EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1046 AM EST WED JAN 27 2016 VALID 12Z SAT JAN 30 2016 - 12Z WED FEB 03 2016 PATTERN OVERVIEW... CURRENT GUIDANCE SHOWS THE LONGWAVE PATTERN BECOMING MORE AMPLIFIED DURING THE UPCOMING MEDIUM RANGE PERIOD...WITH THE FLOW COMPRISED OF AT LEAST 2 STREAMS...A NORTHERN STREAM ALONG THE U.S./CANADIAN BORDER...AND A SOUTHERN STREAM ACROSS THE FOUR CORNERS REGION INTO THE S. PLAINS. WHILE PREDICTABILITY CHALLENGES CONTINUE WITH BOTH STREAMS BASED ON RUN-TO-RUN CHANGES AND THE ENSEMBLE MEMBER SPREAD...THE SOUTHERN STREAM APPEARS MORE PREDICTABLE AS ITS COMPRISED OF LARGER AND STRONGER SHORT WAVE TROUGHS AND RIDGES. ADDITIONALLY...ACCOMPANYING THE SOUTHERN STREAM IS A LIKELY WINTER STORM FOR PORTIONS OF THE FOUR CORNERS REGION TOWARD THE CENTRAL PLAINS AND UPPER MIDWEST FOR EARLY AND MIDDLE PARTS OF NEXT WEEK. MODEL PREFERENCES... FOR DAY 3/SAT...ALMOST ANY COMBINATION OF MODELS LIKELY WORKS EQUALLY WELL AS THE SOLUTION SPREAD IS SMALL AND SYSTEMS OF LOW AMPLITUDE. BY DAY 4/SUN HOWEVER...THE LAST FEW RUNS OF THE GFS SHOW QUESTIONABLE PHASING OF SEPARATE PORTIONS OF THE NORTHERN STREAM OVER THE PLAINS RESULTING IN A MUCH STRONGER SURFACE LOW AND COLD FRONTAL PASSAGE COMPARED TO MORE LIKELY 00Z ECMWF AND THE ENSEMBLE MEANS THAT MAINTAIN MORE SEPARATION. GIVEN THE TYPICAL CHALLENGES OF CAPTURING SMALL-SCALE PHASING AND THAT FEW OTHER SOLUTIONS SUPPORT SUCH A VIGOROUS APPROACH...THE PREFERENCE IS FOR THE WEAKER SIDE OF THE GUIDANCE THAT IS BETWEEN THE 00Z ECMWF AND THE ENSEMBLE MEANS. FOR DAY 5-7/MON-WED...SIMILAR PREFERENCES ARE RECOMMENDED FOR ALL AREAS AS CONCERNS WITH THE PHASING SHORTWAVE TROUGHS CROSS THE OH VALLEY TOWARD NEW ENGLAND WITH THE WEAKER CAMP STILL PREFERRED. ACROSS THE FOUR CORNERS INTO THE S. PLAINS/MIDWEST...THE FOCUS SHIFTS TO PHASING OF INDIVIDUAL PORTIONS OF THE SOUTHERN STREAM OF WHICH THERE EXISTS GOOD AGREEMENT FOR GIVEN ITS LARGER-SCALE. THE TREND SINCE TUESDAY IS FOR SLIGHTLY MORE CONVERGENCE AMONG SOLUTIONS...WITH THE GFS AND ITS OWN ENSEMBLE MEMBERS ACCELERATING EASTWARD AND MORE TOWARD THE MORE CONSISTENT ECMWF AND ITS OWN ENSEMBLE MEMBERS THAN THE ECMWF CAMP SLOWING DOWN. THUS...THE PREFERENCE FOR THIS SYSTEM IS WEIGHTED ABOUT 2/3 TOWARD THE FASTER ECMWF CAMP...WITH ABOUT 1/3 WEIGHTING FOR THE 06Z GEFS MEAN. CONFIDENCE IS ABOUT AVERAGE THROUGH DAY 5...THEN BELOW AFTER THEREAFTER. SENSIBLE WEATHER HIGHLIGHTS... THE DEVELOPING PATTERN IS MORE TYPICAL OF EARLY SPRING...WITH A WINTER STORM ACCOMPANIED BY HEAVY SNOW POSSIBLE FROM THE FOUR CORNERS REGION INTO THE CENTRAL PLAINS AND EVENTUALLY PORTIONS OF THE MIDDLE MS VALLEY AND UPPER MIDWEST MONDAY THROUGH WEDNESDAY. AHEAD OF THE SYSTEM'S COLD FRONT WILL BE THE POTENTIAL FOR HEAVY RAINFALL FROM PORTIONS OF THE LOWER MS VALLEY INTO THE TN-OH VALLEYS. PERIODIC MODERATE OR POSSIBLY HEAVY PRECIPITATION COULD ALSO RETURN TO THE WEST COAST AND PACIFIC NORTHWEST...PARTICULARLY TOWARD THE MIDDLE OF NEXT WEEK...WITH THE WEAKER ECMWF CAMP OF SOLUTIONS GENERALLY PREFERRED OVER THE MUCH WETTER 06Z GFS OVER THE PACIFIC NORTHWEST GIVEN THE STRENGTH AND AMPLITUDE OF THE LONGWAVE RIDGE OFFSHORE THAT SHOULD MITIGATE THE POTENTIAL FOR SUCH A STRONG SYSTEM TO REACH THE COAST SO QUICKLY. JAMES