THE WEATHER.

Star (Christchurch), Issue 16416, 3 May 1921, Page 6

THE WEATHER.

CANTERBURY CONDITIONS, j

(By F. L, WOOIjES.)

APRIL. Fair weather was the prevailing feature during April, although cold and stormy conditions marked a few days of the month. There were only two i or three days ou which rain fell in an appreciable quantity, namely, on the third, eighteenth, twentieth and twenty-fifth. However, although tne . days of rain were few, sufficient pre- ; cipitation occurred, to account for a rainfall that approximated to the average lor the month over a great- part of the province. A heavy rainstorm on tlio eighteenth, amounting to over two inches in parts, was the principal contribution to the monthly aggregate. Thunderstorms occurred in parts of midCanterbury and about Banks Peninsula ! on the eighteenth and twentieth Though there were many days when little or no wind occurred, there were one or two well defined period a when high winds were a prevailing feature. Strong northerly to westerly gales were . in evidence between the eighth and i fifteenth, and strong southerlies be- | tween the eighteenth and twenty-first, j Frost occurred on many nights. One ! or two frosts were fairly sharp, but on. j the whole they were' light and of little j consequence. However, the great num- • ber of cold nights experienced resulted in the average temperature for tho I month being somewhat below the nor- • mal for the time of the year. An outstanding feature of the month was the unusually low barometer reading recorded on the ninth, n minimum of 28.65 being registered, the lowest barometric minimum since March 19. 1918, when 28.64 was recorded. On August 25, 1920, the barometer fell to 28.70. . It is interesting to note that during each of these periods of marked barometric minima a heavy north-east gale has occurred along the coast of North. Canterbury, raising mountainous seas and causing exceptionally high tides. On two occasions, some rain has accompanied the storm, but during the last the weather, with the exception of tho high wind, was fair. On December 6. 1911, when a violent north-west wind was experienced, the barometer* fell to 28.65. The resulting south-wester was n dry one. It is thus seen that even though had weather is to he expected with a very low barometer, little or 1 no rain is experienced as a rule in the province when such marked barometric minima occur. The worst storms that tho province has known have occurred when the barometric minimum lias been 29.50 or over. During tho heavy , snowstorm of Juno 80-July 2, 1918, ■ when the up-country districts were snowbound, the barometer fell no lower than 29.60, while on July 21 and 22, the same year, when the city experienced a record snowfall, the lowest ' barometric registration was 29.50. A still more remarkable instance of the ' unreliability of the barometer sometimes in indicating bad weather oc- ; curred on July 11, 1903. On that oc- j cas ion the barometric minimum was ' 29.85, a reading midway between ; change and fair as indicated bv the j glass. Though this reading indicated nothing unusual in the weather outlook, a very heavy snowfall occurred oyer mid and South Canterbury, 18in of ? n ® TV ' b . ein £ registered at Ashburton, find 3ft 6in at Fairlie. All these readings, of course, apply to a barometer corrected to sea level, and allowance being made for altitude. i; 0 those who wonder why a barometer so often belies its indications the writer desires to point out that the readings of one locality are not- a generally sufficient guide for weather changes, but when readings are obtained over an extended area the differences recorded at n particular hour in widely separated, localities give a better idea, of probable changes, especially when the correlation of such barometer readings is taken m conjunction with the knowledge of the movement and appearance ol clouds, and due allowance is made j9 r . . 10 physio graphical features of a district. OUTLOOK FOR MAY. Weather very changeable. Warm, north-west conditions at times, but cold and stormy during a good portion of i the month, especially the latter part. Expect good rainfall and occasional severe frost.