MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 142 AM EST FRI MAR 03 2017 VALID MAR 03/0000 UTC THRU MAR 06/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION INCLUDING FINAL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ FAST MOVING SHORTWAVE TRACKING ACROSS THE EAST COAST EARLY TODAY SMALL MID-LEVEL CLOSED LOW CROSSING NEW ENGLAND EARLY SAT MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL BLEND CONFIDENCE: ABOVE AVERAGE THE MODELS SHOW SIMILARLY WITH THE MID-LEVEL SHORTWAVE TRACKING ACROSS THE EAST COAST EARLY TODAY. LATER IN THE FORECAST PERIOD...THE 00Z NAM ENDS UP ON THE FASTER SIDE OF THE MODEL SPREAD AND THE 00Z UKMET ON THE SLOWER SIDE WITH THE CLOSED LOW AFTER IT CROSSES NOVA SCOTIA SAT EVENING...BUT BY THIS POINT IN TIME...THE SYSTEM IS FAR ENOUGH OFFSHORE TO NOT IMPACT THE WEATHER OVER NEW ENGLAND MUCH. THEREFORE...A GENERAL MODEL BLEND CAN BE USED FOR THIS SYSTEM. UPPER TROUGH OVER THE BAJA PENINSULA INTO NW MEXICO TODAY/SAT... REACHING THE WESTERN GULF COAST ON SAT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS / 00Z ECMWF BLEND CONFIDENCE: AVERAGE THE LATEST ENSEMBLE SPAGHETTI HEIGHTS AT 576 DAM SHOW THE 00Z ECMWF ON THE DEEPER SIDE OF THE ENSEMBLE SPREAD WITH THE 00Z GFS AND 00Z UKMET TOWARD THE MIDDLE TO FLATTER SIDE OF THE DETERMINISTIC AND ENSEMBLE SPREAD THROUGH SUN MORNING. THE ENSEMBLE MEANS SUPPORT SOMETHING BETWEEN THE 00Z GFS AND 00Z ECMWF WITH 850 MB FLOW ACROSS TEXAS...WITH THE 00Z CMC UNSUPPORTED WITH A STRONGER WAVE OVER THE REGION SUN MORNING. WHILE CONVECTIVE DETAILS MUDDLE THE FORECAST SOME...THE ENSEMBLE MEANS ARE IN GOOD AGREEMENT WITH MASS FIELDS AND SUPPORT A BLEND BETWEEN THE 00Z GFS AND 00Z ECMWF. THE 00Z NAM APPEARS TO BE A GOOD FIT IN THE MIDDLE OF THE SPREAD UNTIL SUN AND MON AT WHICH POINT THE NAM SHOWS STRONGER WITH THE MID-LEVEL WAVE IN THE WRN GULF OF MEXICO COMPARED TO THE REMAINING AVAILABLE GUIDANCE. UPPER TROUGH/CLOSED LOW IMPACTING THE NORTHWEST U.S. THROUGH SUN LEADING EDGE OF TROUGH APPROACHING THE PLAINS WITH SURFACE LOW IN THE DAKOTAS 12Z/MON ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS/ECMWF/CMC BLEND CONFIDENCE: AVERAGE THE GREATEST DIFFERENCES NOTED WITH THIS SYSTEM WERE WITH THE TIMING OF THE TROUGH AXIS MOVING INTO THE WRN U.S. ON SUN. THE 00Z NAM WAS A BIT SLOWER WHILE THE REMAINING MODELS WERE MORE SIMILAR TO ONE ANOTHER AND FASTER BY MID-DAY SUNDAY...WITH THESE DIFFERENCES CONTINUING INTO MONDAY. IT SHOULD BE NOTED THAT THE 700 MB REFLECTION IN THE 00Z UKMET IS STRONGER AND SLOWER ACROSS THE NRN HIGH PLAINS BY MON MORNING COMPARED TO THE REMAINING DETERMINISTIC GUIDANCE. REGARDING THE SURFACE LOW IN THE PLAINS...AT LEAST THROUGH 12Z/MONDAY...THE PAST 2 RUNS OF THE ENSEMBLE SCATTER LOW PLOTS HAVE BEEN CONSISTENT AND SUPPORT A LOW NEAR THE ND/SD BORDER. THIS POSITION IS NEAREST TO THE 00Z GFS AND 00Z ECMWF...BUT THERE IS ROOM FOR ADJUSTMENT IN THE ENSEMBLE CLUSTERING FOR ADJUSTMENTS OF 150 TO 200 MILES IN EITHER DIRECTION OF THE 00Z GFS/ECMWF BLENDED POSITION. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO