WEATHER EVENTS OF RECENT WEEKS Not only was the spring of 1929 notable for its numerous tornadoes (see article in the May issue of the BULLETIN), but there were some general storms of marked severity. On a low pressure area of slight proportions appeared over western Texas. On the 13th it was still rather harmless looking on the weather map. But this storm was destined to pass, four or five days later, up the Atlantic coast with great fury. The center of the disturbance moved slowly eastward the first two days, being near Shreveport, La., at 8 P. M., , still of only moderate strength. By the morning of the 15th it had developed considerably in intensity and had moved to Alabama. The Weather Bureau ordered "whole gale" storm warnings to be displayed on the Middle and North Atlantic coasts. By 8 A. M. of the 16th the storm was one of intense low pressure, 29.1 inches at the center, which was on the coast between Norfolk and At- lantic City. Then its northeastward movement was checked and it travelled very slowly up the coast for two days, being retarded by the presence of a big high pressure area over eastern Canada, which had been in that region for several days. There was a great conflict as the low pressed north-northeastward against the big Canadian high, and northerly gales and excessive down- pours of rain resulted on the 16th and 17th at coast stations from Vir- ginia to Maine. Atmospheric pressure was as low as 2:8.94 inches at Nantucket, Mass., at 8 A. M. of the 17th. At Boston 2.66 inches of rain fell within 24 hours and a 60-mile northeaster tied up shipping for a day or two. The Boston newspapers characterized it as "the wildest and most spectacular storm in 50 years." By the morning of the storm had passed north-northeastward to New Foundland. Other noteworthy storms were, (1) one that originated on in and took an irregular east-northeast course, passing to Iowa by 8 A. M. of , and to southeastern Quebec by 8 A. M. of the 26th; (2) one that moved from northern Texas to western New York during the period May 1-4, then curved to the north and northwest (a very un- usual course) and disappeared from view in the Hudson Bay region by May 6. These storms were attended by widespread precipitation, but no severe winds. The remainder of May was free from general disturbances of un- usual severity; but disastrous local storms occurred, for example, a snow storm in Illinois on May 2 and tornadoes in Maine on May 15. The Illinois snow storm was almost unprecedented in severity for so late in the spring. Snow was as deep as 5 inches on the ground in some places in a belt about 50 miles wide extending from St. Louis northeastward to Indiana. Fruit trees were broken down by the weight of the moist, clinging snow, and telephone poles were broken down by the accumula- tion of snow on the wires.

Unauthenticated | Downloaded 10/05/21 10:31 PM UTC From the National Weekly Weather and Crop Bulletin of the U. S. Weather Bureau it is learned that April was abnormally cold in the more western States and warmer than normal in practically all of the eastern half of the country. In the Plains States about normal warmth prevailed. While April, as a whole, was warm in the East, some low temperatures occurred in northern districts, with local reports of pre- vious minima for the month broken in the upper Lake Region. On the other hand, some hot days occurred along the Gulf coast and in the Middle Atlantic districts, with some stations reporting maxima as high or higher than ever before recorded in April. May, in most of the principal agricultural States, was abnormally cool, while more than normal warmth prevailed west of the Rocky Mountains. But over a wide belt extending from northern Texas and northwestern Louisiana northeastward over the lower Missouri, central Mississippi, and Ohio valleys, the month was decidedly cool. The month closed with a hot spell in the Northeast, Boston experiencing such heat the last three days of May that a number of prostrations resulted. April precipitation, as compared with the normal, varied greatly in different sections; but the main feature was the excessive amounts in the northeast, the lower Lake region, and in parts of the lower Missouri and middle Mississippi valleys, and in some Rocky Mountain sections. May precipitation was mostly above normal east of the Rocky Moun- tains, except light in some central-northern States, and was scant gen- erally west of the Rocky Mountains. The first three weeks of June were characterized by the usual early summer quieting down of weather movements and contrasts. No big general storm occurred. The month opened with high temperatures in the eastern half of the country. A spell of cool weather quickly fol- lowed, bringing temperatures to near freezing on the morning of June 5 in the upper Lake Region and northern Alleghaney Mountain sections. The third week of June was marked by a heat wave, which affected all sections east of the Rocky Mountains, but especially the northeastern .quarter of the country. Rainfall during the first three weeks of June was generally ample in the United States and in some middle western sections it was excessive, especially in Texas, Oklahoma, Kansas, and in parts of Nebraska, Iowa, and South Dakota, during the first week.—R. N.

UNUSUAL PRESSURE EXTREMES IN MAY Records for both extremes of atmospheric pressure at Plainfield, New Jersey, for May were established this month when the barograph record- ed a minimum of 29.02 on the 3rd and a maximum of .30.55 on the 11th. The previous records were 29.15 and 30.52, 30.53 having been recorded on May 10th the previous day. The A. M. weather map of May 2nd showed that a Southwest disturb-

Unauthenticated | Downloaded 10/05/21 10:31 PM UTC ance had centered to 29.20 at Evansville and progressed by the 3rd to Montreal 28.86. The A. M. map of May 10th showed a high pressure which had oc- cupied the north-central states to have developed eastward to 30.58 at Ithaca and on the 11th to 30.58 at Atlantic City and Richmond.—S. K. Pearson, Cooperative Observer.

HIGH WATER IN THE GREAT LAKES; THE CAUSE Recent newspaper articles concerning the high levels of water in the Great Lakes were rather sensational. It is interesting, however, to con- sider the causes of the considerable fluctuations that occur from time to time in Great Lakes waters. A long period of low water prior to the jautumn of 1926 caused considerable uneasiness in Lake cities whose in- terests were seriously involved. In 1929 the situation is reversed. The very high water in April, 1929, at Chicago, Milwaukee, and other places, was caused, in the main, by strong N., N-NE., and NE. winds that prevailed from the evening of until during the day of . These winds, driving down Lake Michigan, piled up the water on the lee shores, as such w^inds have done many times before. But the visitation of these winds came at a time when the Lake levels were al- ready everywhere high, due to a long period of more than normal pre- cipitation. This combination of circumstances caused the unusual con- ditions of high water. There has been a steady rise of water in the Lakes from early in 1926 to the present time. The facts are given in data published in the Monthly Weather Reviewy Washington, from month to month. It is seen that after an almost normal precipitation in the Great Lakes drain- age basin in August, 1926, the tendency of precipitation has been pretty constantly upward. The total accumulated excess in precipitation over the Lake Region drainage area from January, 1926, to April, 1929, in- clusive, was 4.5 inches. The water rose in the Lakes at varying rates, but always tending upward, from early in 1926, to April, 1929, showing a total gain of 2.99 feet from April, 1926, to April, 1929, varying from 2.36 feet in Lake Ontario to 3.57 feet in Lakes Michigan and Huron. The precipitation excess from January, 1926, to April, 19219, in the drainage area of the Upper Lakes was 3.9 inches, and the total rise in Lakes Michigan and Huron between the same dates was 4.02 feet. The dominating influence for changes in the levels of the Lakes is precipitation, and while the Lakes are almost immediately responsive to any considerable excess of precipitation, the effect of such precipita- tion is prolonged for some little time after the precipitation falls below the normal. The newspaper reports state that "authorities agreed that the Lake levels rise and fall in cycles of about a decade." This could hardly be true unless precipitation runs in similar cycles, and the precipitation records do not exhibit anything like well defined cycles.

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