Saturday, April 10, 2010

Monsoon Watch - 1

This annual series is a follow up and chasing of the South-West Monsoon. For now, this series will be chasing and closely following up the actual developments of the monsoon, and how much it is progressing. We are not yet contemplating the quantum of rains or the monsoon strenght as yet.
These reports are my study an obsevations and the progress as analysed will be discussed and explained in this blog.
In this initial stage, we will observe the basic root and foundation,the initial seed of the monsoon.
1. Seasonal Low over India/Pakistan.
2. El-Nino Status.
3. Pre Monsoon Low in the Bay.
4. .Cross Equtorial Winds from Southern Hemisphere.

1. Currently, the day and night temperatures are above normal and extremely high in the Sub-Continent. Yesterday, 9th. April, saw Nawabshah (Pakistan) reach 47.0c.
And, the 45c mark has been touched in India today, 10th. April. 45c at Jharsuguda. I estimate it is about 15 days early than what I would consider normal. Our blog poll showed 47% vote for 45c before 15th. April.
Today's highs in the Sub-Continent: Putting up the list down till 44c, which too is quite a number !
Jharsuguda 45°
Jamshedpur 44.6°
Pbo Raipur 44°
Nagpur Airport 44°
Gaya Airport 44°
Now, this heat should be a plus point in the formation, or a quicker formation of one of the important pre monsoon weather requirment, the seasonal low. The seasonal low, over Arabia thru India stretch ,normally starts forming in the Barmer and adjoining regions in the second week of April. Today, the MSL is around 1002mb in the Sindh/Rajasthan region. (The ultimate low, in June when ready, should be 994mb.)
The Seasonal Low normally is required to start taking shape for the monsoon by the second week of April, but has started early this year.

2. The El-Nino is gradually weakening, though it is required to neutralise before the Monsoon date.
However, the UN agency said that it could not rule out the possibility that El Nino would persist beyond mid-year.
"The most likely outcome by mid-year 2010 is for the El Nino event to have decayed and near-neutral conditions to be re-established across the tropical Pacific," the World Meteorological Organization (WMO) said in a statement.
"Even during the decaying phase of the El Nino expected over the next few months, the conditions associated with it will continue to influence climate patterns at least through the second quarter of the year," it added.
Some sources admit that El-Nino might linger on till June .
Then,monsoon rains and will be back to normal in early July if the El Nino starts to neutralize in June,

3.Another pre monsoon seasonal normal requirment is the creation of a low in the Bay by the second week of April. This is necassary to trigger off the flow and formation of lows from the bay.
Progress this year is bad, as the Bay shows a ridge today. High pressure is prevelent in the Bay. No forecast of any low. (Last year,a low formed by the 12th. of April, and later it intensified into cyclone "Bijli").

4. Cross Equtorial Winds should start forming, and taking shape from mid -April, especially in the South Indian ocean region.
The Mascrene Highs are the main "Power House" of the South -West Monsoons. This generates the South -East winds, which after gaining strenght, cross the equator and become south west.
Initial forming has commenced near the East African Coast. But the winds are not organised. Stronger wind currents are required to be observed near the Eastern side of the Indian Ocean, as the Monsoon stikes the Andaman Sea by mid May.

Summary: Parameter; 1. +ve, Parameter 2. -ve, Parameter 3. -ve. Parameter 4. Normal.
Next update on 18th. April.


anant said...

Any thoughts on premonsoon showers, generally El nino years is belived to result in scarce premonsoon showers. But again co-relation is not confirmed. Do you antcipate any deviation, how are the anticpated western disturbances pattern thios summer ?

rajesh said...

Due to excessive heat, and the development of a line of dis-continuity in the south, I think pre-monsoon thundershowers will be good in the southern peninsula.
About W.D. i feel there may not be too frequent, and may stop by April. Not too sure about this though.

anant said...

what exactly is line of discontinuity, what are its implications ?