Westerlies blow off the heat in Northwest India

Original from: http://www.thehindubusinessline.com/2009/05/04/stories/2009050450420500.htm

Cooler winds from a passing western disturbance helped rein in the runaway mercury in Northwest India but no such relief was there for the asking in Central East-Central India during the past 24 hours ending Sunday morning.

But dry and hot westerlies blowing into the peninsula continued to curve around the peninsular tip to head north and even cross the east coast to sustain the wind discontinuity/trough along the coastal interior.

MOISTURE CARRY

Moisture carried by these winds is being dumped as isolated showers along this formation, especially over soastal Andhra Pradesh and south interior Karnataka.

Some of the activity spread to the immediate north and northeast, with parts of West Bengal, Sikkim, Orissa and the north eastern States too witnessing some weather.

thunder squall forecast

Isolated thunder squall has been forecast to continue over these very areas for two days more. Similarly, the Regional Met Centre, Chennai, expected thundershowers to continue over interior Tamil Nadu, Kerala, Rayalaseema and south interior Karnataka.

SCORCHED EARTH

But the pre-monsoon sun continued to scorch the earth in central and east-central India.

The highest maximum temperature of 46.6 deg Celsius was recorded at Nagpur, but Darsi in Andhra Pradesh clocked 47 deg Celsius as per hourly automatic weather station data.

India Meteorological Department (IMD) said in its update that heat wave conditions had abated from Rajasthan, Haryana, Delhi, Uttar Pradesh and west Madhya Pradesh.

But they continued to hold strong over parts of Vidarbha, interior Orissa and isolated pockets of east Madhya Pradesh, Jharkhand, Himachal Pradesh, Punjab and Chandigarh.

MAY ABATE

The eastward movement of the western disturbance is expected to help in the abatement of the heat wave conditions over these areas as well from Monday, the IMD said in its outlook.

The prevailing western disturbance would trigger scattered rain or thundershowers over the western Himalayan region during the next three days.

Isolated dust storm or thundershowers accompanied with squall have been forecast over the plains of north west India across Punjab, Haryana, Chandigarh, Delhi, Rajasthan and Uttar Pradesh. This is expected to bring down the maximum temperature by a further 1 to 2 deg Celsius.

Rain or thundershower has been forecast over Jammu and Kashmir, Himachal Pradesh and Uttarkhand. Thunderstorms with squalls are likely at isolated places over Uttar Pradesh, Punjab, Rajasthan, Haryana, Chandigarh and Delhi.

MONSOON BUILD-UP

Meanwhile, the US National Centres for Environmental Predictions (NCEP) continued to signal initially hesitant coverage of the Bay of Bengal by what appears to be the seasonal (southwest monsoon) rains during the week ending May 10.

But forecasts for the week that follows (May 11 to 19) show rains unravelling over Kerala spearheaded by a low-pressure area over the south-east Arabian Sea.

This is also the time when an eastward bound and pan-global Madden Julian Oscillation (MJO) wave is predicted to sit over the Southwest Arabian Sea and the adjoining equatorial Indian Ocean.

Periodical MJO waves with alternating wet and dry phases have been known to sit over monsoon onsets and intra-seasonal excess rain spells in the wet phase and the `break-monsoon' in the dry phase.

Meteorological experts swear by an early monsoon onset for India this time around - their only matter of interest being how early the onset could actually turn out to be.