Saturday, September 30, 2006

With 05B depression trooping in westward,I feel that Mumbai will once again get some rain Sunday through Tuesday.The forecasts show good rain along the pathe from M.P. to interiorMaharashtra and S.Gujarat coast and scatterd in Saurashtra.The system will weaken fast in land.This late season rain may not be in excess of 10 cms. that too in in some places.

Wednesday, September 27, 2006

To continue from my last writing, the expected low over the bay has formed today. But with a weakening wind shear, I have my doubts whether the low will gain much strength. It develops near the 20 line and may move inland and weaken fast. The high pressure anticyclone is also pushing in now from the north and pulling the ITCZ southwards. This withdraws the monsoon currents and the monsoon has started retreating southwards. According to the IMD, the monsoon has moved away from Kashmir, Punjab, Haryana and Rajasthan.

Maharashtra may only get a stray thundershower or two before the monsoon finally moves out by the end of the week.

But for the east coast next week, maybe near Tamil Nadu, we still have to watch the New typhoon "Xangsane" now in full strength over the Phillipines. For its full magnitude see Jim's blog of the 27th.

Mumbai, we have only a shower or two to come, before the monsoon withdraws by the end of the week. And then brace up for the October heat!

Saturday, September 23, 2006

Yes,Ashokbhai,I agree with your comments.The Cyclonic storm in the Arabian Sea,will dissipate over water within 24-48hrs. The storm turned out to be something of a non starter.After being stationary over the Sea at 19.5Nand 66.5E for almost 3 days,and keeping the meterologist guessing,it has now taken a steady course of slowing down and maybe not stricking land at all.

On the other side of the African continent,somewhat weather history has been created by tropical storm Gordon.Gordon was a Category 1 hurricane when it moved through the Azores Islands in the Atlantic.It remained a category one storm while it headed into the Azores. Rarely does a hurricane stay a hurricane and cross that region of the far eastern Atlantic. Last year, Tropical Storm Vince was the first tropical cyclone in weather history to ever hit the Iberian Peninsula, which includes the nations of Spain and Portugal.

Well, here it seems the strong bay depression will also weaken now,though after causing heavy rain and damage to the eastern states of India.Rain between 11cms-17cms. has been recorded yesterday in several places of Jharkahand and W.Bengal.

We may still have to keep a watch on 17w off the Vietnam coast.It can come as a pulse and become a strong depression in the bay soon next week.

In the mean while,with the threat of "Mukda"waning,the hit or miss thundershowers will take place in some places of Maharashtra and Gujarat region and rain gradually reducing and withdrawing from Rajasthan and Kutch.

Wednesday, September 20, 2006

The Indian peninsular is covered on both sides by low pressure systems.To the east the depression has today stationed itself over Jharkhand and adjoining West Bengal. It has caused heavy rain and flooding in W.Bengal and Bangladesh. The depression may move in a North Westerly direction through Jharkhand,Chatisgarh and East M.P.By then,it may curve northwards,if the low in the Arabian Sea is to move North East.All along it will produce heavy rain,but may leave the rain in Gujarat and Maharashtra to the Arabian Sea low.

Now, the other low in the East Central Arabian Sea is today off the Saurashtra coast.The IMD and another model expect it to move North East,that is towards Gujarat.Saurashtra coast has recieved good rain in the last 24 hrs. with Ranavav getting 9cms. and Porbunder 7cms. among others getting between 3-6cms.That is because the anti clockwise winds of the system are now covering a part of Saurashtra.The core of the low is at present producing very heavy rain and may move faster than the bay depression.The next 24hrs. will show its ultimate intention.If it gains strenght,then the two states of Guarat and Maharashtra will get heavy rains,specially along the coast.

This development has again delayed the withdrawal process of the monsoon.Temperatures in Rajasthan and Kutch are still not high to form the high pressure ridge.

The two systems from the bay are the remnants of the busy West Pacific,still producing severe typhoons.

