Monday, December 21, 2009

RT @amolmathur: @Ratzzz It drizzled in tuticorin too. I missed chennai's rain by a day.
Satellite shows moderate showers for North Tamilnadu and Chennai ..
RT @sai_prasanna: The rain god seems to have made chennai base camp in india :) Its raining again..
Chennai - Rains started at 10pm after all day lull.
Latest satellite shows very heavy easterlies rain activity over north-east Srilanka and along South-east, south Tip of Tamilnadu.
Lots of activity over south, and south-west Arabian sea is making the present Easterlies rich in moisture and strong over Bay.
Very heavy cloud formation also seen over south-east Arabian sea, almost over Maldives ..
NCMRWF models predict more heavy showers for North Tamilnadu coast till 27-Dec-09 ..
5th parallel may host a low level cyclonic circulation from 26-Dec-09... It'll bring more showers to Srilanka and southern Tip of Tamilnadu
Latest low altitude wind and pressure analysis shows, more Easterlies are on way ..
More showers for Chennai and entire Tamilnadu coast from 22-Dec, morning ..
Very heavy showers over eastern and almost full of Srilanka ..
Chennai - After that morning bursts.. now 1:22pm its cloudy with Low cloud formation from North-East and with stiff wind from North-east.
RT @Ratzzz: @wiredvijay a friend was reaching chennai.. supposed to meet him at 5, rain spoiled it @softykid .. Always follow our tweets.
Easterly wave may be compressed to extreme south ...

Easterly wave may be compressed to extreme south

The northeast monsoon has managed to carry its surplus run so far (nine per cent until December 16) with almost entire peninsula and central India recording excess to normal rain.

However, the extreme northwest (Saurashtra-Kutch, west Rajasthan, Haryana and Punjab) continued to throw up deficits ranging from 72 per cent to 96 per cent, an India Meteorological Department (IMD) update said.

Chhattisgarh, Gangetic West Bengal, coastal Andhra Pradesh and the entire Northeasttern State, too, have totted up deficits though comparably lower (22 per cent to 39 per cent).

Easterly wave

Going forward, an IMD outlook on Sunday said that an easterly wave is likely to affect extreme south peninsular India during the first four days of the week.

International models had forecast this possibility earlier last week, but they have lately concluded that the resultant precipitation would be confined mostly to extreme south peninsular India.

This is so because they see the rain-suppressing anti-cyclone (high-pressure area with sinking air) being pushed anomalously to the south by rampaging dry westerlies.

Some of them still see the prospect of the easterly wave setting up a blow-up of rain over southeast Tamil Nadu, adjoining Gulf of Mannar and north Sri Lanka around Thursday (December 24).

Parts of coastal Tamil Nadu to the immediate north and south Kerala, too, are forecast to be brought under sporadic showers during this phase.

The warmest seas has now retreated to the south of Sri Lanka and to the northwest along the Kerala coast stretching across southwest to the east African coast.

Trough of low

The European Centre for Medium-Range Weather Forecasts (ECMWF) sees a weak trough of low pressure building progressively from the equatorial Indian Ocean to the northeast Arabian Sea during the whole of the week.

Satellite cloud imagery on Sunday showed convective clouds over parts of south Bay of Bengal, south Andaman Sea and Jammu and Kashmir.

Meanwhile, the Chennai Regional Met Centre has predicted isolated rain or thundershowers for Tamil Nadu, Puducherry, Kerala and Lakshadweep during the next two days.

Towards the north, minimum temperatures were above normal by over Gujarat, southwest Madhya Pradesh, peninsular India, Saurashtra and Kutch, Chhattisgarh, Orissa, Jharkhand, Gangetic West Bengal, parts of Arunachal Pradesh and Rajasthan and remaining parts of Madhya Pradesh.

The lowest minimum temperature of 1.6 deg Celsius was recorded at Sarsawa (Uttar Pradesh).

A feeble western disturbance as an upper air system lay over north Pakistan and adjoining Jammu and Kashmir. Isolated to scattered rain or snow has been forecast over parts of western Himalayan region during next two days.

What is "closed" and "parallel" Isobars ??

