Tuesday, September 07, 2010
Since its arrival on the 3rd, this low from the Bay has lingered on in the Orissa region for the last 4 days, without any significant movement, and throwing all forecasts into the bin.
From 1002 mb yesteday, it has become marked at 1000 mb on Tuesday evening.
On Tuesday evening, it is stationary over Orissa (Thai map), and in this constant position, has precipitated very heavy rains in regions south/south west of the low in the last 2 days. Regular formation of thick clouds were seen in the Vidharbah/Chattisgarh and west M.P. areas due to this position hugging system ! Rains, in the these areas, were as much as 222 mms were recorded in Brahmapuri (Vidharbha) today, Jabalpur 106 mms yesterday, and Jalpaiguri 210 mms on Sunday.
Regions in Rajasthan were receiving very heavy rains, with flooding threats to the Kota area. The hill states of Utteranchall and H.P. have been getting good rainfall. Tehri recieved more than 125 mms yesterday, and Simla around 100 mms in the last 2 days. (IMD map of last 2 days).
It is time now for the system to move ! All forecasts aside, ( by the way, the low is now embedded in the monsoon axis), it is now supposed to move along the axis corridor (see IMD map), and travel north-west. Since it is now 1000 mb strength, I suppose it will survive till north M.P. region.
By the 9th. a pulse from the system will travel west towards Gujarat, and form an UAC, which will precipitate heavy rains in Gujarat and north interior Mah.
Later, due to the system's westward movement, southern coast of Sindh including Karachi can expect showers on Saturday/Sunday.
The coastal regions of South Gujarat and North Mah. should get heavy rains on the 9th/10th.
Bharuch district can expect some heavy rains from Wednesday evening and Thursday.
Off shore trough will keep the rains active along the rest of the western coast till the 10th.
There was some misunderstanding in reading my last blog of 4th. A reader from Gujarat questioned if the monsoon was in its last week now.
The 200 hpa winds jet stream has turned complete westerly above the 30N areas. This is still the initial step of monsoon withdrawal.
In a normal time frame, from todays situation, the south-west monsoon can withdraw from west Rajasthan in a week's time. That is when you may see the jet streams in a westerly direction over the North-West regions.
Systems are generally guided by these jet streams for their tracking directions. In the post monsoon period, we will see the westerly jet streams covering the whole peninsula, north of 10N. And the winter systems from the North move westwards.
Mumbai: Contrary to our forecast, Mumbai had some heavy showers on Monday night, and a few showers on Tuesday, with the rain gauge reading 30 mms during Monday night and about 10 mms on Tuesday.
Wednesday:Cloudy day,with rains intensity increasing from evening into the night. Precipitation amount expected till Thursday morning, around 35-40 mms.
Thursday: Overcast and cloudy with frequent rain showers. Rains decreasing after night. Rains expected around 35-40 mms.
Friday: Skies will be partly cloudy, with heavy passing showers, of shorter durations.