MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 242 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/GFS/UKMET/CMC AND ECMWF ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...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 00Z 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 00Z UKMET GRADUALLY BECOMES FOCUSED A TAD TOO FAR SOUTH AND WITH ITS HEIGHT FALLS OVER THE OH/TN VALLEYS ALONG WITH ITS SURFACE LOW. ALTHOUGH IT HAS TRENDED NORTH FROM ITS PREVIOUS RUN. STRONGER MODEL CLUSTERING IS FOCUSED TOWARD THE 00Z GFS AND 00Z ECMWF WITH SUPPORT ALSO FROM THE 00Z CMC. A BLEND OF THE GFS AND ECMWF WILL BE SUGGESTED. ...TROUGH CROSSING THE NORTHERN TIER STATES WED THROUGH FRI... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF THE 00Z GFS AND 00Z 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 00Z ECMWF TEND TO HAVE THE BEST CLUSTERING AS THE 00Z NAM GETS TO BE TOO WEAK AND 00Z UKMET A TAD TOO PROGRESSIVE. A BLEND OF THE GFS AND ECMWF WILL BE PREFERRED AT THIS POINT. ...SURFACE LOW CROSSING SOUTHERN BRITISH COLUMBIA WED... ...COLD FRONT MOVING ACROSS THE PACIFIC NORTHWEST... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS SHOW GOOD AGREEMENT WITH THIS SYSTEM AS IT MOVES INLAND ON WED. A GENERAL MODEL COMPROMISE WILL BE PREFERRED. ...VIGOROUS TROUGH DIGGING INTO THE WEST ON THURS... ...STRONG CLOSED LOW OVER THE FOUR CORNERS BY FRI/SAT... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z 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 00Z GFS AND 00Z 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 00Z CMC LIKEWISE TENDS TO FAVOR THE MODESTLY STRONGER GFS. 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 00Z ECMWF APPEARS MOST REASONABLE AT THIS POINT...AND WILL CONTINUE WITH THIS PREFERENCE. ...NORTHERN STREAM TROUGH/FRONT CROSSING THE NORTHERN PLAINS FRI... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: AVERAGE THE NEXT NORTHERN STREAM TROUGH WILL CROSS THE NORTHERN PLAINS BY FRI ALONG WITH A WEAK COLD FRONT. THERE IS SUFFICIENT MASS FIELD CLUSTERING DESPITE SOME MINOR TIMING/DEPTH DIFFERENCES TO GO WITH A GENERAL MODEL COMPROMISE AT THIS POINT. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON