Saturday, January 02, 2010

It seems today, the predicted LOW over south-east Bay is taking shape .. http://ping.fm/8ulaV
After 2 days of lull in cloud formation over SOuth & south-East Bay, today it was heavy .. http://ping.fm/FTzNJ
Cyclonic circulation persists over south-East Bay along 5th parallel .. http://ping.fm/w3Q62
Four trains collided Saturday in two separate accidents caused by dense winter fog .. http://is.gd/5Jxx3
Heavy fog in North India hits air, rail traffic .. http://is.gd/5JkpW
Cold wave intensify in North India .. http://is.gd/5JknR
Northwest India, can look forward to some respite as cold northwesterlies might be replaced by the warmer southwesterlies from Sunday.
NCEP: wet spell for south-East India coast is presumably under the influence of westerly flows, the NCEP indicated
NCEP: Coastal Tamil Nadu and the rest of the east coast stretching up to the West Bengal coast are expected to come under a wet spell.
ECMW) said that the ‘low' forecast earlier over south-west Bay of Bengal may fail to organise to that level
Amritsar recorded the lowest temperature of -6 deg Celsius on 30-Dec-09
Cold wave conditions continuing to hold over isolated pockets of Punjab, Haryana and West Uttar Pradesh

Temporary relief from cold wave likely for north-west

India Meteorological Department (IMD) has warned that cold wave conditions would prevail over isolated pockets of Punjab and Haryana for another 24 hours (Saturday).

Cold day conditions are expected to continue over Uttar Pradesh during the next two days as well, it said in its bulletin issued on Friday.

There have been warnings of fog or dense fog in east Uttar Pradesh, Bihar, sub-Himalayan West Bengal and Sikkim during this period.

SOME RESPITE

Northwest India, however, can look forward to some respite as cold northwesterlies might be replaced by the warmer southwesterlies associated with a feeble western disturbance strolling into the region from Sunday.

A feeble western disturbance is classified as such given its lesser sweep and magnitude, which robs it of the potential to carry moisture required to generate secondary cyclonic circulations.

These circulations are known to cause light to moderate showers if supplemented by residual moisture from the closest seas (the north Arabian Sea, which the western disturbance passes over).

These showers propagated from the northwest and adjoining east are in line with the movement of the causative circulation and the parent western disturbance.

The token presence of moisture, which does not fall as rain, is enough to cause fog or dense fog over the plains especially on days when low-level winds are conspicuous in their absence.

This is exactly the scenario that the IMD is seeking to depict as emerging over northwest India and east India – cold over the next 24 hours over northwest before getting slightly warmer.

DENSE FOG

Dense fog has already been reported from most parts of Uttar Pradesh, Bihar, Sub-Himalayan West Bengal and Sikkim.

Foggy to densely fog conditions are expected to hang over Uttar Pradesh and Bihar for two more days as it would take as many days for the western disturbance to transit these regions on its eastward journey.

But the movement away of the westerly system would only clear the way for colder northwesterlies to fill the plains of the north-west and bring down the mercury appreciably to trigger cold wave conditions yet again from next Tuesday.

On Friday, minimum temperatures were below normal by 2 to 4 deg Celsius over parts of Punjab, Haryana, Madhya Pradesh and Chhattisgarh.

Cold wave conditions continue to prevail over isolated pockets of Punjab and Haryana. The lowest minimum temperature of -0.6 deg Celsius was recorded at Adampur in Punjab.


Maximum temperatures too were below normal over Haryana, Uttar Pradesh, Madhya Pradesh, Bihar, Jharkhand, the North-Eastern States, Punjab, north Maharashtra, Chhattisgarh and West Bengal.

In the south, isolated rainfall may occur over extreme south peninsular India during next three days, the IMD said in its forecast. A trough lay extended from the Lakshadweep area into the mainland but convection had been reduced with the required sea-surface temperature regime getting confined to a narrow stretch.

Isolated rain or snow has been forecast over the western Himalayas from Sunday onwards in association with the arrival of the western disturbance.

No respite for North-West from biting cold

There has been no respite from the biting cold in parts of the north-west India during the last 24 hours even as forecasts indicated mercury taking a tumble over east India with the dawn of the New Year.

The cold northwesterlies are expected to keep blowing into the plains of the north-west during this period followed by the entry of another feeble western disturbance.

NO CHANGE

India Meteorological Department (IMD) sees the cold wave conditions continuing to hold over isolated pockets of Punjab, Haryana and West Uttar Pradesh ruling out any turn for the better from the passage of the westerly system.

The IMD did not see any large change in the minimum temperatures over the plains of north-west India with clear skies expected to rule the roost. But the prospect of fog/shallow fog has been indicated due to the interaction of moisture and the cold westerlies.

On a cool and calm night, the air near the ground cools rapidly and the cooling gradually spreads upward. Since cool air is denser than warm air, gravity will pull the coolest air down.

In a hilly area, the cool air settles into the valleys and, therefore, fog forms in the valleys while hilltops may be clear.

Minimum temperatures were below normal by 2 to 4 deg Celsius over Jammu and Kashmir, parts of Punjab, Haryana and west Uttar Pradesh through Wednesday.

But they were above normal over parts of east and south India thanks to moisture of stray moisture and associated cloudiness.

COLD WAVE

Cold wave conditions continued to prevail over isolated pockets of Punjab, Haryana and west Uttar Pradesh. Amritsar recorded the lowest temperature of -6 deg Celsius on Wednesday.

The Chennai Met Centre said in an update that isolated rainfall was reported from a few places over Lakshadweep, Telangana and south interior Karnataka.

Forecast for the next two days said that rain or thundershowers are likely at a few places over Lakshadweep.

Isolated rain or thundershowers have been forecast also over north coastal Andhra Pradesh, Telangana, Tamil Nadu, Puducherry, Kerala and Karnataka.

On Thursday, a trough from Lakshadweep was traced to until south interior Karnataka. Towards the north, a trough/wind discontinuity ran down in a south-southwest direction from Uttar Pradesh to Goa.

IMD forecast until Tuesday (January 5) suggested the possibility of isolated rainfall over extreme south peninsular India.

CYCLONIC WHIRL

The European Centre for Medium-Range Weather Forecasting (ECMWF) said that the ‘low' forecast earlier over south-west Bay of Bengal may fail to organise to that level.

Instead, it saw a cyclonic circulation patrolling the waters around south-east Tamil Nadu coast and adjoining Sri Lanka around January 8 and dissipating sooner than expected.

But, the US National Centres for Environmental Prediction (NCEP) saw the weather system tracking to the north along the east coast aiming to reach the Orissa coast during January 7 to 15.

Coastal Tamil Nadu and the rest of the east coast stretching up to the West Bengal coast and beyond are expected to come under a wet spell presumably under the influence of westerly flows, the NCEP indicated.
Chennai - now 11:49am, we have good low cloud formation and will be cloudy till 2:30pm and nothing threatening.
Chennai - After a 22 deg start to day, now 11:48am its getting warm and humidity is on high side 65%.
Still GFS models predict a LOW pressure system hitting Central & south TN coast from 6-Jan to 10-Jan-10 . http://yfrog.com/4i5fwp
http://ping.fm/ouP1d .. Due to sudden cooling of sea waters in 2 days over south Bay the cloud formation has shifted below 5th Parallel
http://ping.fm/PYXm7 .. At present heavy cloud formations over south-South Bay is below 5th Parallel.
Another clear looking India at 10:30am IST .. http://ping.fm/HzH8K