Run-up to monsoon onset to light up after May 25

Global models indicate a burst of southwesterly would sweep into Bay of Bengal around May 27, the fringes to the far east of which could also whip up a tropical cyclone in the northwest Pacific.

The European Centre of Medium-Range Weather Forecasts predicts even as the westward-moving cyclone hits the Philippines archipelago and takes a rebound to the east-northeast, it would also facilitate the onset of southwest monsoon over the Kerala coast.

This would be preceded by the onset of monsoon over the northeast of India and the initiation of a low-pressure area over northwest Bay of Bengal. Thus, the onset would likely have been accomplished in near-copybook style.

No possibility of a near-sea rogue weather system that could usurp the onset phase is still being forecast; instead the ‘pull' of the brewing northwest Pacific cyclone can only help boost its prospects and expedite the onset.

According to Dr Paul Roundy, renowned tracker of ocean weather systems, there is a possibility that the Gujarat-Mumbai coast might just witness some enhanced activity in the early phase of the onset.

The US National Centres for Environmental Prediction suggests the formation of the offshore vortex in the run up to the onset with maximum convection being set off over the Lakshadweep in southeast Arabian Sea.

Meanwhile, an expansive pre-monsoon phase activity on show in east India and the northeast as tremendous moisture transport is being facilitated from nearby Bay of Bengal.

An India Meteorological Department (IMD) weather update on Friday said that fairly widespread rainfall was reported from West Bengal, Sikkim and the Northeastern States.

It was scattered over Bihar and isolated over the western Himalayan region, Haryana, Uttar Pradesh, east Madhya Pradesh, Chhattisgarh, Vidarbha, Karnataka, Andhra Pradesh, Kerala and Tamil Nadu.

On Thursday, heat wave conditions were prevailing over parts of Punjab, Haryana, Rajasthan, west Uttar Pradesh, north Madhya Pradesh and Vidarbha. The highest maximum temperature of 47.4°C was recorded at Pilani in Rajasthan.

Mainly dry weather has been forecast over northwest, central and adjoining east India until Wednesday. A rise in maximum temperatures by 2 to 4 deg Celsius is likely over northwest and adjoining central India during this period

Mercury rising as heat wave prevails in North-West

The mercury level has been seeking new highs in the central and northwest India as heating of the regions sustained from over the weekend.

An India Meteorological Department (IMD) update on Tuesday afternoon said that heat wave conditions have been prevailing over parts of Rajasthan, south Uttar Pradesh and north Madhya Pradesh and isolated pockets of Punjab and Haryana.

But the highest maximum temperature of 46.8 deg Celsius was recorded elsewhere, at Khajuraho in Madhya Pradesh, as the core heat expanded its foot-print east-southeast.

A weather warning from IMD said that heat wave conditions would continue to hold over parts of Rajasthan, Haryana, Punjab, Delhi, Uttar Pradesh and Madhya Pradesh during this period.

Meanwhile, it maintained the watch for a fresh western disturbance crossing over the border affecting the western Himalayan region and adjoining plains of northwest India from Thursday onwards.

An extended outlook until Sunday (May 22) said that scattered rain or thundershowers would occur over western Himalayan region and adjoining plains of northwest India.

A seasonal upper air trough runs from Punjab to Mizoram across Haryana, Uttar Pradesh and Jharkhand with an embedded upper air cyclonic circulation over West Uttar Pradesh and neighbourhood.

A weather warning valid for the region said that isolated thunder squalls would occur over Jharkhand and West Bengal and Sikkim until Friday.

Another upper air cyclonic circulation has sprung up over southeast Arabian Sea in lower levels. It is seen steering the moisture laden winds to precipitate rain over the Kerala coast over the next few days.

Satellite cloud imagery on Tuesday morning showed convective (rain-bearing) clouds over parts of east-central Bay of Bengal, west Assam and Meghalaya.

Scattered rains for south peninsula from weekend

Fairly widespread rain or thundershowers unfold over the Northeastern States and scattered over adjoining east India, south Karnataka, Kerala and Lakshadweep from late this week.

This is as per the outlook given in an extended forecast issued by India Meteorological Department (IMD) on Sunday evening and valid until Friday.

MERCURY TRENDS

Meanwhile, maximum temperatures have continued to rise by 2 to 3 deg Celsius over parts of Jammu and Kashmir, Punjab and Uttar Pradesh through Saturday.

They were above normal by 2 to 4 deg Celsius over part of Jammu and Kashmir, Himachal Pradesh and Punjab as sustained heating from across the border in Pakistan touched off on local weather.

The maxima were above normal by 2 to 3 deg Celsius over parts of Rajasthan, Uttar Pradesh, Bihar, north Madhya Pradesh, north Chhattisgarh, Jharkhand, the Northeastern States, north Orissa, north interior Andhra Pradesh and north Karnataka.

FRESH WESTERLY

Thus, heating has become widespread from northwest to the interior with Brahmapuri in Maharashtra recording the highest maximum of 45.1 deg Celsius on Saturday.

Meanwhile, the IMD has said that a fresh western disturbance would impact northwest India from Thursday.

Isolated dusts storms or thunderstorms may occur over Rajasthan and west Uttar Pradesh until Tuesday.

The IMD also expected maximum temperatures to rise by 2 to 3 deg Celsius over northwest and adjoining central India until Thursday.

WEATHER FEATURES

On Sunday, however, an upper air trough ran down east-southeast from north Rajasthan to Gangetic West Bengal across Haryana, Uttar Pradesh, southwest Bihar and consummating in an upper air cyclonic circulation over Jharkhand.

Another upper air trough looked down to the south from southwest Madhya Pradesh and extended ended up in another cyclonic circulation over extreme south Tamil Nadu.

A third upper air cyclonic circulation hung over Assam, completing the rollout of pre-monsoon weather formations across the country.

CONVECTIVE CLOUDS

Satellite pictures on Sunday evening showed the presence of convective (rain-bearing) clouds over Andaman Sea and south Arabian Sea.

Low to medium clouds were seen over parts of northwest India, and west, central, east and south peninsular India.

A weather warning said that isolated thunder squalls would occur over Bihar, Jharkhand, West Bengal, Sikkim and Orissa until Tuesday. Isolated dust storms or thunderstorms may occur over Rajasthan, and west Uttar Pradesh.

FAIRLY WIDESPREAD

A short-term outlook until Wednesday said that fairly widespread rain or thundershowers would unfold over the Northeastern States, sub-Himalayan West Bengal and Sikkim.

It would be scattered over Gangetic West Bengal and isolated over rest east India, Chhattisgarh and west Maharashtra.

Scattered rain or thundershowers would break over south Karnataka and Kerala and isolated over the rest of south peninsular India.

"monsoon" has already been declared over mainland Thailand

India Meteorological Department (IMD) has said that below-par heating witnessed over northwest India during the pre-monsoon period need not necessarily have any adverse impact on the subsequent rainy season.

The clarification came on Sunday in the backdrop of doubts over implications of the cooling anomaly for onset and progression of monsoon, which is essentially borne out of land-sea heating contrasts.

In a special bulletin, the IMD admitted that temperatures have been below normal over north and northwestern parts of India thus far during the season.

It attributed this to the enhanced activity of seasonal western disturbances (waves of low-pressure areas) that cross into northwest India in terms of their number.

But the IMD significantly added that their increased frequency has not translated into rainfall over the region.

In fact, northwest India as a met subdivision has piled up a rainfall deficiency during the period. The less than optimum heating up is not unprecedented in the region.

There have been at least six instances of similar rollout of weather during the last 30 years but with varied impact, if at all, on the subsequent monsoon, the IMD said.

No one-to one relationship could be observed between surface heating of northwest India during the pre-monsoon period and the monsoon rainfall, it concluded. Meanwhile, as was forecast by global models, the northwest Pacific has thrown up a named cyclone, Aere, and advancing towards the Philippines for a landfall.

But unlike earlier guidance, the cyclone would not cross into adjoining South China Sea but would instead re-curve and enter East China Sea and onward to Japan.

The western disturbances currently active over India and the rest of East Asia would act in concert with the northeasterly flows around a high-pressure area of the Pacific to blow away Aere in this manner.

Going forward, however, some models indicate that the weak ‘low' over east Bay of Bengal would sustain for an extended period to evolve as a stronger weather system and churn up the waters.

The Climate Prediction Centre of the US National Weather Services has put the Bay under watch for a tropical storm during the week ending May 17.

It could also lead to the onset of monsoon over the Andaman and Nicobar Islands, which are already witnessing heavy to very heavy precipitation.

This has prompted the Thailand Meteorological Department to observe that ‘strong southwest monsoon' prevails over the Andaman Sea.

The monsoon has already been declared over mainland Thailand and the Gulf of Thailand, just across the Bay. 

Global models showed that S-W winds south of Sri Lanka and are racing into the Bay

 Westerly to southwesterly winds blowing into the Bay of Bengal may start gathering momentum over the next few days, an India Meteorological Department (IMD) update said on Friday evening.

This is considered a good augury for the onset of southwest monsoon over Andaman and Nicobar Islands, the country's farthest outpost towards east-southeast, around the normal timeline of May 15-20.

In fact, satellite pictures and global models showed that these winds have already picked up pace over upstream equatorial Indian Ocean just south of Sri Lanka and are racing into the Bay, pulled in by a weak low-pressure area in the southwest Bay.

Clouds have filled the region, and they would continue to be guided towards the Myanmar region as the weak ‘low' heads in a north-northeast direction.

From Myanmar and adjoining western parts of Southeast Asia, some of the floating moisture is seen being diverted northeast India, which may spark further activity in the already turbulent weather over that region.

IMD has also observed that the wind direction and strength indicates that the pressure-gradient - arising from enhanced warming in the Bay - may be building ahead of the onset of the monsoon.

The ideal pressure gradient was conspicuous by its absence through the course of the previous monsoon.

This had kept the Bay unusually quiet and left behind large rainfall deficiencies over east and northeast India.

In contrast, the Bay has warmed up to around 30 deg-Celsius already this year – well above the threshold for it to sustain low-pressure areas, tropical depressions or even a cyclone.

But nothing of that sort has happened so far this year since a barrage of strong opposing flows from prevailing western disturbances have prevented any system from taking shape. The latest in the series of these westerly systems was on show on Friday over north Pakistan and adjoining Jammu and Kashmir with an induced cyclonic formulation clinging to its underbelly.

The IMD has warned of isolated thunder squalls over Himachal Pradesh, Uttarkhand, Punjab, Haryana, Delhi, north Rajasthan, Uttar Pradesh, Jharkhand, Orissa and Gangetic West Bengal until the day after (Sunday).

The induced upper air cyclonic circulation was parked over northwest Rajasthan on Friday.

A trough ran out towards east-southeast from here across Haryana, Uttar Pradesh, southwest Bihar and Jharkhand to end up in a counterpart circulation over Gangetic West Bengal.

Satellite imagery on Friday afternoon showed convective clouds over parts of south and adjoining central Bay of Bengal and Andaman Sea.

An extended outlook valid until Wednesday spoke about the possibility of a fresh western disturbance approaching northwest India

Heating trend may once again get briefly disrupted

Expectations of low-pressure area in the Bay of Bengal having subsided, the focus has once again shifted to the heating pattern in northwest India.

The heating in this geography has a crucial bearing on the strength and prospects of the impending southwest monsoon.

The highest maximum recorded in the country on Monday was reported from this region, but at 44.4 deg Celsius, it might just have failed to warm the cockles of hardened monsoon watchers.

The heating has admittedly been below par during the season until now and arrival by Thursday of a fresh but heat-killer western disturbance as forecast by India Meteorological Department (IMD) may pour cold water on any hopes of a smart pick-up in mercury over this region.

Sustained heating is required to set up the “heat low,” a peculiar atmospheric phenomenon special to this part of the world, that helps moisture-laden southwesterly monsoon winds march up north along the pressure gradient.

The IMD maintained its outlook for the westerly system on Tuesday morning, which would affect the western Himalayan region and adjoining plains of northwest India from Thursday.

As a result, scattered rain or thundershowers are expected to break out over the western Himalayan region, as per a short-term outlook valid until Friday.

Isolated dust storm or thunderstorm would occur over adjoining plains of northwest India during this period.

The IMD has said that no significant change is expected in maximum temperatures over northwest, west and central India. But even dust storms/thunderstorms can cap maximum temperatures by varying margins, even if temporarily.

Meanwhile, an upper air cyclonic circulation persisted over east Uttar Pradesh.

A trough from this system extended downward, but unlike until the previous day, was cut short over north coastal Andhra Pradesh. It ran through east Madhya Pradesh, Chhattisgarh and interior Orissa.

The other upper air cyclonic circulation, which was expected to father the “low” in the Bay, hung above central parts of south Bay of Bengal.

Satellite imagery early on Tuesday evening showed the presence of convective clouds over parts of east-central and south Bay of Bengal and southeast Arabian Sea.

A short-term outlook valid until Friday said that widespread rain or thundershowers would occur over Andaman and Nicobar Islands, scattered over south Karnataka, Kerala and Lakshadweep and isolated over rest of peninsular India.

Fairly widespread rain or thundershowers would occur over the Northeastern States.

Scattered rain or thundershowers would occur over sub-Himalayan West Bengal, Sikkim and isolated over the rest of east India.

An extended forecast valid until Sunday said that fairly widespread precipitation activity would unfold over western Himalayan region.

Isolated dust storm or thunderstorm could break out over the adjoining plains of northwest India.

Isolated rain or thundershowers would occur over the Northeastern States and adjoining east India. 

South China Sea cyclone may launch monsoon into Bay

Global models indicate the possibility of a South China Sea cyclone helping launch the southwest monsoon into the Andaman and Nicobar Islands, its first port of call in the Indian territorial waters, around the normal date.

This is even as India Meteorological Department (IMD) has been keeping a watch for the first pre-monsoon low-pressure area to spring up in the Bay of Bengal. But a core of strong westerlies already blowing across the plains and into the Bay of Bengal may put paid to these hopes.

A fresh western disturbance is expected to check into western Himalayas and northwest India by Thursday and opposing flows from this may snuff out any chance of revival of full-fledged ‘low' in the Bay.

A weak circulation would likely be all that is left of the current churn in the Bay, which would be made to retreat east-northeast towards the Myanmar coast.

The IMD has withdrawn its watch for the “low” effective from the afternoon bulletin on Monday. It is in this backdrop that the forecast about the likely formation of a cyclone in the South China Sea by the European Centre for Medium-Range Weather Forecasts (ECMWF) assumes significance.

The “wet season” has already unfolded over Southeast Asia from Sunday (May 1), regional met agencies confirmed.

This is the usual date for the onset here and the winds would turn southwesterly as a “low” originating in the west Pacific crosses the Philippines and drifts into adjoining South China Sea.

The ECMWF expects this system to drop anchor here, and grow in strength to become a tropical cyclone by May 12, up to which its guidance is available. The US National Centres for Environmental Prediction expects this system to hurl a potent circulation into the Andaman Sea, or extreme southeast Bay of Bengal, during the week that follows.

This could also bring the southwest monsoon into Andaman and Nicobar region around the normal time for onset (May 15 to 20). It will take another fortnight for the Arabian Sea arm of the monsoon to make a splash over the Kerala coast

Low pressure Area in Bay ... "95 B" -- Update #3 .. 'Weakened"

The Low pressure area has weakened today !
and showing very less signs of intensifying.

Present position : 16.8 N and 89.2 E
Pressure : 1010mb
Wind : 25 KmpH

COLA model :: The present Bay low "95 B" will move in N-N-E direction into Bay and die in process .. 

Low pressure Area in Bay ... "95 B" -- Update #2 .. "moved N-N-E"

Present position of Low pressure area ... 95B
11.9 N and 91.2 E
Pressure and wind speed remains the same.
Pressure : 1004mb
wind : 40 to 45 KmpH

According to IMD models "No real threat of this system becoming into a cyclone"... instead it forecasts another LOW system to pop in this same zone.

Bay shaping up to host season’s first ‘low’

A low-pressure is now expected to pop up over the Bay of Bengal by Sunday as a persisting upper air circulation descends to lower levels and matures.

In the run-up to this likely denouement, the Andaman and Nicobar Islands are expected get buffeted by rains or thundershowers over the weekend, India Meteorological Department (IMD) said on Friday.

WARMER SEAS

The seas have warmed up to well above 30 deg Celsius, which is more than enough to sustain the brewing ‘low.’

This would also help steer the flows in the Bay to being more easterly to southeasterly, after having seen the back of a harmful ‘ridge’ or high-pressure region that has been pushed away.

The ‘low’ has been delayed this year from mid-April, which is normally the time around which the Bay gets its act together.

Meanwhile, peninsular India and adjoining east India, constituting two-thirds of the landmass in south, central and east-central regions, has witnessed surplus summer rains for almost two months between March 1 and April 27.

SURPLUS RAINS

Rainfall deficiencies have been confined to extreme west and northwest, according to an update provided by the IMD.

The Gujarat and Sourashtra region, Madhya Pradesh, Rajasthan, Punjab, Haryana and Delhi, Himachal Pradesh and Uttar Pradesh totted up varying deficiencies.

Jammu and Kashmir was the only Met subdivision to record a normal (+5 per cent) rainfall in the northwest while only Gujarat was totally devoid of any rainfall.

