MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1234 AM EDT TUE OCT 27 2015 VALID OCT 27/0000 UTC THRU OCT 30/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION WITH FORECAST PREFERENCES AND CONFIDENCE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ REMAINING TROF ENERGY ALONG THE GULF SHEARING INTO THE MAIN STREAM ACROSS THE SOUTHERN APPALACHIANS AND MID-ATLANTIC ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-NAM BLEND CONFIDENCE: ABOVE AVERAGE THE MODELS REMAIN IS STRONG AGREEMENT WITH THE UPPER LEVEL TROF ENERGY SHEARING INTO THE STRENGTHENING/DEEPENING UPSTREAM MAIN TROF. THE TRACK OF THE SURFACE LOW ACROSS W MS BEFORE TRANSFERRING TO THE UPSTREAM SURFACE LOW ACROSS IL BY WED IS ALSO QUITE AGREEABLE EXCEPT THE 00Z NAM WHICH REMAINS WEST OF THE MISSISSIPPI RIVER WHILE WEAKENING BEFORE THE UPSTREAM ENERGY TAKES OVER. ALL FEATURES GENERALLY WEAKEN TO THE POINT OF RESOLUTION BY 28/12Z OVER THE MID-ATLANTIC WITH AGREEMENT OF PLACEMENT/TIMING OF QPF AND MUCH OF THE SENSIBLE WEATHER FIELDS...TO SUPPORT AN OPERATIONAL MODEL BLEND AT ABOVE AVERAGE CONFIDENCE. AMPLIFIED AND SLIGHTLY NEGATIVE TILTED TROF CROSSING THE ROCKIES WRAPPING INTO A DEEP CYCLONE OVER GREAT LAKES BY THURS...ASSOCIATED SURFACE DEVELOPMENT IN THE MID-MISSISSIPPI VALLEY COMBINING WITH CANADIAN LOW OVER THE GREAT LAKES/ONTARIO ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF OPERATIONAL MODELS CONFIDENCE: SLIGHTLY ABOVE AVERAGE WITH MUCH OF THE TROF ENERGY WITHIN CONTINENTAL NORTH AMERICA...INITIALIZATION AND EARLY EVOLUTION OF THE LARGE SCALE TROF ACROSS THE CENTRAL U.S. HAVE BECOME AGREEABLY RESOLVED AFTER SUCH A TUMULTUOUS PAST FEW DAYS. ENSEMBLE SPAGHETTI PLOTS AND SURFACE LOW CLUSTERS ARE MUCH MORE CONSOLIDATED TO SUPPORT BLENDING MODELS WITH STRONG ALIGNMENT WITH THE 12Z ECENS MEAN/18Z GEFS/12Z CMCE AND 21Z SREF. THE 00Z NAM AS MENTIONED ABOVE...IS A BIT WEST OF THE BEST CLUSTERING PULLING THE GULF LOW NORTHWARD...THIS ALLOWS FOR A BIT OF INCREASE OF INTERACTION EARLIER WITH THE BASE OF THE TROF...WHICH KEEPS A WESTERN TRACK BUT COMES BACK TOWARD BETTER CLUSTERING WED AFTERNOON. ABOUT THURS 29/12Z... THE 00Z GFS AND NAM ALONG WITH THE 12Z UKMET BECOME A BIT FAST WITH THE S/W ACROSS NEW ENGLAND COMPARED TO A BIT SLOWER 12Z CMC/ECMWF. TO BE EXPECTED THE 12Z ECENS MEAN AND 18Z GEFS ARE NOT AS AMPLIFIED WITH THE WAVE...BUT APPEAR A BIT FASTER IN LINE WITH THE 00Z GFS/NAM AND UKMET WHILE THE 21Z SREF FAVORS THE SLOWER CMC. OVERALL IT DOES NOT APPEAR TO HAVE TOO MUCH APPRECIABLE DIFFERENCES TO FAVOR ONE CAMP OVER THE OTHER OR LEAD TO SIGNIFICANT IMPACT DIFFERENCES TO FAVOR AN OVERALL BLEND. OVERALL CONFIDENCE IS GREATLY INCREASED WITH THIS TIGHT PACKING OF SOLUTIONS...HOWEVER WITH ALL THE PIECES OF ENERGY IN THE TROF IMPACTING TIMING DIFFERENCES...FULL CONFIDENCE CANNOT BE WARRANTED JUST YET. AS SUCH IT IS SLIGHTLY ABOVE AVERAGE. NEXT LONG WAVE TROF AFFECTING THE CANADIAN/U.S. PACIFIC COAST BY WED ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF 12Z ECWMF/00Z ECENS MEAN CONFIDENCE: SLIGHTLY BELOW AVERAGE A BIT BETTER AGREEMENT IS STARTING TO RESOLVE WITH TROF ENERGY APPROACHING THE WEST COAST WED. DIFFERENCES APPEAR TWO FOLD IN THE EVOLUTION OF THE SOUTHWEST TROF. THE FIRST INVOLVES THE TIMING OF THE CENTROID OF ENERGY SHIFTING SOUTH ALONG THE CA TO DIG THE SOUTHWEST TROF WHILE THE SECOND RELATES TO THE TIMING OF SHORTWAVE ENERGY WITHIN THE FAST ZONAL ANGLED TOWARD THE CANADIAN COAST THURSDAY...SLIDING DOWN THE WEST COAST TO REINFORCE THE SOUTHWEST TROF. THE 12Z ECMWF AND GEFS (LESSER SO) ENSEMBLE MEANS APPEAR TO BE A BIT MORE PROGRESSIVE AND SHALLOWER WITH THE DEPTH OF THE TROF WHILE THE OPERATIONAL GUIDANCE TREND TOWARD A DEEPER SW SOLUTION PARTICULARLY THE 12Z CMC AND A BULK OF THE CMCE MEMBERS. THE 00Z NAM APPEARS TO HAVE PLACEMENT DIFFERENCES WITH THE INITIAL WAVE COMPARED TO MUCH OF THE OTHER GUIDANCE...LOSING SOME TOWARD THE NORTH AND BREAK DOWN OF THE ROCKIES RIDGE ON WED NIGHT. THIS RESULTS IN A WEAKER SLOWER DIGGING OF THE WESTERN TROF. THE 12Z UKMET RESOLVES THE INITIAL ALONG THE CA COAST QUITE STRONG AND DEEPENS THE TROF IN LINE WITH THE 12Z CMC THOUGH A BIT FASTER/EAST...TYPICAL OF ITS BIAS AS WELL AS THE CMC BIAS OF DEEPER AND SLOWER. THE 00Z GFS AND 12Z ECMWF HAVE A SIMILAR DEVELOPMENT IN TIMING/DEPTH AND GENERALLY MIDDLE GROUND WITH THE OTHER DETERMINISTIC RUNS. PREFERENCE IS TO BLEND THE 00Z GFS/ECMWF BUT GIVEN THE DEPARTURE FROM THEIR ENSEMBLE MEANS CONFIDENCE REMAINS LESS THAN AVERAGE...WITH NO OTHER OPERATIONAL RUN SUPPORTING THE 12Z/ECENS AND GEFS MEAN AND THE 18Z GEFS SHIFTING WEST THOUGH NOT AS DRAMATIC AS THE OPERATIONAL RUNS...CONFIDENCES IS BOLSTERED A BIT IN THE BLEND. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... GALLINA