MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 250 AM EDT MON OCT 26 2015 VALID OCT 26/0000 UTC THRU OCT 29/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ COMBINED SHORTWAVE ENERGY INCLUDING REMNANTS OF TC PATRICIA CROSSING THE NORTHWESTERN GULF COAST SHEARING INTO TENNESSEE RIVER VALLEY TUES/WED BECOMING DRIVEN MORE BY THE UPSTREAM TROF AFTER 28/00Z ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-NAM BLEND PRIOR TO 28/00Z CONFIDENCE: ABOVE AVERAGE THE MODELS ARE IN GOOD AGREEMENT WITH THE PLACEMENT/STRENGTH AND EVOLUTION OF THE GULF COAST LOW AND UPPER LEVEL TROF WITH WELL PRESENTED BAROCLINIC LEAF ON WV CURRENTLY. DIFFERENCES START TO OCCUR IN TIMING OF SHEARING/WEAKENING OF THE UPPER LEVEL TROF AND SURFACE LOW LATE TUESDAY AS THEY BEGIN TO LIFT NORTHWARD UNDER THE INFLUENCE OF THE APPROACHING UPSTREAM WAVE. THE DIFFERENCES ON TUESDAY ARE MAINLY DUE TO THE SPEED OF SUBTROPICAL SHORTWAVE ENERGY CURRENTLY OVER S CA/S NV...THE 00Z NAM IS A BIT EAST OF THE STRONGEST SFC TO 7H CYCLONE AND WITH A STRONGER/FASTER SHORTWAVE...LIFTS AND SHEARS FASTER...OTHERWISE THE ENSEMBLE MEANS AND 00Z GFS AND 12Z CMC/ECMWF/UKMET ARE TIGHTLY CLUSTERED BEFORE THE 7H LOW FILLS AND IS REPLACED FURTHER NORTH AND WEST. THIS CONTINUED WITH THE 00Z CMC/ECMWF AND UKMET. SO FOR THIS CYCLONE'S ENERGY...A NON-NAM BLEND IS SUPPORTED PRIOR TO 28/00Z AT ABOVE AVERAGE CONFIDENCE. AFTERWARD...OVERALL MASS FIELDS/QPF ARE QUITE SIMILAR WITH THE SHEARING OUT 5H ENERGY ACROSS THE TENNESSEE RIVER VALLEY AND MID-ATLANTIC WITH TRAILING FRONTAL BOUNDARY THROUGH FLORIDA. AFTER 28/00Z PLEASE SEE PREFERENCES/DISCUSSION BELOW FOR BAROCLINIC RE-DEVELOPMENT OF THE SURFACE LOW OVER THE MID-MISSISSIPPI VALLEY INTO THE SW GREAT LAKES. HIGHLY AMPLIFIED TROF ACROSS THE WEST COAST EJECTING INTO THE PLAINS TUES; 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 00Z GFS/ECMWF CONFIDENCE: AVERAGE LOOSELY PHASED AMPLIFIED TROF CURRENTLY EXISTS FROM THE WESTERN CANADIAN COAST THROUGH NORTHERN BAJA CALIFORNIA...CONSISTING OF THREE DISTINCT WAVE PACKETS...EACH PLAYING A SIGNIFICANT ROLE IN THE EVOLUTION OF A BROADER NEGATIVE TILTED TROF BY WED MORNING ACROSS THE CENTRAL U.S...AND EVENTUALLY CONSOLIDATING INTO A LARGE STRONG UPPER LOW OVER THE WESTERN GREAT LAKES BY THE END OF THE PERIOD: SOUTHERN SUBTROPICAL, YUKON TERRITORY RIDGE TOPPING ENERGY AND NORTHWEST U.S. WEAKENED CLOSED LOW CURRENTLY OVER CENT OR. OVERALL THE AGREEMENT AT 29/12Z IS REMARKABLY SIMILAR HOWEVER THE EVOLUTION TO GETTING TO THAT POINT IS WHERE THE SPREAD EXISTS. THE INITIAL SALVO STARTS WITH THE SOUTHERN WAVE CURRENTLY OVER S CA/S NV OUT OF THE SUBTROPICAL STREAM GENERALLY OUTPACES THE OTHER FEATURES INCREASING THE BREADTH OF THE BASE OF THE TROF AS IT EJECTS AND SWINGS NE ACROSS THE CENTRAL PLAINS WED...DRAWING THE REMNANTS OF THE GULF COASTAL SYSTEM NORTH WHILE REDEVELOPING A DEEP SURFACE CYCLONE OUT OF MISSOURI. THE 00Z NAM TYPICAL OF ITS BIAS IS A BIT STRONGER RESOLVED THAN THE OTHER GLOBAL GUIDANCE...AND DRAWS THE ENERGY NORTHWARD AND DEEPENS IT FIRST/FASTER PLACING THE TRACK WEST OF THE ENSEMBLE MEAN CLUSTER AS WELL AS THE GFS/ECMWF/UKMET AND CMC...UNTIL COMING BACK INTO BETTER ALIGNMENT AROUND 29/00Z THURSDAY WITH COMBINATION OF NORTHERN STREAM SURFACE LOW OVER THE GREAT