Bay watch

It shows an unsettled setting from the southeastern Arabian Sea and southern India to western Indonesia and the Malay Peninsula. Ill-defined cores seem to be near southern India and near Sumatra. The pattern of high cloud (whitest is coldest and thus highest) to the west suggests upper winds about a ridge, aloft, fanning these clouds westward and northward; the ridge would be anchored over eastern India. This radial flow could be supportive for the growth of a tropical depression in the area, most likely west of southern India, were it to persist.

Lowest pressure now has two centers: one is east of Sri Lanka and the other over the Laccadive Sea. I believe that the one to watch here is the western one, given what I am seeing on numerical weather forecasts. Make no mistake about it, though: there is not yet a consensus as to where and when any depression or cyclone would happen. Indeed, I do not see this as a `done deal` yet.

Latest numerical forecasts include the GFS, which is slow to grow a low over the Arabian Sea. It eventually (after November 5th) brings rain to southern Oman. It also suggests a southern Bay low, but the timing is different--later by 2-3 days--than had been earlier shown.

The NOGAPS has two lows developing including a Bay low that lands in SE India at about Oct 28. This is once again slower than earlier forecast runs. The NOGAPS has a stronger Arabean Sea low--further west and faster--than the GFS.

The ECMWF from earlier Tuesday shows a strong low (if true, it would be an important tropical cyclone) ominously near to southern Oman by October 30th. As for the Bay, the trend is in line with the other models: a low (depression or cyclone) that is shown to be slower to form than on earlier model runs.

It is still a waiting game without much confidence. The time of year is right for a depression or cyclone--and so is the overall weather setting. Yet it may take another few days to get a basic idea of where any such weather system, or systems, takes shape.

Numeric forecast for 25-Oct updated

Still we can see a LOW forming over the bay of bengal.

Below is the rainfall forecast for 25-Oct.

North-east update

A new weather setting has taken hold compared to that of early last week. Then, an upper trough straddled northern India and southwesterlies (the last of the South West Monsoon) were still wetting the far-northeast of the Subcontinent. Now, high pressure has built aloft over the Subcontinent and has shut off the SW Monsoon over Bangladesh and nearby India. Farther south, a broad low has spread over southern India and Sri Lanka, the results being the blow-up of showers and thunderstorms suggested by the above infrared cloud shot (IMD).

The pressure as of Monday evening, local time, is 2-4 millibars higher over Bangladesh than over Sri Lanka. This is enough to drive a weak (north)easterly wind flow over the western Bay of Bengal, so we should be looking at the first days of a North East Monsoon.

Numerical forecasts do not agree as to the coming weather for the greater North Indian Ocean region, although there are important aspect wherein there is agreement. As I had talked up last week, there is still the suggestion that a tropical depression (or cyclone) will happen over the Bay of Bengal later this week. Timing for a visit to the Tamil Nadu coast of India was indicated for the 26th or the 27th. Today, numerical models are not agreed as to this (other than the NOGAPS, which still shows it).

One cause of the straying of the model solutions lies with the low over southern India. There is an tendency on the part of the numerical forecasts to take this low to the southern Arabian Sea, where it would compete with and perhaps slow the growth of any Bay low. By the way, the seeds of any Bay low may already be sown in the blow-up of cloud and rain over Sumatra and the Malay Peninsula (see the satellite image). The last two to three days have seen rainfall of 33 cms, or 13.0 inches, at Sibolga, western Sumatra.

Both the GFS and the ECMWF show lows over the Arabian Sea looking forward 5-7 days. And the longer range outlook of the GFS even shows low pressure reaching southeastern Arabia with rain. This is forecast about two weeks forward in time--far too far ahead for any meaningful confidence.

MSN Foreca

A good way to know your weather.
Provided by MSN and Foreca. Have a look at it here http://weather.msn.com/region.aspx?wealocations=India

Monsoon Picking up

Today the Northeast monsoon picked up in strength, but still i think it's weak. Today the low cloud movement is from NORTH, this is also not good sign. For rains to become heavy it should come from EAST, straight from the SEA. Anyway monsoon weather is nice to see & feel. Here is the latest Insat pic.

Numerical forecast for 25-oct

This forecast is for 25-oct-2007.
You can see a LOW formation over the south-east bay of bengal... will it form or ???

Forecast for 24-oct show...

Numerical forecast for 24-oct shows a deep low formation over south-east bay of bengal. Take a look ...

North-east forecast

Shifts are happening this week that hint at the start of the North East Monsoon in India. The South West Monsoon, which has been slightly slow in withdrawing, has clung to power in the North East. This has been helped by an upper trough in the sub-tropical jet stream (`western disturbance`) over northern India. Numerical forecasts have been consistent in showing that the upper trough will soon be kicked eastwards leading the westerly flow over the northern Subcontinent to `flatten`. This should boost pressure to the north relative to that over southern India and nearby tropical seas. This would weaken, if not reverse, what remains of the South West Monsoon.

Another factor for flipping the wind flow over India is a tropical depression, or cyclone, that is indicated for the Bay of Bengal on or about the middle of next week. To be sure, this is not a `done deal`, but it has been shown rather consistently for a few days. Anyways, such a low would further bolster the weakening and ultimate reversal of the seasonal wind flow.

A would-be harbinger of the North East Monsoon, which brings with it the seasonal rains to southeastern India, can be seen on the COLA Website. This is the Short Term Climate Outlook, which is compiled from GFS numerical forecasts. In the second week of the two-week outlook, there is a big blow-up of rainfall over East and South East, India.

At last arrived

The northeast monsoon has arrived over chennai.
Initially the showers will be of low intensity.

The first small shower was around 6 AM, 20-Oct-2007.
As of now the showers are not widespread but soon it'll be heavy and widespread.
Let's see how it develops.

IT highway Chennai