Thursday, September 08, 2011

RT @jagadeesan86: @weatherofindia Heavy rain in ambattur chennai now. 9:17 pm
Chennai - the T.shower is still making ground towards W-N-W suburbs of chennai.. now 8:26pm is around 50km from center. Sea breeze is good!
Chennai - a strong T.shower is making progress towards W-N-W suburbs of chennai. Now 7:55pm at 75Km from center.
Signs of a developing positive Indian Ocean Dipole (IOD) event ...
Chennai - The sharp showers has drifted East towards Sea... touching zones south of Tambaram. Now over ECR near Mahabalipuram
"Indian Ocean causes Big Dry" .. more on Indian Ocean Dipole ...
Normally a Positive Indian Ocean Dipole will result in excess North-East Monsoon rain over Tamilnadu ..
@minusminus1 >> Almost NO rain forecast for Mumbai till 9pm today.
Schematic of a positive Indian Ocean Dipole event...

Signs of a developing positive Indian Ocean Dipole (IOD) event

Amid growing signs of a developing positive Indian Ocean Dipole (IOD) event, global weather models have warned about the possibility of continued heavy rain over western India for two more weeks.
This is even as the European Centre for Medium-Range Weather Forecasts saw the next low-pressure area to materialise over south-west and adjoining west-central Bay of Bengal by mid-week next week.
An IOD event refers to the seesawing of sea-surface temperatures (SSTs) in the western and eastern basins of the Indian Ocean.


The IOD is positive when the warmth is more to the west, and vice versa. SSTs are expected to stay at enhanced levels during the period until September 20. A positive IOD event has been seen to boost a concurrent Indian monsoon.
The US National Centres for Environmental Prediction suggests that rains could get heavier towards east India during the latter part of the period, and even going until September 23.
Combined with a suspected La Nina event in the making, which is a magnified mock-up of the Indian Ocean event in the larger Pacific Ocean, the positive IOD would only add to the intensity of the precipitation.


A La Nina-positive IOD combine was witnessed during the years of 2006 to 2008, a rarity in itself, and which underpinned normal to moderately surplus Indian monsoon.
The Climate Prediction Centre of the US National Weather Services says in its latest outlook that the monsoon flows are likely to stay enhanced during the next two weeks.
During week-1 (September 7 to13), this would trigger enhanced rainfall in western India, the Bay of Bengal, Southeast Asia, and the South China Sea. This is attributed mainly to above average SSTs in the western equatorial Indian Ocean.


During week-2 (September 14 to 20), model guidance and above average sea surface temperatures favour enhanced convection in the western Indian Ocean.
But the rains are seen covering more area during this week, with monsoon flow expected to remain enhanced across most of India (including the peninsula), the Bay of Bengal, and parts of South-east Asia. 

Chennai - a sharp shower is approaching Southern outskirts of Chennai.. will reach Tambaram zone in another 10min
RT @venkat5456: @weatherofindia Here it started drizzling in kanchipuram.. :) (3:50pm)
chennai - Sea breeze has just (3:52pm) set in strongly .. and we have a Thunder cell popping up over S-W at around 70km.
Chennai - having another HOT and Humid day .. temp. max was 35.9 C (3:35pm).
Warning, very heavy rain will move in over N.Orissa, entire Chatisgarh in another 24hrs as the N-W bay low moves West.
Rainfall intensity will go down over S-W Rajasthan, N,N-W Gujarat and into S.Pakistan from today evening ..
Heavy rain possible for entire Karnataka coast till 13-Sep
T.showers possible for N. Tamilnadu, Chennai and entire Tamilnadu coast in another 24 to 36hrs..
Monsoon intensity may go down ALL over India after 13-Sep.
Heavy Rains Batter Southern Pakistan...
IMD :: Monsoon would be vigorous over Saurashtra & Kutch, Chhattisgarh and Orissa in association with the low pressure systems.