Among the Met subdivisions which surprised on the upside with surplus rainfall thus far during the season are Telengana (+43 per cent); Rayalaseema (+28 per cent); Vidarbha (+75 per cent); Chhattisgarh (+117 per cent); Bihar (+36 per cent); Gangetic West Bengal (+101 per cent); north interior Karnataka (+67 per cent); and south interior Karnataka (+103 per cent).

COOLING TREND

The larger Maharashtra, Andhra Pradesh, Orissa and Jharkhand states also found themselves falling in the ‘normal’ category.

One significant fall-out of the rainfall pattern has been the less than normal cooling of these regions and total absence of heat waves that normally take a toll on human and animal lives.

Some weather watchers have also tended to view with this caution in terms of the likely impact on the impending of the monsoon that drives essentially on land-sea surface temperature contrasts.

Global weather models are, however, of the view that sustained heating of the land surface has already started from northwest India and would filter into central, east-central and parts of peninsular India from the coming week onwards.

THUNDERSHOWERS

Meanwhile, fairly widespread overnight rain or thundershowers has been reported from Andaman and Nicobar Islands overnight on Friday.

It was scattered over sub-Himalayan West Bengal, Sikkim, Meghalaya and Tripura and isolated over Jammu and Kashmir, east Uttar Pradesh, Orissa, south interior Karnataka and Tamil Nadu.

On Thursday, maximum temperatures were above normal by 2 to 4 deg Celsius over some parts of Punjab, east Rajasthan, northwest Madhya Pradesh.

But they continued to be below normal by 2 to 4 deg Celsius over Chhattisgarh, Jharkhand, Tripura and Orissa.

HIGHEST MAXIMUM

The highest maximum temperature of 44.0 deg Celsius was recorded at Churu (Rajasthan), Jalgaon (Maharashtra) and Khargone (Madhya Pradesh) on Thursday.

Satellite pictures early on Friday morning showed the presence of convective (rain-bearing) clouds over parts of Jammu and Kashmir, Bihar, sub-Himalayan West Bengal, Sikkim, Assam, Kerala, Tamil Nadu, south and east-central Bay of Bengal and the Andaman Sea.

The western disturbance over north Pakistan and adjoining Jammu and Kashmir now lies over Jammu and Kashmir. It would affect western Himalayan region and adjoining plains of northwest India until Monday.

Low pressure Area in Bay ... "95 B" -- Update #1

Present position of Low ..
9.2 N and 90.1 E
Pressure :: 1004 mb
Wind speed :: 40 to 45 KmpH

Expected to become as a Cyclone in next 3 to 4 days and will move in N-N-E direction further into Bay.
More on this brewing system ... "Meandering of WD to flow into BOB"

Heating of land apace in northwest India

A forecast outlook from India Meteorological Department (IMD) indicates that the summer heating of extreme northwest India has started in right earnest.

Arrival of a spoilsport western disturbance has been factored in, but its influence would not extend beyond Jammu and Kashmir and Himachal Pradesh. Mainly dry weather is expected to prevail over the plains of northwest and adjoining west and central India.

The westerly system would be able to do no more than cap the heating trend in the northwest, according to the outlook.

Strong surface winds would prevail over Gujarat, Rajasthan and the Indo-Gangetic plains until Friday. No significant change in temperatures is seen over parts of the plains of northwest India and adjoining central and west India until Friday, the IMD said.

Meanwhile, maximum temperatures recorded on Tuesday ranged between 40.0 deg Celsius to 44.0 deg Celsius at many parts of Rajasthan, west Madhya Pradesh, north Gujarat and Vidarbha.

Global models had indicated earlier that the core heating would cross the northwest border into the western parts of India from this week. This is where the ‘heat low’, a peculiar phenomenon triggered by sustained heating of the land surface develops locally.

This in turn leads to the creation of an elongated area of lower pressure extending from the West Asia desert across Pakistan and into northwest India. This is unlike the usual pattern when heating of the land assumes the sinking motion of air and therefore higher pressure.

The ‘heat low’ is a crucial cog in the wheel of the monsoon system, helping draw, as it would, moisture-laden southwesterly winds from the Arabian Sea and the Bay of Bengal.

Even as the northwest is heating up, the IMD said maximum temperatures were below normal by 2 to 6 deg Celsius over Gangetic plains and Tamil Nadu on Wednesday.

They were near normal over rest of the country except parts of Assam, Meghalaya, Arunachal Pradesh and interior Maharashtra where they are above normal by 2 to 3 deg Celsius. The highest maximum temperature of 45.2 deg Celsius was recorded at Ganganagar in Rajasthan.

During the day on Tuesday, scattered rain or thundershowers occurred over Tamil Nadu and Jharkhand and isolated over east Uttar Pradesh, sub-Himalayan West Bengal, Sikkim and Kerala.

Satellite imagery early on Wednesday morning showed the presence of convective (rain-driving) clouds over parts of south and east-central Bay of Bengal, Assam, Nagaland, Manipur and southeast Arabian Sea.

The IMD traced a trough extending from west Rajasthan to southwest Bay of Bengal across interior Maharashtra, interior Karnataka and Tamil Nadu with embedded upper air cyclonic circulations over west Madhya Pradesh and southwest Bay of Bengal.

Another trough lay extended from an upper air cyclonic circulation over west Madhya Pradesh and ‘telescoped’ into a counterpart circulation over Gangetic west Bengal. In the process, the trough passed over east Madhya Pradesh, north Chhattisgarh and Jharkhand.

A weather warning said that isolated thunder squalls would occur over Jharkhand, Orissa, West Bengal, Sikkim and the Northeastern States until Friday.

A short-term outlook said that fairly widespread rain or thundershowers would occur over Andaman and Nicobar Islands and Lakshadweep until Friday. Scattered rain or thundershowers may break out occur over south and coastal Karnataka, Kerala and Tamil Nadu during this period.

Scattered rain or thundershowers would unfold over the Northeastern States, West Bengal, Sikkim, Jharkhand, Orissa and Chhattisgarh. It may relent later over Jharkhand and Chhattisgarh from Friday.

