EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1054 AM EST WED FEB 01 2017 VALID 12Z SAT FEB 04 2017 - 12Z WED FEB 08 2017 ...OVERVIEW... THE 00Z/06Z MODEL CYCLES HAVE CONTINUED THE TREND OF THE LOW/TROUGH OVER THE NORTH PACIFIC TRACKING FARTHER SOUTH/SOUTHEAST TOWARD THE ALASKAN AND BRITISH COLOMBIAN COASTLINE...WHICH WILL RESULT IN ACTIVE WEATHER ACROSS THE NORTHERN STATES THIS WEEKEND/BEGINNING OF THE WEEK. AN AMPLIFIED TROUGH WILL SET UP OVER THE CENTRAL U.S. BY MIDWEEK...IN PART BY LOW OFF THE PACIFIC NORTHWEST AND SHORTWAVE ENERGY CROSSING THE ROCKIES. GUIDANCE IS SUGGESTING THAT A STRONG SURFACE LOW PRESSURE WILL LIFT THROUGH THE MIDWEST/UPPER MIDWEST/GREAT LAKES AREA. ...GUIDANCE EVALUATION/PREFERENCES... SOME ASPECTS OF THE CLOSED LOW NEAR VANCOUVER ISLAND ARE STILL UNCERTAIN AS SOME OPERATIONAL RUNS SUGGEST THAT THE UPPER LOW COULD BE COMPOSED OF A SERIES OF EJECTING AND RELOADING SHORTWAVES RATHER THAN A SINGLE CIRCULATION. THIS ALONG WITH THE NORTHERN PACIFIC BEING AN AREA OF HIGH FORECAST UNCERTAINTY IN RECENT DAYS SEEM TO MAINTAIN THE POTENTIAL FOR MEANINGFUL CHANGES IN FUTURE RUNS. ADDITIONALLY... THE EVOLUTION OF THE INCOMING EASTERN PACIFIC SHORTWAVE TO THE SOUTH AND ITS INTERACTION WITH THE UPPER LOW ADDS TO THIS UNCERTAINTY. MEANWHILE MODELS/MEANS CONTINUE TO SHOW A GENERAL AREA OF LOW PRESSURE CROSSING THE EAST... MOST LIKELY BEST DEFINED ACROSS NORTHERN AREAS... DURING THE WEEKEND IN ASSOCIATION WITH WEAK SHORTWAVE ENERGY EMBEDDED IN LOW AMPLITUDE FLOW. GUIDANCE CONTINUES TO WAFFLE REGARDING THE POTENTIAL STRENGTH OF THIS FEATURE. THE MOST CURRENT RUNS OF THE UKMET/CANADIAN/GFS AND THE ENSEMBLE MEANS ARE IN GENERAL AGREEMENT WITH A SLIGHTLY MORE PROGRESSIVE/SOUTHERN LOW OVER NEAR COASTAL ALASKA/BRITISH COLUMBIA AND AN AMPLIFIED TROUGH OVER THE CENTRAL CONUS FOR NEXT WEEK - WITH INCREASING SPREAD Sunday AND BEYOND. WPC CHOSE A BLEND OF THE 00Z ECMWF AND ITS ENSEMBLE MEAN/06Z GFS AND ITS ENSEMBLE MEAN WITH THE PREVIOUS FORECAST INITIALLY FOR SATURDAY AND SUNDAY. THE ECWMF LAGS BEHIND OTHER GUIDANCE BY MONDAY INCREASING THE SPREAD THEREAFTER. THE 06S GFS IS MORE PROGRESSIVE WITH THE PACIFIC NORTHWEST LOW AND THE AMPLIFIED TROUGH OVER THE CENTRAL CONUS. LESS EMPHASIS WAS PLACED ON THE DETERMINISTIC SOLUTIONS FOR MONDAY - WEDNESDAY IN ORDER TO FIND A MIDDLE OF THE ROAD TRACK FOR THE SURFACE LOW OVER THE PLAINS/MIDWEST/UPPER MIDWEST. ...WEATHER HIGHLIGHTS/THREATS... SOME UNCERTAINTY REMAINS WITH THE EVOLUTION OF THE LOW/TROUGH OVER THE NORTH PACIFIC AND THE BREAK DOWN OF THE WEST COAST RIDGE. HOWEVER ONSHORE FLOW WILL LIKELY RESULT IN HEAVIEST COASTAL RAIN AND INLAND/HIGHER ELEV SNOW TO FALL ACROSS FAVORED TERRAIN ACROSS THE PACIFIC NORTHWEST...NORTHERN CALIFORNIA AND THE SIERRA NEVADA RANGE- WITH SOME ENHANCED TOTALS ALSO OVER THE NORTHERN ROCKIES. THE WIND ASSOCIATED WITH THIS LOW MAY ALSO BE STRONG AT TIMES AS IT IS DIRECTED THROUGH THE MAINLAND. MUCH OF THE NORTHWEST AND INTERIOR WEST WILL HAVE BELOW NORMAL TEMPERATURES DURING THIS PERIOD...WHILE CENTRAL AND SOUTHERN REGIONS WILL BE SLIGHT BELOW OR NEAR NORMAL. EAST OF THE ROCKIES... AN AREA OF PRECIPITATION OF VARYING INTENSITY WILL CROSS THE EASTERN HALF OF THE COUNTRY THIS WEEKEND WITH SNOW TO THE NORTH AND RAIN ACROSS THE SOUTH... POSSIBLY SEPARATED BY A NARROW BAND OF WINTRY MIX. A TRAILING FRONT EXTENDING BACK INTO THE PLAINS MAY SUPPORT ANOTHER AREA OF PRECIPITATION FOR EARLY NEXT WEEK AS IT LIFTS NORTHWARD AS A WARM FRONT. THE SYSTEM THAT SPINS UP AND LIFTS THROUGH THE MIDWEST/UPPER MIDWEST MAY POTENTIALLY HAVE VARYING PRECIPITATION TYPES/INTENSITIES AS WELL AS STRONG ACCOMPANYING WIND GUSTS. HEAVY RAINFALL MAY BE POSSIBLE AHEAD OF THE ADVANCING FRONT. MUCH OF THE CENTRAL AND EASTERN STATES SHOULD SEE A PRONOUNCED WARMING TREND BY NEXT WEEK AHEAD OF THE PLAINS-GREAT LAKES SYSTEM... WITH A DECENT AREA OF PLUS 10-20F ANOMALIES FOR HIGHS AND PLUS 20-30F ANOMALIES FOR MORNING LOWS. MEANWHILE COLDER AIR WILL SPREAD ACROSS THE NORTHERN PLAINS MON ONWARD WITH SOME HIGHS AT LEAST 15-20F BELOW NORMAL. RAUSCH/CAMPBELL