Wednesday, February 16, 2011

Forecasts differ on spread of easterly rains


International model forecasts continue to favour scattered rain along a northeast-southwest gradient along the east coast and immediate interior on Sunday and Monday. Moisture incursion has been indicated both from equatorial Indian Ocean (south of the peninsula) as well as from the coastal waters of the Bay of Bengal to fuel the precipitation.
Contrary to forecasts, there is no formation of any well-defined circulation in the Bay waters; it would just amount to a ‘perturbation’ of available moisture under the influence of easterly winds.

A feeble western disturbance is forecast to affect the western Himalayan region by the weekend but forecasts show the system getting some accentuation presumably from residual moisture from a prevailing ‘active’ western disturbance fanned up further by warmer easterly winds from the Bay.
This is what could likely trigger the rains along the coast and immediate interior, but which India Meteorological Department (IMD) seeks to confine to Orissa, Chhattisgarh and Andhra Pradesh.

An IMD outlook on Wednesday afternoon said that the active western disturbance would continue to affect western Himalayan region and the Indo-Gangetic plains on Thursday and the Northeastern States during the next three days.
An IMD heavy weather alert said that isolated heavy rainfall would occur over Uttar Pradesh, sub-Himalayan West Bengal and Sikkim on Thursday.
Isolated heavy to very heavy rainfall would occur over Arunachal Pradesh and Assam during on Thursday and Friday.
Isolated thunder squalls and hailstorms have been forecast over Uttar Pradesh, Bihar, sub-Himalayan West Bengal and Sikkim on Thursday and over Assam and Arunachal Pradesh on Thursday and Friday.
Meanwhile, during the last 24 hours ending Thursday morning said that widespread rain or snow occurred over Himachal Pradesh and Uttarakhand and scattered over Jammu and Kashmir.
Fairly widespread rain or thundershowers has also occurred over Haryana, Delhi, Uttar Pradesh and east Rajasthan.
It was scattered over Punjab, Assam, Arunachal Pradesh and isolated over Bihar and north Madhya Pradesh.

Minimum temperatures fell by 1 to 3 deg Celsius over Punjab, Haryana,Rajasthan, west Uttar Pradesh and north Madhya Pradesh. The lowest minimum temperature of 9.0°C was recorded at Erinpura Road (Rajasthan) in the plains of the country.

Satellite pictures showed convective clouds over parts of western Himalayan region and Uttar Pradesh.
Minimum temperatures are expected to fall by 2 to 4 deg Celsius over northwest and adjoining central India during the next three days, the IMD outlook said.

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