Observations for 2021 May 17

With Fan & Mortar erupting during the night, it made sense to revist Norris. Was there for four hours, and really didn't see much change from yesterday's short wait. So instead, it was time to do some provisioning and laundry.

There is a huge herd of bison (well over 100, pushing 200?) just west of the Madison Campground, and the backup on the road exteded for six miles. At Seven Mile Bridge, we got a bonus-- a coyote was crossing the bridge, causing its own mini-traffic jam. But since we were headed against the flow, the drive was easy (except for the guy near the end who thought it would be cute to pass on the double yellow to get ahead.) The herd was still there on our return, but with the large turnouts there, the NPS was keeping traffic moving.

Went out to the evening Grand with the expectation of a nice, dry wait. To the north was gray clouds showing some precipitation which wasn't getting down to the ground. Since it was to the north, didn't think much of it.

Arrived at Grand just as West Triplet was ending, and just in time for a long Boop from Grand. The pool then began to drop. To drive the point home, that this was a Delay, Tuban explosively started its eruption, and that eruption lasted well over six minutes.

At the same time, the gray clouds to the north were heading south, and building. The next Turban eruption interval was short, and Grand didn't have any overflow. The Turban interval and eruption after that were normal, but Grand never looked like it was going to erupt.

By that time the gray cloud was overhead, and the precipitation was reaching the ground. The wind was out of the north, and strong. The next Turban eruption interval was a bit surprising, as it was short, without any Grand overflow, despite there not being any sort of Delay related activity before.

The rain subsided by then, and then the wind shifted to come from the opposite direction. Then the rain started back up. The Turban eruption was short, only about three minutes long, and Grand was full and overflowing at the seven minute mark. By the 14 minute mark, Grand could have been having waves on the pool, but we couldn't tell because of the strong wind.

Then the sun came out, even with the rain and wind, just before Grand started to erupt. From my usual vantage point, Grand was at the left end of a full arc rainbow whose other end was near Sawmill. This view persisted for the entire eruption, with a second arc faintly visible.

Then suddenly, at 7m13s, the eruption stopped. Of course we had a second burst, but it lasted just long enough to qualify as a long burst, and that was it for the eruption. As far as I could tell, despite it only being just under nine minutes total duration, there was no attempt at a refill in Grand's vent.

At that point, we had the joy of walking into a strong, wet wind to get to our bikes and back to someplace warm and dry.