Wednesday, June 30, 2010
The monsoon set in over Kerala on May 31 and reached Mumbai on 11 June. A day early, and a date late to the normal dates.
It covered the northeastern states slightly earlier than the normal time, but reached Kolkata only on June 13, about a week later than normal.
As of Tuesday, the monsoon has reached up to central and east India, as per the Monsoon limit line in the IMD map.
Rainfall activity being reported from most of the areas covered are not too uniform, and are sporadic and scanty in the Gujarat region. (Shall put up the monsoon performance map/report till end June as soon as it is published by IMD).
Maharashtra is still on the "pre-monsoon " stage, with thundershowers developing, specially over North Mah. region, every afternoon,but pouring heavy rains in very isolated pockets, and clearing by the the morning.
Else, the rain accumalation map shows some precipitation along west coast, and in patches elsewhere.
But things do not differ much than what has been mentioned in my blog dated 22nd. June, from which I reproduce - "If, after this week, the axis of the monsoon shifts further north towards the Himalayas, and deepens,then the entire peninsula region is in for an unwanted "break". This may delay the monsoon progress into the Northern regions and subsequently into the North-West corner". Mentioned also in my footnote of the blog of 20th.
"The "interfering" monsoon axis has always been my main concern of worry, and has proved that it can create a sort of break monsoon.
My worst fears were that the monsoon would halt, and it sure did ! From the18th, its been stationary, there has not been any advance of the monsoon over new areas since then.
There were many forecasts and "hopes" of the monsoon advancing, but as mentioned in "Vagaries", the MJO has been consistently negative for further advance since the last 12 days.Readers must have checked this point on the link provided in my blog dated the 22nd.
The 200 level jet streams are still stuck at 20N, and will allow the monsoon to progress only when it shifts Northwards.
Now, any further progress will be halted till the formation of a monsoon low pressure area/depressions over the Bay of Bengal.
Interestingly, the COLA has estimated an UAC to form over NorthMaharashtra/South M.P.by 2nd, and the circulation is projected to move west. If so, then good and much needed rains could commence in Saurashtra on the weekend, as COLA estimates rainfall upto 100 mms in the region.
I will cautiously monitor the forming of the UAC.
Strong westerly flows, due to the axix position, over most parts of northwest/ central India and frequent western disturbances have disturbed the monsoon's smooth advance. And the W.D's are making "hay" due to the total absence of any systems from the bay. These are the days for the bay to dominate, not the W.D's.
Now, IMD has said in a special bulletin on Tuesday "that monsoon is unlikely to advance into the remaining parts of east and central India during the next four days.the remaining parts of central and east India are expected to be covered by the end of first week of July and the entire country by the middle of July".
Like i mentioned, nothing on the horizon till 5th. July at least. We preview and monitor again for any good developments each day.
Mumbai June report tomorrow.
India Meteorological Department (IMD) has said in a special bulletin on Tuesday that monsoon is unlikely to advance into the remaining parts of east and central India during the next four days.
But some weather models predict that the monsoon flow will strengthen thereafter, likely leading to its advancement up to northwest India.
LATE IN KOLKATA
In this manner, the remaining parts of central and east India are expected to be covered by the end of first week of July and the entire country by the middle of July.
Tracing back the progress of the rains, the IMD said the monsoon set in over Kerala on May 31 and reached Mumbai on 11 June, both very near to the normal dates.
It managed to cover the northeastern states slightly earlier than the normal time, but reached Kolkata only on June 13, about a week later than normal.
As of Tuesday, the monsoon has reached up to central and east India. Good rainfall activity is being reported from most of the areas covered, too, but there has not been any advance of the monsoon over new areas since June 18.
Further progress is halted mainly due to non-formation of a monsoon low pressure area/depressions over the Bay of Bengal.
Strong northwesterly flows prevailing over most parts of northwest and adjoining central India and frequent western disturbances have upset the monsoon rhythm, inhibiting its advance over the remaining parts of the country.
On Tuesday, an inbound western disturbance persisted over north Pakistan and neighbourhood on Tuesday.
It is expected to affect the western Himalayas and plains of northwest India during next 2-3 days.
Due to the weak Bay of Bengal branch of monsoon, there is some delay in advance over northern parts of Madhya Pradesh, western parts of Bihar and most parts of Uttar Pradesh and Uttarkhand, the IMD said.
Meanwhile, a few international models predicted the formation of a cyclonic circulation/low-pressure area over west-central Bay of Bengal around Thursday.
