Friday, September 24, 2010

SW Monsoon 2010 retreating in near full swing

Akshay Deoras
Severe Weather Forecaster

Confirmations have now started coming after near a week of nil rains in Central India and some time in Rajasthan which is the first place where monsoon retreats
The season had started retreating well by 15th Sept 2010 as I had expected but a low
pressure formation over eastern states and its dominance for more than a week pulled back the retrival
Currently no low pressure is expected to form in bay near India and Central parts with western and eastern maharashtra will remain hot and dry as the monsoon flow retreats

According to IMD, the 2010 season is already 4% more than normal i.e 2010 rainfall till mid september is 104%.

The basic thing for this absence of low pressures is definitely the withdrawal period and the weakening MJO which was -1.5 in mid september. MJO is now turning to positive phase which means that potentials for cyclones and severe low pressures will increase given the perfect November for near active Cyclone season in India.

From 24th Sept data updated models of MJO, in the long 70-90E which is standard area of ocean (bay and arabian sea) whose activity affects inland's weather HAS TURNED TO 0- (-0.5) RANGE.The lowest of this years MJO was -2.0 which was definitely sufficient to trigger rains in Sept also.
The daily Indian Summer Monsoon circulation index from CPC is showing the graph of active monsoon is going down after a final phase in mid september.

I expect the process of withdrawal to be completed by near mid October and winters will likely kick off in North and Central areas by last week of October. However, a delay can be caused and it depends on the intensity of the withdrawal. A positive aspect is the southwards shifting of the local jet streams which is a sign of approaching cool period. 20-30kt jets at 200mb are already digging in upto Rajasthan
Given the La Nina conditions this year, I expect slight cooler than normal in North regions esp NW India.

For latest see-

Earth is still in the path of the high speed coronal stream which is causing high electron flux fluctuations and KP nearing to 3.
NOAA has estimated a Kp 4 soon since now the disturbance is increasing

High latitude areas must watch Auroras connected to the event!!

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