Monsoon Watch - 1.. 2014
The Monsoon developments, as they unfold, will be analysed and discussed and explained in Vagaries.
Well well, time flies, and its Monsoon time again ! The South West Monsoon is just about 35 days away from its normal date of arrival from the shores of India ? Yes ! its just 35 days from the Southern most point of India on the South Andaman Islands, Indira Point, where the normal arrival date is 15th May.
And its about time we start the follow up of its progress and monitor its developments. This would be the correct time and jidgment of the Monsoon progress would be simplified at this stage as the ultimate 2 branches are still not formed, and the overall Monsoon "birth" is just taking formation shape.
The Sub-Continent is eagerly awaiting its share of 2014 monsoon rains !
This annual series is a follow up and chasing of the South-West Monsoon. Every article in this series explains the synoptic situation as it actually is, and based on the day's position, the date and quantum of rains as on THIS SITUATION.
It is very important to firstly estimate the date of arrival of the S W Monsoon, as year to year, variations in dates of onset of the monsoon can occur and there have been several occasions in the past when the monsoon arrived over certain parts of the country about a fortnight earlier or later than the normal dates. The SWM has the weatherman tearing at his hair for the exact date or time, extent and progress. This is never 100 per cent sure though various weather models are used to calculate this event.
Weather forcasters are meteorologists, not magicians !
Initially, in the firsr few articles, this series will be chasing and closely following up the actual developments of the monsoon parameters, and analysing its progress regionally for calculating and estimating the arrival date.
We are not yet contemplating the quantum of rains or the monsoon strength as yet.
There are 2 parts to this article:
A)-This is the Ideal Conditions (Map) During SWM Onset in Early June. and
B)below indiactes the actual situation of the parameters situation today (10th April).
A)- Very very briefly, let us first understand, that the "power house" of our SWM is actually based far away in the southern Hemisphere. The main "generating factory" is the Mascarene Highs, between SE of the Madagascar coast and Australia. The SWM is born down South, 4000 kms from the Indian Mainland !
The proper formation of these high regions,(1032/1034 mb at least) will boost and create proper SE winds to lash the East African Coast near the Equator, and then turn perpendicular towards SW in the Northern Hemisphere.
And the formation of the "Tibetan High" is another factor. An anti-cyclone in the upper atmosphere over the Tibetan Plateau. During the formation stages, there will be thunderstorm activity in the SE parts of Tibet during the months of April and May.
To generate a powerfull SW wind, the cross equatorial flow must be strong and gusty. SW winds (ultimately upto 600 mb levels) then are capable of riding on the warmer Arabian Sea waters (Arabian Sea Branch of SWM) and bring cloud masses towards the West Coast of India. In the Bay, similar SW winds are generated (Bay branch of SWM), but from SE winds below the equator, just below Sri Lanka.
And to attract the SW winds, again, we need a good proper "seasonal low" to develop in the Sub-Continent. This seasonal low, normally should start forming around Barmer, Rajasthan, by mid April, and at its peak stretch upto Arabia. Seasonal low at its peak, in June, should normally be around 994 mb, and the ridge around Kerala should be 1008 mb. This enables a good gradiant to pull the SWM Northwards and inland.
B)- In this initial stage, we will observe the basic root and foundation, the initial 4 parameters only, and the initial seed of the monsoon. From these parameteres, later a few more develop.
1. Cross Equtorial Winds from Southern Hemisphere.
2. Seasonal Low over India/Pakistan.
3. ENSO Status.
4. Pre Monsoon Low in the Bay.
The Monsoon developments, as they unfold, will be analysed and discussed and explained in Vagaries.
Well well, time flies, and its Monsoon time again ! The South West Monsoon is just about 35 days away from its normal date of arrival from the shores of India ? Yes ! its just 35 days from the Southern most point of India on the South Andaman Islands, Indira Point, where the normal arrival date is 15th May.
And its about time we start the follow up of its progress and monitor its developments. This would be the correct time and jidgment of the Monsoon progress would be simplified at this stage as the ultimate 2 branches are still not formed, and the overall Monsoon "birth" is just taking formation shape.
The Sub-Continent is eagerly awaiting its share of 2014 monsoon rains !
This annual series is a follow up and chasing of the South-West Monsoon. Every article in this series explains the synoptic situation as it actually is, and based on the day's position, the date and quantum of rains as on THIS SITUATION.
It is very important to firstly estimate the date of arrival of the S W Monsoon, as year to year, variations in dates of onset of the monsoon can occur and there have been several occasions in the past when the monsoon arrived over certain parts of the country about a fortnight earlier or later than the normal dates. The SWM has the weatherman tearing at his hair for the exact date or time, extent and progress. This is never 100 per cent sure though various weather models are used to calculate this event.
Weather forcasters are meteorologists, not magicians !
Initially, in the firsr few articles, this series will be chasing and closely following up the actual developments of the monsoon parameters, and analysing its progress regionally for calculating and estimating the arrival date.
We are not yet contemplating the quantum of rains or the monsoon strength as yet.
There are 2 parts to this article:
A)-This is the Ideal Conditions (Map) During SWM Onset in Early June. and
B)below indiactes the actual situation of the parameters situation today (10th April).
A)- Very very briefly, let us first understand, that the "power house" of our SWM is actually based far away in the southern Hemisphere. The main "generating factory" is the Mascarene Highs, between SE of the Madagascar coast and Australia. The SWM is born down South, 4000 kms from the Indian Mainland !
The proper formation of these high regions,(1032/1034 mb at least) will boost and create proper SE winds to lash the East African Coast near the Equator, and then turn perpendicular towards SW in the Northern Hemisphere.
And the formation of the "Tibetan High" is another factor. An anti-cyclone in the upper atmosphere over the Tibetan Plateau. During the formation stages, there will be thunderstorm activity in the SE parts of Tibet during the months of April and May.
To generate a powerfull SW wind, the cross equatorial flow must be strong and gusty. SW winds (ultimately upto 600 mb levels) then are capable of riding on the warmer Arabian Sea waters (Arabian Sea Branch of SWM) and bring cloud masses towards the West Coast of India. In the Bay, similar SW winds are generated (Bay branch of SWM), but from SE winds below the equator, just below Sri Lanka.
And to attract the SW winds, again, we need a good proper "seasonal low" to develop in the Sub-Continent. This seasonal low, normally should start forming around Barmer, Rajasthan, by mid April, and at its peak stretch upto Arabia. Seasonal low at its peak, in June, should normally be around 994 mb, and the ridge around Kerala should be 1008 mb. This enables a good gradiant to pull the SWM Northwards and inland.
B)- In this initial stage, we will observe the basic root and foundation, the initial 4 parameters only, and the initial seed of the monsoon. From these parameteres, later a few more develop.
1. Cross Equtorial Winds from Southern Hemisphere.
2. Seasonal Low over India/Pakistan.
3. ENSO Status.
4. Pre Monsoon Low in the Bay.
If interested, Full Article on vagaries
