Thursday, October 29, 2009

North-east Monsoon Outlook:

Rainfall has occurred over coastal Tamil Nadu and over south Tamil Nadu and Lakshadweep during the last 24 hours ending Wednesday morning.

This is seen as a build-up to the northeast monsoon. The easterly and northeasterly winds over Bay of Bengal and peninsular India would now gather further strength over the next few days.

An east-west trough from southeast Arabian Sea thru to south Andaman Sea cutting through extreme south peninsular India has formed with an embedded cyclonic circulation over southeast Arabian Sea.(Thai map)

The international model,NCEP, says that heavy rains would be confined largely to coastal Tamil Nadu between October 28 and November 4.
But after November 5 the rains will penetrate into interior Tamil Nadu and adjoining Kerala.

Again, the NCEP and Albany/Roundy model holds on to the possibility of a storm in the Bay in the first week of November.

The 30-day Southern Oscillation Index (SOI), now at minus 12, was at its lowest value since 2007.
A consistently negative SOI points to the development of some convective activity along the south Andaman/Indonesian sea.and drought-producing "down south."
Ocean surface temperatures in the central equatorial Pacific have warmed further and now exceed levels typical of an El Nino event by their greatest margin of the year, Australia's weather bureau said on Wednesday.
"Climate models suggest tropical ocean temperatures will remain above El Nino thresholds until at least early 2010," said the Australian Bureau of Meterology.

Meanwhile, in the North, nights are getting cooler, and starting from the Northern regions of India, the cool "tongue" can be seen sinking southwards into the central regions. Lows of 11c are observed in Punjab and west M.P.regions. The all India low is as usual in Ladakh at -17c. In H.P, it was 0c in Kalpa.
Another approaching W.D. is expected to precipitate some rain/snow in the Himalayan foothills in the next 2 days, and notch up the night readings by a few degrees.
Later, in the first week of November, cold will dig into the plains of the Northern sub-continent areas.

Sunday, October 25, 2009

Delayed North-East Monsoon:

The wait for the delayed reverse monsoon seems to be over. At least that's what I see. Am I imagining a "loop " of low in the Bay ? ( streamline map).

A easterly wave approaching the eastern coast (T.N.region), is seen as breaking the dryness, and precipitating rains along the T.N. coast and A.P. coastal regions.

According to the COLA forecasts, the rainfall may start along the T.N. coast from Wednessday. Chennai too can expect some rain to commence from Wednessday, with increasing intensity daily, till saturday at least. from Thursday onwards, the rains are seen penetrating inland into the interiors of T.N. and into Karnataka.

Additional information from Albany Roundy ! A cyclone is seen by this model in the bay from the 4th. of November. It will be peaking around the 10th. and crossing the North T.N./ A.P. coast around that date. But, this is their estimate as per the conditions today. And the estimate as of now. Situations normally change, and sometimes change a lot, as we review day by day.

Friday, October 23, 2009

Typical October Sub Continent Weather:
The temperature anomoly map of the region shows a "blow hot-blow cold" picture. Red, in the desert areas- over heating, and in the northern regions,blue - extra cool.

Its typical, and peculiar October weather in the sub-continent. Heat, in the central regions, with the oddest places, like Mumbai (Colaba) at 37c, as the highest with a few other stations in Sindh also at 37c.on Thursday, the 22nd. And Rajkot as the highest at 38c on Friday.
In the northern Himalayan mountains, the nights are getting chilly, with Churshul, Ladakh, at -14c, as the lowest, and Leh close at -5c. Kalpa, H.P. was -1c, and Srinagar at 1c. All on Friday morning.

The current 925 hps streamline does not promise anything to write home about. Nothing Precipitation wise, in the sub-continent area, next 4/5 days. No systems, no W.D's.

Monday, October 19, 2009

Season's First Snow in Leh :

Currently, the 925 hpa streamline( IMD) shows no south-westerly winds over the peninsula; in fact, weak north-easterlies were observed in the southern regions of the east coast.

No model indicates the formation of a low in the bay. With the latest `low' being embedded in the north-south trough, the Bay should now host a fresh low for the north-east monsoon.

The IMD forecasts a feeble western disturbance across the northern Himalayan region next 2/3 days.

Starting from the northern most region of India, with first major snowfall of the winter season in Ladakh, the entire Leh town was snow covered today ( Sunday, 18th.),till afternoon.
An inch at the low-lying areas and one ft of snow at the upper reaches of the district was recorded. Due to snowfall, Khardong la pass remained closed for traffic in the morning.The day however became clear later, and the high in Leh was 9c, and the low at -1c.

