The aurora forecast is updated for May 7. Keep an eye out for our daily weather forecast update below and tour status as noted on the Anchorage Aurora Quest page. The Kp estimate is for the maximum level forecasted for the time between 12:00 a.m. and 4:00 a.m. Alaska time.
FRI MAY 7 – Planetary K-Index [predicted]: Kp 1
Our Anchorage Northern Lights Forecast concludes on May 7. We will resume the forecast when our season returns on August 7.
Additional Information Affecting Aurora Viewing
Moon: The moon will set at 5:14 p.m. as a 12.41% waning crescent and be down all night. The moon will not interfere with aurora viewing.
Twilight: Civil twilight ends at 11:24 p.m. and starts at 4:26 a.m. (May 8). There is no nautical or astronomical twilight at this time in Southcentral Alaska. At this time of the season, there needs to be at least a Kp4 aurora with enhanced solar winds or geomagnetic field in order for the aurora to be visible to the naked eye.
Solar Winds: Solar wind parameters are likely to remain nominal over 07-08 May. A weak enhancement from interaction with a negative polarity CH HSS is possible on 09 May.
Geomagnetic Field: The geomagnetic field is expected to be mostly quiet, with isolated unsettled periods possible on 07-09 May.
Planetary K-Index provides an estimate as to how wide the auroral oval may extend. It does not indicate whether the aurora borealis will appear. The most important factors for aurora viewing are the solar winds and geomagnetic field – so note the information above on those. The Planetary K-Index is measured on a scale of 0-9. Anchorage is within the Kp3 zone (aurora visible overhead), but auroras are often seen here on the horizon as low as Kp1 (except for the early and late season, where a higher Kp is needed.) A fairly accurate Kp index can be determined up to 3-days in advance. For the Kp index indicated in the Anchorage northern lights forecast, that is the maximum Kp predicted during the prime aurora viewing time in the Anchorage area (generally between 9:00 p.m. and 4:00 a.m.). We do not provide the Kp level for a forecast period outside of nominal viewing times (i.e., local daytime).
Last Night’s Aurora
- The Planetary K Index reached Kp0-1 during optimal viewing hours.
- The maximum hemispheric power achieved last night was 12.8 at 3:29 a.m.
- Solar wind parameters, as measured by the DSCOVR spacecraft, reflected nominal conditions. No significant periods of southward Bz were observed. Solar wind speeds varied between 285-335 km/s. Phi angle was oriented in the positive sector. The highest wind speed for Alaska viewing time was 313 at 1:22 a.m.
- The geomagnetic field was quiet. Total magnetic field strength was between 4-7 nT. The best Bz component for Alaska was -2 Bz south at 3:40 a.m.
Current Aurora Ovation
Hemispheric Power is a measure of auroral activity that helps determine how bright and active auroras might be. It measures the rate of deposition of charged particles (mainly electrons and protons) into the atmosphere, where they collide with upper atmosphere particles and eventually stop. This process transfers their kinetic energy to the upper atmosphere. The higher the number, the more charged particles are depositing in the upper atmosphere. It’s measured on a scale of 5-150 GW [Gigawatts]. A power level of 20 or more is usually adequate to produce auroras visible to the naked eye. Hemispheric Power fluctuates and is a short range forecast that can be determined only up to around 30-90 minutes in advance with relative accuracy.