A post on heat is ironical when the talk among weather community of Tamil Nadu is about upcoming NEM. Yesterday as Peninsular India started seeing clearer skies heat returned with a bang over most of Tamil Nadu. While places like Madurai, Karur saw 4°C above max temperatures Tondi was abnormally hot by 6.4°C. The observatories at Nungambakkam and Meenambakkam recorded near identical temperatures of 36.9°C and 36.8°C respectively. Across the state temperatures showed a spike yesterday.
Over the last few days thanks to the Depression of AP / Odisha coast partially cloudy skies kept a check on afternoon heat. The depression is now over MP leading to a substantial reduction in moisture over Peninsular India. On the other hand rains along the Peninsular West coast has also reduced leading to reduced moisture from west. This will bring clear skies during the day providing perfect conditions for afternoon heat over most of Tamil Nadu.
The sub seasonal weather models indicate for the next couple of weeks temperatures over Tamil Nadu may be abnormally hot. The Extreme Forecast Charts indicate temperatures may stay on the upper band of temperatures recorded historically during September. On 5th September Madurai AP recorded 40.8°C which is the highest for September. The earlier highest was 40.4°C during the year 2019. Looking at sub seasonal charts there is very high chance few other IMD stations may also follow suit.
Weather models indicate for the next couple of weeks afternoon temperatures may be 2 – 4°C above normal across the state. With thunderstorm activity expected to remain subdued even night time temperatures may be abnormally high. All in all until middle of September Heat it is fair to say Heat is here to stay. Hopefully the abnormal heat during the next fortnight allows for an active transition season thunderstorms the subsequent fortnight. Looking at satellite charts the weak moisture seen over NW India gives hope for a quick monsoon withdrawal from Northwest India once the back to back lows complete their life cycle.
Until then time to bear the 2nd summer and wait for possible thunderstorms during the late evening hours. Today parts of North TN, particularly around Villupuram and Cuddalore districts may see some rains. Chennai and suburbs may see some rains tomorrow. But the overall pattern would be isolated thunderstorms for the next couple of weeks.