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Historical Weather Service | Exploring the Atmosphere

Radar Detection



Library Introduction: The following short article was written for Weather Bureau personnel in late 1947. It provides a glimpse into the history and philosophy of radar use by the Weather Service at the beginning of a new age of weather forecasting and weather observations. Suddenly meteorologists were able to detect atmospheric phenomena beyond the circle of their vision and predict the arrival of storms hours in advance merely by glancing at their radar screens. The installation of the first operational weather radars were landmarks that began a revolution in the nature of observation and warning systems used by the Weather Bureau, a revolution that has continued through the installation of today's NEXRAD Doppler radar systems.

The Weather Bureau has established a program to install, operate, and maintain radar equipment in a network of Radar Storm Detection stations. These are to be located at strategic Weather Bureau stations throughout the United States. At the present time, however, only four installations have been established. More stations will be installed as equipment becomes available. Present radar equipment used by the Weather Bureau was received from the Navy and is of the airborne type converted for use in radar storm detection.

The type of equipment now being used is designated AN/APS-2, operating on a frequency of 3300 megacycles per second, radiating a radio frequency peak power of 50 kw. Additional sets, it is anticipated, will be transferred to the Weather Bureau from the Navy Department. The range of this equipment is slightly over 100 miles. The equipment is capable of detecting and tracking thunderstorms, frontal activity, tornadoes, hurricanes, etc.

In the practical operation, observations are made every 2 hours both during supposedly fair weather and stormy weather. The reason for an observational program on this time basis in fair weather, as might be shown on the synoptic chart, is for precautionary purposes to insure that developments which would otherwise be overlooked on a spot basis do not go undetected on an areal basis. Radar indicators will report the description of a storm, will describe whether or not it is a line or group or a mass type of disturbance. The intensity of return on the indicators will show whether it is weak, moderate, or strong. The character of the weather situation is indicated by the echoes as to whether or not they are scattered or solid. The tendency is also of importance, showing whether the returns are decreasing or increasing and whether the echoes are scattered or becoming strong over the area under observation. The direction and velocity of movement of the storm is also shown. These items and others can be grouped in a code denoted as a RAREP, and transmitted to other stations. Such information as the foregoing makes it possible to have more accurate 1- to 3-hour short term forecasts, especially for the telephone service. Of the four installations that have been made, the first was completed at Washington, D. C., February 14, 1947. The second was completed at Wichita, Kans., May 5, 1947, and the third was completed at Norfolk, Nebr., August 5, 1947. The final station at Wichita Falls, Tex., was completed for service use September 23, 1947. Additional installations will be made at other points throughout the country, as equipment becomes available. The three midwestern stations form an observational network which can possibly track nearly any storm within this general area.

At Norfolk, Nebr., it has been reported that protection to the public interest has more than paid for the installation, in a short period, in its ability to warn the public of approaching electrical storms, as in the generation of electricity where it is required that special precautions must be made to protect a power system supplying cities in the Elkhorn Valley. Flash flood protection to life and property in this river basin is another example of radar's use. When sufficient experience has been gained in the use of this equipment, it is conceivable that the RAREP can be transmitted on a circuit from Kansas City, Wichita, Norfolk, Wichita Falls, and Fort Worth, making possible more effective use by the forecasting centers of the 3 radars in the Midwest.... [In: Weather Bureau Topics and Personnel October 1947. Pp. 183-184.]

 



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