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.
Further Withdrawal from the Country
i) Further withdrawal from the country is declared, keeping the spatial continuity, reduction in moisture as seen in the water vapour imageries and prevalence of dry weather for 5 days.
ii) SW monsoon is from the southern peninsula and hence from the entire country only after 1st October, when the circulation pattern indicates a change over from the southwesterly wind regime.