This is the first day since June 27 we have had rain in the Otsego/Plainwell area. We have had .77 of an inch as of 7 am.
When it rains, your gauge measures the amount of precipitation that falls through the area at the top of the gauge. When you read the gauge, you measure the depth of water that has fallen through the area and accumulated in the bottom, which is the depth of water.
How, you may ask, can this gauge work properly if the inner tube is 10 inches long but only records 1-inch depth of water? The reason has to do with accuracy. The National Weather Service (NWS) has adopted the criteria that the gauge should be able to measure to an accuracy of 0.01″. The problem with a gauge that’s 4″ (CoCoRaHS) or 8″ (NWS standard) in diameter, is that it’s nearly impossible to read the depth to an accuracy of 0.01″. That’s where the funnel and inner tube come in.
The funnel of the CoCoRaHS gauge squeezes the water into the area of the inner tube, which is 1/10th of the area of outer cylinder (The NWS gauge has a similar funnel and inner tube). By reducing the area that the water falls into, the depth can be stretched by the same factor of 10. In this way, the total volume of water (area times depth) that fell through the top of the gauge and the total volume in the inner tube are the same. This stretching allows us to read the depth of water an accuracy of 0.01″.
We have ended our string of 90° days. Today will we will continue to see scattered showers with perhaps an embedded storm. High temps will be 10 to 15 degrees cooler though humidity levels will be high. This weekend looks to be pleasant with lower humidity and temps compared to the past week.