EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 300 AM EDT WED JUN 17 2015 VALID 12Z SAT JUN 20 2015 - 12Z WED JUN 24 2015 *** A HEAVY RAIN THREAT ASSOCIATED WITH THE REMNANTS OF "BILL" SPREADS ACROSS THE OH VALLEY AND MID-ATLANTIC STATES INTO SRN NEW ENGLAND ASTRIDE 40N THIS WEEKEND*** ...PATTERN OVERVIEW AND SENSIBLE WEATHER HIGHLIGHTS/THREATS... HOT SUBTROPICAL RIDGING SPREAD OVER THE US SRN TIER WILL KEEP NRN STREAM FRONTAL SYSTEMS FROM PRESSING TOO FAR SOUTH...RESULTING IN WAVY WEATHER FOCUSING BOUNDARIES LINGERING ACROSS THE NORTHEAST/MID-ATLANTIC STATES AND BACK TO THE PLAINS AND INTERIOR WEST. THE NATIONAL HURRICANE CENTER TRACKS THE MOIST REMNANTS OF CURRENT TEXAS TROPICAL STORM BILL INTO OKLAHOMA BEFORE TURNING NORTHEASTWARD OVER THE MID-MISSISSIPPI VALLEY OVER THE NEXT COUPLE OF DAYS...WITH A SUBSEQUENT PROGRESSION EFFECTING THE OHIO VALLEY AND MID-ATLANTIC STATES AND SRN NEW ENGLAND THIS WEEKEND. HEAVY RAIN WILL OCCUR NEAR THIS TRACK. MEANWHILE...NRN STREAM MID-UPPER LEVEL TROUGH ENERGY AND LEAD PRECIPIATION FOCUS ARE SLATED TO PROGRESS EASTWARD ALONG THE US/CANADIAN BORDER FROM THE NWRN US SATURDAY...AND WETTER NORTH-CENTRAL US SUNDAY...GREAT LAKES/MIDWEST MONDAY TO THE CANADIAN MARITIMES TUESDAY. UPSTREAM OVER THE ERN PACIFIC...A CLOSED LOW IS FORECAST TO OPEN UP THIS WEEKEND AND WORK INTO THE NWRN US BY MONDAY...WITH AN ADDITIONAL HEIGHT FALLS/CONVECTION FOCUS FOR THE NORTH-CENTRAL ROCKIES/PLAINS TUESDAY/WEDNESDAY. ...GUIDANCE/UNCERTAINTY ASSESSMENT... WPC SURFACE FRONTS/PRESSURES AND 500 MB PROGS HAVE BEEN PRIMARILY DERIVED FROM A BLEND OF THE 12 UTC GFS/CANADIAN/ECMWF SATURDAY INTO MONDAY. THESE DETERMINISTIC GUIDANCE PIECES SEEM TO CLUSTER WELL AND ARE IN LINE WITH THE NHC FORECAST OF BILL. GUIDANCE APPEARS TO REMAIN IN REASONABLE AGREEMENT WITH THE OVERALL FLOW PATTERN INTO NEXT WEEK...BUT INCREASINGLY DIFFER WITH DETAILS OVER TIME. ACCORDINGLY...USED A COMPOSITE OF THE PRETTY COMPATABLE 12 UTC GFS/NAEFS/ECMWF ENSEMBLE MEANS INTO DAYS 6/7 NEXT TUESDAY/WEDNESDAY. SCHICHTEL