Hazy forecasts and how to improve them
2024-10-14
FOR a particular generation of Pakistanis, who grew up listening to weather reports broadcast on Radio Pakistan or PTV`s 9pm Khabarnama, the Malakand Division must have seemed like one of the wettest places on earth.
After all, where else would you find `garaj chamak ke saath baarish ka imkaan` (chances of rain and thunderstorms), day in and day out? The reality, as those who live in the area or have visited it frequently know, is quite different, and those predictions of yore now sound like educated guesses rather than scientific forecasts.
Being sceptical about the Met Office`s predictions has become almost second nature to Pakistanis.
Most have rationalised their allweather cynicism in two ways; either the country`s weather cycles are so unpredictable that they defy all attempts at forecasting, or, thePakistanMeteorologicalDepartment (PMD) lacks the ability to accurately predict the weather.
Guided by gut instinct There are several citizens whosebread and butter is intrinsically linked with an ability to tell what the weather will be like.
Marwan Khan, a Charsadda-based farmer, has been unable to prepare his fields for sugarcane season. Lastyear, he incurred substantial losses due to unpredictable rains, which washed away fertiliser that was essential to his crops, snatching away all their nutrients from the soil.
According to Mr Khan, sugarcane is usually planted in August. But this time, the weather was unfavourable.
`I check all the apps and official forecasts, but none are accurate enough for me to plan my planting and harvesting dates,` he says.
These uncertainties have forced farmers to rely on their own gut harkening back to the old days, before long-range weather radar was a thing.
`Our farmers observe the clouds and make decisions on their own instead of solely relying on official forecasts from the ME T Department, because they are almost always wrong,` says Akram Khaskheli, president of the HariWelfare Association.
Mr Khaskheli is unequivocal; accurate weather predictions would be a significant blessing for people in his line of work. `For example, if weknow that rain is expected on a particular day, we can harvest crops like cotton beforehand, as wet cotton loses its quality,` he explains.
He also notes that this uncertainty has led many-a farmer to harvest his crop prematurely.
Fishermen are also affected by inaccurateforecasts.
Majeed Motani, president of the Karachi Fisherfolk Forum, says that his community has taken a hit from emerging weather patterns; with several fishermen losing their lives and boats during cyclones in recent years.
Their faith in the official weather forecasting system has effectively evaporated.
The question remains: what, if anything, is the PMD doing wrong? Predictive puzzles The PMD weather observation network consists of 195 stations at 110 locations, some of whom are over a century old. Of these, 110 are manual observation centres, while 45 are Automatic Weather Stations (AWS).
In addition to these, PMD has four radars, but only two are functional Karachi and Islamabad.
Atif Hassan, a meteorological assistant at a manual weather observation centre near Karachi`s Jinnah International Airport, takes four daily temperature readings from instruments such as wet and dry bulb thermometers.
At the centre, which was built in 1928, these devices are placed inside an insulated box with gaps for air circulation. This allows him to record maximum and minimum temperatures, the current temperature, dew point, and relative humidity before sunrise and sunset.
Rainfall is measured with a rain gauge typically every three hours, and at hourly intervals during heavy downpour. All instruments are placed on uncemented ground to avoid heat absorption from affecting the readings.
A barometer on the roof of the centre measures air pressure: low pressure indicates rain and high pressure suggests dry/hot weather.
A sunshine recorder, consisting of a glass ball that burns a paper strip placed beneath it using focused sunlight, tells Mr Hassan the duration of sunshine in that day. He also has a wind vane, which indicates wind direction, and an anemometer that measures wind speed.
The readings taken by Mr Hassan are then uploaded into a software, used by PMD to transmit readings from the observation stations to the forecasters stationed at their main office.
`In a densely populated metropolis like Karachi, the World Meteorological Organisation (WMO) requires weather observation stations to be set up every 50kms,` MrHassan tells Dawn.
Karachi`s five weather stations, located miles from each other, are quite a ways off the standards set by the global authority. Two of them are located near the airport, while there is one each in PAF Masroor Base, Keamari and Gulistan-i-Johar.
