EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1100 AM EST MON FEB 29 2016 VALID 12Z THU MAR 03 2016 - 12Z MON MAR 07 2016 ...OVERVIEW... TO BEGIN THE PERIOD...AMPLIFIED FLOW ACROSS THE EASTERN HALF OF THE CONUS WILL FEATURE A PROGRESSIVE SHORTWAVE INITIALLY IN THE VICINITY OF THE KS/OK ON THURSDAY MORNING. THIS WAVE IS FORECAST TO ACCELERATE EASTWARD EXITING THE EASTERN SEABOARD BY THE FOLLOWING MORNING. THE MID-LATITUDE FLOW EVENTUALLY FLATTENS OUT AS QUASI-ZONAL FLOW IS ESTABLISHED...ALBEIT BRIEFLY. HEIGHTS BUILD MARKEDLY ACROSS THE CENTER OF THE COUNTRY IN RESPONSE TO A DEEP UPPER TROUGH STRENGTHENING ACROSS THE EASTERN PACIFIC BY EARLY SUNDAY. THESE HEIGHT FALLS ARE FORECAST TO ADVANCE EASTWARD THROUGH THE WESTERN U.S. TOWARD THE END OF THE PERIOD. ...MODEL ASSESSMENT AND UNCERTAINTIES/WPC PREFERENCES... RECENT DAYS HAD BEEN MARKED BY GREAT UNCERTAINTY AND TREMENDOUS RUN-TO-RUN VARIATIONS REGARDING THE DAY 3/4 WAVE TRACKING FROM THE CENTRAL PLAINS TO THE CAROLINAS. HOWEVER...IT DOES APPEAR THE OVERALL SPREAD HAS DECREASED ALTHOUGH NORTH-SOUTH DIFFERENCES ARE STILL WELL NOTED IN THE ENSEMBLE LOW PLOTS. A GENERAL CONSENSUS HAS FORMED BY 04/1200Z WITH A SURFACE WAVE EXITING IN THE VICINITY OF THE NC/SC BORDER. THE MULTI-DAY TREND HAS SHOWN A MOVE TOWARD THE SOUTH WITH THE 00Z ECMWF/CMC/UKMET WITHIN THE ENSEMBLE NOISE OF RECENT PLOTS. IT SEEMED LIKE THE 06Z/00Z GFS WERE ON THE OUTSIDE OF THIS ENSEMBLE CLUSTERING WITH THE FORMER BEING WELL TO THE NORTH CARRYING A LOW CLOSER TO THE VA/NC BORDER. AS THE SYSTEM EVENTUALLY EXITS INTO THE OPEN ATLANTIC...A LOW-AMPLITUDE NORTHERN STREAM FEATURE DIGS THROUGH THE MIDDLE MS VALLEY/UPPER GREAT LAKES BY SATURDAY. THE 06Z/00Z GFS WERE NOTED TO BE QUICKER AND SOUTH OF THE ENSEMBLE MEANS WHICH MADE THEIR OUTPUT LOWER PROBABILITY OUTLIERS. THE 00Z ECMWF APPEARED TO BE MORE CONSISTENT WITH ITS MEAN AS WELL AS THE 00Z GEFS MEAN. AND LOOKING LATER INTO THE MEDIUM RANGE...A DEEP UPPER TROUGH IS GENERALLY AGREED UPON ACROSS THE EASTERN PACIFIC. ALTHOUGH THERE SEEM TO BE QUITE A FEW DETAIL DIFFERENCES...PARTICULARLY REVOLVING AROUND A SHARPENING PROGRSSIVE SHORTWAVE WHICH SWINGS UNDER THE BASE OF THE TROUGH. MODELS VARY IN THEIR DETAILS BETWEEN MODEL CYCLES WHICH SUGGESTS MORE OF AN ENSEMBLE APPROACH. THE 06Z/00Z GEFS MEANS END UP QUICKER THAN THE 00Z ECMWF ENSEMBLE MEAN DURING THE DAY 6/7 TIMEFRAME. THESE THEMES ARE CONSISTENT BETWEEN THE MODELS DATING BACK TO SOLUTIONS FROM YESTERDAY. THE OVERALL APPROACH WAS TO LEAN MORE ON THE WELL CLUSTERED 00Z ECMWF CAMP WITH SMALLER CONTRIBUTIONS FROM THE 00Z CMC/UKMET THROUGH DAY 4/FRIDAY. AS MENTIONED EARLIER...DID NOT INCLUDE THE 06Z/00Z GFS SOLUTIONS GIVEN THEIR OUTLYING NATURE WITH THE EXITING SURFACE LOW. THEREAFTER...STARTED TO LEAN MORE HEAVILY ON ENSEMBLE MEAN OUTPUT WITH SLIGHTLY MORE EMPHASIS ON THE 00Z ECMWF ENSEMBLE MEAN GIVEN STRONGER STATISTICAL PERFORMANCE IN RECENT MONTHS. ...SENSIBLE WEATHER HIGHLIGHTS... AMPLIFIED FLOW EARLY IN THE PERIOD WILL FAVOR FAIRLY IMPRESSIVE TEMPERATURE ANOMALIES WITH READINGS 10 TO 20 DEGREES BELOW NORMAL OVER NEW ENGLAND ON THURSDAY AND FRIDAY. THIS IS IN RESPONSE TO THE LARGE NEGATIVE HEIGHT ANOMALY CENTERED OVER EASTERN CANADA EARLY IN THE PERIOD. MEANWHILE...WELL ABOVE NORMAL READINGS ARE LIKELY UNDER THE EXPANSIVE RIDGE ACROSS THE WESTERN HALF OF THE COUNTRY. SOME 15 TO 25 DEGREE DEPARTURES FROM CLIMATOLOGY ARE LIKELY...PARTICULARLY OVER THE GREAT PLAINS BY THE WEEKEND. REGARDING PRECIPITATION...A THREAT FOR WINTRY PRECIPITATION IS POSSIBLE IN RESPONSE TO THE EXITING SURFACE LOW OVER THE EASTERN U.S. CONFIDENCE REMAINS RATHER LOW AT THIS POINT HOWEVER. MEANWHILE...OUT WEST...THE DEEP AMPLIFIED TROUGH WILL FAVOR EXPANSIVE PRECIPITATION UP AND DOWN THE WEST COAST WITH HEAVY RAINFALL EXTENDING WELL SOUTH INTO CA. RUBIN-OSTER