WEATHER MAPS 



299 



given place will fall, is calculated from the rate at which the storm 

 is progressing, and the prediction of the time of arrival of a cold 

 wave which an anticyclone is likely to bring, is based on the rate 

 of progress which the anticyclone is making. This rate is known 

 in advance for each anticyclone by telegraphic reports. Pre- 

 dictions concerning the weather may be made more readily for the 



SUNDAY, JANUARY 20, 1895-8 A. M 



Fig. 254. (U. S. Weather Bureau.) 



central and eastern parts of the United States than for the western 

 part, for the storms have been under observation longer before they 

 reach the central and eastern parts. 



Failure of weather predictions. Weather predictions often fail. 

 The reasons are many. Some of them are the following: 



1. Cyclones and anticyclones sometimes depart widely from 

 the courses they are expected to take. Thus a storm may be in 

 line for St. Paul, to which it is expected to bring rain and a rising 

 temperature; but instead of keeping its course, it may turn off to 