Closed Isobars
Regions of high and low atmospheric pressure develop at the earth's surface for a variety of reasons, including heating or cooling, and the rising or sinking of air due to surface topography or movements of air at higher levels in the troposphere. When pressure changes occur gradually over a large area, the isobars describing the horizontal change in pressure, or the pressure gradient, will take on a banded appearance, as seen below.
Example of parallel isobars

Much of the convection that takes place on earth is more localised. When low or high pressure develops more locally, the resulting high- and low-pressure regions are cell-like systems, and isobars describing the patterns of air pressure will include one or more closed, circular isobars, as shown below.
Closed isobars around a low pressure cell.

Closed Isobars

High winds in Kanyakumari ..Why?

Mr. Anonymous said...

There were two closed isobars. One 1012 hPa close to Cape Comorin and other closerby isobar 1014 hPa is close to, say, Chennai. This PGF activated strong winds and it [was] experienced at Cape Comorin and at many places today and even in Chennai.
Wind :[12-15 KNOTS- 22-27 KMPH]
As usual the delata districts experinced moderate rainfall. Atleast by tomorrow evening some active wet weather can be expected in North Coastal TN & South CAP.
North India shivers as mercury dips further ...

North India shivers as mercury dips further

Cold conditions intensified in most parts of the northern region today as mercury dipped by several notches with Leh in Jammu and Kashmir freezing at minus 16 degrees.

The minimum temperature in Punjab, Haryana and Chandigarh hovered between two to four degree Celsius below normal at several places.

Rohtak in Haryana shivered at a low of 1.8 degrees, four notches below normal, while Karnal recorded 4.8 degree Celsius, three degrees below normal, Met office said.

Patiala and Amritsar, in Punjab, recorded a minimum temperature of 5.5 and 5.8 degree Celsius respectively, even as Chandigarh recorded a low of 6.8 degrees.

Icy winds coupled with steep drop in mercury resulted in intense cold in most parts of Jammu and Kashmir on the eve of 'Chilai Kalan', the 40-day harsh winter period.

Leh, in frontier region of Ladakh, was the coldest place in the state with a low of minus 16 degrees while it recorded a day temperature of minus 1.6. Meanwhile, Kargil recorded a low and high of minus 14.2 and minus 3.6 respectively.

Leh coldest in J&K with day temp of minus 1.6 degrees Celsius Srinagar recorded a minimum of 0.4 degrees, while it settled at a maximum of 5.4 degree Celsius, making it the coldest day of the season so far.

People in Himachal Pradesh had no respite from cold as chilly winds swept across the state. Capital Shimla settled at a minimum temperature of 5.7 degrees, while it recorded a day temperature of 13.5.

Cold conditions aggravated in Rajasthan with Churu being the coldest place with a minimum temperature of 4.2 degrees.

Ganganagar and Bikaner settled at a low of 6.3 and 8 degrees respectively, while Jaipur recorded 10.4 degree Celsius.

Delhiites woke up to another misty and chilly morning as the national capital recorded a minimum of 8.4 degree Celsius. The minimum had yesterday dipped to the season's lowest of 7.7 degree Celsius.
In pictures: Europe's cold snap ...
Cold snap wreaks havoc across Europe ...
In pictures: Europe's cold snap ...
Bad weather disrupting North America travel ..
RT @nishfine: Why there is no proper drinage system in chennai? Won't the govt. see how ppls suffer at each rainy season??
RT @Rajapandiansp: cochin hot chennai cool is this starting of the end of 2012 ?????? -- NO
RT @harisankarh: late night roaming around in the Chennai city. cycle ride in the rain @ IIT. Nice ending of a eventful holiday :) gudnite folks
RT @jgblr2008: shortest day of the year has a long spell of rain in chennai. no car wash now. rain water being harvested too!
Chennai - In past 24hrs, egmore zone received 28.4 mm
These easterlies will carry heavy moisture and showers will be generated just off coast over sea and it'll move in fast and dissipate fast.
Satellite will show u nothing as of the present Rain .. ..
Around 24-Dec-09, the easterlies will ease and will stop on 25-Dec-09. .. Entire Tamilnadu coast will get widespread moderate to Heavy showers till 23-Dec-09.
Chennai - These showers are due to the Good easterlies from Bay and it'll continue till Wednesday Morning ..
Chennai - Showers were heavy than expected during early hrs... Still more Sharp showers expected with cloudy & warm intervals thru the day.