Monday, November 16, 2009

MJO latest shows.. DRY phase moving in over peninsula from 22-Nov-09.. .. but GFS predicts no effect on NE monsoon.
Again VERY heavy showers forecast for Southern tip of TN on Sunday(22-Nov-09) ..
GFS predictions as of now... it seems another WET weekend (21-22-Nov-09) coming up for Chennai and North TN coast.
Central and East-central India will get some odd thunder storms for next 2 days.
Heavy showers visible over Interior Karnataka and other region has cleared up ..
Chennai - Will wake up on tuesday to a clear & sunny morning.
Coimbatore - Good shower building-up from North-east.. Shower possibility increased to 90%
RT @amolmathur: @weatherofindia The sun is shining bright!

Arabian Sea ‘low’ persists, may bring more showers

Powered by a low-pressure area around Kanyakumari, the northeast monsoon has returned to being vigorous over Tamil Nadu and Kerala during the past 24 hours on Sunday.

An India Meteorological Department (IMD) update said that the ‘low’ has since snapped up an existing cyclonic circulation over Lakshadweep and extended footprint to the immediate north-northwest. A warning valid for the next two days said that isolated heavy to very heavy rainfall is likely over Tamil Nadu and Kerala.

Westerly system

Meanwhile, to the north, a western disturbance is currently affecting northwest India. The rising motion of air in its front and associated convection will cause a rise in maximum temperatures by 3-4 degree Celsius over plains of northwest India during the next three days.

Moderate fog conditions have been forecast over the plains of northwest India during due to presence of moisture and only light winds. But international models saw possibility of rains of varying intensity at some places.

After the system passes to the east, northwesterly winds likely to set in and bring minimum temperatures down by 4-5 degree Celsius over the plains of northwest India.

International models that track the ‘low’ over southeast Arabian Sea are suggesting two directions that it could eye for forward movement – over land up to the Karnataka coast and westward from Lakshadweep towards the open Arabian Sea waters, away from India’s southwest coast.

These models – NGP of the US Fleet Numerical Meteorology and Meteorology Centre and the UK Met Office – are of the view that the system may avoid the track taken by erstwhile Cyclone Phyan.

An odd model – the Canadian Meteorological Centre – saw the system pushing north from the east of Sri Lanka towards the Chennai coast. But this is more or less ruled out since it has already moved away along a perpendicular direction. The seas surrounding the peninsular tip and around Sri Lanka – south and southeast Arabian Sea and the adjoining equatorial Sri Lanka – continue to present a steaming cauldron featuring some of the warmest seas across the globe.

Given this, this region would continue to witness convection that fuels storm building under guidance from a wet phase of the Madden-Julian Oscillation (MJO) wave in the upper levels of the atmosphere. The most active phase of the wave, which travels from east to west periodically over these seas, may just be transiting from southeast Arabian Sea into equatorial Indian Ocean around Sri Lanka and the adjoining southwest Bay of Bengal. This transit could take place over the next three or four days, and, true to style, trigger another easterly wave featuring moisture-laden easterly winds from southeast Bay of Bengal and adjoining East Indian Ocean.

IMD has already mounted a watch for this easterly wave expected to kick in from this weekend. According to the US National Centres for Environmental Prediction, resultant very to heavy rains could fall over Sri Lanka, southeast Tamil Nadu and south Kerala. The European Centre for Medium-Range Weather Forecasts (ECMWF) sees the easterly wave likely setting up another ‘low’ just east of Sri Lanka by Saturday.

The system may clamber up north-northwest to enter southeast Tamil Nadu and extending the trough to cover Sri Lanka, Kerala and adjoining southeast Arabian Sea.

The ECMWF predicts that the ‘low’ would track westward to emerge into southeast Arabian Sea in almost copybook fashion. Pivoted around this would lie a trough with lower pressure, bringing precipitation over Kerala and south Tamil Nadu.

Vigorous monsoon

The NCEP has maintained its outlook for intermittent showers over a wide area from peninsular India looking north-northeast into Orissa/West Bengal during the week.

But the International Research Institute for Climate and Society at Columbia University has picked west Uttar Pradesh and adjoining western Himalayas as well as parts of Madhya Pradesh for concentrated rainfall during the period. This could be the result of interaction between intervening disturbances and the moisture being fanned inland both from the Bay of Bengal and the Arabian Sea.

The northeast monsoon has been vigorous in Tamil Nadu and Kerala while being subdued over Telangana and north interior Karnataka during the past 24 hours, the IMD said.

The Chennai Met Centre said that rainfall occurred at most places over Tamil Nadu and Kerala, at many places over Rayalaseema and at a few places over coastal and south interior Karnataka. Isolated rainfall occurred over coastal Andhra Pradesh and north interior Karnataka. Satellite imagery on Sunday showed convective clouds over parts of southeast Arabian Sea, Kanyakumari, southwest Bay of Bengal and south Andaman Sea.
Sea temperature can help predict monsoon better ...
So far NO substantial prediction of Depression over south-bay around 20-Nov-09. Only possibility is another LOW near Kanyakumari.
latest satellite shot shows less rain cloud formation along TN coast .. and Bay is also subdued ..
Chennai - No showers till now aftr early morning short shower.
Chennai - calm now 8:47am after some early morning showers.