MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 248 AM EDT THU OCT 22 2015 VALID OCT 22/0000 UTC THRU OCT 25/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z FINAL MODEL EVALUATION...INCLUDING PREFERENCES AND CONFIDENCE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ CLOSED MID LEVEL SYSTEM CROSSING EASTERN CANADA SURFACE FRONT CROSSING THE EASTERN UNITED STATES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF OPERATIONAL MODELS CONFIDENCE: ABOVE AVERAGE EXTREMELY TIGHT 12Z ENSEMBLE SURFACE LOW CLUSTERING AS WELL AS OVERALL MODEL AGREEMENT OF PLACEMENT/TIMING OF THE FRONT AS IT CROSSES NEW ENGLAND BY FRIDAY. ONLY SMALL DIFFERENCES EVOLVE WITH THE DEPTH OF THE UPPER LEVEL TROF WITH THE 00Z RUNS (GFS/UKMET SHALLOW -- ECMWF/NAM DEEPER) ALONG THE SOUTHEAST CANADIAN PROVIDENCES INTO THE GULF OF MAINE AND OFFSHORE BY FRIDAY THAT DO NOT APPEAR TO HAVE MUCH IMPACT OTHERWISE TO CONTINUE SUPPORTING A BLEND OF OPERATIONAL MODELS OVERALL AT ABOVE AVERAGE CONFIDENCE. CLOSED MID LEVEL LOW OVER THE SOUTHWEST LOW PRESSURE TRACKING TO THE GREAT LAKES SAT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF THE 00Z UKMET/ECMWF CONFIDENCE: AVERAGE RUN TO RUN CONSISTENCY SEEMS TO BE PAR FOR THE COURSE WITH THE GLOBAL MODELS...BUT AS WE HAVE SEEN IS NOT PARTICULARLY COMFORTING GIVEN THE REMAINING LARGE SPREAD IN THE GUIDANCE. ALSO...THE GLOBAL MODELS APPEAR TO REPRESENT THEIR ENSEMBLES QUITE WELL WHICH DOES NOT PROVIDE MUCH HELP IN CONFIDENCE OR PREFERENCE ASSIGNMENT. THE 00Z NAM QUICKLY BECOMES TIGHTLY CONSOLIDATED WITH THE UPPER LOW OVER NE COLORADO WHICH REMAINS OUT OF SYNC WITH THE MAJORITY OF THE MAIN GLOBAL MODELS...AND AS SUCH DELAYS EASTWARD MIGRATION OVER THE NORTHERN PLAINS...DEVELOPING THE SURFACE REFLECTION WELL SOUTH OF THE MAIN SURFACE LOW CLUSTER. THE 00Z GFS CONTINUES ITS CONTINUITY TREND TO BE THE FIRST GLOBAL MODEL TO LIFT NORTH A BIT WEAKER AND PHASE WITH NORTHERN STREAM ENERGY...THIS ALSO ALLOWS IT TO LEAD/BE FASTER IN EASTERN PROGRESSION WITH THE SURFACE REFLECTION. THE 00Z UKMET IS FAIRLY CLOSE TO THE GFS THOUGH NOT AS WEAK ALLOWING A BIT SLOWER SURFACE SOLUTION MORE IN LINE WITH THE 00Z ECMWF...WHICH CONTINUED GOOD CONTINUITY SO WILL CONTINUE PREFERENCE HERE. THE 00Z CMC IS SLOW AND DOES NOT PHASE WITH NORTHERN STREAM ENERGY BUT DRAWS IT SOUTH TO DEEPEN THE UPPER LOW BY THE END OF THE PERIOD...MAKING IT CLEARLY OUT OF PHASE AS DRAMATICALLY AS THE 00Z NAM. AS SUCH A BLEND OF THE 00Z UKMET/ECMWF IS PREFERRED AT AVERAGE CONFIDENCE. LONG WAVE TROUGH ENTERING THE PACIFIC NORTHWEST SAT/SUN ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z