Sunday, September 17, 2006

The sudden formation of an embedded low in the Arabian Sea off the N.Maharastra- S.Gujarat coast, rain activity has suddenly increased in the Saurashtra region of Gujarat. Areas recieved between 5 to 9 cms of rain. The sudden formation of the low in the trough running along the west coast has also resulted in the creation of an east west shear zone running along 19° due to the low in the bay off the A.P. coast. The low in the bay has now become well marked and is expected to move inland .

A notable feature was the remarkable and extreme variation of rain within Mumbai. Different locations in Mumbai, from North to South, within a range of 35kms., recorded heavy rain in a short peroid between 5.30pm. and 7.00pm.-Bhandup:80mm, Tulsi lake:75mm, Borivali:62mm, Malad:39mm, Santa cruz:24mm, Colaba:1mm. The variation was a very clear example of micro weather over urban areas. That is the formation of huge rising thunder clouds over urban areas due to urban uneven heating and precipitating more rain in spurts.

The seasonal anticyclone has also formed over Rajasthan, thus resulting in the drier air settling down over the area and resulting in the reversal of the monsoon winds. However the monitoring of the two lows is important now, and the winds feeding the low are gaining ground over the peninsular area. Hence, rains will gradully increase in A.P. and all over Maharastra soon. Gujarat may see a decrease in rains in a day.

Saturday, September 09, 2006

The monsoon may show signs of widhrawing from the extreme west of Rajasthan, maybe from Monday 11th Sept. Signs of withdrawal means the formation of a high pressure area which will bring dry air down (in a low pressure air rises up). This is delayed as the last persisting low had left moisture in the region (see picture). In fact, even today, there was rain across in Pakistan in Chor, Karachi and Jacobabad and in scattered places in Rajasthan (Bikaner had 30mm). The seasonal high will not settle until the moisture rains out, and may take two days as the days are getting hot.

The rain over India as a whole is exactly normal. But we still have September rains to change the figures. Except the north east, the rain is excess or normal elsewhere. See map.

A new low is expected to form in the bay around Monday near the TamilNadu coast. But if there is stressed moisture inland, it may not move too much.

Jim Andrews mentioned about the unexpected longevity and capacity of the previous low. It surely beat all forecasters, but all good meteorologists expect the weather to beat them sometimes. As an expert only studies the weather, not control it. So Jim, man proposes, God disposes!

Tuesday, September 05, 2006

The bay has been churning up a depression this year at the rate of one per week since July.Every one of them has caused heavy to very heavy rain along its path.Rainfalls in the range of 250mm has occurred.Ratnagiri had an extremely heavy pre monsoon downpuor of 647mm in a day in the last week of May,and desert areas have recieved rains upto 150-200mm in a day.

Now,why I mention these statistics is because this trend of heavy rain was recorded in U.K. too as per the article in "The Sunday Times" of 3rd.Sept. which I reproduce below. I am sure it would interest my readers .


"The Sunday Times
September 03, 2006

Britain gets a monsoon forecast: Jonathan Milne,

BRITAIN’S gentle drizzle is giving way to tropical-style downpours and cloudbursts as accelerating climate change disrupts weather systems, according to academic research.
Rainstorms have doubled in intensity in parts of the country and are becoming more concentrated in autumn, threatening the nation’s flood defences.

“Extreme rainfall” events, associated with the onset of climate change, are occurring almost a century earlier than had previously been predicted.
Some parts of Britain are now regularly seeing almost a foot of rain over 10 days. The worst affected area is the east of Scotland, which has experienced a 72% increase in the ferocity of rainstorms over the last 40 years.
Other regions which have experienced a substantial change in rainfall patterns are the northeast and northwest of England.

“Extreme rainfall has doubled over parts of the UK since the 1960s,” said Dr Hayley Fowler, senior research associate at the school of civil engineering and geosciences at Newcastle University. “Intensities previously experienced every 25 years now occur at six-year intervals. There have also been changes in timing, with extreme events now predominating in autumn months.”