Srinagar was 2.6c, as the minimum. In H.P. it was Kalpa at 0.5c, as the lowest.

Delhi, Punjab and the northern plains have now slipped to the range of 15-18c.

Further south, in the central regions, the nights are cooler, in the range of 15-18c, with Ahmednagar at 14.5c and Nasik at 15c.

Sunday, October 18, 2009

A very interesting and useful information of the Global Analysis of the temperatures and precipitation for September 2009 from The National Oceanic and Atmospheric Administration is reproduced below:

Global Highlights:

1.The combined global land and ocean surface temperature for September 2009 was 0.62°C (1.12°F) above the 20th Century average of 15.0°C (59.0°F). This was the second warmest September on record, behind 2005, and the 33rd consecutive September with a global temperature above the 20th Century average. The last below-average September occurred in 1976.
2.The global land surface temperature for September 2009 was 0.97°C (1.75°F) above the 20th Century average of 12.0°C (53.6°F), and ranked as the second warmest September on record, also behind 2005.
3.The worldwide ocean temperature tied with 2004 as the fifth warmest September on record, 0.50°C (0.90°F) above the 20th Century average of 16.2°C (61.1°F). Warmer-than-average sea surface temperatures were widespread, particularly in lower latitudes. The near-Antarctic southern ocean and the Gulf of Alaska featured notable cooler-than-average temperatures.
4.A weak El Niño persisted across the equatorial Pacific Ocean during September. Sea surface temperature observations in the equatorial Pacific Ocean during the month remained above average. According to NOAA's Climate Prediction Center, El Niño is expected to strengthen and last through the Northern Hemisphere winter of 2009-2010. During the month of September, warmer-than-average temperatures were present across Canada, Europe, the northern and western contiguous U.S., eastern Brazil, and most of Asia and Australia. The warmest anomalies occurred in Canada, the northern and western contiguous U.S., western Russia, and parts of Australia, where temperature anomalies ranged from 3-5°C (5-9°F) above the 1961-1990 average.
Northern Hemisphere and the Southern Hemisphere experienced above average temperatures for the combined land and ocean areas, resulting in the second warmest September on record, behind 2005 and 1997, respectively. The Southern Hemisphere September temperature tied with 2003.

The worldwide sea surface temperatures (SST) during September 2009 were warmer than average, but not record-breaking as the June-August seasonal temperature.
Land, +0.97°C (+1.75°F), 2nd warmest(This year), and warmest ever was 2003 (+0.57°C/1.03°F).
Land and Ocean, +0.62°C (+1.12°F), 2nd warmest (This Year), and warmest ever was 2005 (+0.66°C/1.19°F).

Meanwhile, for rainfall, the areas with the wettest anomalies during September 2009 included the southeastern and south central contiguous U.S., southern Brazil, and parts of India, Scandinavia, the Philippines, and northwestern Africa. The driest anomalies during September 2009 were observed across eastern Asia.

Thursday, October 15, 2009

Sub-continent Weather:

1. Northern region will have some light rains and snow in the upper most northern areas. A W.D. is expected topass thru the region next few days. The W.D. will pass thru quickly and precipitate for a day or two. The nights have cooled down into the teens now. (Map). After the W.D. that is say after Divali, I expect a further drop in the night temperatures, and even the days will get a bit cooler.

2. As per the MSLP map, there is a trough leading into the bay. This will result in some rain in the north-east.

3. The southern - most peninsula will get light rain, more so in Kerala. Its the result of the remant moisture of the withdrawing monsoon.

4. A high has settled down in the central regions of India. Ensuring clear weather and cooler nights this week.

El-Nino Status:
The following UPDATE is prepared by Climate Prediction Center / NCEP – 13 October 2009.

The latest weekly SST departures are:
•Niño 4 ~ 1.0ºC•Niño 3.4 ~ 0.7ºC•Niño 3 ~ 0.7ºC•Niño 1+2 ~ (-0.7)ºC

•El Niño is present across the equatorial Pacific Ocean.•Sea surface temperatures (SST) were at least 1.0ºC above-average across much of the central and east-central equatorial Pacific.•Based on current observations and dynamical model forecasts, El Niño is expected to strengthen and last through Northern Hemisphere winter 2009-10.

