MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 355 AM EDT TUE APR 11 2017 VALID APR 11/0000 UTC THRU APR 14/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION INCLUDING FINAL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...UPPER TROUGH REACHING THE UPPER MS VALLEY TONIGHT... ...NEGATIVELY TILTED TROUGH OVER NEW ENGLAND WED NIGHT... ...SURFACE LOW TRACKING THROUGH THE GREAT LAKES EARLY TODAY WITH TRAILING COLD FRONT... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE ONLY MINOR DETAIL DIFFERENCES EXIST WITH THE LATEST MODELS AND A GENERAL MODEL BLEND IS RECOMMENDED TO IRON OUT SMALLER SCALE DIFFERENCES. ...SUBTLE PACIFIC MID-UPPER LEVEL SHORTWAVE REACHING N CA/SW OR TUES SHIFTING TO CENTRAL PLAINS/UPPER MIDWEST BY WED/THURS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS / 00Z CMC BLEND CONFIDENCE: AVERAGE THE ECMWF HAS BEEN TRENDING TOWARD THE MORE CONSISTENT 00Z GFS EARLY IN THE PERIOD AS THE NRN PORTION OF THE MID-UPPER LEVEL SHORTWAVE CROSSES THE ROCKIES WED MORNING BUT THE 00Z RUN CONTINUED A NWD SHIFT PAST THE GFS. THE NRN PORTION OF THE WAVE TRACKS INTO THE OHIO VALLEY FOR THU AND THE 00Z ECMWF APPEARS TOO PROGRESSIVE AND FLAT COMPARED TO THE REMAINING DETERMINISTIC AND ENSEMBLE CONSENSUS. THE FEATURE IS ELONGATED WITH A NRN PORTION AND A SRN PORTION THAT CROSSES INTO THE SRN HIGH PLAINS EARLY ON THU. THE 12Z AND 00Z ECMWF APPEARS TOO FAR NORTH WITH THIS SRN FEATURE AS IT REACHES THE PLAINS THU NIGHT AS EVEN ITS OWN ENSEMBLE MEAN IS SOUTH. RELATIVE GOOD CONSENSUS EXISTS FOR A TRACK NEAR THE GFS BUT ENSEMBLE SPREAD SHOWS REASON TO HEDGE IN A NWD DIRECTION OF THE 00Z GFS TOWARD THE 00Z CMC. ...SHORTWAVE TROUGH/SURFACE LOW APPROACHING THE NORTHWEST COAST LATE TUE/EARLY WED... ...DEEP UPSTREAM CLOSED LOW APPROACHING THE WEST COAST LATE WED... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS/ECMWF/CMC BLEND CONFIDENCE: AVERAGE THE 00Z NAM/GFS ARE A BIT FASTER/EAST WITH THE SURFACE LOW TRACK TUE NIGHT NEAR THE OR COAST BUT ENSEMBLE SCATTER LOWS HAVE BEEN TRENDING IN THAT DIRECTION OVER THE PAST FEW CYCLES. WHILE THE 12Z ECMWF IS CLOSER TO THE LATEST ENSEMBLE LOW CLUSTERING...THE 00Z ECMWF TRENDED TOWARD THE NAM/GFS. THE NEXT SURFACE LOW TO NEAR THE PACIFIC NORTHWEST COAST ON WED...SHOULD STAY OFFSHORE AS 100 PERCENT OF THE SCATTER LOW PLOTS DEPICT THIS SCENARIO WITH NO NOTABLE TRENDS TOWARD THE COAST. THE DEPTH IN THE 00Z UKMET LOOKS TOO STRONG AS IT IS ALSO STRONGER ALOFT RELATIVE TO THE REMAINING GUIDANCE. THE 00Z CMC LOOKS TO HAVE ADJUSTED REASONABLY TOWARD THE PREFERRED GFS/ECMWF POSITIONS WITH A BLEND OF THE 00Z GFS AND 00Z ECMWF APPEARING BEST WITH THE TRACK OF THE SURFACE LOW AND EVEN ALOFT WITH THE 700-500 MB TROUGH AXIS MOVING INLAND. THE 00Z NAM DOES NOT APPEAR TO STAY FAR FROM THE 00Z GFS/12Z ECMWF COMBO BUT THE NAM IS A BIT FASTER TO MOVE THE TROUGH INLAND. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO