Hot October, El Niño fears: Is Mumbai in for a weather shock?

The unpredictability of the seasons has left Mumbaikars on edge With an erratic monsoon behind us and a warm October underway alarming labels such as lsquoSuper El Ninorsquo lsquoMonster El Ninorsquo and lsquoGodzilla El Ninorsquo have added to concerns However meteorologists caution against the hype explaining what the phenomenon means for India Maharashtra and MumbaiWho let El Nino outThe Pacific Ocean thousands of kilometres away plays a major role in shaping global weather patterns Changes in seasurface temperatures and atmospheric circulation in the tropical Pacific form part of the El NinoSouthern Oscillation ENSO a naturally occurring climate patternRepresentation picistockThe World Meteorological Organization WMO identifies El Nino as the warm phase of ENSO and La Nina as its cool phase The pattern recurs cyclically typically every two to seven years while the Oceanic Nino Index ONI helps measure the strength of El NinoThis year the WMO expects El Nino to intensify towards a peak around December However forecasts are probabilistic and the eventual strength and duration of the event remain uncertain Athreya Shetty an independent meteorologist believes labels such as lsquoSuperrsquo lsquoMonsterrsquo and lsquoGodzillarsquo El Nino are an overreachldquoThese phenomena are usually classified as weak moderate strong or very strong We have seen this type of a very strong El Nino shape up in the 1970s 2015 and we are experiencing such a year again These high temperatures have to hold for a few months for us to call it anything resembling lsquosuperrsquordquo he saidAthreya Shetty independent meteorologistRushikesh Agre another independent meteorologist explained that the ONI uses threemonth average seasurface temperature anomalies in the Nino 34 region of the Pacific to assess ENSO conditionsldquoThese indices use the same part of the Pacific Ocean to create a mean of temperatures over time that help with the forecasts While they help calculate the impact and intensity of El Nino they too are evolving This forecast model is a probability and is not the reality so one can think of weather forecasts like the stock market it constantly changes shape and isnrsquot accurate all the timerdquo said AgreShould India worryEl Nino is associated with an increased risk of belownormal southwest monsoon rainfall in India but it does not determine the outcome on its own Experts say its influence also depends on other atmospheric and oceanic conditionsRajesh Kapadia independent meteorologist who runs the Vagaries of the Weather blogldquoThe intensity of El Nino is a crucial climate factor but it isnrsquot everything While El Nino does bring about a droughtlike pattern for Maharashtra as it did in 1972 and 2015 it is not the only controlling factor that impacts the intensity of the droughtrdquo said Dr Akshay Deoras senior research scientist at the University of Reading UKDeoras said prolonged dry spells during the monsoon can worsen drought conditions by affecting groundwater recharge and crops ldquoWhen a monsoon day records less than 25 mm of daily rainfall we call it a dry day This year South and Central Maharashtra recorded 59 days in a row where the daily rain was less than 25 mm We saw longer dry spells in 2018 2015 and 1972 but the spatial distribution of such dry spells is broader this year compared to 2018rdquo he saidBikram Singh head of the IMDrsquos Regional Meteorological CentreOther factors also influence the monsoon These include the MaddenJulian Oscillation MJO an eastwardmoving pattern of tropical atmospheric activity and the Indian Ocean Dipole IOD which measures seasurface temperature differences across parts of the Indian Ocean Their interactions with El Nino can strengthen or offset its influenceDoes El Nino always mean droughtNo El Nino does not cause deficient rainfall uniformly across the country or even within Maharashtra Local geography and the distribution of rainfall can produce sharply different outcomesDr Akshay Deoras senior research scientist at the University of Reading UKldquoThis year for instance Mahabaleshwar received nearly 6442 mm of rainfall and Tamhini Ghat received nearly 9311 mm of rain due to the sheer geography of Maharashtra While Santacruz Mumbai and Goa all lie at the coast Mumbai received adequate rain but Goa was in a 48 per cent deficitrdquo said Rajesh Kapadia an independent meteorologist who runs the blog Vagaries of the WeatherKapadia said rainfall forecasts must account for several interacting climate drivers including ENSO in the Pacific and the IOD in the Indian Ocean The same Nino 34 readings can coincide with different monsoon conditions making it unreliable to base a forecast on a single indexClimate crisis mdash yay or nayEl Nino is a natural phenomenon but it operates against a backdrop of longterm global warming Experts caution against confusing the twoRushikesh Agre independent meteorologistldquoThe warming of the Pacific Ocean is a normal phenomenon and we donrsquot have any proof to say that El Nino has become more frequent than before However the ocean temperatures have grown higher owing to global warming which may lead us to feel the pinch some morerdquo said ShettyEl Nino can shift rainfall and temperature patterns increasing drought risks in some regions while contributing to excessive rainfall in others Higher background temperatures can further aggravate heat stress However individual impacts cannot be attributed to El Nino aloneFor Mumbai water availability remains a concern after the uneven distribution of monsoon rainfall The city is currently facing a 10 per cent water cut while Mayor Ritu Tawade has warned that El Nino could add to the pressure on supplies Agre said rising temperatures could increase evaporation from reservoirs and catchments adding to the citys watermanagement challengesldquoWe may have to observe a cut down on construction and infrastructure sites too given the current water status The high El Nino temperatures may even lead to higher evaporation across the citys catchmentsrdquo he said Any restrictions on construction or other water users would however depend on decisions by the authorities and the prevailing water situationWhat about winterWith El Nino expected to intensify towards the end of the year questions have emerged about its potential impact on winter Experts say warmer conditions are possible but a warmer winter is not guaranteedldquoWestern disturbances in North India lead to colder winters However these disturbances need to have gaps between them for the cold to actually travel southwards This year we may see a shorter winter with fewer colder spells in Mumbai lasting for a few days each over November and Decemberrdquo Shetty saidMeteorologists caution that the current El Nino forecast is not enough to predict the 2027 monsoon A more meaningful assessment will be possible closer to the season with the first broad outlook expected around April or May next yearEl Nino drought and MaharashtraMaharashtra has declared drought conditions in 305 of its 358 talukas with affected areas spanning Marathwada and other regionsAlthough the states overall rainfall has been within normal limits at certain points its uneven temporal and spatial distribution has left several areas facing water stressldquoOver the 17 weeks of monsoon we only had five to six weeks of normal or excessive rainfall All the other weeks recorded a deficit This leads to a lot of surface runoff and the water catchment areas are not properly rechargedThe streams dry up faster and Mumbai lakes though filled adequately deplete fast too if normal water supply is providedrdquo said Bikram Singh head of the IMDs Regional Meteorological CentreSingh warned that January to May 2027 could be difficult for water availability with potential consequences for drinking water agriculture and hydropower generation The IMDs forecasts and reservoir levels will be crucial in assessing the scale of water stress over the coming monthsShould India worryEl Nino is associated with an increased risk of belownormal southwest monsoon rainfall in India but it does not determine the outcome on its own Experts say its influence also depends on other atmospheric and oceanic conditions ldquoThe intensity of El Nino is a crucial climate factor but it isnrsquot everything While El Nino does bring about a droughtlike pattern for Maharashtra as it did in 1972 and 2015 it is not the only controlling factor that impacts the intensity of the droughtrdquo said Dr Akshay Deoras senior research scientist at the University of Reading UK Deoras said prolonged dry spells during the monsoon can worsen drought conditions by affecting groundwater recharge and crops