From Homebrewing.org:
What does lagering do to a beer?
A well-lagered beer is not only going to be clearer (and therefore cleaner-tasting). Its also going to have a more developed set of flavors showing through. You know how if you savor a keg for a few weeks, that last beer looks and tastes so much better than the first one? Thats not just because youre getting sentimental. Its because youve basically been lagering the beer in your fridge the whole time — long enough to reap some of the benefits before its gone.
Try this at home: Go out and buy two six-packs of a good quality ale. Store one six pack somewhere relatively cool (around 60F), like your basement, where itll stay fresh for a while. Store the second six-pack somewhere much colder — as close as you can get to freezing, without quite getting there. (Probably the very back of your fridge.)
Leave both six-packs alone for a few weeks, and then do a taste comparison between the two. Odds are, youll be able to see and taste a real difference, with the advantage going to the cold-stored beer.
How does lagering work?
There are two important processes at work when a beer is in long-term cold-storage:
Precipitation: Take a certain amount of liquid, warm it up, and you can obviously dissolve more solids into that same volume. Take that same warm liquid, and cool it down, and the amount of dissolved solids that it can contain will decrease. Those solids will precipitate, or re-solidify and fall to the bottom of your storage container. (The simplest version of this process is what we all know as cold-crashing.)
Aging: All the chemical reactions going on in your beer — good or bad — take place much more slowly in the cold. As it happens, though, most of the processes you dont want are slowed down more. An extended period of cold storage builds up the benefits that you do want, with less of the effects that you dont. (With some important exceptions: see the discussion of Diacetyl Rest, in the next chapter.)
I guess the answer you're seeking is, yes you can make a lager recipe w/o long-term cold storage after fermenting. It just won't be as good as if you had given it the time at cold (mid-30's) temps. At the temps you are talking about for fermenting, however, you are going to want to use an ale yeast (unless you are wanting to make a "steam beer", but that's a whole different subject). Most lager yeasts ferment best in the mid-40's to mid-50's.
