EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1059 AM EST SAT NOV 14 2015 VALID 12Z TUE NOV 17 2015 - 12Z SAT NOV 21 2015 ...OVERVIEW... UPPER PATTERN WILL BE DRIVEN BY UPSTREAM AND DOWNSTREAM RIDGING OVER THE NORTHEAST PACIFIC AND NW ATLANTIC... RESPECTIVELY. THIS LEAVES TROUGHING OVER THE CONUS THAT IS FORECAST TO FLATTEN IN TIME. AT THE SURFACE... A DEEPENING AREA OF LOW PRESSURE IS FORECAST TO LIFT NORTHEASTWARD FROM THE SOUTHERN PLAINS TO THE GREAT LAKES REGION AND COMBINE WITH REINFORCING ENERGY OUT OF THE NE PACIFIC MIDWEEK. AS THAT CONTINUES TO LIFT NORTHEASTWARD AND BATTLE RIDGING TO ITS EAST... THE PATTERN IN ITS WAKE FAVORS WEAKER TROUGHING AGAIN INTO THE WEST. AS HAS BEEN THE CASE FOR SEVERAL DAYS... AT THE DAYS 6-7 TIME FRAME THE DETAILS BECOME FUZZY. ...GUIDANCE ASSESSMENT... THERE HAS FINALLY BEEN A MEANINGFUL CONVERGENCE OF SOLUTIONS WITH RESPECT TO THE LEAD/MAIN SYSTEM TUE-WED AS IT TREKS THROUGH THE PLAINS INTO THE LAKES. AN ENSEMBLE COMPROMISE HAS SERVED WELL FOR THE EJECTION SPEED OF THE SYSTEM -- NEITHER THE GEFS NOR ECENS MEANS WERE STELLAR IN THAT REGARD. TO THE NORTHWEST... THE ECMWF AND ITS MEMBERS WERE BEST AT SHOWING PAC NW ENERGY PUSHING THROUGH SOUTHERN CANADA TUE-WED AS ALL THE GUIDANCE NOW SHOW A WELL-DEFINED SURFACE LOW MOVING EASTWARD INTO THE LEAD SYSTEM MOVING INTO CANADA... AND THE TWO COMBINE WED INTO THU AS IT CONTINUES NORTHEASTWARD. AS SUCH... THE RECENT 00Z MODELS/ENSEMBLES FORM A GOOD CONSENSUS WITH THIS LEAD SYSTEM TUE-THU AND A BLEND AMONG THE 00Z GFS/NAEFS AND ECMWF/ECENS MEAN WAS USED. FOR THU-SAT... FIRST IN THE EAST... COLD FRONT ATTACHED TO THE LEAD SYSTEM IS STILL FORECAST TO WASH OUT SOUTH FIRST IN THE SOUTHEAST ON THU AND THEN OVER THE MID-ATLANTIC ON FRI AS THE MID-LEVEL SUPPORT LIFTS TO THE NORTH. QUESTION REMAINS AS TO HOW MUCH PRECIP CAN BE CARRIED EASTWARD. SECONDARY FRONT WILL BE ABOUT 24 HRS BEHIND THE LEAD BOUNDARY AND SHOULD PUSH OFF THE COAST AROUND NEXT SAT SHOULD RIDGING TO THE EAST BUDGE A BIT. THEN IN THE WEST... UPSTREAM FLOW NEAR/SOUTH OF CANADA HAS HAD MANY INCONSISTENCIES IN THE PAST SEVERAL DAYS OF ENSEMBLE RUNS. THOUGH RIDGING HAS AND IS STILL FORECAST TO BUILD ACROSS THE ALEUTIANS AND OFF THE CA COAST... THE DETAILS OF THAT SCENARIO HAVE BEEN ELUSIVE. THE ENSEMBLES HAVE BEEN VERY SENSITIVE TO THE SHORTWAVE DETAILS THAT CAN ACT TO HELP DIG THE TROUGH EITHER INTO CA OR LESS SO INTO THE INTERIOR -- NV AND THE FOUR CORNERS REGION. SEEMS THAT ONLY MODEST TROUGHING IS FORECAST TO SLIDE THROUGH THE INTERIOR WEST NEXT FRI-SAT AS THE UPSTREAM RIDGE LACKS ENOUGH COHESION TO SUPPORT MUCH DEEPER HEIGHT FALLS THAT FAR SW INTO CA. THOUGH THAT REMAINS A POSSIBILITY... SEEMS THAT THE STRONGER HEMISPHERIC HEIGHT ANOMALY WILL BE THE POSITIVE ONE OVER GREENLAND PARTIALLY IN RESPONSE TO THE LEAD SYSTEM IN THE CONUS TUE-WED AS IT MATURES/DEEPENS IN CANADA. ...SENSIBLE WEATHER HIGHLIGHTS... VERY WET PATTERN FOR THE MISSISSIPPI VALLEY...OZARKS AND PORTIONS OF THE GREAT LAKES AHEAD OF THE FRONTAL BOUNDARY. ENOUGH MOISTURE MAY CARRY EASTWARD TO SUPPORT AT LEAST MODEST RAINS INTO THE SOUTHERN APPALACHIANS AND EAST COAST AS A WHOLE -- GA NORTHWARD -- AS THE JET SWINGS THROUGH. CONTINUED MILD IN THE EAST FOR MID-NOVEMBER---AHEAD OF THE FRONT. PRIMARILY EAST OF THE APPALACHIAN TRAIL AND ACROSS THE FLORIDA PENINSULA. CONTINUED ONSHORE FLOW AND JET-DRIVEN PRECIPITATION FOR THE WINDWARD CASCADES AND NORTHERN CONTINENTAL DIVIDE (WITH HIGH-ELEVATION SNOWS). FRACASSO/VOJTESAK