Wednesday, November 12, 2008

Some info from Accuweather - Blog

As the week gets into full swing, it is a good time to pause and assess what is happening, broadly, over the northern Indian Ocean region. The roughly last two weeks have seen exceptionally dry weather, not only where it is usually dry at midfall, but also where it should be raining; namely, the southeast of India.

November is the time of the North East Monsoon, which is really the return of Trade Winds to the Bay of Bengal in answer to the southward shift of the Inter Tropical Convergence. Where northeasterlies blow on shore and up slope (southern east India to Sri Lanka) they bring rain whilst the ITCZ is still significantly north of the Equator. The rains later yield to winter's drought.

So it is an abnormally strong anticyclone aloft, settled as it was over the northern Arabian and the western subcontinent, that shut off the NE Monsoon rains as the four week of October got underway. Only as of this early week are there even a few scattered downpours over southernmost India. But some changes have begun; so, where will this lead?

Satellite imagery shows the scattered deep convection (namely, thunderstorms) has spread westward into the southern half of the Bay of Bengal along with some kind of broad, ill-defined tropical entity. It is this weather system that numerical models have been keying on for something like the last week. However, attempts to spin up a tropical cyclone of it have been no more than numerical fantasy, at least thus far, and the forecast scenarios of the last few days have steered away from any well-marked low (cyclone or depression).

Instead, it looks now like broad, shallow low pressure will tend westward and west- northwestward over the Bay with deep convective rains reaching Sri Lanka as well as Tamil Nadu to southern Andhra Pradesh. Maybe, scattered storms will erupt near the sea northeastward to Orissa.

Were a well-marked low to spin up over the Bay, rather than a broad, shallow and ill-defined low, southern India may end up mostly dry, at least away from the track of the would-be low.

lull.. and what next?

On 10-Nov-2008, there was some rain bursts after a 2 week lull.
Yesterday (11-Nov-2008) again there was lull. In fact there was almost no sign of rain till midnight.
Early morning today (12-Nov-2008, 6 AM) there was some heavy drizzles around.
Now (9:21 AM) it's cloudy, humid, no low cloud movement yet and bad scene is the wind is from west-north-west.
After going thru latest satellite pic and 2 day numeric forecast.
We can say that the RAIN is coming.
It seems to be, there is a LOW formation over the North srilanka.
And this LOW may become into a Depression OR just a Low pressure trough system and move north. If this happens then we'll surely in for more heavy rains in next 36 hrs.