EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 221 AM EDT THU MAY 11 2017 VALID 12Z SUN MAY 14 2017 - 12Z THU MAY 18 2017 ...WIDESPREAD HIGHER ELEVATION SNOW LIKELY FOR PORTIONS OF THE INTERIOR WEST NEXT WEEK... ...OVERVIEW... UPPER PATTERN WILL FEATURE INCREASING TROUGHING INTO THE WEST AS THE EAST FINALLY SEES RISING HEIGHTS IN THE WAKE OF YET ANOTHER UPPER LOW EARLY NEXT WEEK. THE CENTRAL PLAINS WILL MOSTLY STAY UNDER RIDGING. ...GUIDANCE EVALUATION AND PREFERENCES... THE MODELS CONTINUE TO SHIFT THEIR TRACK OF THE NOR'EASTER SUN-MON BUT MOSTLY AGREE ON TAKING THE SFC LOW ALONG THE NEW ENGLAND COAST INTO MAINE BEFORE LIFTING OUT THROUGH SOUTHEASTERN CANADA ON TUESDAY. THE ECMWF WAS STILL A BIT REMOVED FROM THE OTHER MODELS, BUT HAS GENERALLY MOVED IN THE 'RIGHT' DIRECTION AHEAD OF THE OTHERS. NEVERTHELESS, A CONSENSUS BLEND WAS A GOOD STARTING POINT AS ALL WERE MUCH CLOSER THAN IN PREVIOUS RUNS -- THE 18Z GFS/GEFS MEAN AND 12Z GFS/ECENS MEAN PROVIDED A GOOD VARIANCE. TO THE WEST, LEAD WEAK VORT MAXES WILL BE SUBSUMED BY AN INCOMING DEEPER UPPER LOW FROM THE GULF OF ALASKA. THIS IS FORECAST TO DIG SOUTHEASTWARD THROUGH OR/NV/UT NEXT TUE-THU. 12Z UKMET AND CANADIAN FORMED THE EASTERN AND WESTERN SIDE (RESPECTIVELY) OF THE ENSEMBLE SPREAD WHILE THE GFS/ECMWF WERE CLOSE TO THEIR MEANS (AND EACH OTHER). A WEAKER PRECURSOR SHORTWAVE MAY LIFT NORTHEASTWARD THROUGH THE CENTRAL/HIGH PLAINS ON WEDNESDAY BUT CONFIDENCE IS LOW IN THESE DETAILS. EITHER WAY, ANOTHER ANOMALOUSLY STRONG UPPER LOW SHOULD BRING QUITE A COLD SHOT TO THE INTERIOR WEST NEXT WEEK. ...WEATHER HIGHLIGHTS... HEAVY RAIN ASSOCIATED WITH THE COASTAL STORM EXITING NEW ENGLAND SHOULD BE LIMITED TO BOSTON AND POINTS NORTH AND NORTHEAST (NH/ME) WITH LIGHTER WRAP AROUND SHOWERS OVER MUCH OF UPSTATE NY INTO WESTERN NEW ENGLAND. WELL BELOW DAYTIME TEMPERATURES WILL WARM BACK TO AVERAGE VALUES BY WEDNESDAY. WAVES OF PRECIPITATION WILL PUSH THROUGH THE PACIFIC NORTHWEST INTO MONTANA/IDAHO SUN-TUE AS THE LEAD SHORTWAVE AND SUBSEQUENT UPPER LOW MOVE THROUGH. SNOW IS EXPECTED IN THE HIGHER PEAKS OF THE RANGES OF THE PACIFIC NORTHWEST AND NORTHERN ROCKIES AS 700 MB TEMPS DROP TO AROUND -10C TO -13C IN WA/OR WHICH IS WELL BELOW AVERAGE FOR MID-MAY. COLD CORE WILL SLIDE SOUTHEASTWARD LATER IN THE WEEK WHICH SUPPORTS PERHAPS SIGNIFICANT SNOW (FOR MID-MAY) IN THE SIERRAS AND MORE MODEST SNOW THROUGH NEVADA INTO UTAH AT HIGHER ELEVATIONS. TEMPERATURES ARE FORECAST TO BE ABOUT 10-20 DEGREES BELOW AVERAGE. EAST OF THE FRONT FROM THE CENTRAL/SOUTHERN PLAINS INTO THE LOWER MS VALLEY AND SOUTHEAST ABOVE AVERAGE TEMPERATURES ARE FORECAST. SOME DAILY RECORD HIGHS ARE POSSIBLE. FRACASSO