Forecasting of Weather Changes. 579 



735. locating the Storm Center. When the weather has 

 been for some time f ajr and the prevailing winds are blow- 

 ing, the first indication of an approaching storm is usually 

 to be found in the long thread-like or hair-like curved cir- 

 rus clouds represented in the outer front side of Fig. 269. 

 If these are seen strongly developed in any quarter of the 

 sky it is usually true that a more or less strongly developed 

 low area exists in that direction. 



If these appearances first develop to the east of a north 

 and south line the first probability is that this storm will 

 not reach the observer because it is already past and trav- 

 eling away from rather than toward the place. 



On the other hand if the cirrus clouds show themselves 

 well developed to the west of a north and south line, and 

 especially if between the southwest and northwest, then a 

 storm center is located where its future course may bring 

 it "over the locality. 



736. Change in Wind Direction. If a storm is approach- 

 ing from the westward in the direction of the cirrus clouds 

 these will advance and in a few hours will overspread the 

 sky, the wind will decrease and finally shift to a direction 

 which will indicate the approach of the storm, and more 

 definitely the direction of the low area from the observer. 



737. Direction of the Storm Center Indicated by the 

 Wind. When a storm has advanced far enough to give 

 definite direction to the wind it is then possible to judge 

 from this the location of the storm center. 



Standing with the back to the wind and extending the 

 right arm directly in front, and the left arm at right angles 

 to this, the storm center is usually in a direction somewhere 

 between the two hands; this will be clearly seen from a 

 study of Fig. 269 and also of Fig. 268. 



It will sometimes happen that winds blowing ontwnrd 

 from a HIGH, or region of heavy pressure which has 

 passed to the eastward, may be mistaken for those due to 

 an approaching storm, because they are easterly, but [Me 



