MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1145 PM EST THU FEB 16 2017 VALID FEB 17/0000 UTC THRU FEB 20/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...SHORTWAVE/COLD FRONT CROSSING THE NORTHERN TIER STATES THROUGH SUN... PREFERENCE: 12Z ECMWF CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 00Z GFS AGAIN LOOKS FASTER THAN MOST GUIDANCE WITH THIS FEATURE AS IT REACHES THE GREAT LAKES LATE FRI NIGHT AND IS NOT PREFERRED GIVEN THIS TIMING DIFFERENCE. THE 12Z UKMET FOR ITS PART THOUGH LOOKS A TAD TOO SLOW. ALOFT...THE 00Z NAM AND 12Z CMC LOOK A TAD FLAT COMPARED TO THE MODEL CONSENSUS. THE 12Z ECMWF IS GENERALLY CLOSEST TO THE MODEL CONSENSUS AND WILL PREFER THIS SOLUTION FOR THE TIME BEING. ...DEEPENING TROUGH/CLOSED DEVELOPMENT NEAR NORTHERN NEW ENGLAND BY MON... PREFERENCE: BLEND OF THE 18Z GEFS MEAN AND 12Z ECENS MEAN CONFIDENCE: SLIGHTLY BELOW AVERAGE THE MODELS SUGGEST NORTHERN STREAM SHORTWAVE AMPLIFICATION OVER SOUTHEAST CANADA AND NEAR NORTHERN ENGLAND BY SUN NIGHT AND MON WITH POSSIBLE CLOSED LOW DEVELOPMENT. THE 12Z ECMWF AND ESPECIALLY THE 00Z GFS ARE IN FAVOR OF THIS CLOSED LOW. THE 00Z NAM/12Z CMC AND 00Z UKMET ARE NOT AS SHARP WITH THE AMPLIFICATION. THE 18Z GEFS MEAN AND 12Z ECENS MEAN TEND TO FAVOR THE STRONGER GFS/ECMWF CAMP...BUT THE GFS OVERALL MIGHT BE A TAD TOO DEEP. WILL LEAN TOWARD A BLEND OF THE ENSEMBLE MEANS AT THIS POINT. ...SHARPENING UPPER TROUGH MOVING INTO CALIFORNIA AND THE SOUTHWEST THROUGH SUN... ...ENERGY EJECTING OUT ACROSS THE HIGH PLAINS ON MON... PREFERENCE: BLEND OF THE 12Z ECMWF AND 12Z CMC CONFIDENCE: AVERAGE THE MODELS ARE IN PRETTY GOOD AGREEMENT ON THE LARGER SCALE WITH AMPLIFYING UPPER TROUGH OFFSHORE CA THAT WILL BE MOVING INLAND ON FRI AND THEN SEPARATING FROM THE WESTERLIES AND DIGGING SOUTHEAST ACROSS THE SOUTHWEST U.S. THROUGH THE WEEKEND. SOME DIFFERENCES APPEAR BY SUN AS THE ENERGY PIVOTS ACROSS THE FOUR CORNERS REGION AND APPROACHES THE HIGH PLAINS. THE 12Z UKMET AND 00Z GFS BOTH GRADUALLY BECOME A BIT MORE PROGRESSIVE IN LIFTING THE ENERGY INTO THE HIGHER PLAINS BY THE END OF THE PERIOD AND SUGGEST STRONGER SURFACE CYCLOGENESIS IN THE LEE OF THE ROCKIES WITH BOTH THE GFS AND UKMET HAVING THEIR RESPECTIVE TROUGHS GOING NEGATIVE TILT. THE 00Z NAM EVENTUALLY APPEARS TO BE TOO SLOW IN PROGRESSING THE TROUGH. THE 12Z ECMWF AND 12Z CMC ARE CLUSTERED IN BETWEEN CAMPS...AND FOR NOW HAVE BETTER SUPPORT FROM THE 18Z GEFS MEAN AND 12Z ECENS MEAN. A COMPROMISE OF THESE TWO SOLUTIONS WILL BE PREFERRED AS A RESULT. ...NORTHERN STREAM TROUGH CROSSING THE PACIFIC NORTHWEST ON SAT... PREFERENCE: