as part of my "quest" for perfect gear - I've used a number of lt. wt. 3-season tents. i'll list some of them for you. i'm not very familiar with 4-season tents, but some other who post here certainly are. i'll list two 4-season tents based upon their posts. they all meet your requirements. i mainly camp 3-seasons (some winter camping though) above freezing in New England - lots of rain (sometimes light-mod for days or torrential downpours for a couple of hours, "skeeters" in So. NE & black flies in Maine, humid & hot in the summer (over 90 deg, sometimes with 70-100% rel. humidity; can even be 80's a night for part of the summer with HIGH humidity), often late afternoon, evening, nightime thunderstorms. all camping in forests & hills.
to keep this post short & so that you will research them for yourself & get better, more accurate info than i could provide you on specifications, i'm not going to say much about each shelter.
there is one, i am seriously considering (for ~2mos - i'm old & move slowly) purchasing. i'll list it last. b/f i buy it, i hope to phone/email the owner/designer of the company & speak/correspond to/with him.
Note: i figure the wts using a small # of Ti skewers & a med. spinLite stuff sack & spectra guys. sometimes it's the min. # of Ti stakes req'd to pitch. other times it's ~2 more skewers for stability of pitch. so my wts are "MY trail wt.", NOT any published figures. i do it this way so that the only variables are the tent, fly, & poles - the only things i can't easily/cheaply substitute with lighter alternatives (for me buying CF poles fr/FibraPlex is not considered as easy/cheap to substitute as stuff sack, spectra guys & Ti skewers) i should also say that my scale is quite old & may not be accurate as to exact wt, but i think that the diff. in wts of the tents i've weighed is at least prob. correct since i weighed them 3x each on the same scale.
3-season solo tents:
MSR Zoid 1 - 2lb 15oz
Eureka Spitfire '05 - never owned it, but it qualifies - very inexpensive (guessing it would be ~2lb, 12oz "my trail wt.")
Sierra Designs Lightyear (i owned last yr's Ultra Lightyear - not sold anymore) - sold it, nice & light, but a couple of minor drawbacks. my co-worker who bought it, loves it though he too has encountered the drawbacks i mentioned to both him & here. (ultra lightyear = 2lb 10oz; '04 lightyear perhaps 4oz heavier; current '05 might be only 2-3oz heavier then the '04 Ultra Lightyear).
Big Agnes Seehouse 1SL - very nice tent. generally well regarded by reviewers & others. Owned it also. Now in the process of selling it. [it's freestanding] 2lb 10oz
Eureka '05 Solitaire - much better than the '04 model. sort of a super bivy. very inexpensive. still req's a lot of stakes to pitch, but otherwise a very nice shelter, IMHO. 2lb 9oz
MSR MicroZoid - one of my favorites & the lightest i've listed thus far - under 2.5lbs (my trail wt.). very small. sort of super-bivy sized, if such a description helps any. both the Zoid 1 & MicroZoid have good ventilation even with fly fully deployed. 2lb 6oz
there are others, some i've tried others i haven't., can't recommend them either b/c of no personal experience, or b/c i tried them & they were "found wanting".(Daniel 5:27).
4-season (OTHERS have recommended)
Black Diamond FirstLight - single-wall, Epic fabric - 2lb 9oz w/o vestibule; ~3lb 9oz with vestibule (these are published wts - not mine; i have never owned this tent)
Hilleberg Akto - ok...maybe a tad over 3lbs, but a very clever poster to these Forums knows how to get it under 3lbs. She's very experienced & swears by this tent. I've been looking at it for next winter's use solely based upon her recommendation - she knows much more than i do.
now, finally, the single-walled, floored, bug-proof tarptent that requires one trekking pole, pole, or stick to erect it. this is the one i may eventually purchase. only 24-27oz depending upon the wt. of the floor mat'l you select: SixMoonDesigns Lunar Solo 'e'. there are other similar shelters from Dancing Light Gear, etc that you might look at. This one is the closest to the Nomad you mentioned, but perhaps more adequately addresses your issue of variable direction driven rain.
hope this info helps. if you buy the SMD Lunar Solo 'e' b/f i do, please share your thoughts/experiences with us all. i, for one, would appreciate it.
if you have any other questions that i failed to anticipate and/or answer adequately, please post back.