Wednesday, November 25, 2009

All models suggest a HEAVY showery december 1st week for all over Tamilnadu.
"95B" .. Canadian Meteorological Centre took the system to a more north-north-west track that would take it to central Tamil Nadu coast.
"95B" ... IMD models also agree with NCEP-NGP model.
NCEP-NGP,model shows "95B" will make landfall over Sri Lanka and adjoining South-East Tamil Nadu coast by 30-Nov.
IMD:: "95B".. system is likely to become more marked in next 48 hrs

‘Low’ pops up over South-East Bay, may intensify

India Meteorological Department (IMD) has traced a low-pressure over South-East Bay of Bengal and adjoining south Andaman Sea on Tuesday.

The system is likely to become more marked, the IMD outlook said. It may persist during the next three days with a movement to west-north-west – towards the Sri Lankan coast.

The cyclonic circulation tracking model, NGP, by the US National Centrefor Environmental Prediction agreed with this outlook positing the system for a landfall over Sri Lanka and adjoining South-East Tamil Nadu coast by November 30.


But the Canadian Meteorological Centre took the system to a more north-north-west track that would take it to central Tamil Nadu coast during the same time span.

Satellite imagery showed convective clouds over parts of south Bay of Bengal and South-East Arabian Sea. The IMD has forecast isolated to scattered rainfall over extreme south peninsular India during until the weekend.

The Chennai Regional Meteorological Centre said that rainfall occurred at a few places over Tamil Nadu. Isolated rainfall occurred over Karnataka, Kerala, coastal Andhra Pradesh and Rayalaseema.

The North-East monsoon was subdued during the past 24 hours ending Tuesday morning as a dry phase of the Madden-Julian Oscillation (MJO) wave began impacting equatorial Indian Ocean and neighbourhood.

But, easterlies still continue to make their presence felt over the Bay of Bengal, more so, to the east and south-east. There is a low-pressure area upstream in the South China Sea as well, sustaining the flows into the Bay.

Tuesday’s ‘low’ over south-east Bay of Bengal would be able to relay in the moisture-laden easterlies further to the west.

In this manner, the scattered to isolated rainfall regime over south peninsular India should hold until the weekend.

Meanwhile, the European Centre for Medium-Range Weather Forecasts (ECMWF) sees the possibility of a busy South China Sea pushing in a fresh circulation into the Bay by the weekend.

It is tipped to keep moving to the west in the Bay basin until December 4 by when it would have washed ashore over the Tamil Nadu coast. It would set off a basin-wide trough that could cover east and south-east Arabian Sea as well.


Forecast by the Chennai Met Centre for the next two days said that rain or thundershowers are likely to occur at a few places over Tamil Nadu, Puducherry, coastal Karnataka, Kerala and Lakshadweep.

Isolated rain or thundershowers are likely to occur over Rayalaseema, coastal Andhra Pradesh and south interior Karnataka.

Towards the north, a feeble western disturbance is affecting the western Himalayan region. Cold wave conditions prevailed in some parts of Himachal Pradesh.

Isolated rain or snow has been forecast over the region during the next two days.

Maximum temperatures are below normal over parts of Madhya Pradesh, north Chhattisgarh and Jharkhand.
Chennai - Seems like a break in NE air current for next 36 hrs.
Chennai - a clear evening with very little cloud movement and formation. No distant over sea thunder cells as well.!
El Nino Resurging in November 2009 ...
The present "95B" system may not be able to move north-west into Bay of bengal, due to cooler sea temperature ..
Latest "Tropical Cyclone Heat Potential " .. which is right over "95B" .. ..
Latest satellite shot of regenerated "95B" ..
Satellite shows signs of "95B" again ..
Chennai - Hot and humid so far, with some low cloud formation.
At LAST ::: the cyclonic circulation over south west Bay of Bengal and adjoining Comorin area had shifted to over southeast Arabian Sea

Active monsoon conditions over south TN, Kerala

North-East monsoon has been active over south Tamil Nadu and Kerala during the last 24 hours ending Monday morning, according to an update from the Chennai Met Centre.

Rainfall occurred at most places over south Tamil Nadu and at many places over north Tamil Nadu and Kerala and at a few places over Lakshadweep, coastal Andhra Pradesh, coastal and south interior Karnataka.

