Where are you located? It makes a huge difference in the type of lawn seed or seed blend recommended.

In the lowland foothills of western Washington

Then it is most likely a blend of fescues and perennial ryegrass. That is by far the most common type of turf in the PNW. There are different regionally formulated blends using different combinations and cultivars suited for various growing conditions but look for them at independent nurseries and garden centers - box stores tend to sell just very generic stuff.

The weedy grass does look a lot like annual ryegrass, Lolium multiflorum.

Ok thanks, I've been hitting other grassy weeds with Tenacity with some luck, does that help get rid of annual ryegrass? Would I have expected any annual ryegrass to die over the winter since it was a long cold one in Seattle this year? A lot of those clumps were the in the fall.

Tenacity is not registered for annual ryegrass so I am not sure how effective it might be. OTOH, your weed grass could just as easily be Poa annua as well - hard to tell at that resolution and with the clump mowed at least once :-) Tenacity IS registered for that.

btw, annual weeds and weed grasses often just appear, especially at the time of year that encourages their seed germination, like right now :-) Or in the fall. They like cool and damp. The seeds blow in or are transported on shoes or equipment or paws/feet.

As an aside, having lived here my entire life, I would not have considered this a long cold winter here in the Seattle area. It was actually quite mild, if overly wet. But it is a late, cool and wet spring!

Great thank you for the advice. I have been struggling with our lawn just being relatively patchy overall since it is in a new construction area ~3 years ago with really compacted soil so have been trying to get as much organics material into ground each year. Any other suggestions for a somewhat patching lawn where some areas are nice a lush and others just don't seem to be filling in well?