The Department of Hyro-Met Services (DHMS) reported that the rainfall levels could fall back to normal monsoon levels within the next few days. The heavy incessant rains have been due to a sustained low pressure zone in the southern Himalayan foothills.
In its report to the Prime Minister on Friday, the DHMS predicted a reduced total rainfall from 26 July to 9 August followed by a slight increase from 10 to 14 August. Improved weather is expected in most parts of western, central and eastern Bhutan with partly cloudy and possibility of light rain towards noon and the evening during next 72 hours.
Senior Meteorologist Tayba Buddha Gurung said that the daily rate of precipitation recorded this year are not the highest from previous years. A high of 430mm rain in a day was recorded in previous years compared to a high of 384mm this July but the problem has been the continuous rain fall.
Excessive rainfall saturates soil and reduces its bearing capacity hence increasing the likelihood of soil foundations giving way.
June to September is the monsoon season for the region Bhutan falls in and so the rains could last well into September.
The East Asia Monsoon approaches from the Bay of Bengal and moves over west India to the Arabian Sea but the low pressure system that has continued in the southern foothills has caused convection currents which result in continuously rising air and hence precipitation.
The low pressure system is also responsible for the delayed monsoon in western India which is experiencing a drought.
Low pressure systems are associated with clouds and precipitation as the surrounding air at higher pressure is drawn towards the lower pressure region. This air is lifted up, cooled and results in precipitation. High pressure points on the other hand cause airflow outwards from the center and towards the surface reducing moisture content and are associated with good weather.