Isolated rain or thundershowers are likely over Jammu and Kashmir and Himachal Pradesh from Friday.

An extended outlook until Sunday said that scattered rain or thundershowers would occur over northeast and adjoining east and south peninsular India. 

Westerly system may stray into North-West by Thursday

India Meteorological Department (IMD) has said that a western disturbance would stray into northwest India from Thursday onwards.

But the system is not seen drastically changing the weather parameters over the region, which would continue to witness mainly dry weather.

Isolated rain or thundershowers would occur over Jammu and Kashmir from Friday onwards.

Strong surface winds are expected to prevail over Gujarat, Rajasthan and the Indo-Gangetic plains during this period.

Meanwhile on Tuesday, an upper air cyclonic circulation persisted over northwest Madhya Pradesh and neighbourhood.

This, in turn, triggered the formation of a southward-bound and weather-making trough that passed through Marathwada, interior Karnataka and Tamil Nadu.

The trough then “telescoped” into a counterpart upper air cyclonic circulation over southwest Bay of Bengal.

A third upper air cyclonic circulation was on view over Gangetic West Bengal, presiding over local weather.

A weather warning from IMD said that isolated thunder squalls would break out over Bihar, Jharkhand, Orissa, West Bengal, Sikkim and the Northeastern States until Thursday.

The 24 hours ending Tuesday morning saw fairly widespread rain or thundershowers break out over Gangetic West Bengal, Orissa, Meghalaya, Kerala and Tamil Nadu.

It was scattered over sub-Himalayan West Bengal, Sikkim, east Uttar Pradesh, Bihar, Chhattisgarh, south Karnataka and the Andaman and Nicobar Islands.

It was isolated over Jharkhand, Arunachal Pradesh, Assam, Telangana and north coastal Andhra Pradesh.

Satellite imagery in the afternoon indicated the presence of convective (rain-triggering) clouds over parts of south and central Bay of Bengal, southeast Arabian Sea and the Comorin area.

A short-term outlook valid until Friday said that fairly widespread rain or thundershowers would unfold over coastal Karnataka, Kerala, Tamil Nadu and Andaman and Nicobar Islands.

However, the rainfall over Tamil Nadu would weaken in intensity from Wednesday as the clouding spreads out in an east-to-northeast direction into the sea.

Scattered rain or thundershowers is likely over Lakshadweep and south interior Karnataka. 

‘Enhanced rain' from May to July, says Korean forecaster

The Busan, South Korea-based APEC Climate Centre has said in updated forecast on Monday that India might witness ‘enhanced rains' during May-June-July.

This was slightly at variance with some other global models that saw a weaker start to the southwest monsoon, only to be followed by a burst mid-season till the end.

SOME DEFICIENCIES

In fact, the APEC centre saw some deficiencies in July, especially over central and east-central India and the northwest. The outlook for August and September was not available on Monday.

The forecast said that the east Asian coast and Indonesia will receive less rainfall than normal. On the other hand, enhanced precipitation is expected over Indochina and the Philippines, apart from India.

Meanwhile, an India Meteorological Department (IMD) outlook on Monday evening said that the scattered rain or thundershowers over east, northeast and south peninsular India would continue until the month-end.

DRY WEATHER

Mainly dry weather would prevail over northwest and adjoining west and central India during this period, with western disturbances staying away.

A satellite picture in the afternoon indicated the presence of convective (rain-driving) clouds over extreme peninsular India, south Arabian Sea, the Comorin area and south and central Bay of Bengal and the Andaman Sea.

A short-term outlook valid until Thursday said that the fairly widespread rain or thundershowers would sustain over Kerala, coastal Karnataka, and Tamil Nadu.

It would be scattered over Lakshadweep, interior Karnataka and Andaman and Nicobar Islands while being isolated over coastal Andhra Pradesh.

CAUSATIVE TROUGH

As has been the case, the causative system for this weather would be a trough that originates from upcountry and extends down to the south.

On Monday, the IMD located this weather-making trough extending from a cyclonic circulation over southeast Rajasthan and adjoining northwest Madhya Pradesh and running down through Madhya Pradesh and Karnataka.

It consummated in another upper air cyclonic circulation over south Tamil Nadu.

Global models as well as the IMD expect this circulation to emerge into the adjoining Bay of Bengal and drive east-northeast towards central Bay. Towards the east, fairly widespread rain or thundershowers are expected unfold over east and northeast India until Tuesday.

MERCURY TRENDS

On Sunday, the highest maximum temperature of 43.5 deg Celsius was recorded at Deesa in Gujarat. A rise in maximum temperatures by 1 to 2 deg Celsius has been indicated for northwest and adjoining central India.

A weather warning said that isolated thunder squalls would occur over Bihar, Jharkhand, Orissa, West Bengal, Sikkim and the Northeastern States until Tuesday. The rollout of the rough weather here would be overseen by two upper air circulations over Assam and neighbourhood and southeast Uttar Pradesh and neighbourhood, the IMD said. 

IMD : weather report till 8:30am of 23-Apr-2011

Rainfall occurred at most places over Tamil Nadu and Coastal Andhra Pradesh, at many places over Rayalaseema, Kerala and South Interior Karnataka. Isolated rainfall occurred over Telangana, Coastal and North Interior Karnataka. Dry weather prevailed over Lakshadweep.

The following stations recorded very heavy to heavy rainfall in centimetres:

Yercaud 14, Kanchipuram 12, Kavali, Bangalore airport, and Tirumangalam (Madurai dt) 11 each, Tuni, Bangalore, Thozudur (Cuddalore dt), Marandahalli (Dharmapuri dt), Omalur (Salem dt) and Thathiengarpet (Thiruchirapalli dt) 10 each, Srirangapatnam (Mandya dt), Malur (Kolar dt), Ponneri (Thiruvallur dt), Gingee (Villupuram dt), Villupuram and Pochampalli (Krishnagiri dt) 9 each, Hosdurg (Kasargode dt), Kaveripakkam (Vellore dt) and Perambalur 8 each and Rayadurg (Ananthapur dt), Koalr, Thiruvananthapuram airport, Kallakurichi and Sankarapuram (both Villupuram dt), Uthamapalayam (Theni dt), Wallajahpet (Vellore dt) and Ariyalur 7 each.

