EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 211 AM EST FRI JAN 26 2018 VALID 12Z MON JAN 29 2018 - 12Z FRI FEB 02 2018 ...GUIDANCE AND PREDICTABILTY ASSESSMENT... THE 18/00 UTC GFS AND 12/00 UTC ECMWF ARE WELL POSITIONED WITHIN THE OVERALL FORECAST DISTRIBUTION OUTLINED BY THEIR ENSEMBLES IN A MEDIUM RANGE FORECAST PATTERN WITH SLIGHTLY BETTER THAN AVERAGE FORECAST SPREAD AND IMPLIED PREDICTABILITY. A FAVORED COMPOSITE BLEND SEEMS TO OFFER A REASONABLE DEPICTION OF THE FLOW DESPITE UNRESOLVED SMALLER SCALE TIMING AND AMPLITUDE DIFFERENCES IN GENERALLY PROGRESSIVE FLOW THAT MAY GRADUALLY DEAMPLIFY NEXT WEEK. THIS SCENARIO MAINTAINS GOOD WPC DETERMINISTIC AND PROBABILISTIC CONTINUITY OVERALL. ...PATTERN OVERVIEW AND WEATHER HIGHLIGHTS/THREATS... AMPLIFIED MID-UPPER LEVEL TROUGHING OVER THE HALF OF THE NATION MONDAY STEADILY WORKS OFFSHORE INTO THE WRN ATLANTIC TUE/WED. THIS WOULD USHER IN ANOTHER COLD SURGE DUG DOWN ACROSS THE CENTRAL AND ERN US AND ACT TO ENHANCE GREAT LAKE SNOWS IN THE WAKE OF LEAD WAVY FRONTAL SYSTEM PASSAGE. THE WPC COMPOSITE SOLUTION OFFERS A MODEST LEAD COASTAL LOW AND SEABOARD WEATHER THREAT...ALBEIT WITH SOME POTENTIAL FOR MORE ORGANIZED DEVELOPMENT AS PER SOME ENSEMBLE MEMBERS THAT WOULD INCREASE THE SNOW THREAT FROM THE ERN MID-ATLANTIC INTO NEW ENGLAND. MEANWHILE...PACIFIC HEIGHT FALLS/SYSTEM APPROACH INTO THE NWRN STATES WILL INCREASE POTENTIAL FOR HEAVIER PCPN WITH TERRAIN ENHANCED RAINS/ELEVATION SNOWS EARLY NEXT WEEK AND AGAIN THROUGH MID-LATE NEXT WEEK WITH ADDITIONAL SYSTEM APPROACHES AND INLAND PROGRESSION IN LESS AMPLIFIED/MORE UNCERTAIN PROGRESSIVE FLOW. DYNAMICS AND ONSHORE FETCH HAS THE POTENTIAL TO YIELD MULTIPLE INCHES OF RAIN INTO FAVORED TERRAIN OF THE PACIFIC NW AND LOWERING SNOW LEVELS IN THE WAKE OF THE LEAD SYSTEM AND WITH ADVENT OF LATER FOLLOW-UP ENERGIES COULD LEAD TO MULTIPLE FEET OF MOUNTAIN SNOWS INLAND OVER THE NWRN US. IN ADVANCE OF THIS...A WARMING/STABLE MID-UPPER LEVEL RIDGE IS SLATED TO PROGRESS FROM THE WRN US MON EASTWARD TO THE ERN SEABOARD BY THU AND PROVIDE ANOTHER TASTE OF SPRING AS LEAD LOWER ATMOSPHERIC WARM AIR ADVECTION AND AN INCREASING RETURN FLOW OF GULF OF MEXICO MOISTURE AHEAD OF CENTRAL NOAM CYCLOGENESIS AND FRONTOGENESIS WOULD BE AVAILABLE TO FUEL AN EMERGING CENTRAL TO US PRECIPITATION PATTERN. THIS WOULD INCLUDE POTENTIAL FOR SOME HEAVIER CONVECTION OVER MID-SRN LATITUDES AND SNOWS OVER THE COOLER NRN TIER STATES MORE UNDER THE INFLUENCE OF PASSING NRN STREAM IMPULSES AND LOWER LEVEL COLD AIR RETURN. SCHICHTEL