ECMWF CONFIDENCE: BELOW AVERAGE THE EARLIER RUNS OF THE NAM AND GFS HAVE BEEN QUITE PROGRESSIVE WITH THE TROF AND ASSOCIATED SURFACE LOW APPROACHING THE WEST COAST BY THE END OF THE PERIOD. THE 00Z NAM/GFS AND UKMET HAVE CONTINUED THE TREND BUT HAVE SLOWED TOWARD THE ECMWF/CMC CAMP. THE 00Z GFS IS REMAINS STRONG WITH THE TROF AND SURFACE LOW WHILE THE NAM HAS WEAKENED CONSIDERABLY...WHICH RESULTS IN A SURFACE LOW THAT IS MUCH FURTHER WEST (AND NEARLY 10 MB WEAKER BY THE END OF DAY 3). THE 00Z UKMET IS ALSO QUITE AGREEABLE WITH THE HIGHLY AMPLIFIED NEARLY CUT-OFF TROF AND THE SURFACE LOW AND COMPARABLE TO THE 00Z GFS...BUT IS A TAD SLOWER WHICH IS ATYPICAL OF ITS BIAS...POTENTIALLY INDICATING THE GFS MAY STILL TOO FAST. THE 00Z ECMWF CONTINUED THE SOUTHWARD TREND BUT SLOWED A BIT TOWARD ITS 21/00Z RUN...THOUGH PROVIDING MUCH BETTER CONTINUITY THAN OTHER GUIDANCE. THE 00Z CMC APPEARS TO BE THE MOST DRAMATIC OUTLIER AS IT LAGS/DEEPENS AND CUTS OFF THE UPPER LOW SW OF EVEN THE 00Z ECMWF. GIVEN CONSISTENCY WITH THE 12Z ECENS MEAN AND ITS PRIOR RUNS AND THE LARGE SPREAD...THE PREFERENCE IS 00Z ECMWF (AND WEIGHTED WITH THE 12Z ECENS MEAN IF AVAILABLE) BUT WITH BELOW AVERAGE CONFIDENCE. SHORTWAVE CROSSING THE SOUTHWEST STATES FRI AND SOUTHERN PLAINS SAT CAPTURING ENERGY FROM TROPICAL CYCLONE PATRICIA INTO S TEXAS BY SAT/SUN ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF 00Z GFS/12Z ECMWF CONFIDENCE: SLIGHTLY ABOVE AVERAGE WITH THE MAIN UPPER LOW LIFTING OUT...A SHORTWAVE OUT OF THE PACIFIC DROPS ACROSS CA INTO THE SOUTHWEST BY FRIDAY KEEPING A WEAK POSITIVE TILT TROUGHING OVER THE SOUTHWEST. THE 00Z CMC REMAINS STRONG AND FAST WITH THIS FEATURE MAKING IT A QUICK OUTLIER AND OUT OF PHASE WITH MUCH OF THE OTHER GUIDANCE AND ENSEMBLE MEMBERS. THE REMAINING GLOBAL MODELS THEN BEGIN TO CAPTURE SOME OF THE ENERGY FROM TROPICAL CYCLONE PATRICIA. THE 00Z GFS AND 12Z ECMWF HAVE REMARKABLE SIMILARITIES WITH THE TROF STRENGTH AND ORIENTATION...AS THE TC ENERGY LIFTS THROUGH CENTRAL MEXICO INTO S TX...IN LINE WITH CURRENT NHC FORECAST TRACK. THE 00Z UKMET ON THE OTHER HAND IS QUITE FAST WITH THE TC ENERGY LIFTING NORTH AND THIS ALLOWS FOR A DEEPER UPPER LEVEL CYCLONE TO EVOLVE OVER NW MEXICO. THIS IS OPPOSITE OF THE 00Z NAM WHICH IS VERY WEAK WITH THE TC ENERGY AND ALLOWS THE S/W TO SHIFT EAST ACROSS TX WITH VERY LITTLE AMPLIFICATION RESOLVED. THE 00Z ECMWF IS SIMILAR THOUGH A SHADE FASTER WITH TC PATRICIA'S ENERGY. STILL A BLEND OF THE 00Z GFS/ECMWF IS PREFERRED AT SLIGHTLY ABOVE AVERAGE CONFIDENCE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... GALLINA