Tuesday, March 16, 2010

‘Rogue' trough to shield wheat from heat

A ‘law-breaking' but weather-making trough is forecast to descend on east India and extend into east-central and north peninsular India over the next few days.

The India Meteorological Department (IMD) has joined the outlook for a passing western disturbance to trigger the formation of the trough extending from Bihar to Rayalaseema with an embedded cyclonic circulation.


Model forecasts still suggest that the core wheat belt over northwest India (Punjab, Haryana and west Uttar Pradesh) would be shielded from the heat by the western disturbance and the strong north-westerly-to-westerly flows.

Formation of a cyclonic circulation over east India from passing westerlies is not a regular occurrence during this time of the year – these are known to materialise over Rajasthan-Punjab-Haryana region.

But an advancing high-pressure region from West Asia, with pretensions of being a ‘blocking high' (which literally blocks inbound westerlies on their path), is causing the western disturbance to take a detour and execute a ‘reverse kick' from over the eastern Himalayas.

The net result is that the cyclonic circulation, with an enveloping trough, will get lobbed into East India (over Orissa and adjoining Chhattisgarh). IMD says this is expected to happen over the next two days, which is in agreement with the outlook of the European Centre for Medium-Range Weather Forecasting (ECMWF).

The cyclonic circulation-trough combo will in turn trigger moisture incursion from the Bay of Bengal, prompting the formation of thunderstorms and squalls. Wind confluence of westerly and easterly flows is expected to add to the unstable weather conditions over north peninsular India.

The IMD has warned of isolated thundersquall over Orissa, West Bengal and north Andhra Pradesh during the next two days. Strong northwesterly to westerly winds are prevailing over Indo-Gangetic plains in the lower levels.

Meanwhile, southern Pakistan and adjoining northwest India have been brought under a spell of sustained heating, which is expected to morph into an intense heating phase during the latter of the week.

The intense heating phase would see parts of Gujarat, west Madhya Pradesh, southern Gujarat and adjoining west Maharashtra being variously brought under its footprint.

The core of the heat is shown by ECMWF as sitting smack over Madhya Pradesh beyond March 20, before extending into Vidarbha, Chhattisgarh, Orissa and north coastal Andhra Pradesh.

This found ready acceptance with the IMD, which says that the maximum temperatures are expected to rise by 2-3 deg Celsius over parts of northwest and central India during next three days.

An IMD update on Monday said that the highest overnight maximum temperature of 40.7°C was recorded at Barmer in Rajasthan. Maximum temperatures of above 40 deg Celsius have been recorded also at isolated pockets over Rajasthan, Gujarat, Vidarbha and Telengana during this period.

An IMD outlook said that isolated light rain to thundershowers may occur over parts of Maharashtra, Karnataka and Andhra Pradesh during the next 24 hours.

Isolated to scattered rain or thundershowers are likely to occur over parts of the north-eastern States during the next three days. Isolated to scattered rain or thundershowers are likely over parts of east India during the next two days.

Satellite imagery showed the presence of low to medium clouds (partly clouded conditions) over parts of western Himalayan regions, Punjab, Maharashtra, Orissa, peninsular and northeast India, the Bay of Bengal and the Arabian Sea.
Isolated thundersquall may occur over Orissa, West Bengal and north Andhra Pradesh on 17th and 18th
cyclonic circulation likely over Orissa and adjoining Chhattisgarh in lower levels on 16th with moisture incursion from Bay of Bengal.
Super HOT on 15-Mar-10,,, Barmer-40.6, Chandrapur-40.5, Bramhapuri-40.3 and Tirupathi-40.4
Chennai - Yesterday touched a super max temperature of 36.2°C (11:41am)... Today also temp. is on rise now (9:21am)
Chennai - a very warm morning.. 27.8°C (6:18am)
http://yfrog.com/0ckpsg ... On 14-Mar, showers over south-west Bengal and area bordering Orissa.
On 14-Mar, Isolated light rain occurred over Telangana .. http://yfrog.com/0ckpsg
On 14-Mar, Nizamabad and Adilabad recorded the highest maximum temperature of 40 degree Celsius in south India
For the past 24hrs, Unusual looking band of cloud movement over central peninsula from west to east .. http://ping.fm/v2pIY