Forecast for the next two days spoke about the possibility of rain or thundershowers mainly over south Tamil Nadu and south Kerala.

A few places over north Tamil Nadu, Puducherry, north Kerala, Lakshadweep, Rayalaseema, coastal Andhra Pradesh, coast and south interior Karnataka also are expected to witness thundershowers.


Sea-surface temperature (SST) maps on Monday revealed that the stretch of hyper-active convection linking southeast Bay and adjoining East Indian Ocean to southwest Bay of Bengal around Sri Lanka has let off some steam due to incessant rains over the past few days. These seas are still warm beyond the threshold limit allowing them to host, or facilitate easy passage to, weather systems that choose to move towards Sri Lanka or mainland India.

This narrow stretch of comparatively cooler waters is bordered on both sides by the warmest waters (entire Bay of Bengal to the north and East Indian Ocean to the south) of the northeast monsoon region.

According to international model forecasts, the Bay of Bengal would increasingly get busier with easterly convective rain bands shown to extend into its northern flanks during the course of the week. The European Centre for Medium-Range Weather Forecasts (ECMWF) projected that the build-up may culminate in the formation of a low-pressure area just off central and south-central Tamil Nadu coast during early December.

This is likely to coincide with the landfall of another powerful typhoon over the Philippines, the ECMWF predictions said.

The US National Centres of Environmental Prediction (NCEP) is of the view that entire southern peninsula would continue to witness scattered to fairly widespread rains during this week.


This outlook also suggested that north Bay of Bengal would witness raised level of activity, which is in line with the ECMWF outlook. NCEP’s forecast for the first week of December indicated fresh convection starting to build over equatorial Indian Ocean.

An India Meteorological Department (IMD) update on Monday said that the cyclonic circulation over south west Bay of Bengal and adjoining Comorin area had shifted to over southeast Arabian Sea

El Nino Resurging in November 2009

El Niño is experiencing a late-fall resurgence. Recent measurements of sea level height from the Ocean Surface Topography Mission (OSTM)/Jason-2 oceanography satellite showed that a strong wave of warm water, known as a Kelvin wave, had spread from the western to the central and eastern Pacific. This warm wave appears as the large area of higher-than-normal sea surface heights in the area between 170 degrees east and 100 degrees west longitude.
This image was created with data collected OSTM/Jason 2 during a 10-day period centered on November 1, 2009. Red and white areas in the central and eastern equatorial Pacific were 100 to 180 millimeters (4 to 7 inches) above normal. In the western equatorial Pacific, blue and purple areas show where sea levels were between 80 and 150 millimeters (3 and 6 inches) below normal.
Sea surface height is an indication of temperature because water expands slightly as it warms and contracts as it cools. The elevated sea levels in the central and eastern Pacific are equivalent to sea surface temperatures more than one to two degrees Celsius above normal (two to four degrees Fahrenheit).
The Kelvin wave was triggered by a large-scale, sustained weakening of trade winds in the western and central equatorial Pacific during October. The change in winds disturbs not only the surface currents but also the deeper ocean circulation. The disturbances reverberate along the thermocline—the boundary between warm, surface water and cold, deep water—as large, slow-moving waves. Similar, weaker events that began in June 2009 initially triggered and have sustained the present El Niño.
Although El Niño means drought in some parts of the world, in other places it can bring drought relief. “In the American West, where we are struggling under serious drought conditions, this late-fall charge by El Niño is a pleasant surprise, upping the odds for much needed rain and an above-normal winter snowpack,” said oceanographer Bill Patzert of NASA’s Jet Propulsion Laboratory in California.

Amazing Wave Clouds from South Sandwich Islands

As they cross the ocean, ships make waves in the water. Even though they sit still, islands can make equally dramatic waves—in the air. This was the case in the southern Atlantic Ocean in late November 2009. The South Sandwich Islands conspired with air currents to make wave patterns in clouds.
The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-color (photo-like) image on November 23, 2009. Saunders, Montagu, and Bristol Islands, part of the South Sandwich chain, all trigger V-shaped waves that fan out toward the east. The white clouds over the dark ocean water vaguely resemble zebra stripes.
The South Sandwich Islands are of volcanic origin—Bristol and Montagu have been active during recorded history—and all the islands poke rugged summits above the ocean surface. The islands disturb the smooth flow of air, creating waves that ripple through the atmosphere downwind of the obstacles.

