No, weather is not the main concern. The Engine Cut-Off sensors in the External Tank are causing problems again. It’s an intermittent electrical failure. They’ve seen it before though, but don’t know what causes it. Usually they work properly during the second tanking, which is what they’ll figure out tomorrow.
Weather is only 30% chance to constrain launch as of the MMT yesterday.
The hydrogen sensors are way more than fuel guages. They have to work with liquid hydrogen, which is a harsh environment to begin with. Is this a science yet, or something of a rocket art?
Eh, much ado ‘bout nothing. They never run those tanks dry. They always include an extra 700# of LiH to ensure rich MECO based on low oxidizer levels.
OTOH, if its the oxidizer sensors that are the one’s fritzing, that could be a problem (don’t want to be cavitating those pumps at 35,000 RPM). Bad.
They should just hover their fingers over the engine kill switch, and if the engines don’t cut off when they should just hit the button. How hard can it be?
They did something similar for Apollo 13 for the main engine burn around the backside of the moon.