Early winter in the European Alps :

"Austrian mountains have seen up to 45cm of snow as Arctic weather has swept through the country. The weather station at Rudolfshütte in Salzburg, which is at 2000 metres above sea level, had received the most snow - 45cm - on the night of Mon/Tues. High wind had accompanied the snow, with gusts of up to 150km/h reported on the Schneeberg in Lower Austria and gusts of more than 100km/h in many areas. Such high winds, the agency said, were recorded on average only once every 25 years. The snow in the mountains is a taste of things to come for some provincial capitals, which are expected to see their earliest snowfalls in history this week. Josef Haselhofer from ZAMG said yesterday the cold weather would probably result in the first snow cover in provincial capitals before 20 October in history and added Innsbruck, Salzburg and St. Pölten were likely to see snow. The record for early snow in provincial capitals was set in 2007, when snow remained on the ground in some of them from 20 to 24 October."

Monday, October 12, 2009

This rainfall map of the last 24 hrs. shows the rains gradually retreating southwards, and spreading dry weather in the rest of the sub-continent regions. Yes, IMD has now withdrawn the monsoon 15N upwards, 2 days after my stating about it.

I estimate almost dry weather all over, except along the coastal regions of Karnataka and Kerala. COLA sees a vortex forming along the Karnataka coast on 15th, for a day. So, we can expect some heavy rainfall along the Karnataka coast for a day on 14th/15th. Manglore can expect good rains around the same days.

No lows seen forming in the bay ! All estimates gone haywire! As yet. Many international models had foreseen a low in the bay in the 1st.week, and subsequently in the 2nd. week. And I had projected the arrival of the reverse monsoon in the south, around the 15th. on the assumption of the lows. But, I do not see that happening this week.

And yes, a W.D. is on its way in the north. By this weekend, the Kashmir region and H.P. will get some rains and snow.

The first signs of the nights getting cooler are seen in the northern and central regions of the sub-continent. Kalpa ( H.P.) saw Oc today, and Keylong and Leh were at 2c.

Next week, after the W.D. a sharper drop in temperatures could be expected, specially in the north.

Friday, October 09, 2009

For all the regions above 15N, that is Karnataka and above, I would say the monsoon is done with, and the dry season has set in. Except for the odd shower, on Saturday, I do not see any rain in the region. For the southern states, thundershowers may still pop up over the region. But that is due to the withdrawing monsoon.

No indications of the low formation in the bay yet, to estimate the north-east monsoon arrival.

The IMD map shows the core of the seasonal low at 1004 mb. Would not really call it a "seasonal low".

As expected, the nights temperatures in the "non monsoon" areas have started dropping, to a certain extent. In Maharashtra, Pune and Nashik have seen temperatures in the 17/18c range, lower than the 22/23 of the last few nights. Mahableshwar was at 13.9c today morning. In the north too, the average is now in the 17/19c range.

For Mumbai, dry weather, and temperatures will be in the range of 33c and 25c. Not much of clouds seen forming, as humidity is dropping.

Wednesday, October 07, 2009

Thank God for small mercies !
We had earlier discussed the stubborn resistance in the monsoon halting its southward withdrawal progress, at the 20N line, that is north Maharashtra/M.P. border, holding on since 15th.september.

Well, all for a reason. Good, and bad. Southern states like Karnataka, Goa and A.P. had too much of the rains in the 1st week of October burst, causing flooding and loss of lives. But, also improving the water levels.

Maharashtra, had a good spell too, causing some damage and flooding.

But for Mumbai, the October rains were very very usefull, and with almost 175 mms of rain in the 1st week of the month. The lakes levels supplying water have increased, and 2 lakes have actually overflowed on the 5th.of October.

Now, for Mumbai, the rainy season is almost over with. An odd chance, say 20%, of a thundershower on Friday evening, at the most.
Drop in humidity in the next 2 days will be a welcome relief, but now i can imagine the days getting to 34-35c, by the end of this week.

Yes ! The monsoon should push down southwards now, from Thursday. The 200 hpa winds do indicate the same, as the winds are seein veering around the 20N line today.

Very limited rains could be expected in the south too next 7 days.

But, the promise of more systems from the Bay holds good. Most of the international models predict a low in the Bay around the 15/16th. Now, that, I repeat, would be the inauguration of the north-east monsoon. The T.N. coast and A.P. can expect commencement of rains from the 15/16th, or around that time, depending on the exact date of the formation of the low.

For the north, look out for drop in night temperatures from the 8th. itself. Those regions with night temperatures in the early 20s, will drop to 18/19c, and those regions in the late 20s, will go down by 3/4c, next few nights.

Monsoon Summary:
For 2009: The June to September rain deficit has been assessed at 23 % as the southwest monsoon figures were officially closed by IMD on 30th. September, making it the second worst monsoon in the last 37 years.
The deficit climbed up close to the 23.9 % recorded in recent memory (1972). The next worst is the 24.9 % recorded way back in 1918. And 1899 was -26%. Lowest ever was 1877 at -29%.
Some related facts about the wet spots of Maharashtra, Mahableshwar and Lonavala.
This year, M'shwar recieved 3811 mms of rain, (normal= 6200). Almost near the lowest ever of 3545mm in 1899.
Lonavala recieved 3476 (estimated normal= 4500).
All rain figures upto september, as previous year's figures relate to that period.

