The results in the Atlas of Precipitation Extremes for the Northeastern United States and Southeastern Canaca (NRCC Research Publication RR 93-5) are based on data which were measured on a daily basis. Because some users require estimates of extreme precipitation omounts occurring over periods shorter than one day, a table of statdard adjustment factors was included in that publication. The table allows the transformation of daily extreme precipitation values to estimates for shorter accumulation periods. These standard adjustment factors, Huff and Angel , were based on analyses of data from the midwestern US and did not contain any spatial structure. In investigating the suitability of these empirical factors for the northeastern US, it was found that on average for shorter periods (one, two, and three hours), the factors tended to overestimate the extreme amounts. In addition, some spatial differences were found for these adjustment factors within this region.
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