LUCKNOW, Aug. 11 -- There will be a significant increase in regional monsoon rainfall again from August 13 from Purvanchal region with a possibility of heavy rain in isolated areas, weatherman said on Monday. Due to the influence of a low-pressure area, the monsoon trough has partially shifted south of its normal position. As a result, western Uttar Pradesh received heavy rainfall over the past 24 hours due to a cyclonic circulation in the lower troposphere over southeast Himachal Pradesh and adjoining southern areas. Muzaffarnagar recorded 138 mm of rain between 8:30am and 5:30pm on Monday. In the 24 hours to 8:30am, Mahroni (Lalitpur) received 111 mm, Lalitpur 90 mm, Kalanaur (Saharanpur) 85.4 mm and Madawara (Lalitpur) 75 mm. Regional rainfall is expected to decrease significantly on August 11 and 12 before picking up again from August 13. Since June 1, Uttar Pradesh has recorded 341.1 mm of rainfall against the long-period average of 430.9 mm, resulting in a 21% deficit. Rainfall distribution, however, remains uneven, with western UP faring better than the east. East UP has received 331.6 mm against the normal 457.6 mm, a 28% deficit, while west UP recorded 354.8 mm against the normal 393.6 mm, a 10% deficit. Lucknow has recorded a 29% rainfall deficit, receiving 269 mm against the normal 380 mm, the weatherman said....