Preliminary models are developed relating 1-minute precipitation rates to commonly available monthly climatology. Regression equations are provided for precipitation rates equal or exceeded 0.1, 0.5, 1.0, and 2.0 percent of the time during a month. Models are developed using a precipitation index (monthly precipitation/number of days per month with precipitation) alone, and the index and monthly mean temperature as estimators. Separate models are presented for tropical and extratropical regimes, with some gain in precision of estimate offset by loss of confidence due to the small amount of data and fewer locations in each subset. The models and regressions are regarded as preliminary, since only 36 months of data are available for four stations. Data for additional stations are being prepared and will be used to refine these models. (Author).

Using preliminary statistical relationships between precipitation intensities averaged over 1-min durations and commonly available monthly climatological tabulations of precipitation, rainfall rates for 1.0, 0.5, and 0.1 percent exceedances were computed for weather stations over Europe and Asia for which monthly totals and frequency of daily precipitation were available for the months of January, April, July, and October. Isolines of intensities were drawn delineating regions of low and high rates for each precipitation frequency. These rates may be used for obtaining calculated-risk design criteria for military equipment and for the evaluation of the probability of operational problems when the intensity of precipitation equalled or exceeded with various low probabilities may be critical. (Author).

The Design Climatology Branch of the Air Force Cambridge Research Laboratories had the scientific responsibility for leading a DoD Task Group effort to revise MIL-STD-210A 'Climatic Extremes for Military Equipment'. This document represents the fruition of the goals of the task group. It relates the background studies supporting the values in MIL-STD-210B, so that MIL-STD-210B users need to consult only this single document for an elaboration on the MIL- STD-210B extremes. In addition, the report contains information on the origin, necessity for and the events leading to a revision of MIL-STD-210A. Discussions of the major changes in the Standard's philosophy and its contents are also provided.

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