Lucknow, Sept. 15 -- Eastern Uttar Pradesh is likely to receive moderate to heavy rainfall this week, as the southwest monsoon begins its retreat from western Rajasthan, according to the India meteorological department (IMD). The monsoon has started withdrawing from western Rajasthan three days ahead of its normal date of September 17. As a result, a low-pressure area formed in the west-central Bay of Bengal has moved towards central India. The weakening of the monsoon trough allowed moisture from the Bay of Bengal to reach eastern and central parts of Uttar Pradesh, reviving rainfall activity in these regions. There is a possibility of thundershowers and moderate to heavy rainfall in the Terai, Purvanchal, and Madhyanchal districts in the coming week. In this pattern, Lucknow is also expected to receive moderate to heavy rainfall between September 17 and 18, said Atul Kumar Singh, senior scientist at the Lucknow Meteorological Centre. According to the IMD, scattered to moderate rainfall is expected in Lucknow between September 15 and 18. Western districts of UP, particularly those bordering Uttarakhand, may also experience light to moderate rainfall, with isolated heavy showers. The forecast for Lucknow suggests a partly cloudy to generally cloudy sky, with one or two spells of rain or thundershowers during the evening or night. The maximum and minimum temperatures are expected to hover around 33degC and 27degC, respectively. The state forecast indicates that rain and thundershowers are very likely at isolated places over western UP, and at a few places over eastern UP. The IMD has also issued a warning for thunderstorms accompanied by lightning at isolated places in eastern UP, along with a possibility of heavy rain in some areas....