Fowler’s findings come amid suggestions that climate change is playing havoc with the country’s weather. This July was the hottest on record for most of England, while last winter was the coldest for a decade.

The temperature extremes have meant British farmers are now planting walnut trees, olive groves and grape vines, which have traditionally flourished in the Mediterranean.
The new research, to be presented this week at the British Association Festival of Science in Norwich, finds that all Scotland and the northwest of England had an average rainfall of more than 8in over the worst 10 days of each year in the 1990s.

Parts of south Asia have fiercer downpours during the monsoon season. Mumbai in India, for instance, averaged 8.2in of rainfall over the same period, according to official statistics.
The prospect of a rain- soaked autumn will come as little surprise to some regions, such as East Anglia, which has just experienced its third wettest August on record.

Fowler predicts the greater frequency of autumnal downpours will lead to more severe flooding and structural damage, such as seen in Boscastle, Cornwall, in 2004 when some 8in of rain fell in just four hours.
“I wouldn’t live near a river,” she said. “We need to think about whether to build homes on flood plains. The government has got to take a lead. We can control what happens on the ground, but we can’t control what falls from the sky.”

The rainfall pattern in the south east has also shown major changes with fewer torrential downpours. This may be linked to an overall decrease in rain across the region, which has led to water shortages. Although there are fewer such events, they are becoming fiercer, meaning the south east is at increased risk of occasional flooding.
Widespread floods in southern England in October 2000 affected 10,000 homes and caused £760m of damage. "
Continueing from my last blog,the merging of the previous low with the W.D. has caused a lot of rain dumping in the norhtern states like Kashmir and Punjab.Amritsar got 140mm of rain and all the rivers in Jammu and Kashmir region are in spate.Flash flooding is reported in the valley.Jammu city recorded 140mm of rain in the last 24hrs.
The latest depression has crossed Orissa and is weakening.Before that,let me state that due to a temporary ridge along the arabian sea,temperatures started rising slightly in Gujarat and going upto 33-34°c in places.But I feel with the approaching low,rains will bring down the temperatures.This depression is already pouring heavy rain (150mm in Govindpur,100mm in Paradip) in Orissa,and is moving N.West towardsM.P. and Gujarat and Vidharbh,portending rain in these areas since it seems to have deep convection in the south.
With another W.D. approaching from the west by the end of this week(by the 8th.),northern areas of Pakistan and India should get rain around that time.
Now is the bay done with?Not yet,according to Jim Andrews.Typhoon "loke" may yet send a remnant this way,maybe next week?But,due to the winds changing along with the season,and the approaching W.D.,the next of ,if it forms,may, I feel, move North/North-east,sheared off by the North- westerlies.

Friday, September 01, 2006

The total rain as of end August for Mumbai is as expected. On the plus side. The city has had a total rain of 1947 mm (78") and the surburbs 2494 mm (100") as of end August. Last year, on this date, the rain was 1603 mm (64") for city and 2545 mm (102") for the surburbs. Not to forget Mahableshwar, it has accumalated 7771 mm (311") as on end August.

The Bay is buzzing again! Its getting back to what it has been doing throughout this season. A new low is expected to form in the bay on 3rd Sept. The existing low has moved north to merge with the W.D. This is after a long instance that I have noticed a low forming in the bay on its own. Most of the lows forming in the bay are migrating remnants of pulse energy and circulations moving from the South China sea.

The movement will have to be monitored, as the last low moved quite differently and unexpectedly initially. It has already dumped substantial rain over M.P. and Chattisgarh and now is active over Rajasthan.

Weather has slightly cooled down in the Northern states of Kashmir and H.P. showing a mild trend of autumn. Gulmarg in Kashmir has gone down to 9°c on the 30th, showing a lowering trend.

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