MODEL DIAGNOSTIC DISCUSSION...CORRECTION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 814 AM EDT THU OCT 13 2016 VALID OCT 13/0000 UTC THRU OCT 16/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION WITH FINAL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. REJUVENATED POST-TROPICAL CYCLONE SONGDA FORECAST TO REACH THE PACIFIC NORTHWEST SAT EVENING CORRECTION TO SONGDA'S LONGITUDE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS...12Z UKMET...00Z UKMET COMPROMISE CONFIDENCE: BELOW AVERAGE THERE IS HIGH CONFIDENCE IN A STRONG STORM SYSTEM TO IMPACT THE WEST COAST SAT INTO SUN...WITH THE STORM TIED TO POST TROPICAL CYCLONE SONGDA...LOCATED NEAR 38N 166E AT 00Z/13 WITH A CENTRAL PRESSURE OF 970 MB. A FAST ZONALLY ORIENTED PACIFIC JET STREAM...WITH AN ELONGATED 150-170 KT CORE...SHOULD ALLOW THE SYSTEM TO QUICKLY TRACK TOWARD THE WEST COAST. HOWEVER...MANY OF THE GEFS/CMC/ECMWF ENSEMBLE LOWS HAVE BEEN FOCUSED AROUND 47N 128W AT 00Z/16...WEST OF THE NON NCEP DETERMINISTIC GUIDANCE. THE 00Z GFS AND 00Z UKMET ARE STRONGEST WITH SUB 960 MB LOW CENTERS WEST OF WASHINGTON/OREGON BY 00Z/16. THE 00Z NAM APPEARS UNSUPPORTED ALOFT BY THE LATEST ENSEMBLE GUIDANCE WITH A FLATTER UPPER LOW WEST OF BRITISH COLUMBIA. THE 12Z ECWMF SHOWS A FASTER/MORE-SOUTH SURFACE LOW RELATIVE TO THE 00Z GFS BY 12Z/15...WHICH CARRIES FORWARD TOWARD THE COAST WITH A SOMEWHAT WEAKER LOW RELATIVE TO THE REMAINING DETERMINISTIC GUIDANCE. THE 00Z ECMWF WAS INITIALIZED POOREST WITH THIS SYSTEM...ROUGHLY 100 MI SW OF THE LOW CENTER AT 00Z/13 AND MUCH WEAKER THAN THE 00Z UNIFIED SURFACE ANALYSIS...WHILE THE 00Z UKMET WAS CLOSEST TO THE LOW POSITION/INTENSITY ANALYSIS. THE END RESULT IS THE 00Z ECMWF IS TOWARD THE SOUTHEAST SIDE OF THE LATEST ENSEMBLE SCATTER LOW PLOTS. GIVEN THE POTENTIAL TO BE QUICKER...WILL BLEND THE 00Z GFS AND 12Z UKMET ALONG WITH THE 00Z UKMET...WHICH IS SIMILAR TO THE PREVIOUS PREFERENCE...BUT WITH LOW CONFIDENCE GIVEN THE COMPLEX INTERACTION WITH A REMNANT TROPICAL SYSTEM AND UPPER FLOW OFF OF THE WEST COAST. DOUBLE-BARRELED LOW MOVING BY WESTERN WA THURSDAY NIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON 00Z CANADIAN COMPROMISE CONFIDENCE: ABOVE AVERAGE THE 00Z CANADIAN REMAINS SLOWER/DEEPER IN MOVING THIS SYSTEM TOWARD THE PACIFIC NORTHWEST COMPARED TO THE ENSEMBLE MEANS AND THE REMAINING DETERMINISTIC GUIDANCE. THE ECMWF IS A BIT SLOWER TO DEVELOP THE LOW THIS EVENING WEST OF WASHINGTON BUT ENDS UP IN A SIMILAR SPOT AS THE NAM/GFS/UKMET. GIVEN A LACK OF SUPPORT FOR THE CMC...A NON 00Z CANADIAN COMPROMISE IS PREFERRED. COLD FRONT MOVING ACROSS THE EAST COAST TODAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE 12Z UKMET/CMC LOOKED TO BE TOO SLOW WITH THE COLD FRONT ACROSS THE NORTHEAST...BUT THEIR 00Z RUNS ARE IN LINE WITH THE REMAINING DETERMINISTIC/ENSEMBLE GUIDANCE. SHORTWAVE TROUGH TRACKING FROM THE SOUTHWEST THIS MORNING TO THE SOUTHEAST BY SAT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS...00Z ECMWF COMPROMISE CONFIDENCE: ABOVE AVERAGE THE 00Z NAM/CMC WERE FLATTER WITH THE 700 MB REFLECTION OF THIS SYSTEM AS IT NEARED THE OZARKS. WHILE MINOR TIMING/STRENGTH DIFFERENCES EXIST WITH THE REMAINING GFS/ECMWF/UKMET...A BLEND OF THESE THREE FORMS A REASONABLE COMPROMISE. AFTERWARD...THE 00Z UKMET BECOMES A SLOW OUTLIER TOWARD THE SOUTHEAST...AND THE CMC BECOMES FAST. THIS LEAVES THE GFS/ECMWF FOR AN OVERALL PREFERENCE FOR THIS SYSTEM. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO