EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 217 AM EST SUN JAN 25 2015 VALID 12Z WED JAN 28 2015 - 12Z SUN FEB 01 2015 ...AN ACTIVE WINTER PATTERN FOR THE COMING WEEK... ...GUIDANCE AND UNCERTAINTY ASSESSMENT... THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A COMPOSITE BLEND OF THE 18 UTC GFS AND 12 UTC CANADIAN/ECMWF/UKMET/ECMWF ENSEMBLE MEAN INTO DAY4 THU. MADE A TRANSITION TO A MUCH MORE ECMWF ENSEMBLE MEAN CENTRIC SOLUTION DAYS 5-7 THROUGH NEXT WEEKEND IN A PATTERN WITH GROWING FORECAST SPREAD AND UNCERTAINTY. THESE GUIDANCE COMBOS KEEP THE WPC FORECAST LEANING THROUGH THE ENTIRE FORECAST PERIOD WITH SCENARIOS GENERALLY ON THE SLIGHTLY MORE AMPLIFIED SIDE OF A COMPOSITE OF THE FULL ENVELOPE OF SOLUTIONS. THIS MAINTAINS GOOD WPC CONTINUITY BUT ALLOWS FOR RECENT OVERALL PATTERN AND RUN-RUN MODEL AND ENSEMBLE TRENDS. ...PATTERN OVERVIEW AND SENSIBLE WEATHER HIGHLIGHTS... THE MEDIUM RANGE PERIOD STARTS LATE WEEK WITH AN AMPLIFYING MID-UPPER LATITUDE PATTERN AT MID-UPPER LEVELS. THIS IS HIGHLIGHTED BY A WARMING WRN NOAM MEAN RIDGE WHOSE DEVELOPMENT ALLOWS DEEPER DOWNSTREAM CARVING OF AN INCREASINGLY COLD AIR FED EAST-CENTRAL NOAM MEAN TROUGH. A SERIES OF ENERGETIC EMBEDDED IMPULSES ALOFT LEND SURFACE BASED LOW/SYSTEM GENESIS. WPC PROGS OFFER A TRAILING COLD FRONTAL SURGE DOWN ACROSS THE US SRN TIER IN THE WAKE OF THE TRACK OF AN ORGANIZED WINTER PCPN FOCUSING LOW FROM THE GREAT LAKES/MIDWEST DAY 4/THU TO THE NORTHEAST DAY 5/FRI HOT ON THE HEELS OF A LEAD SHORT RANGE STORM...BUT WITH LESS AVAILABLE MOISTURE. WPC PROGS THEN SHOW A FRIGID ARCTIC BLAST INTO THE CENTRAL US BY DAY 6/SAT THAT SUBSEQUENTLY SPREADS RAPIDLY ACROSS THE EAST DAY 7 WITH FRONTAL PASSAGE. THIS LEADS TO ANOTHER POTENTIAL COLD LOW/WINTER PCPN THREAT POSSIBLY FROM THE MIDWEST/GREAT LAKES BY SAT TO THE MID-ATLC/NERN US AND OFFSHORE BY SUPERBOWL SUNDAY. MEANWHILE AT LOWER LATITUDES...YET ANOTHER ERN PACIFIC MID-UPPER LEVEL TROUGH WORKS SLOWLY TOWARD CA AND THE SWRN US/NW MEXICO DAYS 4-6 THU THROUGH NEXT WEEKEND. THE APPROACH WOULD ALLOW FOR POTENTIAL FOR INCREASED LEAD MOISTURE FEED AND PCPN INTO SRN CA AND THE SWRN US...EVENTUALLY WITH POTENTIAL TO ALSO REACH AND /INTERACT WITH COLDER AIRMASS DELIVERY THROUGH THE SRN ROCKIES/PLAINS. PLAN THOUGH TO PLAY-DOWN SOME OF THE MODEL AND ENSEMBLE PCPN AMOUNTS FOR NOW GIVEN USUAL UNCERTAINTY WITH THE NATURE/TIMING OF THESE TYPE OF CLOSED SYSTEMS. SCHICHTEL