Thanks for the tip on the wrist watch fish finder - since then I have been able to 'see' fish coming regardless of the weather. Those aren't just new pointy fashion boots I'm wearing, they have a transducer mounted in the toe. :hehe:
I prefer the noaa weather site, it's the source for all the other weather sites but packaged with ads and schpeel I don't care about.
In my opinion, sight fishing in low light is frustrating at best. There are a few spots where it can be done but communicating the fish's location to others is hard enough on a bright day never mind a dim one. Frankly, I'll cancel sight fishing trips if the light conditions are not available, cancelled for tomorrow in fact.
That being said, if the tide is right and you know where fish will be at certain phases you can stake them out and act on less visual feedback to find fish - Nick will tell you about seeing their wakes as they make a push, flashing behavior, or standing off to target fish in very shallow water where you know them to frequent at a given tide. But if the wind kicks up in addition to dim light, or rain dimples the surface, or if the tides don't accomodate you, your time will be much better spent blind casting in productive rips or channels closer to home or in some of the other beautiful locales around the cape.
Lately I've been working South Beach more than North Monomoy if there is a threat of cloud cover. With the right two-hander fishing the ocean side is a piece of cake and there are always grabby fish in the surf if you read the subtleties in the shore and keep the fly in play beyond the breakers. If the cloud bank clears you can walk back to the flats. The backside is not for everyone, it's not an easy place to fish with a single-handed rod.
I pick my days very carefully for sight fishing and ambient light is right up there with tide and presence of fish.
In any case good luck and I envy you for having a fishing daughter!