Subdued Northeast Monsoon Onset likely

Weather Update

The last couple of days a lot of buzz is around “Northeast Monsoon” with questions like “When & How” dominating the thoughts of not only weather bloggers but also common public. It’s also the period of anticipation for the farming community especially those who have sowed in anticipation of the rains.

As mentioned in our post yesterday wind charts indicate Easterlies aligning which is essential for the rains to push in. But still there is a fair bit of ground to cover though.

If one were to look at the 1.5 kms above sea level wind charts, the altitude that drives Northeast Monsoon, we are seeing a fair bit of Northerly winds. This is more pronounced over North Coastal Tamil Nadu and the adjoining parts of Coastal Andhra Pradesh. The winds from North bring dry continental air reducing the rainfall prospects. From around Puducherry latitude we can see a bit more of the moisture pushing in from Bay of Bengal. This will give some rainfall opportunities to the places along the coast between Puducherry and Delta districts. Few places in South Tamil Nadu could receive moderate showers today while isolated places along the Western Ghats could receive moderate to heavy thunderstorms.

A slightly larger worry though is a possibly weak monsoon onset if one were to look at the model outputs. IMD is expecting Southwest monsoon to withdraw from rest of the country by 20th and possibly a simultaneous onset of Northeast Monsoon. With winds still not aligned completely yet the push for Monsoon onset appears missing. Additionally models look consistent on the next pulse near Andaman pushing away towards North Bay bringing a scenario similar to cyclone Titli a few days back.

But looking at the precipitation anomaly chart it appears most of Coastal Tamil Nadu is likely to see below average rains for the next week to 10 days. In particular places like Chennai in North Coastal Tamil Nadu could be seeing a very subdued start.

While a delayed or weak onset has no direct correlation with the overall performance of monsoon a close watch on the overall monsoon  indicators may be prudent.