While this may not help the cause of monsoon progress into areas not covered as on date, another round of peninsular rains may be in the offing.
A ‘low' taking shape near the head Bay of Bengal is the most ideal scenario that can help drive the monsoon current west-northwest into northwest India.
The 24 hours ending Tuesday morning saw widespread rainfall being reported from Assam and Meghalaya in the northeast and fairly widespread over the west coast.
The northern limit of monsoon continued to pass through Rajkot, Ahmedabad, Indore, Seoni, Pendra, Ambikapur, Daltonganj, Gaya, Muzaffarpur and Raxaul, an alignment reached more than a week ago. Satellite imagery showed convective (rain-generating) clouds over parts of Assam, Meghalaya, southeast Arabian Sea, southeast Bay of Bengal and Andaman Sea.
The IMD has forecast isolated heavy to very heavy rainfall over sub-Himalayan West Bengal, Sikkim, Arunachal Pradesh, Assam, Meghalaya, Nagaland, Manipur, Mizoram and Tripura during the next two days.
An outlook until Sunday spoke about the possibility of fairly widespread rainfall activity over east and northeast India and along west coast. Isolated heavy falls are also likely at these places during this period, the IMD said.
Tuesday, June 29, 2010
Monday, June 28, 2010
- NUNGAMBAKKAM – 346 mm
- REDHILLS – 340 mm
- MEENAMBAKKAM – 303 mm
- CHOLAVARAM – 282 mm
- TAMARAIPAKKAM – 275 mm
- GUINDY (ANNA UNIVERSITY) – 250 mm
- MARINA (DGP OFFICE) – 240 mm
- TAMBARAM - 218 mm
- CHEMBARAMBAKKAM - 209 mm
- SRIPERUMBUDUR - 190 mm
- POONDI – 181 mm
- KORATTUR ANICUT – 177 mm
- POONAMALEE - 170 mm
Midnight showers batter chennai 4-5cm would have been recorded in the city. From June Chennai has recorded 130 mm and for the year around 340 mm. Its the heaviest rainfall received in the month of June for more than a decade.
Low pressure to form near chennai coast on 28th June according to GFS.
Sunday, June 27, 2010
Buxaduar 26, Nagrakata 26, Sevoke 22, Diana 22, Murti 20, Champasari 18, Jalpaiguri 18, Alipurduar 17, Gajoldoba 17, Hasimara 16, Bagrakote 15, Neora 15, Balurghat 15
The latest image of Pacific Ocean sea surface heights from the NASA/European Ocean Surface Topography Mission/Jason-2 oceanography satellite, captured on June 11, 2010, shows that the tropical Pacific has switched from warm (red) to cold (blue) during the last few months, perhaps foreshadowing a transition from El Niño, to La Niña conditions.
The blue area in the center of the image depicts the recent appearance of cold water hugging the equator, which the satellite measures as a region of lower-than-normal sea level. (Water contracts slightly when it cools and expands when it warms.) Remnants of the El Niño warm water pool, shown here in red and yellow, still linger in pockets to the north and south of the equator in the center of the image.
The image shows sea surface height relative to normal ocean conditions for this time of year. Red (warmer) areas are about 10 centimeters (4 inches) above normal. Green areas indicate near-normal conditions. Purple (cooler) areas are 14 to 18 centimeters (6 to 7 inches) below normal. Blue areas are 5 to 13 centimeters (2 to 5 inches) below normal
“The central equatorial Pacific Ocean could stay colder than normal into summer and beyond. That’s because sea level is already about 10 centimeters (4 inches) below normal, creating a significant deficit of the heat stored in the upper ocean,” said NASA/JPL oceanographer and climatologist Bill Patzert. “The next few months will reveal if the current cooling trend will eventually evolve into a long-lasting La Niña situation.”
A La Niña is essentially the opposite of an El Niño. During a La Niña, easterly trade winds in the western equatorial Pacific are stronger than normal, and the cold water that is normally located only along the coast of South America extends all the way to the central equatorial Pacific. La Niñas change global weather patterns; they are associated with less moisture in the air, resulting in less rain along the coasts of North and South America. They also tend to increase the formation of tropical storms in the Atlantic.
“For the American Southwest, La Niñas usually bring a dry winter, not good news for a region that has experienced normal rain and snowpack only once in the past five winters,” said Patzert.
