EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 117 AM EST TUE FEB 16 2016 VALID 12Z FRI FEB 19 2016 - 12Z TUE FEB 23 2016 ...GUIDANCE/UNCERTAINTY ASSESSMENT... TODAYS WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A COMPOSITE BLEND OF THE REASONABLY COMPATABLE 18 UTC GFS/GEFS MEAN AND 12 UTC ECMWF/ECMWF ENSEMBLE MEAN DAYS 3-5 FRI-SUN. USED ONLY THESE ENSEMBLES DAYS 6/7 AMID GROWING FORECAST SPREAD. THE OVERALL PATTERN OFFERS ABOVE NORMAL PREDICTABILITY AND CLOSE WPC CONTINUITY. ...FLOW HIGHLIGHTS/THREATS... A DYNAMIC MID-UPPER LEVEL TROUGH AND SURFACE LOW/FRONTAL SYSTEM QUICKLY TRACK ACROSS THE CENTRAL THEN ERN US FRI/SAT. THIS SUPPORTS AMPLE LEAD SPRINGTIME WARMING...BUT GENERALLY MODEST MOISTURE INFLOW AND FRONTAL FOCUSING PCPN. HEAVIEST QPF AND MODERATED BUT STILL WINTERY TEMPS/PCPN MAY LINGER CLOSER TO THE LOW TRACK ACROSS THE NRN TIER OF THE UPPER MIDWEST/GREAT LAKES/NEW ENGLAND. MEANWHILE UPSTREAM...A POTENT MID-UPPER LEVEL TROUGH AND SURFACE FRONTAL SYSTEM SLAMS A BURST OF HEAVY PCPN ACROSS THE PACIFIC NW FRI THEN INLAND ACROSS THE NWRN US INTO SAT...WITH SNOW FURTHER ENHANCED BY FAVORED TERRAIN. IN THE WAKE OF THIS SYSTEM...FLOW AMPLIFICATION OVER THE PACIFIC LEADS TO STRONG MID-UPPER LEVEL RIDGE BUILDING OVER WARMING WRN NORTH AMERICA SUN-TUE. THIS TRANSITION REMAINS WELL SUPPORTED BY GUIDANCE AND WATER VAPOR IMAGERY. THIS ALLOWS INCREASINGLY ROBUST SHORTWAVE ENERGY ALOFT AND COLD LOWER ATMOSPHERIC CANADIAN AIR TO DIG DOWNSTREAM OVER THE CENTRAL THEN ERN US. LESS PREDICTABLE LEAD WAVY/FRONTAL DEVELOPMENTS AND STREAM INTERACTIONS SHOULD SUPPORT RENEWED MOISTURE INFLOW TO FUEL INCREASINGLY WIDESPREAD PCPN. HEAVIEST RAINS SHOULD PERMIATE NEWD FROM THE S-CENTRAL US AND THIS PATTERN ALSO OFFERS SOME EMERGING THREAT FOR WINTERY PCPN ON THE COOLING NRN PERIPHERY OF THE EXPANDING PCPN SHIELD ACROSS THE E-CENTRAL TO ERN US. SCHICHTEL