EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 104 AM EDT TUE OCT 31 2017 VALID 12Z FRI NOV 03 2017 - 12Z TUE NOV 07 2017 ...COLDER AND STORMY FOR THE WEST... ...OVERVIEW AND GUIDANCE PREFERENCES... RATHER PERSISTENT UPPER PATTERN OF STRONG RIDGING IN WESTERN ALASKA AND OVER MEXICO COMBINED WITH AN UPPER LOW JUST WEST OF THE DAVIS STRAIT WILL SUPPORT TROUGHING IN THE WESTERN STATES INTO SOUTHERN CANADA THROUGH THE PERIOD. THE RECENT GFS/ECMWF AND THEIR ENSEMBLE MEANS FORMED A GOOD CONSENSUS. USED A MAJORITY ENSEMBLE MEAN WEIGHTING BY NEXT MONDAY AS THERE REMAINS DISAGREEMENT ON HOW THE TROUGH EJECTS OUT OF THE WEST (I.E., SPEED AND SHAPE OF EMBEDDED VORTICITY WITHIN THE FLOW). ...WEATHER HIGHLIGHTS... A STRONG COLD FRONT WILL MOVE THROUGH THE NORTHWEST AND INTERMOUNTAIN WEST FRI/SAT BEFORE LIFTING THROUGH THE HIGH PLAINS SUNDAY. THE SOUTHERN PORTION OF THE FRONT WILL WORK THROUGH CALIFORNIA AND THE DESERT SOUTHWEST SAT-TUE. TO THE EAST, LEAD COLD FRONT WILL EXIT THE NORTHEAST BUT LEAVE ITS SOUTHERN EXTENSION BACK ACROSS THE CAROLINAS AND TN/OH VALLEY BEFORE LIFTING NORTHWARD AS A WARM FRONT AS THE PACIFIC SYSTEM MOVES THROUGH THE WESTERN GREAT LAKES. THE WESTERN BOUNDARY WILL SEPARATE COLD ARCTIC AIR (TEMPERATURES 10-25F BELOW AVERAGE) ACROSS MUCH OF MONTANA FROM MUCH MILDER AIR ACROSS THE CENTRAL/SOUTHERN PLAINS AND DEEP SOUTH (10-20F ABOVE AVERAGE) UNTIL A FRONT APPROACHES EARLY NEXT WEEK. THE ENTIRE WEST WILL SEE COOLER TEMPERATURES WITH TIME AND MOST AREAS WILL SEE AT LEAST SOME PRECIPITATION, FOCUSED ACROSS CENTRAL/NORTHERN CALIFORNIA AND THE INTERIOR WEST. HEAVY SNOW IS LIKELY FOR FAVORED AREAS IN HIGHER TERRAIN WITH WINDY CONDITIONS AS THE TROUGH PASSES THROUGH. FRACASSO