Defining Week ahead for Bengaluru Rains

Weather Update
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Since the start of 2024 the two IMD observatories at Bengaluru, City & AP, has received total rains of 19 and 3.4 mm respectively. Between 8th of January and 2nd May the city observatory did not receive any worthwhile spell of rains. 2024 was the first instance in more than 40 years April did not see any rains at all. On 20th April parts of the city recorded light rains with only the AP observatory recording traces. On 3rd May the City observatory recorded 17 mm bringing much needed relief. But the AP observatory recorded at HAL Airport is still to see its first good spell of rains for the year.

Our post late March explained how April may be tough for Bengaluru based on history and model outlooks. This spell of dry weather coincided with a spell of hot summer as well for Bengaluru. The April 2024 average maximum temperature even beat the 2016 April records. 39.2°C recorded on 24th April 2016 at the city observatory continues to remain as the hottest recorded day. As they say when you are down the only way forward is to move up.

Thursday and Friday saw scattered rains around Bengaluru with Friday bringing more places under rains compared to Thursday. Yesterday did not see any rains in the vicinity of Bengaluru and surrounding areas of South Interior Karnataka. It is pertinent to point out with thunderstorms though it may rain daily under favourable conditions those rains happen at places which have mechanical advantage in addition to atmospheric support. For eg places along the Ghats may benefit from mechanical lift in the form of winds hitting against mountains. Bengaluru and surrounding areas does not have any such advantage. A few places along the AP / KA / TN border benefit from the broken Eastern Ghats providing this lift for summer thunderstorms.

Sub seasonal weather outlooks indicate the upcoming couple of weeks may see Peninsular India finally see an uptick in summer thunderstorms. Things are looking up for Bengaluru with a defining week of rains indicated by weather models. Favourable wind convergence over South Interior Karnataka for the next few days is expected to be Bengaluru’s lucky break. By Friday there is a very high possibility most parts of Bengaluru may accumulate up to 60 mm of rains. Depending on local conditions this may possibly go up to 80 mm in a few places as well.

South Interior Karnataka and adjoining areas of NW Interior TN may be one of the hotspots for rains the upcoming week. Parts of Nilgiris and adjoining North Coimbatore / Erode Ghats may be another hotspot. Similarly further south Pathanamthitta and Idukki dts along with some parts of South TN may be the 3rd hotspot for thunderstorms. The only bit of concern is Pollachi and Udumalaipettai belt may receive lesser than originally expected rains. Here is hoping Nature brings some rains and relief to the farmers there. With summer thunderstorms expected to peak either this week or next week it remains to be seen what could be the ideal onset window for Southwest Monsoon.

With this upcoming spell of rains Bengaluru can also effectively kiss good bye to its long drawn summer this year. Staying on the Heat theme starting from Wednesday most parts of Tamil Nadu can expect reduction in abnormally hot conditions. It is not yet time to say good bye to the 40s over places like Erode, Karur, Trichy etc though. A possible development of an upper air cyclonic circulation towards end of next week is something to look forward. This could potentially impact not only summer conditions but also bring rains to many parts of Peninsular India. Sub seasonal model outputs show cyclonic circulation is likely to influence rainfall pattern during 3rd week of May. A detailed post will be put up once there is clarity on events.

For Chennai hot and humid conditions is likely to continue. The next couple of days suburbs may continue to see around 40°C with temperature coming down from Wednesday. As far as rains are concerned there is nothing on the store immediately. Any change in fortune will need favourable wind pattern.