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BANNER I. MILLER

Abstract

A single-station technique is used to compute vertical velocities over San Juan, P. R., at standard constant pressure levels from 850 to 100 mb. Periods of strong upward motion are observed to occur rather frequently within the layer 400 to 100 mb. and these are discussed in relation to subsequent precipitation patterns.

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BANNER I. MILLER

Abstract

Hourly rainfall amounts from 16 hurricanes are plotted relative to the center of the storm to obtain the mean areal rainfall rates around the storm. The rates ahead of the center are greater than those to the rear, but the differences in rates between the right and left sides are not large. The frequency distributions of various hourly amounts are tabulated for stations within about 100 miles of the center. Finally, the latent heat of condensation is calculated from the mean areal rainfall data. This is found to be about 6 × 1026 ergs per day.

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BANNER I. MILLER

Abstract

The processes which resulted in the filling of a tropical cyclone over land have been investigated. The eddy fluxes of latent and sensible heat and the dissipation of kinetic energy at the earth's surface have been computed for a 3-day period. On the first two days the cyclone was over the ocean and on the third day it was over land. Hence it was possible to compare the rates of energy exchange at the surface after the character of the lower boundary had changed. Some significant differences in these rates of exchange were detected.

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Banner I. Miller

Abstract

The minimum pressure that can occur within a hurricane is related to the temperature of the sea surface over which it moves. This is done by making certain assumptions and synthesizing an eye sounding, which is used to compute the lowest pressure of the storm. The validity of the computed sounding is tested on eight hurricanes. A series of composite 200-mb charts is constructed from five of the eight hurricanes which reached great intensity to show one synoptic situation which results in maximum deepening. These are contrasted to a similar series of composite charts prepared for storms which reached only minor intensity.

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BANNER I. MILLER and TOBY N. CARLSON

Abstract

Vertical motions have been computed for a 6-day period during which an upper tropospheric cold Low moved through the eastern Caribbean, and a kinetic energy budget for the region has been constructed. During the first 3 days, the kinetic energy inside the volume increased. The computations indicate that the increase was caused by lateral advection of kinetic energy into the volume plus a small internal conversion of potential to kinetic energy. The kinetic energy decreased during the last 3 days, as the circulation became indirect. Visual agreement between the vertical motions and the observed weather was good.

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BANNER I. MILLER and PETER P. CHASE

Abstract

Equations for the prediction of hurricane tracks have been developed by use of statistical methods. Data at sea level, 700 mb., and 500 mb. were selected as predictors. Forecasts are prepared in 12-hr. steps for periods up to 48 hr. The forecast equations have been tested on an operational basis during the 1964 and 1965 hurricane seasons. The accuracy of these forecasts compares favorably with that of other standard hurricane forecast techniques.

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BANNER I. MILLER, ELBERT C. HILL, and PETER P. CHASE

Abstract

The NHC-64 statistical equations for predicting the movement of hurricanes have been in operational use for 4 yr. These equations have continued to perform well. Following the 1966 hurricane season, however, it was apparent that the equations could be improved. A new forecast technique, based on additional data and additional predictors, has been derived. Tests on independent data for 1966 and on an operational basis during 1967 indicate that the 1967 method is slightly superior to NHC-64.

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BANNER I. MILLER, PETER P. CHASE, and BRIAN R. JARVINEN

Abstract

A multilevel primitive-equation model has been designed for regional weather forecasting in the Tropics. Several experimental forecasts have been made on hurricane movement and development and on a nondeveloping tropical weather system. Forecasts of the movement of hurricane Celia were slightly slow and somewhat south of the actual track. Some intensification was forecast as Celia moved into the central Gulf of Mexico, but the model did not predict explosive deepening. Grid spacings of 75 and 150 km were used.

In the nondeveloping case, no deepening was forecast. Areal distribution of the predicted rainfall was good, but the amounts were too light. Forecasts have been made with hand-analyzed input and with interpolated data extracted from the National Meteorological Center's objective analyses.

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