Tropical Storm Nida

Nida formed as a tropical depression over the western Pacific Ocean on November 22, 2009. Late the following day, Nida had strengthened to a tropical storm, with maximum sustained winds of 35 knots (65 kilometers per hour) and gusts up to 45 knots (85 kilometers per hour).
The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this true-color image on November 23, 2009. Focusing on the center of the storm, this image shows what appears to be a tall cloud tower casting a shadow to the north. Thick clouds fan out from this apparent tower toward the west and south. On the north and east sides, a break appears in the clouds, but a larger ring of clouds surrounds the storm’s center.
@@@  Our reader comment  @@@@@@@@@@@
In west Pacific at 10.8 Deg North and 143.7 Deg East NIDA is brewing. Expected Central Pressure 956 hPa.[Terrifying nature, in deed]
27 W & 96 W are also brewing. Similarly in Indian Ocean 5.6N / 92.2 E (96B)is brewing. However as the upper guiding winds are SWly there are chance it may take re curvature when it enters Bay and may hit Myanmar. [But this is too early to be precise]
RT @tam007: Yes its damn hot. Welcome to Chennai! RT @ridwan326: It's freaking hot here!!!

Calcutta - weather mystery

Winter has come a fortnight early but experts are not sure how long it will stay, given the year’s bizarre weather patterns. “For all you know, it might leave earlier than usual,” said O.P. Sharma, the chief meteorologist in a private agency.

Metro decodes the freak meteorological year that is.

Summer heat waves

A heat wave scorched the city from April 18 to 28. The period was the hottest in six decades with the mercury crossing 40 degrees eight times.

May began with a nine-day heat wave when the mercury soared to 41.8 degrees.

Local factors: Nor’westers could not develop as there was not enough moisture in the lower troposphere.

Global factors: Hot, dry northwesterlies and westerlies blew in from central Asia because of the heat wave in central and north India.

Monsoon’s early arrival

Rains arrived on May 25, a fortnight before schedule, powered by Cyclone Aila.

Local factors: The formation of the cyclone over the Bay.

Global factors: Experts blame Aila’s ferocity — responsible for the monsoon’s early arrival — on global warming.

June heat wave

After entering Bengal on May 25, the monsoon flow took 30 days to get activated. So, June was dry and hot. A weeklong heat wave tormented the city from June 7.

Local factors: Lack of enough moisture in the lower troposphere, hindering formation of rain clouds.

Global factors: El Nino (warming of sea water) over the Pacific Ocean delayed monsoon activation.

Maverick monsoon

Rainfall from May to August was 10 per cent below average. But the city finally closed its monsoon account with 15 per cent surplus rainfall, thanks to a surge in showers in September. The city received over 300mm rain between September 3 and 9 and more than 360mm in the Puja month (22 per cent more than usual).

Local factors: Variation in moisture content.

Global factors: El Nino, global warming and MaddenJulian Oscillation or MJo (fluctuation in atmospheric pressure over oceans).

November swelter

The first half was the hottest in five decades. Minimum temperature on November 15 was eight degrees above normal.

Local factors: A high-pressure belt over the Bay.

Global factors: None.

Winter comes early

The mercury started dropping after the November 16 rain; winter set in on Sunday.

Local factors: A low-pressure area over south Bengal.

Global factors: Wet wind from the Mediterranean Sea and the northwesterlies
Almost all models now has played down the formation of Cyclone just north of Andaman... instead they are focusing on "95B" area.
COLA GFS.. now predicts a LOW pressure to move into north TN coast around 30-Nov ..
Where is "95B"?? IMD's MM5 and WRF models still suggest a Depression formation around south-east Bay ..
Very latest satellite shot shows .. a CLEAR lndia ..
Where is "95B"..?? as GFS models predicted, it has vanished ..
Chennai - Where are the rains?? Nothing so far.. but isolated local short shower possible from 10 am to 2 pm.. Not area specific.
Satellite at 5:30am showed some cloud formations over central TN, north Kerala, and Gulf of Mannar ..