The flood situation in Assam today deteriorated further with the water level of the Brahmaputra and its tributaries rising alarmingly and inundating fresh tracts of land. The worst affected districts are Lakhimpur and Jorhat in Upper Assam and the situation was turning worse in several other districts, officials said.
More than 70 villages have been inundated in Lakhimpur by the rising waters of Ranganadi, Dikroi, Kakoi and Singra, all tributaries of the Brahmpautra. In Jorhat district, Brahmaputra's tributary Saraikoni river has breached two embankments under Titabor sub-division inundating 40 villages. The other affected districts are Tinsukia, Dibrugarh, Dhemaji and Morig
These are the images of clouds on 27.06.2010 / 0700 UTC.
 The global picture depicts the monsoonal cloud pattern in South East Asia.
 There is less amount of clouds in North Kerala coast. However winds are of greater force.
 It indicates massive clouds heading towards MUMBAI / NASIK. The rivers flowing through Andhra Pradesh will be getting rainfall at its catchment near Nasik.
Courtesy : Google Earth
According to S.R. Ramanan, Director of Area Cyclone Warning Centre, Regional Meteorological Centre, Chennai has been experiencing unstable weather due to a combination of factors. The development of convective clouds generated in the evening, after intense heat in the day, causes rain, he said. The city has also been experiencing rain due to local thunderstorm activity. This weather is expected to be like this till the end of this month.
Deputy Director-General of Meteorology Department Y.E.A. Raj said it was not unusual to have thundershowers in the evenings during southwest monsoon. “This year, we have had more rain compared to previous years. The rainfall occurs two to three hours after sea breeze sets in as it brings more moisture to the coast,” he said. The sun has been playing hide and seek with the clouds for the past few weeks. This month, so far, the City and Airport has received 84 mm and 117 mm of rainfall respectively, which is much more than the average in June
Courtesy : The Hindu
Saturday, June 26, 2010
This trough is currently north of its normal position. It has been so, and concern for the same has been regularly mentioned in previous blogs.This position allows westerlies to flow south of the trough.
Meanwhile, a W.D.is again moving thru north-west India, bringing partly cloudy sky conditions and isolated thunderstorms.With this, at least the severe heat wave is a thing of the past for now,though days are still slightly above normal.
The low-pressure area off Orissa coast moved inland and is now an Upper air Circulation. Hovering over Madhya Pradesh and adjoining areas, it may precipitate pockets of heavy rains in parts of M.P.and Chattisgarh Monday thru Thursday.
I do not see any international model showing formation of a low, or any system in the bay till 2nd. July. and without this, a major thrust of monsoon rains in the peninsula regions will be absent. This will leave the lone off shore trough along the west coast to hang on, which will result in some 'decent rains" along the west coast.
Due to lack of suitable "waves",I surely see the east coast, south of Orissa, totally dry till Friday next(2nd. July).
A monsoon progress into Gujarat and M.P.could be ruled out till the 2nd. at least.
Delhi, could get the isolated thunder squall produced by the moving W.D.
Today's (Saturday) rainfall map shows very isolated, un-monsoon like rainfall. The rainfall regions could be "hand-picked". The west coast, due to the trough, the eastern sector in patches, due to the UAC, and few regions in the north, due to the W.D. No widespread rains seen anywhere.
Mumbai, like I said, will get diminshed rainfall over the weekend, maybe 5-10mms/day.A couple of short duration heavy falls could be expected,especially during the night.
Some quantum increase in rains, to about 35 mms/day, could be expected on Tuesday and Wednesday, due to the off shore trough lingering on.
Mumbai may be rejoicing with the very heavy rainfall recieved this June,but,as mentioned, the rains are very sporadic, and though Colaba recieved an extremely good amount of 920 mms, Santa Cruz totalled only 650mms. and where it matters the most, the lakes,the rains were measely in comparison. This month,the highest amongst the lakes to get the rains is Bhatsa, with 492 mms,Tansa recieved 263 mms, Vaitarna 236mms and upper Vaitarna 231mms.
Not really impressive, these figures !
Friday, June 25, 2010
The rainfall for this month, till date, 25th, for various places,
Mahableshwar: 492 mms(-88), Agumbe: 887 mms, Mumbai Colaba: 910 mms(+494), Harnai:1037 mms(+532), Cherrapunji:2468 mms(+160).
In sympathy, the western trough off the coast suddenly shot into action, and precipitated heavy rains along the Konkan/Goa coast on Thursday (24th.), wiping out the fears of reducing rainfall there due to the "break Monsoon" scare. And, the monsoon axis, as if in obeyance, has retreated its threatening stand, by forming a core of 992 mb far away from the Indian land mass,deep into the Sindh desert. The correct place for the western end of a typical axis.