The other chief amounts of rainfall recorded in centimeters are:

Tadepalligudem and Polavaram (both West Godavari dt), Narsapur, Lakkireddipalli (Cuddapah dt), K. R. Nagara (Mysore dt), Thiruvananthapuram, Cuddalore, Arakonam and Sholingur (both Vellore dt), Pappireddipatti (Dharmapuri dt), Sankaridurg (Salem dt), Perundurai, Sathyamangalam and Gobichettipalayam (all Erode dt), Thruaiyur (Thiruchirapalli dt) and Mettupatti (Madurai dt) 6 each, Bapatla, Kaikalur (Krishna dt), Bhimavaram (West Godavari dt), Kalayandurg (Ananthapur dt), Kanakapura (Ramanagara dt), Kollegal (Chamrajnagar dt), Koppa (Chikmagalur dt), Honnali (Davanagere dt), Hallimysore (Hassan dt), Kudulu (Kasargode dt), Peermade (Idukki dt), Kollam, Maduranthagam (Kanchipuram dt), Tirukoilur (Villupuram dt), Puducherry airport, Alangayam (Vellore dt), Tirupattur, Vellore, Mettur Dam (Salem dt), Bhavani and Kodumudi (both Erode dt), Karur Paramathi and Periyakulam 5 each, Tada (Nellore dt, Nellore, Eluru and Tanuku (both West Godavari dt), Kakinada, Nuzvid (Krishna dt), Pamidi and Gooty (both Ananthapur dt), Srikalahasthi and Venkatagiri Kota (both Chittoor dt), Pavgada and Y. N. Hoskote (both Tumkur dt), Hoskote (Bangalore Rural dt), Bhagamandala (Kodagu dt), Bangarpet (Kolar dt), Vythiri (Wynad dt), Perinthalamanna (Malapuram dt), Pallipattu and Thiruvalangadu (both Thiruvallur dt), Tiruttani, Virudhachalam (Cuddalore dt), Ulundurpet (Villupuram dt), Vedaranyam, Pamban, Anchetty, Penukondapuram and Thali (all Krishnagir dt), Hogenakkal (Dharmapuri dt), Salem, Thammampatti (Salem dt), Erode, Periyar Dam (Theni dt) and Jayamkondam (Ariyalur dt) 4 each, Hirekerur (Haveri dt), Panambur, Madapura and Napoklu (both Kodagu dt), Krishnarajasagara (Mandya dt), Kanjirapally (Kottayam dt), Munnar (Idukki dt), Koderu (West Godavari dt), Peddapuram and Amalapuram (both East Godavari dt), Sullurpet (Nellore dt), Puttur and Palamaner (both Chittoor dt), Aragyavaram, Chittoor, Poonamalle, Ramakrishnarajupet and Korattur (all Thiruvallur dt), Srimushnam (Cuddalore dt), Tindivanam (Villupuram dt), Karaikal, Madukkur and Pattukottai (both Thanjavur dt), Nannilam (Tiruvaur dt), Nagapattinam, Palacode and Pennagaram (both Dharmapuri dt), Kundha Bridge (Nilgiris dt), Karur, Mayanur (Karur dt), Lalgudi (Tiruchirapalli dt), Madurai airport, Peraiyur (Madurai dt), Vaniyambadi (Vellore dt) and Vembavur (Perambalur dt) 3 each, Manjeri (Malapuram dt), Mannarkkad (Palakkad dt), Alapuzha, Aryankavu (Kollam dt), Bandipura (Chamrajpura dt), Jayapura (Chikmagalur dt), Basaralu and K. R. Pet (both Mandya dt), Sargur (Mysore dt), Humchadakatte (Shimoga dt), Addanki (Prakasam dt), Guntur, Repalle (Guntur dt), Anakapalle and Elamanchilli (both Visakhapatnam dt), Bhimadole (West Godavari dt), Gudivada (Krishna dt), Kalingapatnam, Gudur (Nellore dt), Ananthapur, Pulivendala and Vempalli (both Cuddapah dt), Kuppam, Punganur and Thambalapalle (all Chittoor dt), Chennai airport, Cheyyur, Mahabalipuram and Uthiramerur (all Kanchipuram dt), Cholavaram, Poondi and Red Hills (all Thiruvallur dt), Sethiyathope and Panruti (both Cuddalore dt), Marakkanam and Vanur (both Villupuram dt), Papanasam and Thiruvidaimarudhur (both Thanjavur dt), Ambur (Vellore dt), Dharmapuri, Barur, Rayakottai, Shoolagiri and Uthangarai (all Krishnagiri dt), Attur and Vazhapadi (both Salem dt), Valparai, Mulanur (Tiruppur dt), Gudalur Bazaar (Nilgiris dt), Musiri (Thiruchirapalli dt), Madurai, Gudalur (Theni dt), Kodaikanal and Rameshwaram (Ramanathapuram dt) 2 each, Chennai, Chengalpattu, Sriperumpudur, Tiruvallur, Tamaraipakka, Kattumannarkoil, Parangipettai, Adiramapatnam, Kumbakonam, Tiruvaiyaru, Thanjavur, Mayiladuthurai, Sirkali, Tarangambadi, Aranthangi, Kovilpatti, Gudiyatham, Melalathur, Denkanikottai, Hosur, Tiruppur, Kangeyam, Dharapuram, Naduvattam, Uthagamandalam, Kulithalai, Padallur, Chettikulam, Samayapuram, Chittampatti, Andipatti, Bodinayakanur, Virudhunagar, Vinjamur (Nellore dt), Atchampet (Guntur dt), Udayagiri (Nellore dt), Ongole, Visakhapatnam, Atmakur (Nellore dt), Mangalagiri and Sattenapalli (both Guntur dt), Gannavaram, Avanigadda and Nandigama (all Krishna dt), Gajapathinagaram (Vizianagaram dt), Seetharamapuram (Nellore dt), Chintalapudi (West Godavari dt), Narsipatnam (Visakhapatnam dt), Satyavedu (Chittur dt), Madakasira (Ananthapur dt), Proddatur, Muddanur, Rayachoty and Porumamilla (all Cuddappah dt), Koilkuntla (Kurnool dt), Pakala and Kalakada (both Chittur dt), Owk (Kurnool dt), Mananthavady (Wayanad dt), Kayamkulam and Mavelikara and Haripad (all Alapuzha dt) Madikeri, Somwarpet (Kodagu dt), Honakere (Mandya dt), Mysore, Madhugiri (Tumkur dt) 1 each.

Gulbarga, Cuddapah, Nandyal and medak recorded the highest maximum temperature of 38 degree Celsius in the region.

Chennai - Received Drizzles and sharp showers ALL night and even now 8:53am it's drizzling in some parts.


Showers will continue over N. Tamilnadu, entire Kerala for another 48 hrs... Some of the showers will be Very Heavy with Lightning .


Raining All night long over 80% of Kerala, Tamilnadu, S. Karnataka and S. Andhra ...http://ow.ly/i/aG6Q

IMD : Weather report till 8:30am of 22-Apr-2011

Rainfall occurred at many places over Kerala and Coastal Karnataka and at a few places over Tamil Nadu, and  South interior Karnataka. Isolated rainfall occurred over Rayalaseema and Lakshadweep and dry weather prevailed over Coastal Andhra Pradesh, Telangana and North interior Karnataka.

            The following stations recorded heavy rainfall in centimetres:

            Marandahalli (Dharmapuri dt.) 10, Kozhikode Airport 9, Rayakottah (Krishnagiri dt.) and Kudulu (Kasargode dt.) 8 each and Coonoor 7.

            The other chief amounts of rainfall recorded in centimetres are:

Aminidivi 6, Pattukottai (Thanjavur dt.) , Shenkottah and Tenkasi (both Tirunelveli dt.) and Karur 5 each, Ayikudi (Tirunelveli dt.), Kundhabridge (Nilgiris dt.), Peraiyur and Tirumangalam (both Madurai dt.), Bajpe, Panambur, H.D.Kote (Mysore dt.) and Punalur 4 each, Chidambaram (Cuddalore dt.), Pudukottai, Palacode (Dharmapuri dt.), Aravakurichi and Mayanur (both Karur dt.), Marungapuri and Samayapuram (both Tiruchirapalli dt.), Bhagamandala (Kodagu dt.), Bangarpet (Kolar dt.), Srirangapatnam (Mandya dt.), Sarguru (Mysore dt.), Vadakara (Kozhikode dt.), Chittur (Palakkad dt.) and Aryankavu (Kollam dt.) 3 each, Mulanur (Tirupur dt.), Peravurani (Thanjavur dt.), Alangudi (Pudukottai dt.), Denkanikottai (Krishnagiri dt.), Perambalur, Thuraiyur (Tiruchirapalli dt.), Chittampatti and Mettupatti (both Madurai dt.) Andipatti and Periyar Dam (both Theni dt.), Mangalore, Mani, Puttur and Mudibidre (all Dakshina Kannada dt.), Somwarpet and Virajpet (both Kodagu dt.), Perinthalmanna and Angadipuram (both Malapuram dt.), Ottapalam and Pattambi (both Palakkad dt.), Kunnamkulam (Thrissur dt.), Kollam, Varkala (Thiruvananthapuram dt.) and Porumamilla (Cudappah dt.) 2 each and Mudukur (Thanjavur dt.), Arantangi and Perungallur (both Pudukottai dt.), Sivagiri (Tirunelveli dt.), Kanyakumari, Pechiparai (Kanyakumari dt.), Arakonam (Vellore dt.), Vellore , Anchetty (Krishnagiri dt.), Dharmapuri, Thammanpatti (Salem dt.), Valparai, Kothagiri (Nilgiris dt.), Vembavur (Perambalur dt.), Musiri (Tiruchirapalli dt.), Mettupalayam (Coimbatore dt.), Melur (Madurai dt.), Theni and Nilakottai (Dimdigul dt.), Udupi, Anekal (Bangalore Urban dt.), C.R.Patna (Hassan dt.), Harangi, Napoklu and Poonampet (all Kodagu dt.), Madikere, Malur (Kolar dt.), Mysore, Nanjangud (Mysore dt.), Kannur, Quilandy (Kozhikode dt.), Thrithala (Palakkad dt.), Chengannur (Alapuzha dt.), Thiruvananthapuram Airport and Chittoor 1 each.

            On Wednesday, the maximum temperature fell appreciably to markedly at many places Telangana, North interior Karnataka, fell appreciably at one or two places over Rayalaseema, South interior Karnataka, fell at one or two places over rest North interior Karnataka, Coastal Andhra Pradesh, North Tamil Nadu and changed little elsewhere over the region.

             They were appreciably to markedly below normal at many places over Telangana , at a few places over North interior Karnataka, appreciably below normal at one or two places over North Tamil Nadu, below normal at few places over rest North interior Karnataka, at one or two places over South interior Karnataka, rest North Tamil Nadu, appreciably above normal at one or two places over Coastal Karnataka, above normal at a few places over rest Tamil Nadu, above normal at one or two places over rest Coastal Karnataka, Kerala and North Coastal Andhra Pradesh and were generally normal over the rest of the region.

             Tirupathi Airport, Rentachintala and Adilabad recorded the highest maximum temperature of 40 degree Celsius in the region.

Disturbed weather to sustain over east India, south peninsula

Disturbed weather continued to engulf parts of northwest India, east and northeast India, the eastern seaboard and adjoining peninsular India overnight on Monday.

