What is the aurora chance at my exact location right now?

Duluth, Minnesota sits at 46.78N 92.11W. OVATION rounds that to the cell at latitude 47 and feed longitude 268 (92W written on the feed's 0 to 359 scale). On this request the cell reads 0% for a forecast time of 19:35 UTC.

Darkness at Duluth tonight runs from civil dusk at 19:16 to civil dawn at 06:39 Central time. NWS office DLH forecasts 5% sky cover for the grid square that holds the city.

Read the three rows separately. A high cell value with an overcast sky means the aurora is above the cloud. A clear, dark sky with a cell value of 0% means the model sees no aurora overhead or nearby.

Glow answers "can I see it from here, right now" with three inputs. Each comes from a different source, has its own time stamp and can fail on its own. The tool shows them as three logbook rows and never multiplies them into one number.

The first row is the OVATION value. NOAA's Space Weather Prediction Center publishes a global grid of 1 degree cells, refreshed every few minutes. Each cell carries a number from 0 to 100. Glow rounds your latitude and longitude to the nearest whole degree and reads that one cell. Your exact coordinates go in; the cell center comes out, printed beside the value so you can see the rounding.

The second row is darkness. Glow computes the sun's altitude for your coordinates with SunCalc. Civil night starts when the sun sinks 6 degrees below the horizon. That rule is strict on purpose: in Tromsø in December the sun never rises, yet the sky at noon is still twilight. The row shows tonight's civil dusk and dawn in the time zone you chose.

The third row is cloud. For US coordinates Glow asks the National Weather Service which forecast grid square holds the point, then reads the skyCover percent for the current hour. If the current hour has no value, it takes the next period that starts within 6 hours and labels it as a lookahead. Outside the US the row says the input is not available.

Start with darkness. If the darkness row says "Not dark yet", the OVATION value describes a sky you cannot see. Note the dusk time and come back after it.

Then read the OVATION value together with its mode. "OVATION 30 to 90 minute forecast" means solar wind data from the L1 spacecraft drove the model and the forecast time is ahead of the observation time. "Kp-based fallback" means that input was missing and SWPC drove the model from the Kp index instead, with no forecast lead. Glow flags fallback whenever the forecast time is less than 20 minutes after the observation time.

Finally check cloud. The NWS figure is the percent of sky covered for a forecast grid square, not a camera view. Values of 30% or less leave most of the sky open; values near 100% usually hide everything.

The OVATION value is a model output for a 1 degree cell, roughly 111 km north to south. Your street is not the cell center. The tool ignores light pollution, the moon, terrain and the direction you face. Aurora south of the oval can still be seen low on the northern horizon, which is why the distance tool exists.

If the feed is older than 2 hours, Glow shows no value at all rather than an old one. If NWS does not answer within 3 seconds, the cloud row stays blank. Blank rows are honest rows.