NON-GFS CONSENSUS CONFIDENCE: ABOVE AVERAGE THE MODELS HAVE A NORTHERN STREAM EXTENSION OF THE DEEP TROUGH MOVING INTO CA THAT WILL CROSS THE PACIFIC NORTHWEST THROUGH SAT. THE 00Z GFS IS A BIT FASTER AND DEEPER THAN THE MODEL CONSENSUS...WITH THE REMAINING MODELS RATHER WELL CLUSTERED ON A SLIGHTLY FLATTER SOLUTION. WILL FAVOR A NON-GFS CONSENSUS AT THIS POINT. ...UPPER TROUGH CROSSING THE SOUTHERN PLAINS THROUGH THE SOUTHEAST THROUGH SAT... PREFERENCE: 12Z ECMWF CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 00Z GFS IS A BIT STRONGER THAN THE MODEL CONSENSUS WITH THE UPPER TROUGH CROSSING THE SOUTHERN PLAINS AND MOVING THROUGH THE TN VALLEY AND SOUTHEAST THROUGH SAT. THE BIGGER DIFFERENCES SHOW UP AS THE HEIGHT FALLS CROSS THE TN VALLEY AND SOUTHEAST...AS THE GFS HANGS ON TO A STRONGER TROUGH COMPARED TO THE OTHER MODELS. THE 12Z UKMET GRADUALLY APPEARS TO BE PERHAPS A TAD TOO FAST. THE 00Z NAM/12Z CMC AND 12Z ECMWF ARE BETTER CLUSTERED...BUT EVENTUALLY THE NAM LOOKS TO BE POSSIBLY A LITTLE TOO WEAK. WILL LEAN TOWARD THE ECMWF AT THIS POINT. ...SHORTWAVE/SURFACE LOW APPROACHING THE PACIFIC NORTHWEST EARLY SUN... PREFERENCE: BLEND OF THE 12Z ECMWF/18Z GEFS MEAN/12Z ECENS MEAN CONFIDENCE: SLIGHTLY BELOW AVERAGE THE MODELS SHOW A SHORTWAVE AND ASSOCIATED SURFACE LOW APPROACHING THE PACIFIC NORTHWEST ON SUN BEFORE THEN GRADUALLY WEAKENING INS RESPONSE TO STRONGER UPSTREAM TROUGH AMPLIFICATION. THE 00Z GFS AGAIN IS APPEARING TO BE TOO PROGRESSIVE AND WILL NOT BE PREFERRED. THE 12Z UKMET IS LIKELY SOMEWHAT TOO PROGRESSIVE AND A BIT TOO STRONG WITH THE LEADING EDGE OF ITS HEIGHT FALLS. THE 18Z GEFS MEAN AND 12Z ECENS MEAN ARE MORE CLOSELY ALIGNED WITH THE 12Z ECMWF AND ALSO THE 12Z CMC AND 00Z NAM. WILL PREFER A BLEND OF THE ECMWF AND THE ENSEMBLE MEANS AT THIS POINT GIVEN THE MODEL SPREAD. ...AMPLIFYING UPPER TROUGH/SURFACE LOW OFFSHORE THE WEST COAST ON MON... PREFERENCE: BLEND OF THE 18Z GEFS MEAN AND 12Z ECENS MEAN CONFIDENCE: BELOW AVERAGE THE MODELS ALL SHOW A LONGWAVE TROUGH AMPLIFYING OFF THE WEST COAST ON MON WITH A RATHER STRONG AND BROAD AREA OF LOW PRESSURE HELPING TO DRIVE A RATHER SIGNIFICANT AMOUNT OF ONSHORE FLOW INTO THE WEST COAST. THE 00Z GFS AND 12Z UKMET ARE THE MORE AMPLIFIED SOLUTIONS...WITH THE 00Z NAM/12Z CMC AND 12Z ECMWF ALL A BIT FLATTER ALONG WITH SOMEWHAT WEAKER SURFACE REFLECTIONS. WILL PREFER TO LEAN TOWARD THE ENSEMBLE MEANS AS PER THE 18Z GEFS MEAN AND 12Z ECENS MEAN AS A COMPROMISE GIVEN THE SPREAD WITH THE SURFACE LOW DETAILS AND OVERALL TROUGH AMPLIFICATION. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON