Updated: 2018 Aug 08: Uploaded video at Giant Eruption 2018 Jul 24.
This is the time of the month to go out for moonlight Grand eruptions. So we were out for a steamy one burst that really didn't have much to recommend it. Then Beehive erupted without an indicator, so we didn't even get to see that.
Today's plan was to wait in the Bijou Cage for a hot period, probably the first since the previous Giant eruption. I arrived around 08:30 after a steamy Grand eruption. The platform looked much like it did yesterday morning. There was obvious runoff down from Mastiff. All the catch pools by the Southwest Vents were wet, which implied that there had at least been a long Bijou pause. The only anomaly was there was quite a bit of wetness around Feather and friends, implying, perhaps, a weak hot period.
The weather was mostly cloudy, and felt a bit humid. When the sun showed through gaps in the clouds, it felt hot and uncomfortable. I deployed an umbrella to make it easier to read a book on the iPad screen and to keep the sun off of me.
Grotto started right after Grand, before I could get to the cage. Within twenty minutes of arriving, there was a four minute pause that turned into a bathtub with some Southwest vent activity. Like yesterday, Bijou went into a noisy steam-phase, but it wasn't as powerful as the one yesterday.
After Rocket and Grotto shutting down, the next Bijou was at 10:07. This started a series of short pauses, durations about a minute every fifteen minutes or so.
Then, at 11:42, we had a nice 6 minute bathtub pause where Feather overflowed but didn't try to erupt. That was my cue to take a break, as previous experience said that it would probably be about an hour before the next platform event.
I took longer than that to get back, so I missed the Grotto start and the subsequent medium length (3 minute) Bijou pause at 12:41. I chose to skip the Grand eruption, which meant I missed a two burst eruption at 13:51. Rocket had a major eruption just before Grand, and Grotto was off by 14:01.
It was about this time that Mastiff's south vent (the one in the back) had one of its massive jetting surges. The kind of activity that seems to keep the water flowing all the way to the front of the platform.
The cloudiness had mostly disappeared by then, but the wind had picked up.
I've got to the point were I expect good things to happen soon after Grotto quits, and this was no exception. Bijou paused at 14:21, and water finally appeared in Mastiff about two minutes later. About 30 seconds later the Southwest Vents started to put out water. This was a slow start, and I was assuming (hoping) that we'd get Feather so we could finally have our first hot period.
It wasn't until 14:26 that Feather, which had been overflowing and burbling for several minutes, finally started up. Almost immediately, the Satellite and Cave started erupting. Mastiff was surging to several feet, wide thick boils like the ones before an eruption. Bijou turned back on at 14:28, which seemed a bit early. It was about that point that I realized that I might want to start recording the hot period, as it seemed like it was going to be a good one, perhaps similar to the one a week ago that should've started an eruption.
Even with all that activity, it was hard to believe that this was going to be more than just the first hot period in the series leading up to an eruption. I was already trying to figure out how much time I would have before getting back out-- would it be 6 hours for a minor, or could I risk waiting until tomorrow morning?
At this point I can refer to the video for events. (Posting will have to wait until I get home for the proper bandwidth.) As Mastiff dropped, Giant started to surge. The first couple of surges were angled, then the activity died down. Giant started surging again when Feather's Satellite shut down and Feather tried to stop. But then switched to vertical as Feather built up again. At times it looked like the entire contents of Giant's vent were lifting as a unit.
By this point, many of the vents on the platform had restarted, and Mastiff was having powerful "depth-charging" bursts. The entire platform was active again.
Then the cone filled with water several times, each time a bit higher. The surges started shooting the subsiding previous surge, with each surge higher. It was a surge that was at least twice as high as the cone that appeared to start the eruption, and even that had another, higher jet come through it to finally start the continuous activity.
After a couple of minutes, I went back to the 60 meter baseline marker to take a height measurement. It was quite windy, so the tops of jets were being pushed away from me. Because of all that, the best reading I got was 60%, which translates into 36 meters or about 120 feet. It was probably higher, maybe 150 feet, about as tall as a good start of a Grand eruption.
There was quite a crowd gathered there. Since the activity proceeded slowly, it allowed a number of gazers to join us for the start, or at least to be within sight of the start. The only problem was that once again, the NPS personnel kept breaking in and making it difficult for those in the cabin area to hear what was going on.
None of the signs moved. Obviously a few of them are too well situated.
After we return home, I should be able to make video of this start available.
The rest of the day was kinda anti-climatic. Did go out for the sunset Grand, but while the clouds to the west were pretty colors from an incoming thunderstorm, the one burst Grand itself was gray on gray.