MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 129 PM EST FRI MAR 11 2016 VALID MAR 11/1200 UTC THRU MAR 15/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION INCLUDING FINAL MODEL PREFERENCES AND FORECAST CONFIDENCE UPPER TROUGH CROSSING THE WEST COAST FRI NIGHT...CROSSING THE SOUTHERN PLAINS SAT/SAT NIGHT...REACHING THE OH VALLEY/MID ATLANTIC MON ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z GFS/12Z ECMWF BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 12Z NAM IS CLOSE TO THE CONSENSUS DURING THE DAY 1/2 TIME FRAME...AS THE UPPER TROUGH CROSSES SOUTHERN CA BEFORE CLOSING OFF OVER THE SOUTHERN PLAINS DURING DAY 2. AFTER THAT POINT...THE 12Z NAM IS SLOWER AND DEEPER WITH THE TROUGH AS IT CROSSES THE OH VALLEY INTO THE MID ATLANTIC DURING DAY 3. THE 12Z GFS IS CLOSE TO THE 12Z ECMWF TIMING/PLACEMENT WITH THE SHORT WAVE...SHOWING LITTLE CHANGE FROM ITS 00Z SOLUTION. THE 12Z CMC CONTINUES TO BE SLOWER WITH THE TROUGH ON DAY 3 ACROSS THE OH VALLEY AND MID ATLANTIC...AS WAS THE 12Z UKMET (WHICH WAS ALSO FLATTER WITH THE WEAKENING SHORT WAVE DURING DAY 3). WEAKENING UPPER LOW LIFTING ACROSS TX FRI NIGHT AND SAT...WHICH CROSSES THE MID MS VALLEY SAT NIGHT SUN...THEN THE OH VALLEY MON ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z GFS/12Z ECMWF/12Z UKMET CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 12Z NAM SPINS DOWN THE UPPER LOW OVER TX FRI NIGHT/SAT WITH THE CONSENSUS...BUT AFTER THAT TIME PERIOD THE 12Z NAM BECOMES SLOWER AS IT CROSSES THE MID MS VALLEY DURING DAY 2...AND SLOWS A BIT MORE ACROSS THE OH VALLEY MON. THE 12Z GFS IS A BIT SLOWER THAN ITS 00Z SOLUTION...BUT ITS REMAINS CLOSE TO THE CONSENSUS (AND THE 12Z ECMWF) AS IT SPINS DOWN THE MID LEVEL SYSTEM AND LIFTS IT ACROSS THE MID MS VALLEY. BOTH THE 12Z UKMET/CMC BECOMES WEAKER/SLOWER DURING DAYS 2/3 WITH THE TROUGH THAT EXITS THE SOUTHERN PLAINS. THE 12Z GFS IS ALSO CLOSE TO THE 12Z ECMWF AS IT TRIES TO PHASE A NORTHERN STREAM SHORT WAVE OVER THE UPPER GREAT LAKES INTO THE OPENING AND WEAKENING SYSTEM ON DAY 3 ACROSS THE OH VALLEY AND MID ATLANTIC. THE 12Z NAM APPEARS TO KEEP THESE TWO SYSTEMS SEPARATE. MID LEVEL SHORTWAVE MOVING ACROSS THE PACIFIC NORTHWEST SUN INTO SOUTH CENTRAL CANADA MON ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z GFS/12Z UKMET/12Z ECMWF BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 12Z NAM IS CLOSE TO THE CONSENSUS BRINGING THE SHORT WAVE ASHORE OVER THE PACIFIC NORTHWEST DURING DAY 2. HOWEVER...THE 12Z NAM BECOMES FASTER WITH THE SHORT WAVE...THEN CLOSES THE SYSTEM OFF OVER SOUTH CENTRAL CANADA DURING DAY 3. THE 12Z GFS IS SIMILAR TO ITS 00Z SOLUTION WITH THE TIMING OF THE SHORT WAVE...THOUGH ITS BECOMES A BIT FASTER DURING DAY 3 ACROSS SOUTH CENTRAL CANADA. THE 12Z UKMET MIMICS THE 12Z GFS WITH ITS TIMING...INCLUDING CLOSING OFF THE MID LEVEL SYSTEM LATE...WHILE THE 12Z CMC BECOMES FASTER THAN THE CONSENSUS DURING DAY 3. THE 12Z ECMWF HAS REMAINED FAIRLY CONSISTENT WITH ITS TIMING/PLACEMENT OF THE SHORT WAVE IN SOUTH CENTRAL CANADA ON DAY 3. A BLEND OF THE SLIGHTLY FASTER 12Z GFS AND SLOWER 12Z ECMWF PROBABLY AFFORDS THE BEST SOLUTION DURING DAY 3. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... HAYES