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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />They had double checked their readings and were very confident. They normally read and <br />record rainfall totals to the nearest 0.1 inches. They were also sure that the gauge was <br />empty that morning, since they had written down 1.3 inches of rain from the previous <br />evening 7/28/98 and were conscientious about reading, recording and emptying. Their <br />records showed that an additional 2" of rain had fallen 7/19-7/27, so local conditions were <br />fairly moist immediately preceding the big storm. As an independent measure, they had at <br />least two 5-gallon buckets sitting out which were both full to the top after the storm. <br />They were thought to be empty before the storm. <br /> <br />Of meteorological interest, the rain came in with an east wind and actually seemed to <br />move over them from east to west. Ms. Blake recalled that the rain felt warm and that <br />there was no hail with the storm. They recall a lot oflightning but no sharp thunder. <br />They described the lightning as "sheet lightning." <br /> <br />In reviewing this observation, I conclude that the family members were very conscientious, <br />their memories were consistent, and their "Country General" cone-shaped rain gauge was <br />located in a wide-open area of their back yard, well away from any trees or buildings in <br />what would normally be considered an excellent exposure (photographs were taken <br />7/29/98). Since there was no hail and no strong winds, gauge catch efficiency and <br />accuracy should be good with almost any gauge of reasonable quality. <br /> <br />There was one matter that concerned me that could have adversely affected the <br />reading, The gauge was the type that has a small plastic mount that sticks in the ground. <br />The gauge stands upright in that holder. When installed, the top of the gauge is no more <br />than 10 inches above the ground. This is normally satisfactory, but in this case the gauge <br />was mounted in a small depression that most certainly would have been filled with water <br />during the storm to a depth of at least four inches. Thus, the top of the gauge would have <br />only been about six inches above a water surface. During heavy rain, a great deal of <br />splashing would take place near the water surface. It is likely that some water would <br />splash in a manner that would enhance the gauge catch. It seems unlikely that splash <br />would enhance the gauge catch by more than 10-20%, but a field test would be needed to <br />test this hypothesis. <br /> <br />An additional concern is that several neighbors don't recall any significant precipitation <br />after 2 AM. The 1.6" they measured between 2 AM and the next morning seemed larger <br />than expected, This could be evaluated by comparing to NWS radar data. <br /> <br />Because of this ground-level exposure in a local depression, and the uncertainty about the <br />rainfall after 2 AM, I feel that the quality of this observation must be considered "B." But <br />even if splash was a problem, it seems likely that at least 12-13 inches ofrain really did <br />fall -- an exceptional amount for a period of just over seven hours. The 15 inch <br />measurement is still possible ifit can be demonstrated that splash was not a problem, <br /> <br />9 <br />