Values of persistence of precipitation for each of the four seasons have been derived for 108 cities in the conterminous United States for a selected combination of time intervals. These values show significant differences between stations and seasons and shed considerable light on the general behavior of storm systems and atmospheric circulations responsible for precipitation occurrences. Examples are given illustrating the application of persistence to the forecasting problem, and the relationship between persistence and the coefficient of correlation involving successive precipitation events is developed. The data presented should serve as important supplementary information to the forecaster in evaluating continuity trends in precipitation.

Numerical means are used to compute storm surges (meteorological tides) in a standard basin of constant slope, bounded by a straightline coast. All storm tracks in this study are constrained to lie parallel to the coast; the storm can lie at any distance from the coast and travel with any speed, but once set, the distance and speed are invariant with time. Two driving forces, wind stress and atmospheric pressure gradient, are used to generate surges; they are derived from an analytic wind profile. The model storm is described with two invariant parameters, storm size and difference between ambient and central pressure of the storm.

The mean maps show average geopotential metric heights for the 850-, 700-, 500-, and 300-mb pressure surfaces at 000 and 1200 GMT for each month of the year. The maps were derived by computer from objectively analyzed grid-point data for November 1961 through January 1969. The use of these maps is briefly described to obtain the average monthly height for any day and 12-hour period

Map of mean diurnal (12-hourly) and median (midway between 0000 and 1200 GMT) monthly height changes at the 850-, 700-, and 500-mb levels over North America and vicinity from January through December are presented, using grid-point data from an earlier study. The height changes were objectively derived and analyzed by computer. The use of these charts as an aid to weather forecasting is briefly described