Due to this sparse network, predicting rapidly developing weather phenomena like cloudbursts is a major challenge. To mitigate this, the department relies on radar data for short-range weather predictions and warnings of potential calamities, such as thunderstorms or tsunamis, Mr Hassan explains.
Observations from the five weather stations do not provide sufficient data to predict the sprawlingmetropolis` weather, admits Anjum Nazir, a senior officer at the PMD`s Early Warning Centre.
Asked if the lack of data points was the reason for the inefficient forecasts, he says: `On ground weather stations` readings are not the only ones we use to predict the next day`s weather.
Elements of a forecast To draw up a forecast, a forecaster has four different reports at their disposal.
The Aircraft Meteorological Data Report (AMDAR) tells forecasters about the weather in the upper reaches of the atmosphere.
These observations are obtained using sensors carried by commercial aircraft, which land at airports across Pakistan.
A Meteorological Aerodrome Report (METAR) is generated internationally every 30 minutes, and domestically every hour. It tells forecasters the visibility, cloud position, temperature and dew point in an area. Based on the readings in these reports, a weather trend can be drawn up.
The Significant Meteorological Warning (SIGMET) report, which is issued by the WMO. The report is primarily meant for aircraft pilots and gives them updates on what the weather would be en route to their destination, or warns them about other phenomena that may have an impact on the safety of their aircraft.
A Terminal Area Forecast (TAF), which is a message in adefined format, reports the weather forecast for a single airport and its immediate vicinity. These reports are generated four times a day and are valid for 24 hours. The message is generated by the International Civil Aviation Organisation (ICAO) based on information it receives from its Flight Information Regions (FIR), located around the world. In Pakistan, these regions are located in Karachi and Lahore.
Armed with readings from the 110 local MET observation centres, satellite images and reports, weather models, surface charts of weather from 5,000ft to 10,000ft above sea level, as well as other data, a team of forecasters can draw up weather predictions for next day, month and season.
`We collaborate with departments in different cities before drawing up forecasts; it is a long, tiresome process,` Mr Nazir says.
He acknowledges gaps in weather station coverage in Sindh and Balochistan, but notes that a World Bankfunded project is underway to install AWS at the tehsil level across Pakistan, which expected to take five years.
Meanwhile, he says, the current system is `good enough.` But is it really? Lack of resources A quick look at the PMD website yields vague `now-casts` and shortterm forecasts three-day predictions that lack specificity. They just tell you if the weather is going to be sunny, or rainy.One may be tempted to give them the benefit of the doubt, given Pakistan`s tropical location and erratic weather changes. But neighbouring India, which has similar geographical conditions, provides far more detailed forecasts.
When asked inquired why India is able to issue better forecasts, PMD`s Chief Meteorologist Dr Sardar Sarfaraz attributed this to their use of far superior technology.
He explained that Pakistan`s meteorological network was quite limited.
International standards dictate that there should be at least 353 weather stations in different locations for a country of Pakistan`s size, as opposed to the 110 currently in place.
Furthermore, while India operates its own weather observation satellites, Pakistan relies on the satellites of neighbouring countries.
Addressing the absence of an effective local weather model, Dr Sarfaraz says that the department, with the help of a World Bank soft loan, will soon acquire the muchneeded supercomputers required to make these mammoth calculations.
`Hopefully, after that, we can develop our own weather model,` he said.
However, as the department struggles to equip itself with the necessary technology a process that officials say could take around half a decade social media-savvy citizens have turned towards private weather channels, whose forecasts often do not line up with the PMD`s predictions.
One Karachi-based journalist says she usually goes by Pak_Weather, a private channel, for everyday updates and finds it to be far more reliable. Several other people Dawn spoke to expressed similar views.
The PMD, however, views these newcomers with suspicion, saying that they do nothing but `spread panic amongst people because that is the only way they can get attention to generate money for running their operations`.
`Their machines are placed on top of buildings, whose height can impact the readings. Who knows if they are up to the standards [set] by the World Meteorological Organisation (WMO),` Mr Nazir wonders.
`PMD, on the other hand, has to calibrate their machines every six months and comply with international standards.
