MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1254 AM EDT WED MAR 29 2017 VALID MAR 29/0000 UTC THRU APR 01/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...STRONG CLOSED LOW CROSSING THE CENTRAL/SOUTHERN PLAINS... ...ADVANCING EAST THROUGH THE MID MS/TN/OH VALLEYS BY THURS/FRI... ...ENERGY CROSSING THE MID-ATLANTIC BY FRI NIGHT... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF CONFIDENCE: AVERAGE THE 00Z NAM BECOMES A BIT SLOWER THAN THE MODEL CONSENSUS BY 36 HOURS AND BEYOND WITH THE STRONG SOUTHERN STREAM CLOSED LOW/TROUGH AND ACCOMPANYING SURFACE LOW EJECTING ACROSS THE CENTRAL/SOUTHERN PLAINS AND THEN ADVANCING EAST ACROSS THE MID MS/TN/OH VALLEYS THURS AND FRI BEFORE CROSSING THE MID-ATLANTIC FRI NIGHT. THE 12Z UKMET GRADUALLY BECOMES FOCUSED TOO FAR SOUTH AND WITH ITS HEIGHT FALLS OVER THE OH/TN VALLEYS ALONG WITH ITS SURFACE LOW. STRONGER MODEL CLUSTERING IS FOCUSED TOWARD THE 00Z GFS AND 12Z ECMWF WITH SUPPORT ALSO FROM THE 12Z CMC. A BLEND OF THESE SOLUTIONS WILL BE SUGGESTED. ...TROUGH CROSSING THE NORTHERN TIER STATES WED THROUGH FRI... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF CONFIDENCE: AVERAGE THE MODELS HAVE A WEAK NORTHERN STREAM TROUGH CROSSING THE NORTHERN PLAINS/UPPER MIDWEST AND GREAT LAKES REGION WED THROUGH FRI BEFORE THE ENERGY THEN SCOOTS INTO NORTHERN NEW ENGLAND BY SAT. THE 00Z GFS AND 12Z ECMWF TEND TO HAVE THE BEST CLUSTERING AS THE 00Z NAM GETS TO BE TOO WEAK AND 12Z UKMET A TAD TOO PROGRESSIVE. A BLEND OF THE GFS AND ECMWF WILL BE PREFERRED AT THIS POINT. ...VIGOROUS TROUGH DIGGING INTO THE WEST ON THURS... ...STRONG CLOSED LOW OVER THE FOUR CORNERS BY FRI/SAT... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z ECMWF CONFIDENCE: SLIGHTLY ABOVE AVERAGE A STRONG UPPER TROUGH WILL BE DIGGING ACROSS THE PACIFIC NORTHWEST ON THURS AND THEN AMPLIFYING VIGOROUSLY INTO A CLOSED LOW ACROSS THE FOUR CORNERS REGION FRI AND SAT. THE 00Z NAM BY FRI AND SAT BECOMES A TAD FASTER THAN THE GLOBAL MODELS IN EJECTING THE CLOSED LOW OFF TO THE EAST. THE 12Z UKMET BY THE END OF THE PERIOD BECOMES A TAD SLOWER THAN THE MODEL CONSENSUS. THE 00Z GFS AND 12Z ECMWF ARE WELL CLUSTERED ALONG THROUGH THE PERIOD WITH TIMING...BUT EVENTUALLY THE GFS BECOMES A BIT MORE ROBUST WITH ITS CLOSED LOW THAN ANY OTHER MODEL. THE GFS ALSO TENDS TO HAVE MORE LOW PRESSURE FARTHER ACROSS THE CENTRAL ROCKIES AND INTO THE HIGH PLAINS COMPARED TO THE REMAINING GUIDANCE. THE 12Z ECMWF APPEARS MOST REASONABLE AT THIS POINT...AND WILL CONTINUE WITH THIS PREFERENCE. ...NORTHERN STREAM TROUGH/FRONT CROSSING THE NORTHERN PLAINS FRI... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS CONFIDENCE: AVERAGE THE NEXT NORTHERN STREAM TROUGH WILL CROSS THE NORTHERN PLAINS BY FRI ALONG WITH A WEAK COLD FRONT. THE 12Z ECMWF AND TO A LESSER EXTENT THE 00Z NAM APPEAR A BIT TOO SLOW WITH THIS. THE REMAINING MODELS ARE A TAD MORE PROGRESSIVE. THE 00Z GFS APPEARS QUITE REASONABLE WITH THIS SYSTEM AND WILL BE PREFERRED. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON