The OVATION Oval Model, Simply

Search for any aurora map and you'll eventually land on NOAA's OVATION Prime — the swirling green oval that shows the aurora's expected footprint right now. It's a genuinely useful tool, and confusing if you don't know what it does and doesn't claim. Here's the plain-language version.

The oval is geometry, not weather

Aurora is not random: it rings the magnetic poles in a more-or-less permanent oval. Quiet conditions shrink the oval tight around the Arctic; storms inflate it and push its southern edge toward mid-latitudes. OVATION takes solar wind measurements, runs a statistical model built from decades of observations, and paints where that oval's glow is expected right now and about 30 minutes ahead.

How to read the map

Colour encodes the model's estimated aurora power, from faint green to bright red. Three practical reading rules: (1) look at where the oval's equatorward edge sits relative to you — if your city is under or just inside the edge, you have a shot; (2) remember the map shows probability of aurora overhead, not what you'll see — at the edge you'll see it low on the horizon; (3) the map knows nothing about clouds, moonlight, or your light pollution.

Where OVATION ends and our job begins

OVATION answers "is the aurora up?" for the next half hour. It says nothing about whether you can see it — that requires the other four factors: cloud cover, moon, the darkness window, and light pollution. That's exactly why our city pages exist: the same NOAA data that feeds OVATION is combined with the local sky factors into one honest answer per city. If you want to watch the oval live for storm-chasing, the NOAA SWPC aurora dashboard is the canonical source; if you want "is tonight a GO for me?", that's what the city pages compute.

Using the oval in practice

The oval map shines in one specific moment: a storm is forecast, the sky is clear, and you want to know whether the show has actually started. Open the NOAA aurora dashboard, find your longitude on the oval's southern edge, and look: under the edge means faint horizon glow; well inside means the display is overhead. Pair that with your city page's live verdict, which already folds in the same solar wind data plus your local sky. The oval answers "is it happening?" — the city page answers "will I see it?"

Common oval-reading mistakes

Reading brightness as altitude: the map shows probability of aurora overhead, so a green-to-yellow gradient at your latitude means "look north, low on the horizon", not "look up". Ignoring the 30-minute horizon: the oval is a nowcast — useless for planning tomorrow, invaluable for the next hour. Forgetting the map can't see clouds: a blazing oval under overcast is still a night indoors; that's why cloud carries 25% of our score.