Upper-Air and Surface Winds 

 in Northern Idaho Vicinity 



We may view the winds aloft from another 

 standpoint, in the form of a time graph for an 

 individual station. Figure 24 shows such a 

 graph of the mean windspeed in the 5,000 to 

 7,000-ft. m.s.l. layer for Spokane, 70 statute 

 miles southwest of Sundance Mountain. For 

 comparison, the corresponding windspeeds 

 are given for two adjacent upper-air stations 

 (to the west and east). These stations are 

 Quillayute, on the northern Washington coast, 

 and Great Falls, Montana. A pronounced peak 

 in speed in the 5,000- to 7,000-ft. layer is seen 

 to have occurred at aU three stations. The 

 peak at the coastal station occurred approxi- 

 mately 12 hours before that at Spokane, 

 whereas the peak at Great Falls occurred 

 about 12 hours after that at Spokane. The 

 peak speed in this layer, 45 knots (from the 

 southwest), is highest at Spokane; however. 



nearly as high a speed, 43 knots, was observed 

 in a lower layer (2,000-4,000 ft. m.s.l.) at the 

 coastal station. This diagram gives further 

 evidence that the strong lower level winds in 

 the Sundance Fire vicinity were a more or less 

 sustained, broad-scale, moving feature which, 

 at least in retrospect, was trackable. 



Sustained windspeeds of 40 to 45 knots at 

 5,000 to 7,000 ft. m.s.1. appear to be excep- 

 tional in the northern Idaho area during the 

 fire season. This is the impression gained from 

 an examination of Spokane winds-aloft re- 

 ports for the period June 15 to September 15 

 of the years 1957 through 1967. Speeds of 38 

 knots or greater at 5,000 feet appear to occur 

 on an average of only 2 days per season 

 (based on four wind soundings per day). In all 

 but one of 12 actually observed cases in this 

 11-year period (wind soundings were made 

 only three times per day during five of the 

 years), the days with such windspeeds oc- 

 curred in June or September. The wind direc- 



56 



48 - 



40 



a 



J 32 — 

 o 



a. 



CO 



9 24 



16 



SPOKANE 10,000 - 12,000 FT. m.s.l. 



SPOKANE 5,000 • 7,000 FT. m.s.l. 



LUNCH PEAK (6,400 FT. m.s.l.) 



• •• HANFORD (400 FT. ON TOWER) 



• ROMAN NOSE LOOKOUT (7,264 FT. m.s.l.) / 



/ 



/ 



• / 



/ / 



y / 

 / 



\ 



\ \ 

 \ \ 



\ 

 • \ 



A 

 / • •• 



..// ^ 



i -.N 



i — 



TIME 



J. 



X 



56 



48 



40 



32 



24 



16 



24 



20 



16 

 SEPT. 2 



12 



08 



04 



24 



20 



16 12 

 SEPT. 1 



08 



04 



Figure 25. - Time graph comparing free-atmosphere wind^eeds at Spokane and surface or tower wind^eeds 

 at several observation points, September 1-2, 1967. 



29 



