Cold nights in interior Tamil Nadu will come to halt with the incoming dip from the westerly trough. With increase in cloud cover it is obvious the heat will be trapped and will not escape atmosphere. Munnar 2 days ago was freezing at 0 C now Munnar, Valparai and Ooty all are settling at around 4-5 C.
We can see slowly the number of stations recording less than 15 C is coming down in the last 2 days but in the next few days it will not increase much and similar night will be there till 18.02.2021.
Dip from Westerly Trough
Normally the westerly trough will affect north India but at times they even dip down to southern peninsular India, thereby bringing unsettled weather to parts of Karnataka, Andhra, Kerala, Telangana and Tamil Nadu.
What to expect
Unlike monsoon rains, these rains are difficult to predict as they dont rain in widespread area. In the past the upper level trough dip have brought hailstorms and severe thunderstorms in Central India, Karnataka, Telangana and Andhra. For Tamil Nadu the lower level winds are still blowing from east and it has to be seen where the westerly trough plays a role in creating instability. It is very difficult to pin-point the areas of rainfall now, may one day to go before the event we can guess which are the areas can expect rainfall with thunderstorms. The instability is seen more in the areas close to eastern coast and interiors where the trough is having a sharp turn and resulting with high divergence at upper level.
2013 westerly trough dip
In 2013 we saw one tough dip, similar to what we are expecting and there was good rains in Tamil Nadu with 120 mm recorded in KTC belt and TN ending 8.30 am on 17.02.2013 in cm is given below
Thiruvalangadu (Tiruvallur Dist) 12,
Poondi (Tiruvallur Dist), Peraiyur (Madurai Dist) 6 each,
Tiruvallur (Tiruvallur Dist), Sriperumbudur (Kancheepuram Dist) 5 each,
Ennore AWS (Tiruvallur Dist), Ponneri (Tiruvallur Dist) 4 each,
Arakonam (Vellore Dist), Tiruttani (Tiruvallur Dist), Sholingur (Vellore Dist) 3 each,
Poonamallee (Tiruvallur Dist), Vaniaymbadi (Vellore Dist), Gudiyatham (Vellore Dist), R.k.pet (Tiruvallur Dist), Red hills (Tiruvallur Dist) 2 each,
Watrap (Virudhunagar Dist), Melalathur (Vellore Dist), Cholavaram (Tiruvallur Dist), Tambaram (Kancheepuram Dist), Ambur (Vellore Dist), Krishnagiri (Krishnagiri Dist), Pallipattu (Tiruvallur Dist), Vellore (Vellore Dist) and Chennai AP (Kancheepuram Dist) 1 each.
Next update on 17/18th February, 2021