Monsoon to arrive by the first week of June

The monsoon season in Bhutan, which will begin within the first week of June this year, is expected to have normal rain, forecasts the National Center for Hydrology and Meteorology (NCHM).

Monsoon usually starts on June 5 and ends towards the end of September in the country. The southwest monsoon starts from Kerala in India. An average rainfall of 1,373mm is predicted this monsoon, which is considered normal.

The forecast was shared during the fourth annual session of national climate outlook forum (NCOF-4) in Thimphu on May 28.

NCHM’s deputy executive engineer, Tshencho Dorji, said that rainfall forecast is made with the past 30 years of rainfall data in other countries.

“Bhutan only has data from 1996 and the prediction is made with average rainfall from 1996 until last year,” he said.

He said the forecast they made for 2017 and the observations presented today tally.

A press release from NCHM stated that the forecast was prepared using a statistical model with inputs such as the global sea surface temperature and observed rainfall data of Bhutan. The outputs from the 12th South Asian Seasonal Climate Outlook Forum (SASCOF-12) for monsoon season 2018 and the seasonal probabilistic multi-model ensemble of World Meteorological Organisation  (WMO) Lead Centre for Long Range Forecast were used, it states.

NCHM also studied the 2018 monsoon with the interactive tool for analysis of climate system (iTacs), which predicts the monsoon for this year to be slightly above the normal rainfall. This was tried for the first time in the country.

NCHM also released the state of climate report for Bhutan 2017 and climate data book 2018.

While the climate data book is released annually, the climate report for Bhutan was published for the first time at the NCOF-4 meeting.

Officials say NCOF is held every year to create a platform for a dialogue between the climate information providers and the users of the services such as the agriculture sector and aviation.

Currently, NCHM provides aviation-met services, weather forecasting, seasonal prediction, and climate projection.

Senior Meteorologist, Tayba Buddha Tamang, said that NCHM is also working for an extended range prediction (ERP), which will provide weather forecast for a week.

He said the weekly forecast for rainfall and temperature would be made available. “ERP weekly forecast of summer monsoon active (rainy) and break (dry) phases are useful information for agricultural planning and water management.”

ERP is currently in pilot phase and is expected to take few months to start the prediction.

The meeting yesterday suggested downscaling the rainfall prediction of 24 hours to an hour, to also produce rainfall intensity data, and to make ERP available for the agriculture department to provide agro advice.

NCOF-4 is part of the global framework for climate services (GFCS), a UN initiative led by the WMO.

Phurpa Lhamo

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