EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1059 AM EST SUN NOV 05 2017 VALID 12Z WED NOV 08 2017 - 12Z SUN NOV 12 2017 ...GUIDANCE/UNCERTAINTY ASSESSMENT AND WEATHER HIGHLIGHTS/THREATS... A WAVY TRAILING FRONT FROM THE WRN ATLC TO SRN/SERN US WILL FOCUS MODERATE TO HEAVY RAINS. POST-FRONTAL HIGH PRESSURE COOLS TEMPS IN ITS WAKE OVER THE W-CENTRAL TO ERN US. THERE REMAINS SOME POTENTIAL TO FURTHER DEVELOP EJECTING LOWS OFF THE EAST COAST UP TOWARD THE CANADIAN MARITIMES. SHORTWAVE SUPPORT FOR THIS HAS BEEN HIGHLY INCONSISTENT WITH RECENT GUIDANCE...BUT THE 06 UTC GFS AND 00 UTC ECMWF NOW SHOW A SIMILAR SOLUTION ALOFT WITH ENERGY REACHING THE SERN US COAST THU...ENHANCING POTENTIAL. THAT SAID...THE 06 UTC GFS SEEMS TO OVER-DEVELOP SURFACE LOW RESPONSE LATER TUE ONWARD DUE TO CONVECTIVE FEEDBACK. UPSTREAM...GUIDANCE DIGS AN AMPLIFIED CLOSED LOW/TROUGH OFF THE NWRN US INTO MIDWEEK WHOSE ENERGIES EJECT INLAND OVER THE WRN US/ROCKIES FRI/SAT ALONG WITH UNSETTLED WEATHER AND PCPN ENHANCEMENT. THIS INCLUDES PAC NW/NRN CA MODERATE TO HEAVY RAINS/MOUNTAIN SNOWS. TERRAIN ENHANCED HEAVY SNOWS SUBSEQUENTLY SPREAD INLAND ACROSS THE INTERMOUNTAIN WEST/ROCKIES THROUGH LATER WEEK. ENERGY/HEIGHT FALLS REACH THE PLAINS NEXT WEEKEND TO SPAWN FRONTOGENESIS/CYCLOGENESIS AS GRADUAL GULF OF MEXICO MOISTURE RETURN BECOMES AVAILABLE TO INCREASINGLY FUELS PRECIPITATION UP THROUGH THE CENTRAL THEN E-CENTRAL US AS A LEAD DOME OF COOLED WEDGED HIGH PRESSURE SLOWLY RECEDES EASTWARD. OVERTOP...A SERIES OF DYNAMIC SHIRTWAVES WILL MEANWHILE DIG UNDERNEATH A MEAN CLOSED HUDSON BAY LOW AND FORCE SEVERAL SURGES OF COLD CANADIAN AIR INTO THE N-CENTRAL AND NERN US TO FURTHER REINFORCE A COOLED MID-LATER NEXT WEEK AUTUMN PATTERN. THESE SURGES HAVE MODEST PCPN POTENTIAL/MOISTURE...BUT DO OFFER GREAT LAKE SNOW POTENTIAL AND COULD ACT TO INTERACT DOWNSTREAM WITH POTENTIAL LEAD WRN ATLANTIC LOWS. OVERALL...THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A BLEND OF THE 06 UTC GFS/GEFS AND 00 UTC ECMWF/ECMWF ENSEMBLES THAT CLUSTER WELL ALOFT. HOWEVER...DUE TO THE AFOREMENTIONED APPARENT 06 UTC GFS CONVECTIVE FEEDBACK ISSUE BY LATER WEEK...PLACED MORE WEIGHTING ON THE ECMWF BY NEXT FRI-SUN. SCHICHTEL