The trough which has prevailed through the central & eastern portions of the country through the bulk of the month so far will give way to a brawny longwave ridge this week, bringing a notable surge of heat along with it.
Meanwhile, additional upper-level disturbances dropping into the mean western trough position will eject along the newly-established ridge’s periphery and spark an active convective regime for the battle zone caught in the middle.
The 12 Euro ensembles depict the next lively ULL carving into the western USA as the H5 ridge stands it’s ground downstream @ day 4:
Ridging then develops along the west coast as the previous system tracks NE through the Upper Midwest and ridging remains in place downstream, albeit with lower heights holding sway for parts of Atlantic Canada @ day 7:
Another shift looks as if it could take hold with W/NW ridge & eastern trough becoming established by day 10:
The precip outcome of this medium range forecast via the 18z GFS ensembles, highlighting the regions at greatest risk for stormy weather through the midsection of the continent:
Farther out in the extended range these are the temp probabilities for days 8-14 from the 12z NAEFS: