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Date with drizzle turns dud
- Odisha system fades, Delhi disturbance to cut out Nor’wester

Calcutta was left high and dry on Wednesday as its predicted date with a thundershower fizzled out and the Celsius shot up to 37.8 degrees.

The rain forecast was based on a cyclonic circulation over Odisha that was drawing moisture from the Bay of Bengal on Tuesday. The system dissipated before it could deliver.

The weather office said there was no possibility of a squall for at least the next two days. All that the city can hope for now is the “consolation prize” of light showers on Thursday and Friday brought by passing clouds from a condition developing over Assam and Bangladesh.

Light rain is unlikely to offer any reprieve from the hot and dry weather.

The maximum temperature in the city rose to 37.8 degrees Celsius on Wednesday, three notches above normal from Tuesday’s 36.6.

The air in the city, which was already dry, became drier as the minimum relative humidity dropped from 27 to 17 per cent. Even in the peak of winter in January, the air didn’t get this dry.

“Calcutta is going through a hot and dry spell since Saturday and the only hope was the cyclonic circulation over Odisha to bring some relief. Since the circulation has dissipated, the supply of moisture from the Bay would stop for the time being or until a new system develops. There will be no rain accompanied by squall as predicted on Tuesday,” a weather expert said.

The sky promised to deceive last Tuesday afternoon as it suddenly turned partially cloudy and a few fat droplets fell at scattered places for less than 60 seconds. Residents near Mani Square on the EM Bypass got a taste of the nature’s freak show around 12.30pm while shoppers at Esplanade found some large drops of water falling on their head around 5pm.

The city and its adjoining areas get Nor’westers around this time of the year from the Chhotanagpur Plateau — spread over Jharkhand and parts of Odisha, Bihar, Chhattisgarh and western Bengal.

Weather experts said the plateau gets heated up in the summer sun very fast because of its altitude and the hot surface air draws moisture from Gangetic Bengal. “The heat and moisture act in tandem to produce a Nor’wester. At the moment, the supply of moisture from Gangetic Bengal is at its lowest,” said a senior official of the India Meteorological Department in Calcutta.

Chances of a Nor’wester were dim over the weekend because of a Western Disturbance that could bring rain to Delhi but provide no relief to Calcutta.

Cool winds from the Delhi region would reduce the heat over the Chhotanagpur Plateau by Friday and Saturday and kill all hopes of a Nor’wester.

“This desert-type bone dry weather is unbearable. The skin singes in a couple of minutes in the sun,” said a mother escorting her son back from school.

The light rain forecast for Thursday is a silver lining she and fellow Calcuttans can look forward to.

“The circulation lost its height from 1.5km on Tuesday to 0.9 km the day after, showing how fast it is fading. The one that has formed over Assam is a trough of low pressure extending up to Bangladesh,” a senior Met official said.

The stronger the system, the better the chances of rainfall in Bengal.

The weather office said a wind system, a high-pressure belt over the Bay, was pushing moisture inland but more towards Bangladesh than Bengal.