EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1204 PM EDT SAT JUL 08 2017 VALID 12Z TUE JUL 11 2017 - 12Z SAT JUL 15 2017 ...PATTERN OVERVIEW AND GUIDANCE EVALUATION/PREFERENCES... UPPER RIDGING WILL BEGIN TO EXPAND OVER THE CENTRAL U.S. TOWARDS THE MIDDLE OF NEXT WEEK, BEFORE BUILDING BACK WESTWARD INTO THE CENTRAL/NORTHERN ROCKIES AND GREAT BASIN BY NEXT WEEKEND. THE WESTWARD SHIFTING RIDGE LATE NEXT WEEK SHOULD ALLOW AN UPPER TROUGH TO RELOAD OVER THE EASTERN U.S. AND SHOULD ALSO KEEP HEIGHT FALLS FROM A DEEP VORTEX DROPPING SOUTHWARD OUT OF THE GULF OF ALASKA FROM PROGRESSING TOO FAR INLAND OVER THE NORTHWEST. THE SUITE OF 00Z MODEL GUIDANCE IS SHOWING VERY GOOD AGREEMENT WITH THE LARGE SCALE PATTERN OVER THE CONUS NEXT WEEK. THE PAST FEW RUNS OF THE ECWMF/CMC AND THEIR ENSEMBLE MEMBERS HAVE GRADUALLY TRENDED SLOWER WITH THE DEEP VORTEX DROPPING OUT OF THE GULF OF ALASKA, WITH THEIR 00Z RUNS NOW ALIGNING WELL WITH THE 00Z GFS AND GEFS MEMBERS. THE 00Z GFS IS STILL ON THE AMPLIFIED SIDE OF MODEL SPREAD WITH THE TROUGH RELOADING IN THE EAST, BUT NO LONGER APPEARS TO AN OUTLIER SINCE IT SHIFTED FLATTER THAN ITS PREVIOUS RUNS AND NOW HAS SUPPORT FROM A FEW 00Z GEFS AND EVEN ECMWF/CMC ENSEMBLE MEMBERS. THE WPC DAY 3-7 FORECAST WAS BASED ON A BLEND BETWEEN THE 00Z GFS/ECMWF/GEFS MEAN/ECMWF ENSEMBLE MEAN/CONTINUITY, WITH MORE WEIGHT THAN NORMAL GIVEN TO DETERMINISTIC GUIDANCE DUE TO SUCH GOOD AGREEMENT WITH THE LARGE SCALE PATTERN OVER THE LOWER 48. HOWEVER, DESPITE CONVERGING SOLUTIONS WITH THE LONGWAVE PATTERN, THE DETAILS OF SHORTWAVE ENERGY CROSSING THE NORTHERN TIER AND FEEDING INTO THE RELOADING EASTERN U.S. TROUGH MID TO LATE NEXT WEEK REMAIN A FORECAST CHALLENGE (ESPECIALLY WHEN TRYING TO PREDICT THE DETAILS OF CONVECTION EXPECTED TO DEVELOP NEAR A WAVY FRONTAL BOUNDARY STRETCHING FROM THE UPPER MIDWEST TO THE MID-ATLANTIC STATES NEXT WEEK). ...WEATHER HIGHLIGHTS... THE GREATEST POTENTIAL FOR ORGANIZED HEAVY RAINFALL WILL BE NEAR A WAVY FRONTAL BOUNDARY STRETCHING FROM THE UPPER MIDWEST TO THE MID-ATLANTIC STATES NEXT WEEK, WHERE ONE OR MORE IMPULSES ALOFT WILL AIDE IN THE GENERATION OF CONVECTIVE SYSTEMS. THE HIGHEST RAINFALL TOTALS SHOULD BE WITHIN AN AREA EXTENDING FROM THE MIDDLE MISSISSIPPI VALLEY TO OHIO VALLEY AND CENTRAL APPALACHIANS, BUT ACTIVITY MAY EXTEND INTO PORTIONS OF THE MID-ATLANTIC REGION BY LATE NEXT WEEK. PLEASE REFER TO THE STORM PREDICTION CENTER FOR THE LATEST INFORMATION ON THE POTENTIAL FOR SEVERE WEATHER. ELSEWHERE, EXPECT DIURNAL CONVECTION WITH SOME LOCALLY HEAVY TOTALS ACROSS THE GULF COAST, FLORIDA, AND THE SOUTHEAST, WHILE MONSOONAL MOISTURE WILL SUPPORT PERIODS OF SHOWERS AND THUNDERSTORMS PRIMARILY OVER THE FOUR CORNERS STATES. AFTER A RELATIVE LULL IN THE HEAT OVER THE WEST AND NORTHERN PLAINS EARLY NEXT WEEK, TEMPERATURES ACROSS THE NORTHERN HALF OF THE WEST INTO THE NORTHERN PLAINS WILL RETURN TO MUCH ABOVE NORMAL VALUES (10 TO 20 DEGREES ABOVE NORMAL) WHILE RIDGING BUILDS BACK IN ALOFT. THERE MAY BE A FEW DAILY RECORDS FOR MAX/WARM MIN DEPENDING ON THE DATE AND PERIOD OF RECORD AT A LOCATION, THOUGH MID-SUMMER RECORD VALUES MAY PROVE BE DIFFICULT THRESHOLDS TO REACH ON A WIDESPREAD BASIS. THE REMAINDER OF THE INTERIOR WEST, AWAY FROM CLOUDS/PRECIP, SHOULD BE ABOVE NORMAL BUT TO A LESSER EXTENT. ALSO, THERE SHOULD BE A BAND OF ABOVE NORMAL TEMPERATURES ON THE WARM SIDE OF THE UPPER MIDWEST TO MID-ATLANTIC WAVY FRONTAL BOUNDARY. GERHARDT