MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 301 PM EDT WED MAR 23 2016 VALID MAR 23/1200 UTC THRU MAR 27/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/CMC AND ECMWF ...DEEP TROUGH/CLOSED LOW EJECTING ACROSS THE HIGH PLAINS/FRONT RANGE... ...EJECTING ACROSS THE MIDWEST/GREAT LAKES REGION TONIGHT/THURS... ...ASSOCIATED DEEP SURFACE LOW GRADUALLY LIFTING INTO THE NORTHEAST FRI... PREFERENCE: BLEND OF THE 12Z UKMET/12Z CMC AND 12Z ECMWF CONFIDENCE: AVERAGE THE MODELS CONTINUE TO CONVERGE ACROSS THE CENTRAL PLAINS INTO THE GREAT LAKES WITH THE EVOLUTION OF THE DEEP UPPER TROUGH/CLOSED LOW EJECTING ACROSS THE FRONT RANGE/CENTRAL HIGH PLAINS TODAY. THE 12Z NAM THROUGH ABOUT 36 HOURS TENDS TO BE A LITTLE SLOWER THAN THE MULTI-MODEL CONSENSUS WITH THE HEIGHT FALL EVOLUTION AND THE ASSOCIATED SURFACE LOW. THE NAM IS ALSO A LITTLE SOUTH OF THE CONSENSUS AND TENDS TO REMAIN A BIT SOUTH OF THE CONSENSUS THROUGH THE PERIOD AS THE 12Z UKMET/12Z CMC AND 12Z ECMWF ALL CLUSTER WITH THE 12Z GFS IN BEING A LITTLE FARTHER NORTH. THE 12Z GFS BY 36 HOURS AND ONWARD TENDS TO OCCASIONALLY OUTPACE THE REMAINING GUIDANCE AND ESPECIALLY AS THE SHORTWAVE ENERGY/HEIGHT FALLS AND SURFACE WAVE LIFTS ACROSS THE GREAT LAKES AND INTO THE NORTHEAST. THE GFS TOWARD THE LATTER PART OF THE PERIOD TENDS TO BE A BIT DEEPER THAN THE MODEL CONSENSUS AS WELL. BASED ON THE LATEST TRENDS AND CLUSTERING...WILL PREFER A NON-NCEP CONSENSUS LED BY A BLEND OF THE UKMET/CMC AND ECMWF. ...UPPER LOW SHEDDING ENERGY INTO THE PACIFIC NORTHWEST TONIGHT/THURS... ...ASSOCIATED COLD FRONT MOVING INLAND AND REACHING THE HIGH PLAINS FRI... ...SURFACE CYCLOGENSIS OVER THE NORTHERN HIGH PLAINS... PREFERENCE: 12Z ECMWF CONFIDENCE: AVERAGE THE MODELS ARE IN FAIRLY STRONG AGREEMENT WITH THE OVERALL SHAPE/STRENGTH OF THE UPPER LOW APPROACHING THE ALASKAN PANHANDLE BY EARLY THURS. SHORTWAVE ENERGY EJECTING OUT OF THE BASE OF THE LARGER SCALE TROUGH WILL ADVANCE SOUTHEAST ACROSS THE NORTHWEST AND THROUGH THE INTERMOUNTAIN REGION ON THURS WITH THE ENERGY THEN EJECTING OUT ACROSS THE PLAINS AND UPPER MIDWEST FRI AND SAT. THE 12Z NAM OVERALL APPEARS TO BE OVERALL A BIT TOO SLOW AND TOO DEEP WITH THE HEIGHT FALLS...AND DRIVE A SLOWER AND SOMEWHAT DEEPER SURFACE LOW ALONG A FRONTAL ZONE AS WELL THAT WILL BE MOVING EAST TOWARD THE UPPER MIDWEST. THIS SAME FRONT WILL ALSO BE ADVANCING SOUTH DOWN THE FRONT RANGE AND INTO THE SOUTHERN PLAINS BY SAT. THE 12Z GFS FOR ITS PART IS STILL PERHAPS A TAD TOO PROGRESSIVE WITH THE LOW TRACK AND SURFACE FRONT...ALTHOUGH IT IS GRADUALLY TRENDING SLOWER AND IS CLOSE TO THE NON-NCEP GUIDANCE. WILL PREFER A NON-NCEP CONSENSUS AT THIS POINT...LED BY THE 12Z ECMWF. ...SECONDARY SHORTWAVE DROPPING THROUGH THE INTERMOUNTAIN WEST/HIGH PLAINS ON FRI/SAT... PREFERENCE: BLEND OF THE 12Z GFS/12Z UKMET AND 12Z CMC CONFIDENCE: SLIGHTLY BELOW AVERAGE LIKE ITS PREDECESSOR...THE 12Z NAM IS A BIT DEEPER AND GENERALLY SLOWER THAN THE MODEL CONSENSUS WITH A SECONDARY SHORTWAVE IMPULSE DROPPING SOUTHEAST THROUGH THE INTERMOUNTAIN WEST FRI AND TOWARD THE HIGH PLAINS SAT. THE 12Z GFS OVERALL IS THE MOST PROGRESSIVE...WITH THE 12Z UKMET AND 12Z CMC JUST A TAD SLOWER AND ALSO TRENDING SOMEWHAT MORE PROGRESSIVE. THE 12Z ECMWF THOUGH IS NOW THE SLOWEST SOLUTION AND IS EVEN A LITTLE SLOWER THAN THE 00Z ECENS MEAN. THE 12Z GEFS MEAN HAS COME IN SUPPORT THE MORE PROGRESSIVE GFS/UKMET/CMC CAMP. CONFIDENCE IS LIMITED GIVEN THE INCREASE IN MODEL SPREAD THIS CYCLE...BUT WILL LEAN TOWARD THE SLIGHTLY MORE PROGRESSIVE CONSENSUS GIVEN THE DEGREE OF CLUSTERING TOWARD THIS SCENARIO. ...UPPER TROUGH/FRONT APPROACHING THE PACIFIC NORTHWEST BY LATE SAT... PREFERENCE: NON-CMC CONSENSUS CONFIDENCE: AVERAGE A PROGRESSIVE BUT DEEP UPPER TROUGH WILL BE APPROACHING THE PACIFIC NORTHWEST ON SAT ALONG WITH A COLD FRONT. THE 12Z CMC IS STILL SOMEWHAT OF A STRONGER OUTLIER WITH THE DEPTH OF THE TROUGH. THE REMAINING MODELS EXHIBIT BETTER AGREEMENT WITH DEPTH AND SHOW GENERALLY MINOR TIMING DIFFERENCES. THUS...WILL PREFER A NON-CMC CONSENSUS. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON