For the week ahead of May 20, rain or thundershowers are likely at many places in Kerala, Andaman & Nicobar Islands, north-eastern states and at few places in West Bengal, Sikkim, coastal Karnataka and Lakshadweep. Isolated rain is also likely over Konkan, Goa, central Maharashtra, Andhra Pradesh, interior Karnataka, Orissa, the Bihar plateau and eastern Madhya Pradesh.

The southwest monsoon has already advanced into the south Andaman Sea on May 15. It further advanced into the Andaman & Nicobar Islands, parts of south Bay of Bengal and rest of the Andaman Sea on May 18. During the period March 1-20, the cumulative pre-monsoon rainfall was normal to excess in 27 out of 35 meteorological sub-divisions in the country.

Expertssaid that tests conducted on both the days of the month were fully contained with no release of radioactivity into the atmosphere. The three tests conducted on May 11 were with a fission device with a yield of about 12 kilo tonnes, a thermonuclear device with a yield of about 43 kilo tonnes (kt) and a sub-kilo tonne device. All the three devices were detonated simultaneously and were designed to meet stringent criteria like containment of explosion.

Similarly, on May 13, two more sub-kilo tonne nuclear tests were carried out. These devices were also detonated simultaneously. The yields of the sub-kilo tonne devices were in the range of 0.2 to 0.6 kt. Experts said that with such a low-yield range, the contained tests can hardly have any major impact on the atmosphere.

The prevailing heat wave in Rajasthan is not a fallout of the nuclear tests. The first spell of heat wave occurred around May 4-6 which was much before the nuclear tests. The second spell of heat wave of course started from May 13. But itcannot be attributed to the tests and it was only a matter of coincidence, the experts stated.

The experts further stated that climatologically, May is the hottest month of the year in most parts of north India. The normal day temperatures in Rajasthan during May are usually of the order of 42 degrees celsius (C). Conditions worse than those prevailing have been recorded earlier on many occasions. For instance in 1995, there was a prolonged and intense heat wave over Rajasthan when temperatures reached 50 degrees celsius. In June 4, 1991, the temperature recorded at Jaisalmer was 49.2C and in June 3, 1991 the recorded temperature in Phalodi was 49C. However, the recorded maximum temperature this year is 48.8C on May 20 at Jallore in Rajasthan.

In Delhi, the recorded highest temperature in May is 47.2C on May 29, 1944. In the current year, the maximum temperature in Delhi is 44.6C on May 22. This is also lower than the other recorded maximum temperatures in Delhi. In May 17, 1995, the temperature was 45Cin May 31, 1994, it was 46C, in May 25, 1993, it was 45C and on May 30, 1996 it was 44C. Only in May 19, 1997, the maximum temperature recorded in Delhi was 42C due to the cooling effects of pre-monsoon showers. Pre-monsoon rains are, however, expected in Delhi in a day or two this year due to maximum heating.