@vagaries....
Considering the reasons below, and if the situation continues this way, we may see the South West Monsoon withdrawing from Pakistan, West Rajasthan and Southern Parts of adjoining Punjab (to begin with) around 3rd/4th September.
Explanation:
South West Monsoon Criteria for Withdrawal as per IMD:
Withdrawal of SW Monsoon
South West Monsoon Criteria for Withdrawal as per IMD:
Withdrawal of SW Monsoon
a) Withdrawal from extreme north-western parts of the country is not attempted before 1st September.
b) After 1st September:
The following major synoptic features are considered for the first withdrawal from the western parts of NW India.
i) Cessation of rainfall activity over the area for continuous 5 days.
ii) Establishment of anticyclone in the lower troposphere (850 hPa and below)
iii) Considerable reduction in moisture content as inferred from satellite water vapour imageries and tephigrams.
i) Cessation of rainfall activity over the area for continuous 5 days.
ii) Establishment of anticyclone in the lower troposphere (850 hPa and below)
iii) Considerable reduction in moisture content as inferred from satellite water vapour imageries and tephigrams.
The anti cyclone in 850 hp level is not established today. But wee see a ridge forming around 1st week of September in the Pakistan/Rajasthan region. So, effectively, the anti cyclone gets into formation.Upper winds in North and Central India change directions.
Another factor is the 200 hp jet stream. This is one of the main and assertive parameter. The Easterly winds at 200 hp, gradually become Westerly starting from the Northern regions as the Monsoon withdrawal line moves South. In fact, these winds bring down the axis and the withdrawal line.
As the Monsoon withdrwal commences, the seasonal Low weakens, and the core (then becoming around 1000 mb during initial withdrawal ) moves to North Pakistan region.
Another factor is the 200 hp jet stream. This is one of the main and assertive parameter. The Easterly winds at 200 hp, gradually become Westerly starting from the Northern regions as the Monsoon withdrawal line moves South. In fact, these winds bring down the axis and the withdrawal line.
As the Monsoon withdrwal commences, the seasonal Low weakens, and the core (then becoming around 1000 mb during initial withdrawal ) moves to North Pakistan region.
Today, the West winds (at 200 level) are firmly above the 30N line, and gradually sliding South. An anticyclone High forms in the jet streams around the Sindh coast by 1st week of September, thereby creating Westerly winds almost throughout the region of Pakistan and Rajasthan.
-Another factor, connected is the Outgoing Longwave Radiation (OLR).
Today, OLR is also not conducive for the Monsoon to hold on much longer in Pakistan and Rajasthan.
-Also, the Upper Troposphere Humidity plays an important part in supporting and "holding " the Monsoon. The current humidity position indicates a weak situation for Monsoon sustenance.
-Another factor, connected is the Outgoing Longwave Radiation (OLR).
Today, OLR is also not conducive for the Monsoon to hold on much longer in Pakistan and Rajasthan.
-Also, the Upper Troposphere Humidity plays an important part in supporting and "holding " the Monsoon. The current humidity position indicates a weak situation for Monsoon sustenance.
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