Decoding Mumbai's weather: Science behind forecasting and its complex challenges

Nestled on Indiarsquos western coast the bustling metropolis of Mumbai is known for its vibrancy fastpaced life and rains Therersquos a vast collection of media and literature that has romanticised Mumbai rains However whenever the city is lashed with heavy rains the challenges for the residents increase manifold as they have to deal with flooding public transport disruptions and massive traffic jamsSince flooding and traffic interruptions therefore precise weather forecasting is critical for the citys residents and infrastructureThe monsoon is caused by a seasonal reversal in wind patterns with moistureladen winds from the Indian Ocean blowing over the subcontinent Mumbai due to its unique geographical location is frequently subjected to heavy rainfall However predicting when and how these rains will fall is not a simple undertakingIt is an endeavour that requires advanced equipment intricate methodology and a thorough understanding of atmospheric dynamics The most important of them all are the scientists who analyse the data to present the most accurate forecast for the publicMiddaycom spoke to scientists of the India Meteorological Departmentrsquos regional centre in Mumbai to understand the process behind weather forecastingSpeaking to the newspaper Sunil Kamble director of IMD Mumbai said that the scientists keep monitoring the weather physically at threehour intervals as suggested by the World Meteorological Organisation Kamble added that additionally they receive data from automatic weather stations at 15minute intervalsldquoIn todayrsquos day and age almost all departments including aviation require weather forecasting In the Mumbai airportrsquos Air Traffic Control Room alone IMD has 80 officers who constantly monitor the cityrsquos weather The scientists donrsquot just analyse the readings obtained through the local tools to issue a forecast for Mumbai but also have to take into consideration the global weather conditions and what impact it will bear on the cityrdquo Kamble explainedHe added that the scientists also have to gauge the impact of weather systems across India and rely on the climatology of a particular area while issuing a forecastldquoEven when we issue a forecast it is a possibility and not an absolute factrdquo he chimedTechnologies in weather forecastingThe tools used in weather forecasting by the IMD are satellite imagery doppler radar systems automatic rain gauges and automatic weather stations Kamble said and added that apart from these tools the weather agency relies on radiation instruments ships and flightsSatellites orbiting the Earth give realtime information on cloud formations sea surface temperatures and atmospheric conditions These satellites transmit data to ground stations which meteorologists use to forecast rainfall storm systems and other weather occurrencesDoppler radar systems emit radio waves that bounce off raindrops providing precise information about the location intensity and movement of precipitation The information gathered allows meteorologists to forecast the commencement and severity of rainstorms allowing individuals and administrations time to prepareldquoSatelittes gives us nearly 3040 products images of which limited ones are shared with the public Meanwhile each Doppler radar covers an area of 500 km radius and gives a 360degree picture of the precipitation 40 such radars across India send snapshots every 10 minutesrdquo explained the IMD directorHe elucidated that the IMD keeps receiving information on weather updates from all airports across India Similarly the ships have meteorological devices like barometers amp anemometers and information recorded by these devices is received by scientists at the weather agency and used while forecasting the cityrsquos weatherldquoWe at IMD also release four balloons every dayndashonce in the morning and one in the eveningndashto get recordings of the upper air weather The balloons go up to 3540 km high Across India 60 such balloons are releasedrdquo Kamble explainedAnother scientist working at the IMD elaborating on it said that these balloons are attached to instruments that record weather patterns such as ridges troughs upper air disturbances and upper lowsKamble responding to a query said that these tools are used 24x7 through all seasonsWeather models in forecastingThe scientists explained that after collecting the data they use different weather modelsndashwhich are based on complicated mathematical equations that represent the mechanics of the atmosphere including temperature humidity wind speed and pressurendashto arrive at a forecast that aligns with prevalent weather systemsThe scientists explained that after collecting the data they utilise various weather models These models are grounded in complex mathematical equations that stimulate atmospheric mechanics factoring in elements like temperature