Emulsion failure -- heat?

[ScreenFoo]

2/1 on S mesh?
Sounds to me like you probably have a stencil that's too thick to expose anywhere near properly.

Try it out--coat one 1/1, even try a single pass on the shirt side, dry shirt side down.

IMHO, buy a humidifier if you have humidity problems. 
A heater in the screen room (NOT a cabinet) works great here, as the RH is almost never over 40%.

[Maxie]

I recently built a screen drying room, it has an air conditioner and dehumidifier, we keep the temp between 72 and 78 and the humidity under 40.
Today it was 32.