He adds that private weather stations mostly depend on international forecasting websites, combining them with their on-ground observations based on data from one or two individual AWS.
`If we stop providing ground data to the WMO, the international websites won`t get Pakistan`s data,` Mr Nazir says, emphasising that at the end of the day, the private channels also rely on data from the PMD.
Private forecasting solutions Junaid Yamin, who runs Weatherwalay, another local private weather channel, says that his company`s raison d`être was a lack of trust in PMD and the need for better forecasts.
`We realised very soon that themain reason for the inaccuracy was a lack of data points,` Mr Yamin told Dawn, explaining that to address this issue, the company has installed more than 250 AWS across Pakistan.
When asked if the placement of these instruments on the rooftops of buildings affected the reliability of their readings, Weatherwalay forecaster Faizan Khan says the systems are built with the ability to overcome possible errors.
Once the data is recorded, it is syncedtothe cloudusedbyforecasters in their main station, in Islamabad.
At their headquarters, a team of forecasters analyses the on-ground weather conditions, comparing them with past weather patterns, looking at international numerical weather model predictions, satellite imagery and weather charts.
They then draw up short-range forecasts that predict the weather for 24 hours; mid-range forecasts that cover the next 10 days; longrangeforecastsforthenext15 to30 days; and, extended-range forecaststhatlookupto42daysahead.
`We have achieved almost 90pc accuracy in now-casting and shortterm weather forecasting and are working towards improving our mid-range and long-range forecasts,` he says.
However, Mr Yamin notes that around the world, forecast accuracy halves for every 10 days, the further you go.
Mr Khan concurs, adding that their inability to maintain 90pc accuracy with now-casts and shortrange forecasts is due to a lack of sufficient AWS around Pakistan.
In Karachi, Weatherwalay has 10 AWS located in Bahria Town, Gulshan-i-Iqbal, Gadap Town, Airport, Malir, Gulshan-i-Hadeed, PIB Colony, Keamari, Korangi, and North Karachi. `But in a densely populated city like Karachi, we need at least 50-60 such stations to provide an accurate picture,` Khan said.
Mr Yamin also mentions that the company has a long way to go. `In the first stage, we divided Pakistaninto 600 climate zones, each of which requires an AWS, based on topography.
With almost 300 AWS nationwide, Mr Yamin claims they are already predicting weather better than the PMD, but admits that challenges remain.
`The lack of network infrastructure makes it difficult to get data from Balochistan, which is a virtual `black hole` in our forecasts.
He also says that without mobile network coverage, data transmission from centres to the head office becomes a challenge. A similar issue exists in the country`s northern areas, where frequent electricity outages and internet disruptions hinder data-syncing from the AWS, delaying forecasts.
No weather model Another major challenge is the absence of a dedicated weather model for Pakistan.
`Currently, we use international models that are downscaled to understand Pakistan`s weather conditions,` Mr Yamin says.
However, these models are not calibrated with Pakistan`s data, nor are international agencies pushed to make the adjustment. `They aren`t interested because updating these models requires a significant amount of money, and the returns from Pakistan wouldn`t be profitable enough,` he notes.
In his view, predictions made using these models are only 40pc accurate, due to a lack of detailed information on Pakistan`s topography, climate conditions and current weather conditions.
`For now, we need to get Pakistan`s data calibrated into an international model, but in the long run, we need our own weather model,` Mr Yamin says. `A local weather model could include the smallest of details, each of which would help improve the accuracy of predictions.
Mr Yamin admits that they faced challenges initially. `PMD always had a monopoly over forecasting.
When we entered the market, there were many reservations from them.
However, with time, relations have improved, and now the company collaborates with government departments like PMD and the National Disaster Management Authority (NDMA).
`Pakistan is the world`s sixth most vulnerable country to climate change, and the absence of spring and autumn seasons is proof of its impact,` he warns.
`The weather in the coming years will become more erratic, making it essential for us to have the capability to predict it in advance and prepare for the disasters it may bring, he concludes.
All maps by Dawn Creative, Dawn GIS A detailed version of this article can be accessed on Dawn.com