MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1215 PM EDT FRI OCT 14 2016 VALID OCT 14/1200 UTC THRU OCT 18/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z NAM/GFS EVALUATION WITH PRELIMINARY MODEL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. TRINARY INTERACTION WITH TRIO OF LOWS MOVING INTO VANCOUVER ISLAND BETWEEN NOW AND MONDAY TROUGH MOVING THROUGH NORTHWEST INTO SRN CANADA SHORTWAVE EMERGING INTO PLAINS LATE MONDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ THE GUIDANCE SHOWS GOOD AGREEMENT WITH THESE THREE CYCLONES. PREFER A COMPROMISE OF THE AVAILABLE GUIDANCE TO DEAL WITH ANY DETAIL ISSUES WITH ONLY SLIGHTLY ABOVE AVERAGE CONFIDENCE AS THE GUIDANCE SOMETIMES HAS STABILITY ISSUES WHEN MULTIPLE SYSTEMS INTERACT. SHORTWAVE MOVING THROUGH THE SOUTHEAST UPPER LOW CLOSING OFF NEAR FL SUNDAY NIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GFS/ECMWF COMPROMISE CONFIDENCE: AVERAGE WHILE THE GUIDANCE HANDLES THIS SYSTEM REASONABLY INTO SUNDAY MORNING, THE 00Z UKMET/00Z CANADIAN TAKE OFF TO THE EAST INTO THE SARGASSO SEA, WHILE THE 12Z GFS/12Z NAM/00Z ECMWF FIT IN WITH THE 06Z GEFS/00Z ECMWF ENSEMBLE MEAN SOLUTIONS. A BUILDING PROGRESSIVE POSITIVE 500 HPA ANOMALY (BY OVER 100 METERS) ACROSS PA/NY/OH LENDS ITSELF TO A CLOSED LOW UNDER ITS BASE MOVING MINIMALLY 20 DEGREES UNDER ITS BASE IN THE MID 20S LATITUDE. THIS SUPPORTS THE GFS/ECMWF/NAM CAMP. BY LATE MONDAY, THE GFS RETROGRADES THIS SYSTEM WHILE THE ECMWF ATTEMPTS TO TUG IT EASTWARD, WITH BOTH HAVING THE SUPPORT OF THEIR ENSEMBLE MEANS. THE 12Z NAM IS NEARLY A COMPROMISE OF THE TWO CAMPS, BUT LOOKS TOO STRONG ALONG. A COMPROMISE OF THE 12Z GFS/00Z ECMWF APPEARS BEST HERE WITH AVERAGE CONFIDENCE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ROTH