EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1159 AM EDT TUE JUL 05 2016 VALID 12Z FRI JUL 08 2016 - 12Z TUE JUL 12 2016 ...PATTERN OVERVIEW AND GUIDANCE/UNCERTAINTY ASSESSMENT... WITHIN A PATTERN FEATURING SOMEWHAT AMPLIFIED TROUGHING OVER THE WEST AND NORTHEAST FOR PORTIONS OF THE FCST PERIOD AND RIDGING ACROSS THE EXTREME SRN TIER AS WELL AS BTWN THE TWO TROUGHS... THE GREATEST UNCERTAINTY EXTENDS ACROSS THE NERN PAC INTO WRN NOAM. INTO DAY 4 SAT THERE IS REASONABLE CLUSTERING WITH A LEADING VIGOROUS UPR LOW TRACKING INTO THE PAC NW. AFTER THAT TIME GUIDANCE DIVERGES FOR TIMING/TRACK WITH SIGNIFICANT SENSIBLE WEATHER EFFECTS ON THE NRN TIER. ESTABLISHED CONSENSUS FAVORS AN UPR LOW TRACK THAT IS FARTHER NWD THAN THE 06Z GFS AFTER LATE SAT AND SLOWER THAN THE 00Z GFS AFTER LATE SUN. BEHIND THIS SYSTEM INDIVIDUAL SOLNS ARE QUITE DIVERSE WITH A COMPACT BERING SEA UPR LOW THAT SHOULD TRACK SEWD WITH TIME. THE PAST COUPLE ECMWF RUNS AND MULTI-RUN GEFS/ECMWF MEAN CONSENSUS ALONG WITH THE 00Z CMC MEAN ALL SUGGEST THIS TRAILING UPR LOW SHOULD NOT TRACK INTO THE WRN U.S. AS QUICKLY AS FCST BY THE 00Z/06Z GFS RUNS. FARTHER EWD THE 00Z/06Z GFS RUNS ARE SLIGHTLY DEEPER SFC/ALOFT THAN A MAJORITY OF OTHER GUIDANCE WITH THE SYSTEM TRACKING EWD FROM THE UPR MS VLY FRI ONWARD. BY THE LATTER HALF OF THE PERIOD THERE IS A FAIR DEGREE OF UNCERTAINTY REGARDING LOWER PREDICTABILITY SMALLER SCALE IMPULSES THAT MAY EVOLVE AT THE SRN PERIPHERY OF THE NERN TROUGH AND OVER THE SRN PLAINS WITHIN A BROAD SRN TIER MEAN RIDGE. BASED ON THE ABOVE CONSIDERATIONS THERE APPEARS TO BE NO COMPELLING NEED FOR ADJUSTMENTS ASIDE FROM THOSE FOR TYPICAL RUN TO RUN DETAIL DIFFS. THIS LEADS TO FAVORING A BLEND OF VARYING WEIGHTS OF THE 00Z ECMWF AND 06Z GEFS/00Z ECMWF MEANS ALONG WITH WPC CONTINUITY... WITH THE CONTINUITY COMPONENT GRADUALLY INCREASING FROM 20 TO 40 PCT OVER THE COURSE OF THE PERIOD. ...WEATHER HIGHLIGHTS/THREATS... STRONG NERN PAC UPR LOW MOST LIKELY TRACKING THROUGH THE PAC NW AND INTO W-CNTRL CANADA WILL BRING A PERIOD OF ACTIVE WEATHER TO THE NWRN AND NRN TIER STATES. SOME ACTIVITY MAY BE LOCALLY HVY AND SPC IS MONITORING SEVERE POTENTIAL BY THE TIME THE LEADING COLD FRONT REACHES THE NRN PLAINS. BASED ON CURRENT CONSENSUS THE HIGHEST MULTI-DAY RNFL TOTALS WITH THIS SYSTEM SHOULD BE TO THE N OF THE CANADIAN BORDER. NOTE THAT THERE IS A LOWER PROBABILITY SRN TRACK POTENTIAL AS PER THE 06Z GFS THAT WOULD LEAD TO MUCH HEAVIER RNFL OVER PARTS OF MONTANA. DEPENDING ON DEPTH/TRACK OF THE UPR LOW IT MAY NOT BE OUT OF THE QUESTION FOR HIGHEST ELEVS TO SEE A LITTLE SNOW. UPSTREAM SYSTEM APPROACHING THE PAC NW MAY BRING SOME UNSETTLED WEATHER TO THE PAC NW BY THE FIRST HALF OF NEXT WEEK BUT WITH LOWER CONFIDENCE AS TO TIMING/EXTENT. SYSTEM TRACKING FROM THE UPR MS VLY/WRN GRTLKS THROUGH THE NORTHEAST DURING THE FIRST HALF OF THE PERIOD... ALONG WITH ITS TRAILING FRONT THAT MAY SETTLE OVER THE S-CNTRL PARTS OF THE EAST BY NEXT MON-TUE... MAY HELP TO FOCUS EPISODES OF ORGANIZED CONVECTION AND HVY RAIN WITH SOME TRAINING PSBL. MID-UPR LVL DYNAMICS AND ABUNDANT DEEP MSTR SHOULD ALSO PLAY A ROLE OVER SOME AREAS FROM THE MIDWEST/GRTLKS TO NORTHEAST/MID ATLC. CONSULT LATEST SPC PRODUCTS FOR LATEST INFO ON SEVERE THREATS. EXPECT EVOLUTION OF THE LARGE SCALE PATTERN TO BRING ONE OR MORE DAYS OF COOL DAYTIME TEMPS TO THE NORTHWEST/GRTBASIN WITH SOME LOCATIONS AT LEAST 10F BELOW NORMAL... ALONG WITH A GRADUAL SUPPRESSION OF INITIAL ERN U.S. HEAT. BEST POTENTIAL FOR DAILY RECORDS SHOULD BE FOR VERY WARM MIN TEMPS OVER THE SOUTH AND EAST WITH GREATEST COVERAGE OF SUCH RECORDS LIKELY TO BE EARLY IN THE PERIOD. RAUSCH