Blogging The Chase
- Eric Bleicher
- Oct 5
- 3 min read
Updated: Oct 5
For a week that was looking to give cloudy skies with plenty of precipitation, we sure did luck out.
Enhanced solar wind was prevalent through most of the week due to a few different things - high speed streams coming in, speculation on stealth CMEs, a modeled near miss from a CME potentially clipping Earth, and also some potential continued effects at high latitudes that occur around equinox.
All of that in itself is plenty to unpack! Looking at this week as a whole, the key highlights were:
1. Sunday - caught sub auroral arc through the clouds
2. Monday - auroras from nautical twilight through until astronomical twilight closed, capped off by a really nice substorm expansion on Turnagin Arm (highlight of my week!)
3. Tuesday - caught a modest substorm in the Knik River Valley during continued enhancements
4. Thursday - two large releases just north of our location as the clouds rolled in to close the week
From Sunday Night: The sub auroral arc observed was a really nice surprise - I didn't have high expectation of catching clean sky, especially since September to October is a tough weather window in Southcentral Alaska. To our surprise though, we did catch enough of an opening to the east for a few shots of this phenomenon next to soft aurora!
From Monday Night:
This was a vibe, reminding me of those first few substorm expansions I caught after first moving to Fairbanks in 2021. Conditions were good before sunset, so we were proactive and got on the road about two hours before dusk finished. *Here to the right is what NOAA solar wind data looked like - he black and red lines at the top of the image show a big downward run on the red line and a big upward run on the black line. This represents a strong enhancement of solar wind in its IMF intensity (black) and the polarity of that enhanced wind supporting aurora brightening (red).
Being on the southern edge of the auroral zone near Anchorage, I saw this as an opportunity to go south since the data supports probable stronger activity southward.
As for the activity itself, we had aurora immediately on arrival as nautical twilight set in!
As skies transitioned from nautical to astronomical twilight, continued enhanced conditions were represented through HP30. The HP30 index is a great snapshot to get more global ratings of activity in 30min increments (as opposed to KP, which gives you maximum peak forecast for an entire day and isn't based on real time at all).
Click the link in caption to bookmark this!
As HP30/HP60 note elevated activity between 0230-0700UTC, Alaska is 8hrs behind UTC right now with us having dark enough skies at nautical twilight near 830pm local time (0430UTC). The picture above was the first nice look, and as you'll see below, expansion came about an hour later!
And then here, a corona overhead! And a good reminder to go portrait orientation for these looks.
All in all, a pretty good week on the edge of the auroral zone near Anchorage! Especially considering it was due to be cloudy and rain most of this last week.
Looking into next week, we do have bad sky coverage forecasted with a couple of slow moving CMEs coming our way. Those impacts may be limited to the auroral zone & northern ends of the sub auroral zone depending on variables such as acceleration in transit, configuration, etc. As always, I'll monitor Earth weather and wait for solar wind to cross L1 to get back at it!
