KOCHI: The prevailing conditions are not favourable for the India Meteorological Department (IMD).
Already facing brickbats for failing to issue a timely alert for the hailstorm that left a trail of devastation in New Delhi, the weather agency is now being accused of manipulating parameters to prove its forecast regarding the onset of monsoon in Kerala right.
Private weather forecaster Skymet has levelled the charges against IMD for announcing the onset of monsoon in Kerala on May 29. Lending credence to the allegation is the fact that the season has hit a lean patch in south and central Kerala over the past few days. Skymet alleged that IMD declared monsoon by relying on data of just one day (of May 29), instead of two as is the norm.
“Declaring monsoon based on single day observations amounts to gross violation of standards, never attempted in the past. Any reputed scientific body can ill afford to bend rules and criteria, just to prove the forecast right. Such a step, if taken knowingly, becomes highly objectionable and if otherwise, amounts to illusion of knowledge,” Skymet wrote in its website.
Analysis of rainfall, strength of westerly winds and outgoing longwave radiation (OLR) are used by IMD uses to confirm monsoon. For making the announcement, 60%, or eight, of IMD’s 14 weather stations should record 2.5mm rainfall for two consecutive days after May 10, westerly winds should record a depth of 600 hPa (hecto Pascals – a unit of sea level pressure) and the OLR value should be below 200 watts per sqm. Though the wind and OLR touched the required value on May 29, the 14 stations did not receive the required rain either on May 28 or May 30. However, IMD has refuted Skymet’s allegations.
State authority calls for accurate rain intensity data
IMD scientist V K Mini told TNIE that six weather stations in coastal Kerala had received the required rainfall on May 28. “We also collected rainfall data for May 28 from the surrounding areas of four other weather stations – Kannur airport, Kumarakom, Koyilandy in Kozhikode and Thiruvananthapuram – to confirm the onset, which is not a violation. The next day, on May 29, all these stations received good rain,” Mini said, adding, “Monsoon will gain strength soon.”
KSDMA member secretary Sekhar Kuriakose said they had highlighted the inaccuracy in IMD’s 2018 weather forecast. “The agency also failed to issue a timely alert for the recent hailstorm in New Delhi. We have no option but to accept information provided by IMD and Skymet, who are the top agencies in the sector. The date of onset is irrelevant for us. We want accurate forecast on the intensity of rain,” he said.
To announce onset
60%, or 8 of IMD’s 14 weather stations in Kerala should record 2.5mm rain for two consecutive days after May 10
Westerly winds should record a depth of 600 hPa. Outgoing longwave radiation value should be below 200 watts per sqm
What happened in Delhi?
IMD had failed to issue a timely alert on the hailstorm that hit the national capital on Monday. It had first forecast thundery development on the day. It was upgraded to a yellow alert at 3pm and orange alert at 4.30pm. The hailstorm left a trail of destruction in New Delhi.