The low in the bay is likely to become ‘well marked' soon.That's the repeated expectation since the last 24hrs,but as and when it does, it should travel west into India, and merge into a W.D. approaching from the northwest, and set up rains over the Gangetic plains, and rain in some places in the North, bringing some respite from the severe heat.
But as estimated, the interiors of the peninsula region are relatively drier. Rainfall figures of interior Maharashtra and peninsula cities are still wanting, and rains are badly needed there. And may remain so for the next 2/3 days.
Mumbai has got more than its a fair share of drenching. With Colaba recieving 210 mms of rain in the last 24 hrs, ended Friday morning, the June total has leaped to 909 mms. Now thats a whopping 495 mms above the noraml, or +54%, for this time of the year. The all time high for June is 1280 mms.
But the all India average is -11%, a big improvement from last year, after the disastrous 54 per cent deficit recorded up to June 25 last season. The year 2009 had witnessed the worst drought in three decades.
The +ve regions are the areas where the monsoon has not yet arrived. Like Rajasthan, with+214%. But mainly due to the interaction of the remant of Phet with a W.D. over the region. -ve is in the East.
One of our readers has rightly commented today, that Mumbai is recieving very good rains in spite of no system or active MJO, either from the bay or the Arabian Sea. Defying forecasts, the off shore trough along the west coast, a permanent feature during the monsoon, has shown "its strenght" in the last 4 days and produced very good rainfall along the Konkan and specially off the Mumbai coast.
You see, the trough has been "going on and off" very frequently. It formed a embedded vortex, which suddenly disappeared, without crossing the coast. But still precipitated rains off the Mumbai area (see previous blog). Now today, its Northern end has abruptly moved North to the Saurashtra coast. While observing the trough. I had judged about 100 mms of rain for Mumbai Thursday/Friday, but Thursday itself brought 210mms in Colaba, but 120 mms in the suburbs.Sporadic and differentiating.Santa Cruz total till today is 643 mms !
Ahead,I see the rains lessening a bit in Mumbai during the weekend, only to pick up slightly from Monday.
Further Monsoon movement will depend on the behaviour of the low in the bay. Dont see much prospects of the low picking up till Monday.Hence, rainfall in the interiors of Maharashtra, Karnatak,and eastern plains of Northern India will be restricted. But rainfall can be expected, next 2 days,in Chattisgarh and Eastern M.P. due to the weak low persisting.
Do not see rains advancing much into Saurashtra too.
Thursday, June 24, 2010
SN NAME OF THE DISTRICT ACTUAL in mm NORMAL in mm DEPARTURE [%]
1 ALAPUZHA 360 480 [-] 25
2 KOLLAM 223 374 [-] 41
3 THIRUVANANTHAPURAM 159 285 [-] 44
4 WAYANAD 297 443 [-] 33
5 LAKSHADWEEP 201 260 [-] 23
This shows that SWM winds have not spared well in lower latitudes. But the picture in Tamilnadu is different. Here SWM winds spared well and normal to excess rainfall is realized in these corresponding latitudes. Though not unusual, it indicates some message.
Indian Summer Monsoon Rainfall Index is said to be one indicator of SWM performance. If more convective activities is present in Bay of Bengal it is said that west of 80 Degree East will be getting more rainfall. If convective activities are more near Philippines’ Sea then East of 80 Degree East will be getting relatively more rainfall. Perhaps this assumption is holding good now.
According to Dr Akhilesh Gupta, leading operational forecaster and Advisor to the Department of Science and Technology, the ‘low' may not carry strength to drive itself deep inland.
After crossing land, it may hang over land for a while before weakening as a cyclonic circulation. Still, it would be able to generate some rain. It may move slowly inland and help increase rainfall over eastern parts of the peninsula such as Andhra Pradesh, adjoining Orissa, Chhattisgarh and Madhya Pradesh.
From June 28 (Monday next), this situation may also help bring some rainfall over Bihar, Jharkhand, east Uttar Pradesh and parts of north Madhya Pradesh. With this rain, it is expected that monsoon may further advance into certain areas of east Uttar Pradesh around this date.
Forecast charts also hint at the possibility of monsoon easterlies making their way into west Uttar Pradesh and Delhi by July 2 but have low confidence in the eventuality.
Chennai (Nungambakkam) - 3.0 mm
Chennai (Meenambakkam) - 11.0 mm
Mumbai (Colaba) - 63.0 mm
Mumbai (Santacruz) - 83.0 mm
Wednesday, June 23, 2010
Thankfully, we can forget about the "break Monsoon" in that case.
IMD predicts that "an upper air cyclonic circulation may form over west-central and adjoining coastal areas of north Andhra Pradesh and south Orissa".
The system could transform into a low-pressure area over central Bay by as early as Thursday. The system would head westward along the axis line, over land and might inter act with a prevailing W.D. coming Eastwards from Thursday. The actual interaction region would definitely see good precipitations and advancement of the Monsoon,and go on to set up clouds over further northwest,
The low, on crossing land (could be by Friday), will, in all probibilities, form a North-south trough from the centre of the low thru maharashtra Southwards upto the interiors of Karnataka.Northern peninsula could possibly experaiance widespread rainfall till Monday.
But,the CPC sees the revival of the monsoon covering the entire peninsula,during the week ending June 28.
The existing trough off the west coast is precipitating rains,in its limited capacity.All this due to the stubborn mosoon axis in the North not allowing yesterday's UAC to cross the land.
As discussed in yesterday's blog, the rainfall amounts along the West coast, were much less than originally estimated, save and except the Mumbai coastal regions,which recieved heavy rains.In the Konkan region, only the the Mumbai coast region,has recorded the highest rains.Thane Belapur 17cms,Thane 13cms,Mumbai Colaba 12cms,Dharavi 11cms and Uran 9cms.Even the ghats did not recieve much rains, just between 2-4cms.
Mumbai: Yesterday's revised rain estimates of reduced rains in the Konkan proved correct, but Mumbai turned out to an exceptional "iso;lated wet spot".
As an exception for Mumbai, Vagaries of the Weather original forecast for Wednesday, the forecast published on 20th.June blog,was accurate, with the rain intensity increasing from Tuesday night. Wednesday was a rainy day, with 60 mms at Colaba and 44 mms at Santa Cruz of rain in the day.On revision, the estimate was scaled down to 30mms yesterday.
Overnight Tuesday rain was 123mms in Colaba and 87 mms in Santa Cruz.
Heavy showers, some prolonged, will continue into thursday morning, with rains decreasing in frequency later after friday.Thursday thru Friday should total upto 100 mms of rain for the 2 days.
Seems as of now, weekend rains will reduce to 25-30mms per day, with sunny patches.
Hot Night: Gwalior recorded a minimum temperature of 36.4c yesterday night(22nd. June). One of the hottest on record anywhere, I suppose.The nearest i know is the 38c recorded as the minimum at Sibi(pakistan) a few years back. The hottest night, in my record books, was at Khandwa. the lowest the mercury could go down to was 40c !!
Tuesday, June 22, 2010
A 10-day outlook for monsoon suggests that seasonal rains might just make it to Bihar and eastern Uttar Pradesh, but only with a lag of as many days.
“The normal date for onset over east Uttar Pradesh is June 18, which means that the monsoon caravan is already late by three days,” said Dr Akhilesh Gupta, leading operational forecaster and Advisor to the Ministry of Science and Technology.
NO MAKING UP
And there is no possibility of this delay being made up if initial conditions as obtaining on Monday are any indication, Dr Gupta told Business Line on Monday. This would mean that June would end up with a cumulative delay of eight to 10 days before monsoon rains can reach parts of northwest India beyond east Uttar Pradesh.
Crucially enough, the delay is not seen as pausing a major threat to sowing operations despite the crop (rice, pulses, oilseeds and maize) being largely rain-fed. This is because the transplanting operations in the region are usually taken up between the first week and third week of July only. Rains falling during the intervening period, though, are a blessing for the nurseries.
By the same token, the monsoon may not reach west Uttar Pradesh until July 1, done in by the ‘lag effect.' The big difference is that west Uttar Pradesh is entirely irrigated, and is in a position to cope with the likely delay in onset of monsoon.
According to Dr Gupta, forecast beyond a 10-day period is fraught with risk and it may not be fair to comment on how things would pan out during the rest of July.
For now, however, forecasts indicate a reasonably strong revival of monsoon from Wednesday/Thursday. This active phase may last the whole of the next 10-day period.