LAKES. THE 12Z SUITE OF THE ECMWF/CMC AND UKMET ALL ARE A BIT FASTER WITH THE CENTRAL OR SHORTWAVE DIGGING SW ACROSS THE CENTRAL ROCKIES INTO THE TENNESSEE RIVER VALLEY AND MID-ATLANTIC BY THURSDAY MORNING WHILE THE 00Z NAM LAGS A BIT AND THE 00Z GFS IS SLOWEST. HOWEVER...ALL THREE 00Z RUNS OF THE UKMET/CMC/ECWMF SLOWED TOWARD THE 00Z NAM SOLUTION WITH THE ECMWF NEARLY ON PACE WITH THE 00Z NAM. THIS ALSO IMPACTED THE RELATIVE SPEED AND DEPTH OF THE NORTHERN CANADA ENERGY AND WAS DISAGREEING WITH THE RELATIVELY STRONG AGREEMENT OF THE ENSEMBLE MEANS 12Z ECENS MEAN 12Z/18Z GEFS AND 21Z SREF. THE 00Z BACKED OFF AND SHIFTED BACK TOWARD THE ENSEMBLES...WITH MUCH STRONGER AGREEMENT COMING FROM THE 00Z ECMWF. THE UKMET AND CMC THOUGH SLOWER WERE A BIT STRONGER WITH THE NW US WAVE ENERGY WHICH ALLOWED AN EARLIER DIGGING OF THE MAIN NORTHERN CANADIAN WAVE A BIT DEEPER THAN THAN THE 00Z ECMWF. THE 00Z GFS IS GENERALLY WEAKER WITH THE NORTHERN ENERGY WAS AND SLOWER TO DEEPEN AND DROP SOUTH PUTTING IT OUT OF PHASE WITH THE OTHER DETERMINISTIC MODELS...BUT IN AGREEMENT WITH THE ENSEMBLE MEANS. THE 00Z NAM ACTUALLY WAS A MIDDLE GROUND FOR THIS NORTHERN STREAM ENERGY...BUT NOW THE UKMET AND CMC AGREE WITH THAT AND THE 00Z ECMWF SHIFTED FURTHER TOWARD THE 00Z GFS AND ENSEMBLES. THESE OVERALL TRENDS TOWARD THE ENSEMBLES AND 00Z GFS...STRENGTHENED CONFIDENCE TOWARD A 00Z GFS/ECMWF BLEND WHICH REPRESENTS THE ENSEMBLES WELL. NEXT LONG WAVE TROF AFFECTING THE CANADIAN/U.S. PACIFIC COAST BY WED ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF 00Z ECWMF/12Z ECENS MEAN CONFIDENCE: BELOW AVERAGE SIMILAR TO THE CENTRAL U.S....THE WESTERN U.S. IS PROBLEMATIC WITH THE NCEP MODELS AND ECMWF/CMC/UKMET SHOWING SIGNIFICANT DIFFERENCES...BUT THE 00Z RUNS OF THE ECMWF/UKMET HELD THEIR GROUNDS ON THE WHOLE WITH HANDLING THE PACIFIC TROF. DIFFERENCES IN TIMING OF THE BREAK DOWN OF THE ROCKIES HIGHLY AMPLIFIED RIDGE SEEM TO DETERMINE THE TIMING/DEPTH OF THE TROF. OVERALL SPAGHETTI PLOTS HAVE BEEN TRENDING TOWARD A DEEPER TROF THAT WAS LEAD BY THE ECMWF FOR THE LAST FEW DAYS...AND SIMILARLY THE 00Z ECMWF CONTINUED THE TREND THOUGH WAS A BIT FASTER AND LESS DEEP THAN ITS 12Z PREDECESSOR. THERE IS CONTINUED SUPPORT FROM THE 00Z CMC AND UKMET...BUT NOW THE 00Z UKMET IS STRONGEST WITH A SMALL CUT-OFF OVER S CA AND THE CMC IS DEEPER INTO NORTHERN BAJA. THE SHIFT IN THE TREND IS THE RETENTION OF THE RIDGE IN A FEW OF THE CMC AND ECMWF ENSEMBLE MEMBERS DROPPING THE BULK OF ENERGY SOUTHWARD. THE 00Z GFS IS SLOWER WITH THE TROF BUT MAJORLY DIFFERENT IN PLACING THE ENERGY IN THE NORTHERN PORTION OF THE TROF. THE 00Z NAM IS CENTRAL TO BOTH CAMPS BEING A BIT FASTER THAN THE 00Z GFS BUT A LITTLE SLOWER THAN THE 12Z ECMWF. CONTINUITY FAVORS THE ECMWF AND ECENS MEAN...AND WITH THE 00Z GFS BEING AN OUTLIER...SEE NO REAL REASON TO SHIFT TOWARD THE GFS YET. ALSO THE ECMWF/NAM/CMC/UKMET ALL HANDLE THE CIRCULATION OF OLAF SIMILAR...WHILE THE GFS HAS SLOWED AND TRENDED TOWARD THAT SOLUTION AS WELL...BEING LESS CONFIDENT IN ITS OWN PRIOR RUNS. AS SUCH THE BLEND REMAINS 00Z ECMWF WITH THE 12Z ECENS MEAN BUT AT BELOW AVERAGE CONFIDENCE KEEPING WITH CONTINUITY AND TRANSITION FROM MEDIUM RANGE PREFERENCES. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... GALLINA