Sunday, June 27, 2010
Adios El Nino, Hello La Nina?
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.
Courtesy: Nasa
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
Google Earth's depiction of clouds
These are the images of clouds on 27.06.2010 / 0700 UTC.
[1] The global picture depicts the monsoonal cloud pattern in South East Asia.
[2] There is less amount of clouds in North Kerala coast. However winds are of greater force.
[3] 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
Sudden downpour throws Chennai traffic out of gear
CHENNAI: The city experienced a sudden downpour on Saturday afternoon leaving hundreds , including office-goers, stranded at bus stops and railway platforms. Several roads and subways were inundated and traffic was thrown out of gear. Meteorology Department officials said the observatory in Nungambakkam recorded 30 mm of rain during the 12 hours ending 8.30 p.m. on Saturday. The Meenambakkam observatory registered 38.7 mm during the same period. Weather officials said the heat during the daytime helped the development of thunder cloud activity.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.
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 !