In fact I now notice the original "pizza pie" in the image indeed has eight slices, apparently trying to express the same thing
(that a slice pointing north is called "S"(outh), etc.)

OK. Here is my method to figure it out:

1. Pick some place in the ocean with high winds.
   The animated arrows there are the clearest on Windy.
   The least likely to not be misunderstood.

2. OK, now click the map.

As we see, it reveals "60°" confirming that Windy names winds by the
direction they blow FROM. (And 60 is thus close to NE (and not SW.))

(Sure, you could say that that is standard weather practice. But we are
not all weather professionals here, and "▶" could look like an object
being blown by winds FROM the east too.)

Thanks!
100% "I would have never guessed" if you didn't tell me!

Re: Alerts
It would be good in the menus, to have an additional item: Alerts.
That way one could see a list of the alerts one set up.

Indeed, that way one could figure out if he has one, or two alerts set up.
(Currently one cannot tell if he is adding a second one, or editing the first one.)

Also one could toggle a checkbox to make an alert active or not.

When setting up an alert, the winds are described with direction names.
This contrasts with the rest of the site, which completely uses various styles of arrows.
So the alert menu should also include arrows too. Or the rest of the site should have mouseovers describing the name of a given arrow.

In the app go to settings. Now look at temperature rain snow excetera. Some of them have the metric units on the right, and some of them on the left. They all should be on the same side. The English units should be on the other side.

If I press the arrow the animation starts. The pause button also works correctly. The problem I'm having is how to reset to the current time? If I pull the time bar backwards, I end up pulling too far.

Problem seen on both mobile and website using a cell phone.

(Yes, I know. I was hoping for accumulation.)

OK! (Impressed with the Picker: ultimate precision for two dimensions (latitude and longitude) (Alas no Picker for fourth dimension (time).)

UI Glitich: Idea: regarding

Rain accumulation
Next 12 hours	Next 24 hours	Next 3 days	Next 5 days	Next 10 days

Perhaps there also could be a slider or something added so the user could choose an arbitrary point, e.g. "Next 2 days", "Next 2.5 days", etc.

E.g., I have a guest visiting my forest for what will be the first half of a typhoon period, next two days only, and want to predict how much rain will accumulate.