A reviving monsoon approaches the mainland always from the south, and triggers activity over the Bay of Bengal as well. Thus, the new monsoon pulse would cover Kerala, Karnataka, Tamil Nadu and parts of Andhra Pradesh before hitting Konkan and the rest of the west coast in phases.
By Saturday, there is a possibility that some kind of a circulation may show up over the Andhra Pradesh coast, which may move inland.
This would bring rains over the north peninsula and central India. Some rains are also likely over Bihar and Uttar Pradesh from a weak interaction of the Bay system with an incoming western disturbance.
It may not bring the monsoon into the northwest, but it would lead to abatement of the severe heat wave conditions in the region.
India Meteorological Department (IMD) said on Monday that heat wave to severe heat wave conditions were prevailing over Rajasthan, Delhi and parts of Haryana.
Heat wave conditions were also reported from many parts of west Uttar Pradesh, northwest Madhya Pradesh and isolated pockets of Gujarat region and Jammu. The highest maximum temperature of 48.1 deg Celsius was recorded at Sri Ganganagar in Rajasthan during the 24 hours ending Monday morning. The heat wave is being anchored by a seasonal trough over northwest India (northwest to southeast), which is aligned slightly north of its normal position.
The northward bias brings a barrage of hot northwesterlies into play over the region, crowding out cooler easterlies from the Bay of Bengal. This is what sustains the heat wave.
But from Thursday onwards, the brewing system in the Bay would allow the easterlies to start filling the plains of the northwest. The resulting cloudiness would gradually help cap the heat.
By July 1, the entire north-west India, except west Rajasthan, would see the heat abate completely as cool easterlies make headway as far northwest as Punjab.
Meanwhile, India Meteorological Department (IMD) sees renewed wet spell along the west coast during the next two days in what is projected as a revival of monsoon.
Seasonal rains had gone into a lull over the last week, delaying the progress of the monsoon into east and east-central India. Fairly widespread rain or thundershowers have been forecast over Konkan, Goa, coastal Karnataka, Andaman and Nicobar Islands, Kerala and Lakshadweep during next 24 hours and may scale up thereafter.
A warning valid for the next two days said that isolated heavy to very heavy rainfall may unfold over Assam, Meghalaya, and Arunachal Pradesh. Heavy rainfall is likely over Nagaland, Manipur, Mizoram, Tripura, Konkan, Goa and coastal Karnataka during this period.
Widespread rainfall activity has been forecast over the west coast during the four to five days. Fairly widespread to widespread rainfall will occur over the Northeastern States while being scattered to fairly widespread central and east India and the rest of peninsular India and Maharashtra.
Northwest India may have to wait beyond July 6 to see the onset of monsoon rains, according to latest updates by international models.
The US National Centres for Environmental Prediction (NCEP) is of the view that entire Rajasthan, parts of west Madhya Pradesh, Punjab, Himachal Pradesh, Uttarkhand and Jammu and Kashmir may be denied timely onset of the rains.
However, west Uttar Pradesh, Delhi and Haryana may just be able to slip themselves under cover during this period.
Northwest India, however, is shown in positive territory, assessed at 25 per cent above normal rainfall for the season (June 1-17) until now. This was largely due to non-seasonal rains dumped over west Rajasthan and adjoining areas by an incoming circulation from erstwhile super cyclone, Phet, early this month, as also by passing western disturbances.
South peninsula is shown at +22 per cent and central India -3 per cent in terms of cumulative rainfall received during this period but northeast India lagged at -22 per cent.
The normal timeline for monsoon to cover the entire landmass is June 30, but this could now get stretched by at least a week, if not more, according to NCEP. The monsoon covers south peninsula, east and central India in calibrated movements mandated by helpful churns mostly in the Bay of Bengal. It then turns west-northwest to head into Rajasthan, Punjab and Haryana, among others, forming part of northwest India.
The Bay of Bengal appears to be the weakest link for now in the vulnerable monsoon chain underpinning its spatial and temporal spread.
India Meteorology Department (IMD) too accepts this fact saying in its latest forecast update that a monsoon-boosting ‘low' might take shape only late this week (around Friday).
But the European Centre for Medium-Range Weather Forecasts sees northwest Bay of Bengal (as against Head Bay), which is not ideal for monsoon to move west-northwest.
Instead, the system might cross the Andhra Pradesh-Orissa coast and head west (as against west-northwest) into east-central and adjoining central India, Maharashtra and Mumbai-south Gujarat, before slipping into the Arabian Sea by June 30.
In a marked deviation from this outlook, though, the NCEP says the system in the northwest Bay might initially track a little east-northeast along the coast and cross the West Bengal coast.
