EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1000 AM EDT WED JUL 05 2017 VALID 12Z SAT JUL 08 2017 - 12Z WED JUL 12 2017 ...HOT ACROSS THE WEST & NORTHERN HIGH PLAINS THIS WEEKEND... PATTERN/MODEL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~ THE GUIDANCE AGREES ON TROUGHING ACROSS EASTERN CANADA AND THE NORTHEAST PACIFIC, BUT THERE ARE ISSUES CONCERNING A SYSTEM RIDING OVER THE TOP OF THE INTERMEDIATE RIDGE WHICH ATTEMPTS TO AMPLIFY THE EASTERN CANADIAN TROUGH AND THE PROGRESSION OF THE EASTERN PACIFIC TROUGH INTO BRITISH COLUMBIA. IN BOTH PLACES, THE 06Z GFS WAS A BETTER MATCH TO THE 00Z NAEFS/ECMWF ENSEMBLE MEANS THAT THE ECMWF/CANADIAN SOLUTIONS. ISSUES WITH A POSSIBLE CONVECTIVE LOW SNEAKING INTO THE MAP WELL OFFSHORE BAJA CALIFORNIA AND A POSSIBLE TROPICAL CYCLONE AND/OR ITS "POST-TROPICAL" REMNANTS EAST OF THE NORTHERN BAHAMAS ARE EASILY DEALT WITH USING A BLEND OF THE AVAILABLE DETERMINISTIC AND 00Z GLOBAL ENSEMBLE GUIDANCE. TO ACCOUNT FOR THE UNCERTAINTY, THE FRONTS/PRESSURES/500 HPA HEIGHTS/WIND GRIDS USED A COMPROMISE OF THE 00Z CANADIAN/00Z UKMET/00Z ECMWF/06Z GFS FROM SATURDAY INTO MONDAY MORNING BEFORE THE BLEND SHIFTED SOMEWHAT TOWARDS THE 00Z NAEFS/00Z ECMWF ENSEMBLE MEANS. THE TEMPERATURES, PRECIPITATION CHANCES, CLOUDS, WEATHER, AND DEW POINTS WERE BASED ON A MORE EVEN BLEND OF THE DETERMINISTIC/ENSEMBLE MEAN SOLUTIONS, WITH SLIGHTLY MORE WEIGHT ON THE 06Z GFS/LESS WEIGHT ON THE 00Z ECMWF THAN USUAL. THE DAYS 4-7 QPF WILL PROBABLY LOOK LIKE A ROUGH COMPROMISE OF THE 06Z GFS/00Z ECMWF FOR DAYS 4-5 BEFORE TRANSITIONING MORE TOWARDS THE 06Z GFS FOR DAYS 6-7. WE AWAIT THE 12Z GFS AND SEE IF IT HAS UTILITY QPF-WISE. SENSIBLE WEATHER HIGHLIGHTS ~~~~~~~~~~~~~~~~~~~~~~~~~~~ SCATTERED RECORD HIGHS APPEAR LIKELY THIS COMING WEEKEND OVER THE WEST AND NORTHERN HIGH PLAINS/DESERT SOUTHWEST DUE TO THE STRONG RIDGE EXPECTED TO BE CENTERED OVER THE GREAT BASIN/INTERMOUNTAIN WEST. HIGHS OF 100-105F ARE EXPECTED THROUGH THE LOWER VALLEYS OF THE NORTHERN INTERMOUNTAIN WEST WITH READINGS NEAR 120F ACROSS THE DESERTS OF SOUTHEAST CA. A SYSTEM MOVING INTO THE PACIFIC NORTHWEST WEAKEN THE NORTHERN PORTION OF THE WESTERN RIDGE AND LEAD TO DECREASING TEMPERATURES BACK TOWARDS SUMMERTIME NORMALS EARLY NEXT WEEK. IN THE EASTERN STATES, SHOWERS AND STORMS ARE FORECAST TO OCCUR ACROSS THE GREAT LAKES AND NORTHEAST WITH EACH FRONT THAT PROGRESSES ACROSS THESE AREAS. ACROSS THE SOUTHEAST, GULF COAST, AND FLORIDA, SCATTERED TO NUMEROUS MAINLY AFTERNOON/EVENING SHOWERS/STORMS WILL DEVELOP EACH DAY TO THE EAST OF A MID-LEVEL WEAKNESS/POSSIBLE UPPER LEVEL LOW. A WAVY FRONT STALLED NEAR THE CAROLINA COASTLINE SHOULD ACT AS A FOCUS FOR SHOWER/STORM DEVELOPMENT. MONSOONAL MOISTURE ADVECTING INTO THE SOUTHWEST AND COLORADO ROCKIES SHOULD SUPPORT SCATTERED SHOWERS/STORMS DEVELOPING THROUGH THE PERIOD. RETURN MOISTURE ADVECTING NORTHWARD THROUGH THE PLAINS/MIDWEST SHOULD RESULT IN SHOWERS AND THUNDERSTORMS. ROTH/PETERSEN