Northern lights in Estonia tonight
The aurora reaches the far north of Estonia at about Kp 5.6, and its southernmost listed town at Kp 5.8. SWPC forecasts a highest Kp of 2 over the next three days, in the 03-06 UTC block on Mon, Sep 21.
From NOAA’s Space Weather Prediction Center, read Sep 20, 14:08 UTC.
By region
5 regions with a town at 48 degrees geomagnetic latitude or higher, most poleward first.
Kp by 3-hour block
SWPC’s planetary K index forecast, three days ahead. Kp is a single number for the whole planet, from magnetometers around the world, on a scale of 0 to 9 in thirds.
| Block (UTC) | Kp | Level | Seen from | Central US |
|---|---|---|---|---|
| 1.00 | Quiet | 65° geomag. | 57°N | |
| 1.00 | Quiet | 65° geomag. | 57°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 1.67 | Quiet | 64° geomag. | 56°N | |
| 2.00 | Quiet | 64° geomag. | 55°N | |
| 1.67 | Quiet | 64° geomag. | 56°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 0.67 | Quiet | 65° geomag. | 57°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 1.67 | Quiet | 64° geomag. | 56°N | |
| 1.67 | Quiet | 64° geomag. | 56°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 1.67 | Quiet | 64° geomag. | 56°N | |
| 1.67 | Quiet | 64° geomag. | 56°N | |
| 1.67 | Quiet | 64° geomag. | 56°N |
The forecast is for the planet, not for your sky. A block at Kp 5 means the field is disturbed enough for the aurora to reach 60 degrees geomagnetic somewhere along the night side; whether you see it depends on being on the night side, on darkness, and on the clouds.
How far south each storm level reaches
NOAA’s space weather scales state the geomagnetic latitude each level of geomagnetic storm reaches, and the places its aurora has been seen from. The geographic latitudes are those lines converted with the geomagnetic dipole; the aurora sits low on the northern horizon there, and overhead far poleward of it.
| Storm | Geomagnetic | Central US | Eastern US | Northern Europe | NOAA says the aurora |
|---|---|---|---|---|---|
| G1 MinorKp 5 | 60° | 52°N | 51°N | 61°N | commonly visible at high latitudes: northern Michigan and Maine |
| G2 ModerateKp 6 | 55° | 47°N | 46°N | 56°N | has been seen as low as New York and Idaho |
| G3 StrongKp 7 | 50° | 42°N | 41°N | 51°N | has been seen as low as Illinois and Oregon |
| G4 SevereKp 8 | 45° | 37°N | 36°N | 45°N | has been seen as low as Alabama and northern California |
| G5 ExtremeKp 9 | 40° | 32°N | 31°N | 40°N | has been seen as low as Florida and southern Texas |
Source: NOAA space weather scales, swpc.noaa.gov/noaa-scales-explanation. Below Kp 5 the oval contracts more slowly; this section runs the line from 66 degrees geomagnetic at Kp 0 to the scale’s 60 degrees at Kp 5.
What this means
Each place is placed by its geomagnetic latitude, measured from the geomagnetic dipole pole, and compared with the reach NOAA states for each storm level on its space weather scales: G1 (Kp 5) about 60 degrees geomagnetic, G2 55, G3 50, G4 45, G5 (Kp 9) 40. Reading that backwards gives the Kp a place needs. Below Kp 5 the oval contracts more slowly and the line runs from 66 degrees at Kp 0 to 60 at Kp 5.
The forecasts have different horizons and the pages keep them apart: OVATION is the only thing that knows whether an aurora is out now, and it reaches 30 to 90 minutes ahead; the planetary Kp forecast runs three days; the 27-day outlook names likely active days and is not a forecast of any one night. None of them knows the clouds, which is why a town page reads its own forecast for those.
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 20, 14:08 UTC.