Aurora Viewing in Southcentral Alaska

The aurora forecast is updated for September 24. 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 10:00 p.m. and 4:00 a.m. Alaska time. 

SAT SEP 24 – Planetary K-Index [predicted]: Kp3

SUN SEP 25 – Planetary K-Index [predicted]: Kp3

MON SEP 26 – Planetary K-Index [predicted]: Kp2

Additional Information Affecting Aurora Viewing

Moon: The moon rises at 5:48 a.m. as a 1.93% waning crescent. The moon will not interfere with viewing a quiet aurora.

Twilight: Astronomical twilight will end at 10:22p.m. and resume at 5:21 a.m (Sep 25). Twilight will not impair aurora viewing.

Solar Winds: A later than expected arrival of a trans-equatorial CH HSS is still possible in the latter half of 24 Sep. HSS conditions are expected to continue through 26 Sep, but likely weaker than originally thought.

Geomagnetic Field: The geomagnetic field is expected to be at quiet to active levels with G1 (Minor) storm levels likely later on 24 Sep in response to positive polarity CH HSS influences. Quiet to active levels are expected on 25 Sep followed by quiet to unsettled conditions on 26 Sep as the HSS slowly wanes.

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 maximum level for the Planetary K-Index was a Kp4 at prime viewing time for Southcentral Alaska.
• The maximum hemispheric power reached during Alaska viewing hours was 50.1 GW at 4:45a.m.
• Solar wind parameters were weakly enhanced through the period. Solar wind speed ranged from 380-481 km/s. Total field ranged from 2-8 nT while the Bz component was between +/-6 nT. Phi angle was variable.
• The geomagnetic field was at quiet to active levels under a weakly enhanced solar wind environment.

Current Aurora Ovation

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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.

The forecast is updated for the night of September 24.

Anchorage

Showers likely, mainly after 2am. Mostly cloudy, with a low around 42. East wind around 5 mph becoming calm. Chance of precipitation is 60%. Estimated cloud cover is 100% (10:00 p.m.) to 71% (4:00 a.m.).

Girdwood

Showers before 11pm, then rain after 11pm. Low around 41. East wind 5 to 10 mph. Chance of precipitation is 80%. Estimated cloud cover is 98% (10:00 p.m.) to 98% (4:00 a.m.).

Butte/Knik River

Palmer

Chickaloon

Glacier View

A chance of rain showers before 7pm, then a chance of rain and snow showers between 7pm and 10pm, then snow likely after 10pm. Mostly cloudy, with a low around 29. Calm wind becoming northeast around 5 mph in the evening. Chance of precipitation is 60%. New snow accumulation of less than a half inch possible. Estimated cloud cover at Lion Head is 73% (11:00 p.m.) to 68% (4:00 a.m.).

Wasilla

Willow

Showers likely, mainly after 1am. Mostly cloudy, with a low around 38. Calm wind. Chance of precipitation is 60%. Estimated cloud cover is 98% (10:00 p.m.) to 24% (4:00 a.m.).

Talkeetna