Monday, October 05, 2009

On Sunday, a W.D. trough was dipping down to Rajasthan and adjoining north Gujarat and west Madhya Pradesh.

The W.D. trough and the ‘low’ have almost interacted and, now, should to some extent strenghten the W.D. Rains can now be expected to continue for another 2 days across central India, northern and northeast India.

IMD has also confirmed that -" the W.D. and the monsoon easterlies would interact to bring fairly widespread rainfall with isolated heavy to very heavy falls over Uttar Pradesh, Uttarakhand, Himachal Pradesh, East Rajasthan, and Haryana until Tuesday."

I would predict very heavy rains, as the combined strenthened W.D. moves eastwards, in the Himalayan foothills adjoining Bihar and sub-Himalayan West Bengal, Uttar Pradesh, Uttarakhand and H.P. Regions of U.P. are already recieving heavy rains, like Agra with 115 mms today.

The well-marked low-pressure that caused some of the worst flooding in Maharashtra, Karnataka and A.P. has weakened into an upper air system, and was over south Gujarat/Maharashtra on Sunday.
Large tracts of Northern Maharashtra and the adjoining M.P.regions were lashed by heavy rains on Sunday and Monday morning.

I would now estimate the rains in this region to gradually decrease, starting Monday evening. The rainfall in interior Maharashtra would reduce from Tuesday, and the coastal regions can expect rains, though less than the current spell, till Thursday. Gujarat should go dry from Tuesday.

For the south, its another story with the new lows projected in the bay.

Mumbai: Substantial reduction in rains from Monday night. Much less rain on Tuesday, a few showers in some parts. Rainfall reducing from Wednessday, at least till the weekend.
The city recieved heavy thundershowers with gusty winds Sunday/Monday, with Colaba getting 115 mms in these 2 days, and S'Cruz recieving 105 mms. Yes ! The October totals cannot be neglected like we discussed earliar. The vortex low actually traversed across Mumbai, from east to west on Sunday. This was apperant as the wind direction changed 180 degrees from north-east to south-west in a 12 hr. period.
Mumbai was the coolest city in the state (outside M'shwar) on sunday ! The day was highest at 24.7c, 7c below normal ! Cool for a Mumbai day, even if it were December !

Saturday, October 03, 2009

Post Script :Some figures of very heavy rain on Friday/Saturday in Konkan/Goa.

Canacona-38, Margao-27, Panjim, Sanguem-26 each, Dabolim, Pernem-25 each, Ponda, Marmugao-23 each, Ratnagiri, Mapusa-12 each, Sangola-11, Jat, Panderpur, Dahiwadi-10 each, Chiplun-8, Phaltan-7, Gaganbawda, Mangalvedha, Karmola, Akkalkot, Guhaghar, Khed, Lanja, Koregaon-6 each.
Now, the stationary well marked low has at last started moving westwards, crossed into land and is over Telangana region. As result, Orissa and North A.P. recieved rainfall ranging from 30-90 mms.

The "pushing pulse " from the low has formed an upper air circulation off the west coast, somewhere around the Konkan-Goa coast on Saturday night.
Hence, again, some extermely heavy rains could occur in South Konkan, Goa and northern regions of interior Maharashtra. As per COLA predictions, very heavy rains can be expected in Nasik and districts of N.Maharashtra. These heavy rain predictions can be expected on Saturday/Sunday.

Another low could still be expected in the bay early next week. The Climate Prediction Centre ( US National Weather Services) predicts an intensification of the upcoming low to a depression level or more.

This year looks like an extensive typhoon churning weather from the South China Sea/West Pacific Ocean. The region is already alive with two Category-4 typhoons closely after typhoon Ketsana making a landfall over Vietnam two days ago.
One of them, Parma, is heading for the South China Sea, and intensifying.
The other prevailing Category-4 storm is Melor, and heading for Cat.5.
A trough extending from India right into the west Pacific (Map ) is the reason for development of weather systems in the west Pacific/South China Sea. And, reason for pulses to continue in the Bay of Bengal, at least till end of October. ( This could mean a good begining to the N.E. monsoon for the south).

Mumbai: Sunday will be cloudy, with a high of 31c, and low at 27c, with showers in some parts of the city, and evening will be windy and thundery. Rains of medium intensity will continue on Monday. Sunday/Monday rainfall could be around 25-30 mms.

