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IMD gets its rain data wrong, then quietly fixes it. Delhi yet to cross its average for August showers
Delhi rain news: IMD had also updated rainfall data for August 5-6 to 18.77mm in the current chart, in comparison to the earlier 56mm.
A brief spell of showers in Delhi on Monday helped push the quantum of rain this August past the long-period average for the month. Or did it?
On Monday, the India Meteorological Department (IMD) said Delhi had received 234.5mm of rain in the first 10 days of August this year, more than the month’s total expected quantum of 233.1mm.
On Tuesday, IMD quietly cut this month’s rain figure to 197.2mm in its bulletin.
Hours later, IMD, in response to a query from HT, said the cumulative August rain numbers it released on Monday were “incorrect” and that the Capital was still about 36mm short of its expected August rain quota.
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“That (the earlier figure) was incorrect. 197.2mm is the correct figure being displayed now,” said an IMD official in the agency’s WhatsApp group for national media.
Another official confirmed the error.
IMD officials declined to pinpoint the cause of the error.
August 6 rain data ‘corrected’
HT compared the weather agency’s monthly online weather chart for Delhi which details the daily rain and maximum-minimum temperatures for the month with an earlier version of the same chart.
It found that the entry for rainfall between 8.30am on August 5 and 8.30am August 6 was updated from 56mm in the earlier version to 18.7mm in the chart currently visible on the site.
The difference – 37.3mm – corresponds to the shortfall in IMD’s rain readings for August this year between its logs on Monday and Tuesday.
An IMD official confirmed the discrepancy.
“Safdarjung’s cumulative rainfall data displayed yesterday was 230.5mmwhich happened due to incorrect rainfall entry of 56 mm instead of 18.7 mm for August 6 in the table...However it was correctly displayed in the Delhi bulletin issued every day in August. This has been corrected and 197.2mm is the correct figure, which is being displayed currently,” said Krishna Mishra, regional meteorological scientist, IMD.
IMD has ‘gone wrong’ before
IMD has often gone wrong with its predictions of rain, Tuesday being a case in point. Monday was an occasion the weather agency was also wrong with its logs.
The agency at 2:30pm on Tuesday issued an orange alert, predicting light or moderate rain for most parts of the city, with heavy showers in some pockets. The IMD categorizes rainfall up to 15.5mm as light, between 15.6mm to 64.4 mm as moderate, between 64.5mm to 115.5mm as heavy, and between 115.6 to 204.4 as very heavy.
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By 5.30pm, Safdarjung was the wettest part of Delhi with 4mm of rain. Delhi Ridge recorded 3.7mm, followed by Mayur Vihar and Pusa at 3mm each. Chhatarpur and Narayana both clocked 2mm of rain, followed by Ayanagar (1.6mm), Lodi Road (1.5mm), and Palam (1.4mm). Najafgarh got 1.5mm, with Jafarpur (1mm) and Jharoda Kalan (1mm) next. Pushp Vihar recorded no rain during the same period.
The IMD has predicted “very light to light rain” on Wednesday and Thursday.
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