Southwest Monsoon is having an extended stay over the northern parts, albeit without any significant weather activity for more than a week. The retreat is drawing closer and is likely to commence in the first week of October. A large portion of Nepal and east and northeast India will be vacated by 07 October.
The salient features for declaration of withdrawal include cessation of rainfall, drop in humidity as inferred from the satellite-derived water vapour images and most importantly the reversal of wind pattern establishing anticyclone over Rajasthan. So far only the first feature has complied and accordingly rising temperatures in excess of 40°C are being observed over the west and north Rajasthan for the last one week. However, the southwesterly winds from the Arabian Sea continue to draw moisture and also high-pressure cell (anticyclone) is awaited.
A weak western disturbance is moving across northern parts of the country affecting Jammu & Kashmir and Himachal Pradesh and foothills of Punjab between 26th and 28th September. This will restrict any change in the wind pattern over Rajasthan. After the passage of the weather system, a conducive wind pattern with anticyclonic tendency seems favorable over the area.
Accordingly, monsoon withdrawal looks imminent w.e.f. 01st October from West Rajasthan. The further withdrawal is taken up from other parts considering the same criterion. The withdrawal invariably gets completed by 15th October and paves way for change over to Northeast Monsoon season.
Source: Skymet Weather