At least 81,630 pilgrims have performed this year's Amarnath Yatra since it began on July 1, while another batch of 4,773 pilgrims on Sunday left Jammu for Kashmir Valley, officials said.The yatris left Bhagwati Nagar Yatri Niwas in two escorted convoys."Of these, 2,022 yatris are going to Baltal base camp while 2,751are going to Pahalgam base camp," a police officer said.The 45-day long Amarnath Yatra started this year on July 1 and will conclude on August 15 coinciding with the Shravan Purnima festival.The regional Met Office has forecast generally cloudy weather along the two routes to the cave shrine on Sunday with possibility of rain/thunderstorm in the afternoon.The Met department has installed special weather forecasting equipment along Baltal and Pahalgam routes for accurate forecast.The cave shrine is situated 3,888 metres above the sea-level in Kashmir's Himalayas. It houses an ice stalagmite structure that symbolises mythical powers of Lord Shiva, according to the devotees.The ice stalagmite structure waxes and wanes with the phases of the moon.Local Muslims have historically lent a helping hand to ensure that their Hindu brethren are able to perform the pilgrimage with ease and convenience.Two pilgrims have so far died of natural causes while performing the yatra.