Mussoorie, Sept. 13 -- The India Meteorological Department (IMD) has forecast heavy to very heavy rainfall across the state over the next four days, issuing an orange alert for Saturday and a yellow alert for the following three days, a release from the climate authority said on Friday. According to the IMD's centre at Dehradun, heavy rainfall accompanied by thunderstorms and lightning is expected at isolated parts of Dehradun, Tehri, Pauri, Almora, Nainital and Bageshwar on Saturday. Rudraprayag, Chamoli, Champawat and Pithoragarh have been placed under a yellow alert for the day. From Sunday to Tuesday, a yellow alert will remain in effect across the state, said the statement. On Sunday, heavy rain is likely in isolated areas of Dehradun, Bageshwar and Nainital. On Monday, several districts are expected to see heavy rainfall and thunderstorms with intense spells at isolated places. By Tuesday, intense to very intense rain spells are likely in Dehradun, Bageshwar, Nainital and Pithoragarh, added the statement. Meanwhile showers lashed parts of the state on Friday. In Dehradun district, Song received the highest rainfall at 35 mm between 8.30 am and 3 pm. Nainital recorded 21.5 mm, Chorgalia 19 mm, Mukteshwar 8.5 mm and Haldwani 6 mm. Bhimtal recorded 6 mm. In Pithoragarh district, Ganai Gangoli received 15 mm of rain, followed by Berinag with 10 mm, and Sama and Didihat with 9 mm each. Champawat town recorded 9.5 mm, while Pati got 9 mm and Tanakpur, Devidhura and Lohaghat 6 mm each. Almora's Chaubatia, Ranikhet and Sitlakhet each saw 9.5 mm of rain, Dwarhat 7.5 mm, and Masi 6.5 mm. Jageshwar and Bhikiyasain received 6 mm and 5 mm, respectively. In Bageshwar district, Bageshwar town recorded 7 mm and Kanda 5 mm. Uttarakhand Technical University in Dehradun logged 5.5 mm. "Orange alert has been issued for Saturday while yellow alert has been sounded for the next three days with forecast of heavy rains in several districts. This is primarily due to changes in monsoon activity," said CS Tomar, director of the IMD Dehradun centre. The latest alert comes against the backdrop of an active monsoon season in the state. Uttarakhand has received 1,306 mm of rainfall from June 1 to September 12, about 21% above the long-term normal of 1,081.7 mm. As per IMD data, last month alone, the state recorded 574 mm of rain-49% above normal. Bageshwar reported the highest excess at 312%, followed by Chamoli (111%), Haridwar (133%), Tehri (83%), Almora (63%), Uttarkashi (49%) and Dehradun (47%). So far this season since June 1, Bageshwar has logged 2,452.5 mm of rain, 238% above its normal of 726.2 mm. Chamoli received 1,284.1 mm, 91% above average, while Tehri recorded 1,318.2 mm, 49% above normal. Haridwar received 1,354.9 mm (46% excess), Almora 937.8 mm (29% excess), Dehradun 1,703.2 mm (26% excess) and US Nagar 1,288.3 mm (24% excess)....