVE AND THOUGH SLIGHTLY SLOWER OUT OF THE CENTRAL PLAINS WITH THE BASE OF THE TROF...THERE IS REDUCED SPACING OVERALL SHOWING A MORE CONSOLIDATED WAVE INTO THE GREAT LAKES FRIDAY INTO SAT. WHILE THE NAM APPEARS SIMILAR THE GFS...THE GFS APPEARS MORE SENSIBLE WITH THE MAGNITUDES OF THE WAVE. TO ENCOMPASS THESE EVOLUTIONS WILL SUPPORT A 2/3 00Z ECMWF AND 1/3 12Z GFS BLEND AT SLIGHTLY BELOW AVERAGE CONFIDENCE. 19Z UPDATE: THE NON-NCEP SOLUTIONS TRENDED TOWARD THE SHIFT NOTED IN THE 12Z NAM/GFS SHOWING INCREASED SPACING OF THE BASE ENERGY FROM THE CENTRAL PLAINS AND THE NORTHERN STREAM SHORTWAVE. WHILE THE 12Z UKMET AND ECMWF ARE A BIT FASTER AND FURTHER NORTH WITH THE NORTHERN STREAM WAVE WHILE THE 12Z CMC IS SLOWER BUT MORE ON THE SOUTHERN TRACK LIKE THE GFS/NAM; THIS LEADS TO INCREASED MODEL AGREEMENT WITH THE EVOLUTION TREND YET INTERNAL TIMING/PLACEMENT DIFFERENCES REMAIN. WILL SUPPORT A GENERAL MODEL BLEND THOUGH CONFIDENCE IS ONLY AVERAGE AS THE SPREAD REMAINS BROAD THROUGH DAY 3. AMPLIFYING TROF OFF THE WEST COAST FRIDAY (INCLUDING LEAD S/W & SFC LOW CLIPPING NW ON THURS NIGHT/FRIDAY MORNING) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL BLEND UP TO 25/12Z 12Z ECWMF/CMC/GEFS AND 00Z ECENS MEAN BLEND AFTERWARD CONFIDENCE: AVERAGE UP TO 25/12Z...SLIGHTLY BELOW AVERAGE AFTER THE APPROACH OF STRONG JET STREAK ON WED EVENING TOWARD VANCOUVER ISLAND SHOULD SUPPORT THE DEVELOPMENT OF A SOLID/STRONG UPPER LOW ON THE NORTHERN ROTOR OF THE JET STREAK BY THURSDAY JUST WEST OF HAIDA GWAII (QUEEN CHARLOTTE ISLANDS). THE 12Z NAM IS THE ONLY PIECE OF GUIDANCE NOT PRESENTING THIS DEEP INNER CORE... MAKING IT SUSPECT. WHILE THE TIMING OF THE SHORTWAVE NEARING THE COAST THURSDAY EVENING/FRIDAY MORNING IS IN LINE WITH OTHER SOLUTIONS...WITHOUT THE INNER CORE...A VERY DEEP SURFACE REFLECTION RESULTS. THE OTHER SIGNIFICANT OUTLIER: THE 00Z CMC, IS UNCHARACTERISTICALLY FAST IN DESCENDING IN LATITUDE AND SHIFTING EASTWARD OVERALL EVEN MORE SO THAN THE 12Z NAM. SPREAD IN THE REMAINING MODELS DEPEND ON THE SHARPNESS OF THE TROF AS THE INNER CORE DEVOLVES AND THE TROF AS A WHOLE AMPLIFIES NEARING THE WEST COAST FRIDAY. THE 00Z ECMWF IS A BIT BROADER AND FORWARD LEANING. THE 12Z GFS CONTINUES TO TREND SLOWER AND A BIT SHARPER AMPLIFIED FURTHER WEST BY THE 00Z SAT. THIS TREND WAS SUPPORTED BY THE 12Z NAM...SO IT IS POSSIBLE UPSTREAM DATA INGESTION IS SUPPORTING THIS TREND AND WILL WAIT FOR 12Z UKMET/ECMWF/CMC/GEFS FOR FURTHER CONFIRMATION. THE 00Z UKMET IS CLOSER TOWARD THE ECMWF SOLUTION OVERALL AND THE ENSEMBLE SUITES GENERALLY SUPPORT THEIR OPERATIONAL RUN. STILL GIVEN THE UNCERTAINTY BY FRIDAY WILL SUPPORT A 12Z GFS AND 00Z UKMET/ECMWF BLEND BUT WILL FAVOR TOWARD THE CONTINUITY OF THE ECMWF/UKMET BUT CONFIDENCE REMAINS SLIGHTLY BELOW AVERAGE OVERALL (BUT MORE SO AFTER 00Z FRIDAY). 19Z UPDATE: MODEL CONSENSUS IN EVOLUTION SEEMS TO BECOMING INTO BETTER FOCUS AS ALL 12Z DETERMINISTIC RUNS SUPPORT A TIGHT SPIN UP NEAR WA COAST WITH RAPID SURFACE DEEPENING EARLY FRIDAY MORNING...SO CONFIDENCE IS IMPROVING WITH THIS PORTION OF THE LARGER SYSTEM. SPREAD REMAINS IN THE DEVOLUTION OF THE INNER CORE AND SOUTHWARD EXTENSION OF THE TROF AFFECTING NEAR/OFFSHORE OR/CA BY THE END OF DAY 3. THE NON-NCEP SOLUTIONS HAVE TAKEN A HINT FROM THE 12Z GFS/NAM SOLUTIONS SUPPORTING A DEEPER/SHARPER AMPLIFICATION OVERALL WITH THE ECMWF LESSER SO. THOUGH THE 12Z UKMET AND CMC ARE CLEARLY OUTPACING EASTWARD ADVANCEMENT OF THE TROF THAN THE GFS/NAM. HOWEVER THE ECMWF SPLITS THE DIFFERENCE IN AWAY WITH A BROADER TROF SOLUTION...THE 12Z GEFS MEAN DOES SHOW A BROADER TROF AS WELL...BUT THIS IS INDICATIVE OF THE SPREAD IN THE TIMING/PLACEMENT OF THE TROF AXIS. CONTINUITY/TIMING AND ENSEMBLE MEANS ARE BEST REFLECTED BY THE 12Z ECMWF/CMC SOLUTIONS AS A WHOLE AFTER 25/12Z. ALL CONSIDERED A GENERAL MODEL BLEND IS SUPPORTED PRIOR TO 25/12Z AT AVERAGE CONFIDENCE FOLLOWED BY A 12Z ECMWF/CMC/GEFS AND 00Z ECENS MEAN BLEND AT SLIGHTLY BELOW AVERAGE CONFIDENCE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... GALLINA