This (around the head Bay) is the ideal position for it to swing the monsoon current west-northwest into east India, covering West Bengal, Jharkhand, Chhattisgarh, Uttar Pradesh and Madhya Pradesh during the week ending July 6.
NCEP weather chart also shows a counterpart spinning up from the Arabian Sea and setting up a rendezvous with the incoming Bay system over land. Even this would not be enough to take the rains into Rajasthan and other places in the northwest.
According to monsoon experts here, they would not be surprised to find on retrospect that these areas have had to wait until July 10 to see the monsoon unfold. These areas would probably need to wait for the next system to get initiated in the Bay of Bengal, of which no clear forecasts were available from any model on Sunday.
The International Research Institute for Climate Prediction at Columbia University sees possibility of heavy to very heavy rains over coastal Karnataka, Konkan and northeast India during the six days ending Thursday.
The IMD too has said in its outlook for the week that the monsoon would be weak over the country except these two regions mentioned by the IRI. In a warning valid for the next two days, the IMD said that isolated heavy to very heavy rainfall would occur over Assam, Meghalaya and Arunachal Pradesh. Heavy rainfall is likely over Nagaland, Manipur Mizoram, Tripura, Konkan, Goa and coastal Karnataka also during this period.
The outlook valid until Wednesday spoke about the possibility of widespread rain or thundershowers over Konkan, Goa and coastal Karnataka.
Fairly widespread rain or thundershowers are likely over the Northeastern States, West Bengal, Sikkim, coastal Andhra Pradesh, Kerala, Lakshadweep and Andaman and Nicobar Islands. The rains would be scattered over Vidarbha, interior Karnataka, Telangana and Rayalaseema, the IMD said.
Now, this development means that there is no UAC present to cross the coast near Mumai as estimated earlier, and as a result, I would scale down the quantum of rainfall estimated earlier.
Since the coastal trough still hangs on (see IMD map),we can expect rains on a lesser scale to continue along the coast North of Karnataka this week.
As mentioned yesterday, I personally think that the Monsoon axis trough running west-east along the Northern plains of India, has had some role to play in the vanishing of the UAC. I have always been sceptical when this axis shifts northwards, as it heralds a "break" period for the peninsula regions, and can weaken the trough, or any embedded low in it.
With the trough intact, as it will be till Friday 25th. at least,rainfall to some extent will continue along the coast and in the interior areas of Maharashtra and Karnataka thru this week.
If, after this week, the axis of the monsoon shifts further north towards the Himalayas, and deepens,then the entire peninsula region is in for an unwanted "break". This may delay the monsoon progress into the Northern regions and subsequently into the North-West corner.
Though nobody wants a break now, the MJO forecast (see this link) shows the "unwanted negative" MJO waves during the next 15 days. When positive, it creates the "lows" and the depressions, and the rain bearing systems into the monsoon currents. When forecasts show a negativity, it reads as less systems in the regions.It is one of the few aspects of the weather that can be skilfully predicted beyond about 2 weeks into the future.
But, I really hope that things change for the better, and Nature eventually ridicules man's forecasting. We will keep our observations updated and monitor the same.
Meanwhile, the extreme in the Northern belt continues with a special mention of a minimum of 33.8c at Gwalior last night, and 32.6c as the low at New Delhi.
Mumbai: Will continue to get the passing showers on Tuesday, with about 10 mms of rain. Wednesday's forecast may have to be scaled down due to the reasons discussed. City can expect a few more showers, with rainfall during the day totaling 20mms. Thru Friday, Mumbai can get passing thunder rain, and with the rainfall scaled down, city may just about recieve 25-30mms till Friday.
Monday, June 21, 2010
Highest in Asia: Mecca and Jeddah (S.Arabia), Sibi (Pakistan): 50c
Highest in India: Dholpur 48.8c, Ganganagar 48.7c, Hissar 47.8c
Sunday, June 20, 2010
"Vagaries of the Weather" mentions today (afternoon write up) of the possibility of a heat wave returning to the region. But before "the ink could dry",we have it on us !
Today's highest in Asia reading returns back to Pakistan, with Larkana and Sibi notching 51c.Followed by 50c at Al Ahsa Airport in Saudi Arabia.
Bhawalnagar(Pakistan) was next with 49c
In India, it was Ganganagar as usual with a high of 48.1c.(Information from smaller towns not yet in).
