I am going to be using an AT4073a with a Rycote at the beach. I can not afford an industrial-strength windshield, so I was wondering whether it would be a good idea to use an umbrella or other obstacle in addition to Rycote, between the mic and the wind? I imagine this would color the sound, but would it be worse than the effect of the wind? I will try to conduct a test of my own, but appreciate I your input.

really the simple answer I came to was NO. I tried umbrellas, coats and blankets, always the wind seemed to just creep around the object and disturb the mic, plus it was awkward to use, got in the shot sometimes and a pain to hold along with the boompole. So I knuckled down and bought a Softie by Rycote, it works in most winds and in high winds does a good job too.

Would an umbrella further increase the effectiveness of the rycote?

the noise of the wind over the umbrella is far worse that the direct wind on the rycotte. solution would be to use some heavy material to build a deflector between the mic and the wind but far from the mic of at least 10 feet.

Try renting the Rycote heavy wind shield. Probably cost 15 buck or less for the day

The 4073a is a hot mic. The extra sensitivity and high output which can be a blessing and a joy can also be a headache in wind.

I was using one this weekend in moderate winds and the Rycote had long been abandoned in favor of a blimp, and even then I was fighting wind rumble. Low cutout was no comfort.

In the end I sacrificed my high end (was diaglogue being recorded and a single line in the take) and beat the wind noise by putting a deadcat on the mic INSIDE the blimp and then another one on the blimp itself. It did pretty well kill the highs though.

Prior to that attempts to shield it were fruitless.

When using a shotgun with its wind jammer, always try and work side on to the direction the wind is coming from.
Cheers.

Most objects will only cause more turbulence, which will cause yet more noise.

If you had a solid, teardrop-shaped item that would smoothly re-direct the wind, it might work, but then you'd get the resonance of being inside a large teardrop-shaped item...