Comparison of generalized estimates of probable maximum precipitation with greatest observed rainfalls

This study summarizes known storms of record over the United States east of the 105th meridian and west of the Continental Divide that have point or areal rainfall depths that are _> 50 percent of PMP. More than 240 storms met this criteria. The storms are identified and percentages of PMP are shown on maps. Some judgement on the relative magnitude of PMP in the two large regions is given by comparison of the ratios of PMP to 100-yr return period rainfall. Such ratios for 24 hours range from 4 to 6 east of the 105th meridian. For the western mountainous states, these ratios are as low as 2 in the more mountainous locations and as high as 6 in the desert and sheltered spots.