|First, it is easy to get confused when looking for Grand Geyser. The Park Service has put out a sign to help you but the first thing most people notice is the large raised rim around Turban Geyser and they miss the large flat pool just to the right of Turban. This large pool, with almost no rim, is Grand Geyser. When Grand Geyser finally erupts, it does so just before the start or within one, or rarely two, minutes after the start of a Turban eruption. If Grand doesn't start at this time, you'll have to wait for the next eruption of Turban and hope. After an eruption of Grand, Grand's pool is empty. Water slowly fills the pool and reaches first overflow about 5 hours after the eruption. Once in overflow, it can be noted that the pool rises and falls in approximately 20 minute cycles. These cycles correspond to the eruptions of Turban Geyser. At about the time an eruption of Turban starts, the water in Grand will usually begin to slowly drop and will continue to drop as Turban erupts. Once Turban stops, the water in Grand will slowly begin to rise again. With some practice, a good eye and favorable weather conditions, you may be able to see these drops and rises. Look around the front edge of the pool and you will notice some slightly raised sinter formations. At high water they form small islands or may even be covered by the water, at low water they will stick out of the water by about an inch. What you are looking for is for the water to stay high at the time you expect Turban Geyser to erupt. If this happens, you then want to look for large ripples (called waves) on Grand's pool. These waves are hard to see. It often takes practice to see them. Once large waves start while Grand's pool is staying full, you are almost assured of an eruption. The eruption will start just prior to Turban or within a minute or so of Turban. If it doesn't erupt within this period, sit back and wait for the the next Turban eruption.
Once Grand erupts, there is the possibility of more than one burst. A Grand burst is defined as continuos eruption of water from Grand. The shorter this first burst, preferably less then 10 minutes, the more likely it is that you will see a second, third or more bursts. (The most bursts seen in one eruption during the last few years is 11 bursts but the average is usually between 2 and 4 bursts.) After a burst has ended, watch Grand's pool. Sometimes the water will be out of sight, sometimes it will still be visible. Watch to see if the water rises. If the water rises and begins to bubble be prepared for a spectacular sight as Grand erupts to its full height in one continuous motion. If the water drops, well, there's always the next eruption.