Windy conditions and heavy rain create wind to drop to zero

Heavy rain and wind today made my winds suddenly go to 0 mph.

What causes this?

Attached photo. Station8254

As you mentioned you had a combination of heavy rain and wind. Probably the gap between the wind sensors was washed with water and the sensors ‘lost’ it with moments. I guess the routine sends a ‘null’ when it can’t measure anything sensible (this is a guess but we see it regularly).
scroll a bit further on your graph and then you’ll see that you wind indicates almost a constant speed (avg, gust and lull are +/- equal). This is typically happening when there is hardly any wind but the plate is still full of water drops and it needs to dry out before you’ll get again ‘normal’ readings.
Newer Sky models and future Tempest model have a special coating that minimises this phenomena.
In your case there is not much you can do to avoid this. Mostly the problem is rare and usually resolves itself rather quickly. Keep an eye on the reading for the coming day or so and if there is still suspicious problems, come back and we’ll try to look at it closer and/or ask for help from those that have server access.