MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 158 AM EST FRI FEB 17 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/GFS/UKMET/CMC AND ECMWF ...SHORTWAVE/COLD FRONT CROSSING THE NORTHERN TIER STATES THROUGH SUN... PREFERENCE: 00Z 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 00Z UKMET FOR ITS PART THOUGH LOOKS A TAD TOO SLOW. THE 00Z CMC LOOKS A TAD FLAT COMPARED TO THE MODEL CONSENSUS. THE 00Z 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 00Z GFS AND 00Z ECMWF CONFIDENCE: 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 00Z ECMWF AND 00Z GFS ARE IN FAVOR OF THIS CLOSED LOW. THE 00Z NAM AND 00Z UKMET ARE NOT AS SHARP WITH THE AMPLIFICATION...WITH THE 00Z CMC TENDING TO LEAN TOWARD THE STRONGER GFS/ECMWF CAMP BUT WITH A MODESTLY SLOWER EVOLUTION. THE 00Z GEFS MEAN AND 12Z ECENS MEAN BOTH FAVOR THE STRONGER GFS/ECMWF CAMP. WILL LEAN TOWARD A BLEND OF THE GFS AND ECMWF AS A RESULT. ...SHARPENING UPPER TROUGH MOVING INTO CALIFORNIA AND THE SOUTHWEST THROUGH SUN... ...ENERGY EJECTING OUT ACROSS THE HIGH PLAINS ON MON... PREFERENCE: 00Z ECMWF 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 00Z 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 00Z ECMWF AND 00Z ARE CLUSTERED IN BETWEEN CAMPS...WITH THE ECMWF JUST A TAD MORE PROGRESSIVE THAN THE CMC. THE ECMWF HAS STRONGER OVERALL SUPPORT FROM THE 00Z GEFS MEAN AND 12Z ECENS MEAN. THUS WILL LEAN TOWARD THE ECMWF AT THIS TIME. ...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: BLEND OF THE 00Z ECMWF AND 00Z CMC 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 SLIGHTLY STRONGER TROUGH COMPARED TO THE OTHER MODELS. THE 00Z NAM NOW AT THIS POINT IS LOOKING A TAD TOO WEAK AND PROGRESSIVE OVERALL...WITH THE 00Z UKMET ALSO GRADUALLY APPEARING TO BE A LITTLE WEAK AS THE ENERGY MOVES THROUGH THE SOUTHEAST. THE 00Z ECMWF AND 00Z CMC ARE WELL CLUSTERED AND CLOSEST TO THE MODEL CONSENSUS...SO A BLEND OF THESE TWO SOLUTIONS WILL BE PREFERRED. ...SHORTWAVE/SURFACE LOW APPROACHING THE PACIFIC NORTHWEST EARLY SUN... PREFERENCE: BLEND OF THE 00Z UKMET AND 00Z ECMWF 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 00Z UKMET AND 00Z ECMWF ARE NOW CLUSTERED TOGETHER ON A SLOWER SOLUTION BY COMPARISON. HOWEVER...THE 00Z CMC IS EVEN SLOWER AND IS LIKELY A BIT TOO SLOW. A BLEND OF THE UKMET AND ECMWF WILL BE PREFERRED SINCE A CONSENSUS OF THESE SOLUTIONS IS VERY CLOSE TO THE MODEL CONSENSUS AND BETTER SUPPORTED BY THE 00Z GEFS MEAN AND 12Z ECENS MEAN. THE 00Z NAM ALSO IS QUITE CLOSE TO THE UKMET/ECMWF CAMP. ...AMPLIFYING UPPER TROUGH/SURFACE LOW OFFSHORE THE WEST COAST ON MON... PREFERENCE: BLEND OF THE 00Z NAM/00Z UKMET AND 00Z ECMWF CONFIDENCE: SLIGHTLY 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 IS A NOTABLY MORE AMPLIFIED SOLUTION...WITH THE 00Z NAM/00Z CMC/00Z UKMET AND 00Z ECMWF ALL A BIT FLATTER ALONG WITH SOMEWHAT WEAKER SURFACE REFLECTIONS. THE CMC THOUGH IS LIKELY A BIT TOO PROGRESSIVE WITH ITS LEVEL OF ENERGY COMING INTO THE PACIFIC NORTHWEST BY THE END OF THE PERIOD. BASED ON THE LATEST TRENDS...THERE IS A FAIR DEGREE OF GOOD MODEL CLUSTERING SEEN WITH THE NAM/UKMET AND ECMWF. SINCE THE 00Z GEFS MEAN AND 12Z ECENS MEAN FAVOR THIS CLUSTERING A BLEND OF THE NAM/UKMET AND ECMWF WILL BE PREFERRED. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON