Alaska aurora

Northern lights in Two Rivers tonight

Possible tonight

Possible. The forecast Kp of 2- is about what this place needs, so an aurora may show low on the northern horizon. The sky is forecast overcast.

  • The aurora reaches this place at about any night the sky is dark and clear, which is 66 degrees geomagnetic latitude on NOAA's storm scales.
  • SWPC forecasts a highest Kp of 2- (1.67) during tonight's dark hours: quiet.
  • The forecast for the dark hours is overcast, 93% sky cover on average.
  • The moon is waxing gibbous, 81% lit, and up for part of the dark hours.

Two Rivers forecastLive radar hereKp forecast

From NOAA’s Space Weather Prediction Center and the National Weather Service forecast for this grid cell, read Sep 21, 15:14 UTC. Times are Alaska Daylight Time.

The oval right now

NOAA’s OVATION model: the chance of aurora overhead 30 to 90 minutes from now, valid Sep 21, 16:26 UTC. Green is a low chance, red a high one.

NOAA Space Weather Prediction Center aurora forecast: the probability of aurora over the northern hemisphere, with the oval drawn in green through red

Rain and snow mean cloud, and cloud is the last thing between a forecast aurora and the sky you are standing under. Each town page carries that town’s own sky cover forecast for the dark hours.

Open the live map with the aurora forecast

Aurora forecast from NOAA’s Space Weather Prediction Center. Original at SWPC

Tonight at Two Rivers

Geomagnetic latitude
65.8° (64.87°N, 147.04°W)
The aurora reaches here at
any night the sky is dark and clear
Highest Kp forecast tonight
2- (1.67), quiet
Chance overhead right now
4% (OVATION, 30 to 90 minutes ahead)
Cloud cover in the dark hours
93% on average, overcast
Moon
81% lit, some interference
Hour by hour through the dark window, in local time
HourKpSky coverSkyAurora
2-93%overcastWithin reach
2-93%overcastWithin reach
2-93%overcastWithin reach
1+93%overcastWithin reach
1+93%overcastWithin reach
1+93%overcastWithin reach
1-92%overcastWithin reach

Darkness and the moon

5.7 hours of full darkness tonight. The moon is waxing gibbous, 81% lit, and up for part of the dark hours.

Sunset
Mon 7:52 PM
Civil twilight ends
Mon 8:41 PM
Nautical twilight ends
Mon 9:41 PM
Full darkness begins
Mon 10:51 PM
Full darkness ends
Tue 4:32 AM
Sunrise
Tue 7:32 AM
Moonrise
Mon 7:59 PM
Moonset
Tue 1:00 AM

Full darkness is astronomical twilight’s end, the sun 18 degrees below the horizon. Town lights matter as much as the moon: a few minutes’ drive away from them is usually the difference between seeing an arc and not.

The best hours tonight

Mon 10:51 PM to Tue 1:51 AM. Chosen for the darkest, clearest stretch nearest local midnight, which is when the auroral oval swings furthest toward the equator over any one place. Face north, away from town lights, and give your eyes twenty minutes.

The next three days

The highest Kp forecast each UTC day, against the any night the sky is dark and clear this town needs. A UTC day runs from early evening to early evening in North America, so the night of the 21th sits in two of these rows.

Day (UTC)Highest KpLevelHere
Mon, Sep 212QuietWithin reach
Tue, Sep 222QuietWithin reach
Wed, Sep 232QuietWithin reach
Thu, Sep 243+UnsettledWithin reach

What this means

This town is at 65.8 degrees geomagnetic latitude, measured from the geomagnetic dipole pole. NOAA’s space weather scales state where a storm of each level is seen: a G1 (Kp 5) at about 60 degrees geomagnetic, a G2 at 55, a G3 at 50, a G4 at 45 and a G5 (Kp 9) at 40, five degrees a step. Reading that backwards gives the any night the sky is dark and clear this town needs. Below Kp 5 the line runs from 66 degrees geomagnetic at Kp 0 to the scale’s 60 at Kp 5.

Against that go three things the sky does: how dark it gets, from the sun’s altitude here; the moon, from its phase and whether it is above the horizon in those hours; and the cloud cover in this town’s own National Weather Service forecast. The Kp forecast runs three days and is a forecast of the planet’s magnetic field, not of one sky. Only OVATION knows whether an aurora is out right now, and it sees 30 to 90 minutes ahead, because that is how long the solar wind takes to arrive from the spacecraft that measures it.

At the viewing line the aurora is low on the northern horizon, not overhead, and often only a camera sees color in it. Sources: SWPC 3-day forecast, NOAA space weather scales.

Sources

From NOAA’s Space Weather Prediction Center: the OVATION aurora forecast, the planetary K index forecast, the 3-day forecast, the 27-day outlook, its watches, warnings and alerts, and the real-time solar wind. Read Sep 21, 15:14 UTC.

Aurora forecastBy countryLive radar