EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1148 AM EDT TUE MAR 25 2014 VALID 12Z FRI MAR 28 2014 - 12Z TUE APR 01 2014 ...SYNOPSIS... THE MEDIUM RANGE PERIOD BEGINS FRIDAY MORNING...WITH THE LARGE STORM IN THE WESTERN ATLANTIC HAVING EXITED AND LOWER AMPLITUDE PROGRESSIVE FLOW HAVING BECOME ESTABLISHED ACROSS THE PACIFIC AND NORTH AMERICA. THE LOBE OF THE CIRCUMPOLAR LOW THAT HAS BEEN QUASI-PERMANENT IN EASTERN CANADA THIS WINTER RETROGRADES TO CENTRAL CANADA AND REMAINS ANCHORED THROUGH DAY 7. THIS SIMPLIFIES THE PATTERN FOR THE U.S...AS WE ARE MAINLY CONCERNED A TRAIN OF PACIFIC SYSTEMS OF SHORT TO MEDIUM WAVELENGTH. ONE WILL MOVE THROUGH THE EASTERN U.S. ON DAYS 4/5...ANOTHER WILL AMPLIFY TO SOME DEGREE ACROSS THE PLAINS/MIDWEST ON DAY 6...AND ANOTHER WILL KEEP THE WEST COAST UNSETTLED INTO DAYS 6/7. ...MODEL DIAGNOSTICS... THE ECMWF MEAN AND GEFS MEAN SHOW FAIR AGREEMENT THROUGH SEVEN DAYS OVER THE PACIFIC AND WESTERN U.S. THERE ARE GREATER DIFFERENCES DOWNWIND OF THE ROCKIES TOWARD THE EAST COAST...WHERE RECENT GFS AND GEFS RUNS HAVE TENDED TO BE MORE FLAT AND PROGRESSIVE. ALTHOUGH THE PATTERN IS TRANSITIONING TOWARD ZONAL...IT IS STILL ENERGETIC ENOUGH TO ALLOW GROWTH OF INDIVIDUAL WAVES AS THEY EMERGE FROM THE ROCKIES. THE ECMWF ENSEMBLE MEAN TENDS TO BE DEEPER AND BETTER DEFINED WITH THESE WAVES...AND IS PREFERRED. THROUGH DAY 4...THE OPERATIONAL ECMWF WAS ALSO USED HEAVILY FOR THE WPC FRONTS/PRESSURES...AND SOME 00Z GFS INFLUENCE WAS ALLOWED INTO THE POPS/TEMPS. BEYOND DAY 4...HOWEVER...THE OPERATIONAL GFS IS TOO FAST AND FLAT...AND THE ECMWF IS ON THE DEEP SIDE OF THE SPREAD FOR THE EASTERN SYSTEMS. THERE IS SOME TREND IN THE ENSEMBLES TOWARD SHARPER SOLUTIONS...BUT THERE IS NOT YET ENOUGH SUPPORT FOR US TO PUT MUCH WEIGHT ON THE VERY PRONOUNCED ECMWF SOLUTION. WE TURNED INSTEAD TO A BLEND OF THE EUROPEAN MEAN WITH THE NAEFS ON DAYS 5/6...DROPPING THE NAEFS ON DAY 7. ...IMPACTS... WITH THE EVER INCREASING SUN ANGLE AND PREDOMINANCE OF PACIFIC AIR THIS PERIOD TEMPERATURES WILL BEGIN TO FEEL MORE SPRING-LIKE FOR A GREATER MAJORITY OF THE NATION. BRIEF INTRUSIONS OF ARCTIC AIR WILL BE MORE LIMITED IN INTENSITY AND CONFINED MAINLY TO THE NORTHERN PLAINS AND GREAT LAKES. THE WARMER WEATHER WILL BE MOST PERSISTENT ACROSS THE SOUTHWEST STATES...WHEREAS THE REST OF THE U.S. WILL SEE SOME FLUCTUATION WITH EACH PASSING WEATHER SYSTEM. THE WAVE AMPLIFYING IN THE EAST THIS WEEKEND SHOULD PRODUCE A BROAD SWATH OF MODERATE PRECIPITATION...MOSTLY RAIN EXCEPT PERHAPS FOR INTERIOR NEW ENGLAND. AT THE SAME TIME OUR SECOND SYSTEM WILL BRING GENEROUS RAIN AND HIGH ELEVATION SNOWS FROM NORTHERN CALIFORNIA TO THE PACIFIC NORTHWEST AND NORTHERN ROCKIES. PRECIPITATION WILL FOLLOW THIS SYSTEM INTO THE CENTRAL U.S. WHILE OUR THIRD SYSTEM MAINTAINS WET WEATHER IN THE WEST. THROUGH ALL OF THIS...THE HEAVIEST PRECIPITATION TOTALS ARE EXPECTED NEAR THE WEST COAST. THERE IS NO INDICATION OF PARTICULARLY HEAVY PRECIPITATION ON A LARGE SCALE IN THE EAST...MAINLY BECAUSE A PERSISTENT STATIONARY FRONT IN THE SOUTHERN GULF OF MEXICO WILL LIMIT THE QUALITY OF MOISTURE RETURNING NORTHWARD. BURKE