A STUDY OF WEATHER MAPS 261 



Sometimes the south wind continues until the advancing 

 front of NW. wind is only a few miles away, and the complete 

 change from S. to NW. occurs within a few minutes. If both 

 LOWS (Figs. 180 and 186) travel 40 miles per hour, compare 

 the time required in each before the wind at Davenport com- 

 pletes the shift from southeast to northwest. 



Review the law of winds in a LOW, and how you can tell by 

 the wind shift which side of you the storm center is passing. 



FIG. 186. The winds of an elliptical low. Additional arrows have been 

 entered to show winds more clearly. Solid lines are barometer, broken lines 

 are temperature. 



The U. S. Weather Bureau gives the following summary of 

 wind and barometer indications: 



"WIND, BAROMETER INDICATIONS. When the wind sets in from 

 points between south and southeast and the barometer falls steadily, 

 a storm is approaching from the west or northwest, and its center will 

 pass near or north of the observer within 12 or .24 hours with wind 

 shifting to the northwest by way of southwest and west. When the 

 wind sets in from points between east and northeast and the barome- 

 ter falls steadily, a storm is approaching from the south or south- 

 west, and its center will pass near or to south or east of the observer 

 within 12 or 24 hours with the wind shifting to the northwest by way 



