Saturday, May 16, 2009
Potential "95B"
US Navy has started tracking the system which lies over south-south Bay.
South-east of Srilanka.
Take a look at the latest sat pic...
This potential circulation system has been marked as "95B" and this is a perfect Monsoon puller for Andaman and Southern mainland.
Stage set for monsoon onset in Bay of Bengal
Conditions are becoming favourable for advance of southwest monsoon into south Andaman Sea and adjoining southeast Bay of Bengal during the next two to three days.
Rain-bearing southwesterly winds are forecast to head increasingly into the region powered by a compliment of relatively stronger southerlies from the southern hemisphere.
ONSET LIKELY
This is expected to precipitate the onset in the Andamans where prevailing southwesterly winds were weak on Friday. On the other side of the peninsula, India Meteorological Department (IMD) expects an increase in rainfall over peninsular India from Monday.
According to the European Centre for Medium-Range Weather Forecasts, weather conditions would take a decisive turn after May 20 when wind speeds and moisture carry are forecast to scale up dramatically.
'LOW' LIKELY
This phase could also throw up the expected low-pressure area in the southeast Arabian Sea and the adjoining equatorial Indian Ocean-southwest Bay of Bengal. The Head Bay may also be readying to host a separate circulation.
Three-hour forecasts being made available by an international model suggests that the flows would become southwesterly over Sri Lanka by Monday and the monsoon get established over the island nation.
But Thiruvananthapuram in Kerala, the monsoon gateway for India, would still feature predominantly west-northwesterlies around the same time. A series of thundershowers is forecast to unravel over the region as a prelude to monsoon onset.
THUNDERSHOWERS
The US National Centres for Environmental Prediction (NCEP) has said that the week ending May 22 would see Kerala awash with rain or thundershowers, which may spill into neighbouring Tamil Nadu and Karnataka.
The rains would have simultaneously become well established over southwest and central Bay of Bengal, east and northeast India where a westerly trough is shown to combine with the monsoon current to trigger widespread rainfall through the following week (May 23 to 31).
HEAT LOW
On Friday, the 'heat low' over west Rajasthan and adjoining east Pakistan held relatively strong aided by prevailing heat wave conditions. The 'heat low' must sustain to be able to provide the ideal pressure differential for monsoon to drive up from the relative 'high' over the south peninsula.
Meanwhile, India Meteorological Department (IMD) has warned of the possibility of thunder squall and hail flaring up over the seasonally 'vulnerable' West Bengal, Sikkim, the Northeastern states, Jharkhand, Orissa and coastal Andhra Pradesh during the next two days.
TROUGH WEAKENS
In a major development, the weather-maker trough/wind discontinuity from Orissa to south Tamil Nadu has become less marked on Friday. A counterpart trough in westerlies from Assam and Meghalaya to northeast Bay of Bengal too has become less marked.
This is a major enabling condition for the southwest monsoon to set in over the Bay of Bengal. The unsettled weather triggered by the Nor'westers (winds associated with a prevailing western disturbance) has to shut out for the monsoon to set in.
Giant hailstones kill 27
Hailstorms were big news this week. Fierce thunderstorms unleashed barrages of giant hailstones across northern India and killed 27 people. The storms were stoked by temperatures reaching up to 49C (121F) that clashed with colder air higher up. Hailstorms often strike before the arrival of India's monsoon. On April 30, 1888, the deadliest hailstorm on record killed 246 people in Moradabad, east of Delhi, with hailstones reported as large as cricket balls
Friday, May 15, 2009
IMD: Forecast for the 2009 Monsoon Onset over Kerala
INDIA METEOROLOGICAL DEPARTMENT
Forecast for the 2009 Monsoon Onset over Kerala
1. Background
Since 2005, India Meteorological Department (IMD) has been issuing operational forecasts for the monsoon onset over Kerala using statistical techniques. During all the four years (2005 to 2008), the operational forecasts were correct. In 2008, IMD predicted 29th May as the date of monsoon onset over Kerala and the actual monsoon onset took place on 31st May just one day prior to the normal date of monsoon onset, i.e., 1st June. IMD has now prepared the forecast for the 2009 monsoon onset over Kerala.
2. Advance of monsoon over Andaman Sea
The normal date of advance of monsoon over Andaman Sea is 20th May. It is expected that within 2-3 days, monsoon flow will start appearing over Andaman Sea and monsoon is likely to cover the Andaman Sea close to its normal date. Past data suggest absence of any one to one association between the date of monsoon advance over Andaman Sea and the date of monsoon onset over Kerala.
3. Forecast for the 2009 Monsoon Onset over Kerala
For predicting the 2009 monsoon onset over Kerala, IMD used an indigenously developed statistical model, based on the following six predictors:
i) Minimum Temperature over North-west India ii) Pre-monsoon rainfall peak over south Peninsula, iii) Outgoing Long wave Radiation (OLR) over south China Sea (iv) Lower tropospheric zonal wind over southeast Indian ocean, (v) upper tropospheric zonal wind over the east equatorial Indian Ocean and (vi) Outgoing Long wave (OLR) over south-west Pacific region.
The statistical forecast model has a model error of ± 4 days. The mean monsoon onset date over Kerala is 1 June.
The onset forecast model suggests that the monsoon onset over Kerala in 2009 is likely to be on 26th May with a model error of ± 4 days.
original from: http://imd.gov.in/section/nhac/dynamic/pressrelease.htm
Mercury rises; Orissa toll up to 130
Most parts of northern India on Thursday experienced high temperature with Churu and Kota in Rajasthan recording 46.5°C each as death toll in Orissa rose to 130 with two more people succumbing to blistering heat wave.
Casualties due to suspected sun-stroke were reported from Jagatsinghpur and Keonghar in Orissa where Titlagarh sizzled at 44°C though some places in the state were lashed by rains.
Normal life and public transport were badly affected in Rajasthan as scorching heat continued to sweep the State with mercury soaring at almost all places.
Churu and Kota remained the hottest with 46.5°C each followed by Bikaner which recorded a maximum of 46.4°C.
Heat wave conditions intensified in some parts of Punjab and Haryana with Hisar touching 44.4°C, which was hottest place in the region.
Chandigarh recorded a two degrees below normal temperature at 35.8°C while Amritsar in Punjab experienced a hot day at 40.2°C.
Mercury rose marginally in Himachal Pradesh in the absence of rain and snowfall. Occasional cool breeze, however, kept weather in capital Shimla relatively pleasant that registered 17°C.
Thursday, May 14, 2009
Low pressure may spur monsoon
India's monsoon could arrive a few days earlier than usual, sped up by a low pressure area around Lakshadweep from mid-May, a weather official said on Wednesday.
"We are expecting some low pressure area around Lakshadweep from 18th May...If the low pressure area becomes a cyclone, the monsoon will arrive faster," a director-level official of the Indian Meteorological Department told Reuters.
The monsoon normally arrives around June 1 in Kerala. Lakshadweep is an adjoining island and a part of Indian territory.
Earlier, the government predicted India's annual monsoon at 96 percent of the long-term average, which would make it the worst season in five years, although the near normal forecast raised hope for economic support and bumper crops.
The weather office regards rainfall to be nearly normal if it ranges from 96 percent to 104 percent of the long-term average.
A weather official based in Pune in western India echoed similar hopes on the back of a low pressure formation.
"The monsoon may come a few days earlier...formation of low pressure area may influence the monsoon flow," D.Sivananda Pai, director of government-run National Climate Center at Pune, said on Wednesday.
IMD: Doppler radar to be functional by mid-July
The India Meteorological Department (IMD) at a press conference on Tuesday stated that efforts were on to get the Doppler Weather Radar (DWR) operational by mid week of July, for better prediction of rains in the city. However, the DWR is not the sole tool that IMD depends on to predict monsoon - it is just one of the several paraphernalia used to collect information on cloud formation, advancement and wind direction - the Met Department clarified.
Updating the status of the installation, Dr R V Sharma, deputy director general of IMD, Mumbai, said, "The DWR equipment has arrived at the Mumbai port on April 27 and IMD office on May 7. Now, we are conducting terrace modification work at Archana building in Navy Colony so that the antenna could be installed before the monsoon."
He said the Navy had assured to complete the work by May 31. Depending on the progress, plans are on to hand over the equipment to the suppliers, Indian Firm of Radar, on May 20.
"Installation and integration would take about a month after which we will need two to three weeks to test the equipment. Considering all these factors, we are trying to get the radar commissioned in about one-and-a-half months."
He pointed out that there could be several road blocks and that heavy rains and strong winds may create difficulties during installation.
The Met department of Mumbai was so far using a conventional radar which would relay the cloud movement, cloud formation and moisture precipitation every half-an-hour. DWR is a more advanced equipment which would relay the same factors every 15 minutes.
27 killed as storm lashes northern India
At least 27 people were killed in India's northern state of Uttar Pradesh in heavy rainstorms that uprooted trees and caused several houses to collapse, news reports and officials said Tuesday.
The PTI news agency, quoting police sources, reported 27 people had died in seven districts including Hardoi, Mathura, Lucknow, Mainpuri, Aligarh, Etawah and Kannauj.
According to the report, the highest number of deaths was reported from Hardoi and Mathura districts where 13 locals lost their lives.
'Most of the deaths were caused in incidents of house collapses or trees and electrical poles falling down on locals or their dwellings,' revenue official Manvendra Gupta said by telephone from the state capital of Lucknow.
Winds up to 110 kilometres per hour also disrupted power supplies in the affected districts. The movement of trains at several places in the state was hampered by the weather, officials said.
The storms were typical of the pre-monsoon period and were caused by an 'upper-air cyclonic pressure formed over the northern regions of the country,' Gupta said. India's monsoon season usually lasts from June to October.
Freak weather mystery - Bahrain
WEATHER conditions in Bahrain over the last two days are highly unusual for this time of the year, according to meteorology officials. The high-velocity north-westerly, "40-day winds" normally begin in early June and continue till the middle of July, said Civil Aviation Affairs (CAA) Meteorology assistant under-secretary Abdul Majeed Isa.
"We are experiencing these conditions because of a low pressure area over India and Pakistan," he told the GDN.
"They begin as soon as the monsoon season begins to set in in the Indian sub-continent."
Mr Isa said it was also unusual for the monsoons to set in so early.
"This is very unusual and experts all over the region have nothing else to blame than global warming and climate change," he said.
The official said it was not, however, a matter of concern.
"It is unusual now, but if it happens over and over again, it will affect the weather patterns in this part of the world," said Mr Isa.
Strong surface winds, with average speeds of between 24 and 25 knots have been reported in Bahrain since Monday night with gushes of wind sometimes reaching between 34 and 36 knots.
"This is expected to continue over the next few days and should subside by Friday," said Mr Isa.
He said people should take care in the high velocity winds and warned fishermen not to venture out into the sea unless necessary.
"Care should be taken to prevent any mishaps," said Mr Isa.
He said the winds were leading to rising sands in several places, which was causing discomfort to workers and motorists.
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