MONTHLY SUMMARY 



April, 1947 



Barometer, in inches 



(Readings reduced to sea level) 



Maximum 30.51, 22nd 



Minimum 29.51, 27th 



Mean semi-daily 30.100 



Range --- -1.00 



Air Temperature, in degrees F. 



Highest 74, 6th, 30th 



Lowest 23, 4th 



Mean 44.7 



Range 5 1 



Highest mean daily 61.5, 30th 



Lowest mean daily 33, 20th, 21st 



Mean maxinmm 55.1 



Mean minimum 34.3 



Greatest daily range 37, 6th 



Least daily range 4, 20th 



Precipitation, in inches 



Precipitation -4.59 



Snow .— , 2.25 



Maximum precip. in 24 hrs. .— 1.23, 5th 



Number of days with .01 or more 10 



Wind, in miles 



Total movement 5714 



Greatest daily movement 355, 7th 



Least daily movement 83, 9th 



Mean hourly velocity 7.9 



Maximum velocity 32, 27th 



'Wind, direction 



.W 



Prevailing direction .... 



North, days .. 6 



Northeast, days 



East, days . 2 



Southeast, days _.. 3 



South, days 2 



Southwest, days 6 



West, days 7 



Northwest, days 4 



Weather 



Mean relative humidity, percent 61.5 



Mean cloudiness, percent 58% 



Number of clear days -..9 



Number of fair days 9 



Number of cloudy days _ 12 



Number of hours bright sunshine 183 



Percent of possible hours of bright 



sunshine _ 45.5 



Thunder and lightning 30th 



Normal 



30.48 



29.38 



29.99 



1.11 



79.4 

 22.0 



45.7 



57.4 



56.8 



34.8 



3.35 

 2.17 



11 



5404 



7.5 

 31.4 



WNW 



61.6 



51.8 



11 



9 



10 



220 



54.7 

 Apr. 15 



Extremes 



30.71, 1911 

 28.98, 1943 



1.52, 1930; .72, 1919 



90, 1941 



8.5, 1923 



52, 1921 ; 41. 1943 



6.89, 1929; .55, 1941 

 11. 1891; 0, 1910, 1934 



18, 1909; 3, 1892 



8208, 1908; 3853, 1917 



40, 1935, 1938, 1940, 1945 



75, 1901; 34, 1925, 1927 



23, 1941; 3, 1898, 1902 



18, 1915; 2, 1894, 1901 



22, 1901; 1, 1941 



329, 1941; 103, 1901 



Mar. 14, 1910; May 11, 1907 



N')le — The hrs't colunm in the above summary gives observations made during 

 tl.e month. Tlie second column gives the averages based on observations made 

 friitii 1889 to 19.'^8, except that humidity records are based on observations mnde 

 from 1929 to 1938. The third column gives extremes observed from 1889 to 1946. 



