THE RAINFALL OF GUERNSEY FOR THE 

 YEAR 1917. 



BY MR. A. COLLENETTE, F.C.S. 



1917 has been a dry year, its total being 31*81 against an 

 average of 36*67 in., a deficit of nearly five inches (4*86). 



Eight months were dry and of the four wet months, only 

 two, August and October, were excessively wet. These two 

 gave excesses of 2*93 and 1*34. March and May together 

 had an excess of 1*05 in. 



Of the dry months September failed to reach its average 

 by 2*08 ; December by 2*37. January and November gave 

 deficits of 1*80 in. and 1*44 in. respectively. (See Table 1.) 



The year divides itself into two periods, one, January to 

 July, inclusive, with five dry months and two wet, and a 

 second, August to December, inclusive, with three dry months 

 and two wet. 



There we eight days which were very wet and these days 

 contributed no less than eight inches to the year's fall. 



Had the eight very wet days had normal falls, the year 

 would have been one of the driest on record ; this fact shows 

 how dry the rest of the year was. (See Table end of Paper.) 



The driest month of the year was September, with a fall 

 of less than an inch (0.88). There were 17 wet days during 

 that month, but they were remarkable for their small totals, no 

 fewer than 12 being under 0*02 in. This month was sand- 

 wiched in between the two wettest months of the year — 

 August and October — and these three months are responsible 

 for the usually large number of wet days of the year, having 

 contributed no fewer than 60 to the total. 



It should be noticed that the dry months were with two 

 exceptions in series of twos. January and February ; June 

 and July, and November and December. April and September 

 were dry months with, in each case, a wet month preceding 

 and following them. This, of course, is only another way of 

 saying that the anticyclonic periods were longer than the 

 cyclonic. 



