Think through what visuals are needed and how to arrange them before creating them in Tableau. The most important thing, the starting point, should be the first thing the audience views. If there are to be multiple visuals in the same dashboard, it should be in the upper-left part of the screen.

Since a simple count is all that is really needed to answer the question, this can just be a number. No chart is necessary. You should make it large, so it is instantly noticed. Make it what may feel uncomfortably large, and it will be obvious to the audience without needing to point out that it is the most important piece of information in the view.

A trend of the number of reporting stations is needed so the audience can understand if more or less are reporting usable data over time versus the total number. This aligns with the first follow-up question. A monthly trend should work.

Then, for any given period, the water planning group wants to know where the reporting stations are located and whether there was significant precipitation for the period at the stations. They also want some idea of locations in the state with significant reported precipitation. A map is a good way to fit in a lot of spatial information in a way that can be easily comprehended. This aligns with the secondary follow-up question.

For any station or group of stations in an area, the planning group wants to be able to see daily trends, so anything unusual can be detected quickly for additional investigation. This aligns with the last follow-up question. Now, we can start building the views one at a time, then assemble them into a dashboard.