Alert Conditions and Logic

AND conditions are temporal, not instant: each one writes a pending match that expires, and the alert fires only once every other condition has an unexpired one, which is why AND alerts can fire late. OR fires immediately.

What can a condition check, and how many can I stack?

Each condition checks either SST or chlorophyll, using above / below / between a threshold, in °F or °C for SST and mg/m³ or estimated visibility for chlorophyll (see dive visibility for the conversion). An alert can hold one to six conditions. Because higher chlorophyll means lower visibility, choosing visibility units flips "above" and "below" under the hood: the app handles that for you, so set the condition the way you'd say it out loud ("visibility above 20 ft") and it'll convert correctly.

What's the difference between OR and AND?

With a single condition, or with OR logic across several, the alert fires the moment any one condition matches on a new pass, immediately. AND logic works differently: when one condition matches, it's recorded as a pending match with an expiration window you set (the "tolerance"), measured against the satellite's own capture time rather than the wall clock. The alert only actually fires once every condition has an unexpired pending match at the same time, which means an AND alert can trigger noticeably after the first condition was true, once the rest catch up within the tolerance window. If the window closes before every condition lines up, the alert simply doesn't fire that round.

How does cooldown work?

Cooldown applies to the whole alert, not to individual conditions. Once any notification fires, the entire alert stays quiet for the cooldown period you chose (every new pass, or 6, 12, or 24 hours) before it can fire again, even if a different condition combination becomes true in the meantime.

Does a match need to cover the whole box?

You choose: match on any single pixel inside your rectangle meeting the condition, or require every non-cloud pixel in the box to meet it. The first catches an edge or break entering any corner of your area; the second is stricter and better suited to confirming a condition has taken over the whole box.

Do alerts check composites too?

No, alerts evaluate satellite passes only, never composites, and a pass older than 48 hours is skipped. See passes vs. composites for what that distinction means, or setting up an alert if you haven't drawn one yet.