SIGNIFICANCE OF DEVIATIONS FROM NORMAL 



The preceding discussion shows what is 

 considered the normal expectancy for local cli- 

 matic conditions. A firm knowledge of the nor- 

 mal situation is vital to intelligent planning and 

 strategy for fire control. Knowledge of devia- 

 tions from the normal is also extremely impor- 

 tant. If the strength of the attack organization 

 is to be based on average bad conditions, then 

 the extent of variation of present conditions from 

 the normal must be known within some given 

 limit of accuracy. It is not logical to build up a 

 fire control force strong enough to handle the 

 worst season; neither is it logical to build one 

 only strong enough to handle a normal season. 



Weather conditions during two recent fire 

 seasons — 1950 and 1957 — are considered 

 critical. Deficient precipitation, stronger-than- 

 average winds, low levels of air moisture, and 

 abundance of dry lightning storms all increased 

 the incidence and affected the behavior of fires. 

 This buildup in fire load, of course, very soon 

 taxed beyond breaking point the ability of the 

 fire control forces to cope with the immediate fire 

 situation. 



1950. — The year 1950 was one of the driest 

 recorded. Precipitation was below normal over 

 the entire Interior. The lowest annual precipita- 

 tation measured in Alaska that year (at Fort 

 Yukon) was 3.83 inches, about 55 percent of 

 normal. Large forest fires in that area occurred 

 from early spring until fall. More than 2 million 

 acres of forest land were burned by 224 fires 

 that summer. This was one of the worst fire 

 seasons experienced since the beginning of or- 

 ganized protection in the State. (In the first years 

 of organized f irefighting, 1940 and 1941, 4.5 

 and 3.6 million acres, respectively, were burned; 

 records for these years are sketchy.) 



Many new weather and fire records were 

 established in 1950. Stations over most of the 

 State reported above normal temperatures for 

 March and April. Drought persisted in the Yukon 

 and southern valley regions from January 

 through September. A forest fire between the 

 Chandalar and Porcupine Rivers in the Fort Yukon 

 area burned 246,000 acres in the month of June; 

 if spread over the whole month this would mean 

 burning more than 13 square miles each day. 



USPS 



Figure 29. — High velocity down-canyon winds are -often 

 associated with glaciers. Matanuska Glacier. 



The many dry thunderstorms from June through 

 August caused a serious outbreak of fires each 

 month in both the Yukon and southern valley 

 regions; temperatures remained above normal at 

 many stations in these regions. Some relief from 

 the drought came in October, yet precipitation 

 reported by many stations was still below 

 normal. 



1957. — As the 1957 season progressed, 

 weather conditions approached the critical point. 

 April's maximum temperatures climbed to new 

 records at many stations. Above-normal read- 

 ings continued through May; record highs were 

 reached in the Kenai Peninsula. June tempera- 

 tures were the highest ever in a wide belt ex- 

 tending from the northern Arctic Coast through 

 the central mainland on to the Alaskan Penin- 

 sula. 



Temperatures dropped to near normal over 

 most of the State during July, but rose to ab- 

 normally high levels again in August. Warming 

 trends continued at most points into September- 

 Fairbanks registered a record high of 84° F. 



As a rule, above-normal temperatures indi- 

 cate airflow associated with above-normal pre- 

 cipitation. However, this year vast areas of the 

 State experienced temperatures well above nor- 

 mal but received relatively light precipitation. The 

 driest area was in Alaska's interior, where the 

 precipitation total remained consistently below 

 normal month after month. • 



32 