Delhi airport has jumped to 46.7c today.The list of 47s and 46s are long, so putting up a map of the highs today would be better.
Monday could see higher temperatures in the region...
On Sunday, Mumbai had a high of 32.2c at Colaba and 32.6c at S'Cruz, with 2.2 mms of rain (Colaba) and 9.4 mms at S'Cruz. (Prediction for Sunday in this blog was 32c and 15mms of rain.)
Kerala can be divided into three unique rainfall regions, each region having a similar covariance structure of annual rainfall. Stations north of 10.N (north Kerala) fall into one group and they receive more rainfall than stations south of 10.N (south Kerala). Group I stations (table 2) receive more than 65% of the annual rainfall during the south-west monsoon period, whereas stations falling in Group II (table 3) receive 25-30% of annual rainfall during the pre-monsoon and the north-east monsoon periods. Group III stations (table 4) with IIIrd factor as the primary loading, i.e., IIIrd factor greater than Ist and IInd factor.
Abstract of Heaviest Rainfall places in Kerala
Neriamangalam 451 cm
There is a lack of direct relationship between the height of a station and its rainfall from this study. The spatial variability of mean annual precipitation depends upon the topographic factors like exposure of the station to the prevailing wind, elevation, orientation, and slope of the mountain.The study is, however, limited to the number of rainfall stations available and a better network of stations in the region will reflect more local-scale phenomena. The results are useful for mesoscale and synoptic scale atmospheric modelling.
More Rainfall data & the detail study can be found in
For the west coast of India, this is the trough we have been observing. The embedded UAC which was expected to form off Mumbai, and now going by our estimate, should strenghten to some extent, and cross the coast south of Mumbai by Tuesday evening.
Resultantly, the entire west coast North of Karnataka (included) should get enhanced rainfall from Tuesday thru Friday. The brunt of very heavy rains, on Wednesday/Thursday will be taken by the Konkan region and the adjoining western ghat stations.
I do not expect the UAC to go to great strenghts, but still could pour some extreme rainfall of +250 mms on Wednesday/Thursday in extreme cases along the Konkan coast or ghat stations.
The rain spell will be restricted mainly along the coast, and may not venture much into the interior of the peninsula regions. The much needed parched regions of interior Maharashtra and adjoining Karnataka, M.P.will get scanty rainfall, in pockets, during the week, not exceeding 10-15mms /day.Vidharbh could get some good rain on Wednesday.
The push into Gujarat will be after Wednesday. From then we see the rain areas pushing into Saurastra, with rain in almost all the regions of Saurashtra from Wednesday thru the week.
But the Monsoon throughout this week, till the 25th. at least, will refuse to move further.On 22nd,It will just about enter Gujarat region, barring the Northern Kutch and adjoining Rajasthan region.
Till the 25th, it will remain stationary in the eastern sector, without moving towards east U.P. That's the gateway to the Northern plains including Delhi. No formation of any low is seen in the head bay till the 25th, which makes me conclude the stationary monsoon prediction in this sector.Even the 200 hpa jet streams do not "fall in place" before that.
That translates to a continuation of the heat wave in Rajasthan, Punjab/Haryana and delhi.With a mainly clear sky, the maximum temperature would hover at around 44c in Delhi. And the desert state could see 47/48c next few days.On saturday, Phalodi in Rajasthan sizzled at 46.5c and Kota registered 46.3c.
Mumbai: Well, we had our hot day on Sunday,with just about 5 mms of rain. Expect some passing showers on Monday, rainfall upto 15 mms.
Tuesday will be overcast, and by evening, an increase in rainfall can be expected.
Wednesday thru Friday, will be days of heavy rains, with flooding in vulnerable areas. Rains on Wednesday could be around 50mms, And 80-100mms on Thursday/Friday.
The trough of low at mean sea level passes through Churu, Gwalior, Rewa, Gaya, Asansol, Kolkata and thence southeastwards to eastcentral Bay of Bengal.
Now,something has got me thinking.The forecast prediction for this trough is a bit confusing. IMD's GFS maps show this monsoon trough, along the Northern plains,dropping pressure to 994 mb, with a core of 992 mb, by the 24th. Frankly, if that were to happen,I would fear a Break Monsoon condition. Now that's quite scary ! A Break Monsoon is the last thing we need now!I am not predicting this,I am just putting up my point of view. It may not happen, and I hope not, but a low trough of 992 mb in the East-West axis is certainly not the ideal situation during, or even before the monsoon has set in !