humidity wind speed and pressure By doing so they can generate forecasts that accurately reflect the prevailing weather systemsCertain wellknown weather models such as NOAAs Global Forecast System GFS provide longrange global forecasts up to 16 days in advance The GFS is updated every six hours ensuring that the predictions remain current and accurateThe European Centre for MediumRange Weather Forecasts ECMWF model is renowned for its accuracy in mediumrange forecasting It employs an ensemble approach which enhances the reliability of its predictions Meanwhile the highly customisable Weather Research and Forecasting WRF model is widely used for regional forecasting and for predicting specific phenomena such as hurricanesOther models such as the UK Met Offices Unified Model UM provide detailed shortrange forecasts notably for the UK Meanwhile the HighResolution Rapid Refresh HRRR model focuses on shortterm highresolution forecasts which are important for severe weather occurrences in the United StatesLongterm projections are backed by models such as the Climate Forecast System CFS which makes seasonal predictions Ensemble Prediction Systems EPS and NAVDAS improve forecasting accuracy by taking into account a wide variety of possible weather events resulting in reliable global and regional forecastsChallenges in forecasting Mumbairsquos weatherAlthough the technology of weather forecasting is advanced in India and at par with global standards Kamble noted there are certain limitations in forecasting Mumbairsquos weatherldquoMumbai is a reclaimed city and there are several lowlying areas which flood easily It becomes crucial for the IMD to provide impactbased forecast to different agencies like the disaster management agency to alert themrdquo said Kamble and added ldquohowever giving accurate localised weather forecast is not possiblerdquoThe IMD official said that the microclimates in Mumbai cause considerable differences in weather over short distances making it difficult to provide accurate citywide forecasts For instance one part of the city may have severe rainfall while another may remain relatively dryldquoIn such cases it is very difficult to convince the people about the accuracy of the forecast The public often questions the accuracy of our forecast if they donrsquot experience rain outside their homes and it is one of the challenges before usrdquo said KambleWhile El Nintildeo and La Nintildea eventsndashwhich modify sea surface temperatures and wind patternsndashcause Indian monsoon to be highly unpredictable the issue has been exacerbated by climate changeWhen asked about the impact of climate change and global warming which has escalated to global heating Kamble said that extreme weather events have increased due to the phenomenon He added that climate change and global heating have also led to an increase in the frequency of cyclones and caused changes in the monsoon patternsldquoEarlier the coastal area saw a cyclone once in three years however off lately the frequency has increased The region now sees a cyclone every year additionally the heatwave days have also gone up This year Mumbai witnessed at least four days of heatwave conditions wherein temperature went above 37 degrees Celcius Every city has a set temperature range which is suitable for the residents For coastal regions like Mumbai temperatures soar above 37 degrees C translates to heatwave conditionrdquo the IMD official explainedldquoMumbairsquos monsoon pattern has changed For instance this year we have already received 2200 mm of rainfall Mumbai on average receives 2300 mm of rainfall throughout the four months of monsoon We already have received 550 mm of excess rainfall and most of the rainfall happened during nighttime With monsoon patterns changing longterm forecasting becomes a challengerdquo he notedAdditionally there is a data limitation said the scientist highlighting that there are some areas where they donrsquot have weather stationsndashautomatic or physicalThe scientists also said that with the advent of social media misinformation based on weather is circulated without verification There have been instances wherein people have used old products satellite images and shared misinformation regarding prevailing weather conditions which cause panic among the publicrdquo explained the senior officialThe path aheadDespite the challenges the IMD officials say their monsoon prediction is at least 85 per cent accurateThe IMD is trying to expand our observational network with the installation of additional AWS automatic weather stations Expanding the observational network will give the department access to more data which will help in bettering the accuracy of the forecast the official notedMeanwhile the Met department the officials said issues Nowcast which upgrades their forecast every three hours ldquoNowcast allows us to upgrade and downgrade alerts based on the prevalent weather systemsrdquo said Kamble