EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 126 AM EDT SAT JUL 11 2015 VALID 12Z TUE JUL 14 2015 - 12Z SAT JUL 18 2015 ...PATTERN OVERVIEW... UPPER RIDGING IS FORECAST TO STAY ANCHORED OVER TEXAS NEXT WEEK WHILE TROUGHING WILL LINGER ALONG BOTH THE EAST AND WEST COASTS. AT THE SURFACE... MULTIPLE WEAK WAVES OF LOW PRESSURE WILL DEVELOP ALONG A FRONTAL BOUNDARY STRETCHED FROM THE NORTHEAST/MID-ATLANTIC COAST TO THE CENTRAL PLAINS. A CANADIAN COLD FRONT WILL STEADILY PRESS SOUTHWARD AND EASTWARD ACROSS THE GREAT LAKES AND OFF THE NEW ENGLAND COAST BY THURSDAY. ...MODEL EVALUATION/PREFERENCES... MODELS CONTINUE TO WAVER ON THE SMALLER-SCALE DETAILS IN THE FORECAST... WITH LESS THAN DESIRABLE CONTINUITY IN BOTH THE GFS AND ECMWF. THEIR ENSEMBLE MEANS REPRESENT A MORE STABLE SOLUTION... BUT A BLEND OF THEM ALL -- 18Z GFS/GEFS AND 12Z ECMWF/ECENS MEAN -- IRONED OUT SOME ROUGH EDGES EARLY IN THE PERIOD /TUE-THU/. RATHER LARGE CHANGES IN THE GUIDANCE WERE CONFINED TO CANADA WITH THE MODELS POINTING TO A MUCH DEEPER AREA OF LOW PRESSURE IN QUEBEC TUE-WED. SURFACE BOUNDARY SHOULD SETTLE INTO THE SOUTHERN BAROCLINIC ZONE ACROSS THE MID-ATLANTIC LATER IN THE WEEK. IN THE PAC NW... ENSEMBLES ARE REALLY STRUGGLING WITH THE UPSTREAM PATTERN ACROSS THE NORTH PACIFIC... TIED TO THE EXTRATROPICAL TRANSITION OF CHAN-HOM AMONG OTHER NORTHERN STREAM DETAILS. TREND HAS BEEN TOWARD STRONGER UPPER RIDGING AROUND 40N/150W WHICH SHOULD FAVOR INCREASED TROUGHING IN THE PAC NW... BUT LEAD UPPER LOW WILL PLAY A PART IN HOW FAR EASTWARD THE TROUGH PROPAGATES. LOW CONFIDENCE IN WHAT WILL ACTUALLY TRANSPIRE SO SPLIT THE DIFFERENCE BETWEEN THE FARTHER EAST GEFS MEAN AND SLOWER ECENS MEAN. ...SENSIBLE WEATHER HIGHLIGHTS... CONVECTION/HEAVY PRECIPITATION FOCUS WILL FOLLOW THE FRONT FROM THE GREAT LAKES/OHIO VALLEY/NORTHERN MID-ATLANTIC STATES EARLY NEXT WEEK. SECOND AREA OF ENHANCED PRECIPITATION WILL BE POSSIBLE OVER THE CENTRAL/NORTHERN PLAINS WITH ENERGY EJECTING OUT OF THE ROCKIES TOWARDS THE LATTER HALF OF THE WEEK. MORE ISOLATED CONVECTION/PRECIP IS EXPECTED IN THE ROCKIES AND INTO THE SOUTHWEST. TEMPERATURES ACROSS THE CONUS SHOULD FALL WITHIN 5-10 DEGREES OF AVERAGE... GENERALLY BELOW AVERAGE IN THE WEST AND NORTHEAST BUT ABOVE AVERAGE THROUGH A GOOD PORTION OF THE SOUTH... WITH MANY DAYS AROUND 100F IN INTERIOR TEXAS. FRACASSO