LUCKNOW, June 16 -- As the state capital experienced a brief spell of sporadic pre-monsoon showers in the early hours of Sunday, the Lucknow meteorological office is hopeful that the southwest monsoon may enter the eastern parts of the state anytime between Tuesday and Friday. Even the normal date for monsoon onset in Uttar Pradesh, which is through Gorakhpur, is June 18, weathermen said. The sporadic pre-monsoon rainfall activities are signs that conditions are favourable for the southwest monsoon's onset between June 17 and 20. There is a possibility of a gradual increase in rainfall activities, which will be accompanied by thunderstorms and lightning, from Wednesday. "Temperatures may plummet by 3 to 5 degrees over the next three to four days, resulting in a significant decrease in the heat index. A complete relief from the humid conditions is expected after June 16," said Atul Kumar Singh, a senior scientist at the Lucknow Met. "The northern limit of monsoon is currently passing through major places, such as Mumbai, Ahilyanagar, Adilabad, Puri and Balurghat; and favourable conditions are developing for the advancement of monsoon into some parts of Gujarat, Vidarbha, Chhattisgarh, Odisha and eastern Uttar Pradesh in the coming 3 to 4 days," he said. The widespread fall in temperature is due to pre-monsoon rains over the last 24 hours. This has happened due to the upper atmospheric cyclonic circulation forming in the lower troposphere over eastern Uttar Pradesh, and an active western disturbance in the middle and upper tropospheric westerly winds. Heatwave conditions in the state have become limited to south-eastern Uttar Pradesh (Varanasi and Ghazipur)....