With the process of withdrawal of the monsoon getting stuck, for almost 15 days now at 20N, a heat wave in the northwestern areas of the subcontinent is created. On Friday,2nd, Chorr (Pak) reached 44c, highest in Asia for the day, Karachi was an unbearable 42c, and in India, Bikaner and Jaisalmer were 41c, while Bhuj in Kutch touched 40c. This regional heat wave can continue till Sunday.
The temperature chart of India shows a clear division of heat in the west, and normal/below normal temperatures in the "monsoon areas" of the eastern/southern half.

Thursday, October 01, 2009

Post Script continuation:
Just got info. from Regional centre Mumbai of some very heavy rain in Maharashtra on Wednessday/Thursday: CHIEF AMOUNT OF RAINFALL IN CMS:
Rajapur-28, Lanja, Malwan-27 each, Devgad-25, Vengurla, Kudal-18 each, Dabolim, Kankavli-10 each, Sangamneshwar-8, Sangli, Sawantwadi, Hatkalanglw-7 each, Ratnagiri, Sholapur, Vaibhavwadi, Panjim, Gadinglaj-6 each, Marmugao, Ajra, Miraj, Akkalkot-5 each, Gaganbawda, Gargoti, Kavathe Mahankal, Jat, Kadegaon, Jat, Uran Isalampur, Tuljapur-4 each, Igatpuri, Beglan, Kolhapur, Wada, Akkalkuwa, Kagal, Changad, Radhanagari, Shirala-3 each, Nasik, Dindori, Shahada, Panhala, Shahuwadi, Tasgaon, Mohol, Mangalvedha, Sangola, Umergaon, Lohara, Latur, Nelanga, Ausa, Renapur, Davani-2 each, Surguna, Sinner, Osmanabad, Parbhani, Chiplun, Dapoli, Khed, Vita, Partur, Osmanabad, Jalkot, Akola, Lonar-1 each.
GHATS:- Koyna(N)-3, Koyna(P)-2.

As on Wednesday, the well-marked ‘low’ in the bay held to its position of the last two days and is not showing any fast signs of westward movement inland. But the IMD streamline shows it partly inland as of today.

As a result, the system showed good cloud bands in its western quadrants, and the monsoon has been vigorous over Marathwada, south Maharashtra, coastal Andhra Pradesh, Telangana and north interior Karnataka while being active over konkan, Goa and coastal and south interior Karnataka.
27 cms of rain in Sangamneshwar, and 14cms in Ratnagiri were the heavy downpours in southern Maharashtra.
These late season rains in the overall peninsula regions are sure to be of great help to an otherwise weak monsoon.

Montoring the system now, at the coast off A.P, it is likely to move west, weaken, and bring rain along its path in the next 2 days.
Maharashtra, A.P. and north Karnataka will be the main beneficiary states. Around the 3rd. of October, coastal regions of south Maharastra and Goa can get very heavy rains, maybe upto 300 mms /day.
Northern regions will continue to remain dry.

International Model predictions also continued to predict westward movement but without time commitment. I feel, it should re-emerge in the Arabian Sea by the 3/4 October.
ECMWF predicts the prevailing well-marked ‘low’ may cross the peninsula and show up over the west coast around October 5.

Anyway, after crossing into the sea, we will watch and see if it gets "deeper", and in which direction it moves. If there is a north/west movement, coastal Gujarat may start getting heavy rains from the 4th. I would restrict the rains to coastal Gujarat, as inland penetration of any system, into Gujarat, around the 3/4th. is not possible. This is due to a W.D. "aloft", which may be over the Kashmir region around those days.
Also, all eyes on look out for the new low in the bay, remant of Typhoon Ketsana.

Mumbai: Having recieved some showers on Wednessday night, I think Mumbai can expect thundershowers on Thursday night in some areas. Moderate rain and showers can be expected too, on Friday/Saturday, with cloudy skies. Thundershowers can form in the evenings. With the temperature going down to 31c, it should bring some relief from the sweltering heat.

Mumbai has recieved 1761mm of rain in the 4 months of this rainy season. Of-course this is -264mm , and S'cruz has recieved 1971 mms, -294 mms. IMD ends its official monsoon rain count on 30th. September. But, on many occasions, as in this year, the monsoon season continues well into October.
And, October does recieve sizable amounts of rain too. The highest Oct rain for Colaba was way back in 1917, when in this month Colaba had 507 mms or rain.( No mean amount !). And not too far back, in 2006, Colaba recieved 246 mms of rain in Oct. S'Cruz got 238 mms that month.
So, we just cannot neglect the October rains for the seasonal totals, not till the monsoon withdraws from the city.

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