An India Meteorological Department (IMD) update said that widespread rain or snowfall was recorded in Jammu and Kashmir and Himachal Pradesh while it was scattered over Uttarakhand.

TO CONTINUE

Fairly widespread rainfall occurred over Punjab, Haryana, Chandigarh and Delhi during this period.

But it was isolated over Rajasthan, Meghalaya, east Madhya Pradesh, Orissa, Maharashtra, coastal Andhra Pradesh, Karnataka, Kerala, Lakshadweep, Tamil Nadu and Andaman and Nicobar Islands.

Satellite imagery on Monday afternoon indicated that the unstable weather would continue to hold over many of these regions on Tuesday as well.

Convective (rain-bearing) clouds had gathered over Jammu and Kashmir, Himachal Pradesh, Bihar, Jharkhand, Sub-Himalayan West Bengal, Sikkim, Assam, Meghalaya, Kerala, Tamil Nadu, the Comorin area, south Bay of Bengal and south Arabian Sea.

WEATHER WARNING

A weather warning issued by the IMD said that isolated thunder squalls would occur over east Uttar Pradesh, Bihar, Jharkhand, West Bengal and Sikkim on Tuesday.

Meanwhile, the weather-maker western disturbance has on Monday crossed in fully over Jammu and Kashmir.

An evening bulletin said that the system and the retinue are moving eastwards. It would affect western Himalayan region and adjoining plains of northwest India on Tuesday.

The induced upper air cyclonic circulation over Punjab is moving eastwards while a counterpart circulation persisted over north Madhya Pradesh and adjoining south Uttar Pradesh.

It is from here that a ‘trough couple' – one reaching all the way down to south Tamil Nadu across Vidarbha and Andhra Pradesh and the other east-southeast to Nagaland.

WARM SURPRISE

The spike in maximum temperature to within touching distance from the 45 deg Celsius-mark provided a pleasant surprise overnight on Monday.

The IMD said that Sunday's highest maximum of 44.1 deg Celsius was recorded at Umaria in Madhya Pradesh during the 24 hours ending in the morning.

Weak pre-monsoon ‘low' indicated in Bay of Bengal

There is an emerging consensus among some global forecast models on the possibility of a weak low-pressure area building in the south and adjoining central Bay of Bengal over the next five to seven-day period. A ‘low' in the Bay around this time is a typical pre-monsoon season feature, and will help steer the flows to converge during the rest of the season.

LIKELY ENCORE

Last year the Bay had to wait for the third week of April for the ‘low' to shape up, while the just year before was fortunate witness the same as early as April 12.

It had gone to become a tropical cyclone, but no such forecast was indicated for the impending ‘low' in the Bay.

A favourable phase of the periodical Madden-Julian Oscillation (MJO) wave is seen transiting southwest Indian Ocean below Sri Lankan latitude and towards Indonesia around April 20.

WIDESPREAD RAIN

At least two major MJO trackers suggested that the impact of the upper-level wave, which is known to trigger weather over the region it passes, would last until the month-end.

No consensus outlook was available as to the exact location for the formation of the ‘low,' but the vast seas between Sri Lanka and the Andaman and Nicobar Islands suggested themselves as the most likely area.

Meanwhile, the 24 hours ending Friday morning saw widespread rainfall being reported from Assam, Nagaland, Manipur, Mizoram, Tripura, sub-Himalayan West Bengal, Sikkim, Karnataka and Lakshadweep.

Peaking pre-monsoon activity over land also saw fairly widespread during this period over Bihar, Gangetic West Bengal, Chhattisgarh, Vidarbha and Kerala, an India Meteorological Department (IMD) update said in the evening.

It was isolated over Jharkhand, Orissa, east Madhya Pradesh, Uttar Pradesh, Marathawada and Tamil Nadu.

Isolated rain or snowfall was also reported from Himachal Pradesh and Uttarakhand. 

Unstable weather to persist over large parts of country

With a fresh western disturbance expected to cross into the western Himalayas and the adjoining plains of northwest India, regional weather is expected to remain unstable during the weekend and into the next.

The rumble would also be heard in distant east and northeast India as well as the south, as offspring troughs and associated circulations dig in over these regions.

WEATHER WARNING

An India Meteorological Department (IMD) update on Thursday evening said that the fresh westerly would start affecting the western Himalayas and adjoining plains from Friday onwards.

An upper air cyclonic circulation in the lower levels over Bihar and neighbourhood persisted from overnight as did a counterpart circulation over Nagaland.

A weather-making trough lay extended from southwest Madhya Pradesh to coastal Kerala across Maharashtra and Karnataka.

A weather warning valid until Saturday said that isolated thunder squalls would occur over Bihar, Jharkhand, Chhattisgarh, Orissa, West Bengal and Sikkim.

Global weather models also indicated that the unstable weather (as distinct from stable or clear) would spill over into the next week.

WIDESPREAD RAIN

The 24 hours ending on Thursday morning said that fairly widespread rain or snowfall was reported from Himachal Pradesh while it was scattered over Uttarakhand and isolated over Jammu and Kashmir.

Fairly widespread rainfall also broke out over Assam, Meghalaya and Kerala; scattered over Uttar Pradesh, Karnataka, Lakshadweep, Orissa, sub-Himalayan West Bengal, Sikkim and Chhattisgarh.

It was isolated over Madhya Pradesh, Maharashtra, Andhra Pradesh, Jharkhand, Bihar, Gangetic West Bengal, Tamil Nadu and Andaman and Nicobar Island.

Satellite pictures on Thursday afternoon revealed the presence of convective (rain-bearing) clouds over parts of sub-Himalayan West Bengal, Sikkim, the Northeastern States, south interior Karnataka and southeast Arabian Sea.

MORE RAIN SEEN

A short-term IMD outlook valid until Sunday said that widespread to fairly widespread rain, thunderstorms and dust storms would be unleashed over most of these areas in varying intensities.

An extended forecast valid until Tuesday said that scattered rain or snow would occur over the western Himalayan region.