You are here
Home > Tech > Tech Talk > That’s how you get your weather forecast…

That’s how you get your weather forecast…

In chapter-4 of the book ‘Three men on a boat’- Jerome K Jerome lamented about weather forecast.

In his unparallel sarcastic tones, he wrote-“I do think that, of all the silly, irritating tomfoolishness by which we are plagued, this “weather-forecast” fraud is about the most aggravating. It “forecasts” precisely what happened yesterday or the day before, and precisely the opposite of what is going to happen to-day.”

Then he went on giving few examples of times when the weather that came seemed to be a day late. Jerome wrote this novel in the 1880s in England. Things have obviously changed now. With processing of insanely large amount of atmosphere data gathered across the world, the weather forecasts have become precise and accurate. Now if weather forecast says, it’s going to rain, then it’s actually going to rain.

The weather forecasts of Bangladesh Meteorological Department (BMD) have also become precise and reliable. In December 27, 2016, the BMD officially launched its app to give people a regular update on weather.

The BMD Weather App, available on Google Play Store, is connected to automatic weather machines installed at 42 spots across the country. Updates on air temperature, pressure and rain can be availed instantly through the app.

The app also sends alerts on cyclones, earthquakes, cold waves and droughts to users. Weekend Tribune visited the BMD headquarter to learn how the weather forecasts are actually being made.

It’s workhouse

Interestingly, the very office premise of BMD in Agargaon is not like other government establishments. Yes, the old administrative building still has that age old furniture and the stereotypical scenery of a middle-aged clerk nonchalantly reading newspapers but if someone enters the operational office premise, he/she would get the vibe that “real work” is being done here.

The weather forecast that we see round the clock on TVs and radios and now in the mobile app are produced in BMD with thorough rigorous calculation and diversified methodologies.

We found meteorologist Rashed-uz-Zaman, who was in charge of the forecast centre on the day of our visit, busy analysing a pile of paperwork, schematic diagrams and outputs from particular software and plotting his observation and analysis in a large forecasting sheets.

“We need to send and analyse data every hour and send the results in different places. We, in the BMD work 24/7 in three shifts. From 8am-2pm, 2pm-8pm and 8pm-2am.

There is hardly any time to rest,” said Rashed-uz-Zaman.

How the forecast is produced

The operational office of the BMD does all sorts of weather forecasting including the daily forecast.

The BMD has a total of 42 weather stations across the country. These are all manual stations which are run through manual observation.

Explaining manual observation, Zaman said that there are a numbers of observers who read weather measuring instruments like thermometer, barometers, anemometers, rain gauges and wind speed gauges in cyclic manner in every three hours.

Data including temperature, wind pressure, and humidity is collected with these measuring instruments. These are all synoptic data or surface data. In 24 hours, these data are collected eight times.

The 42 manual stations also observe the times of sunrise and sunset. It also records the maximum and minimum of the measurements. The data observed and collected from those weather forecasting instruments are sent back to the BMD headquarters in Dhaka.

Zaman said that apart from surface data, the BMD also conducts pilot balloon observation. “We have ten weather observation balloons in ten of those weather observation stations. From pilot balloons, we get wind speed and directions.”

He said that there are three stations from where the BMD gets Radio Sounding Observations (RSO). “We use special balloons with transmitters there. The transmitter receives and cross matches data through GPS satellite.”

Data analysis process

The data received from the RSO balloons includes wind speed, geo-potential height and temperature of the higher surface. Zaman explains that the first existence of any weather formation is found in the atmospheric height, then it gradually shifts down to the surface level. That’s why the condition at the upper surface is important and all meteorological departments need to profile that.

“For example, if there was an approaching cyclone, our observation station would first locate it at the upper atmosphere, then it gradually comes down to the surface. If we can’t plot that cyclone at the upper surface then we cannot provide warning in time.”

He said that the BMD cannot predict weather and create a forecast just by collecting surface data from their observation centres because weather doesn’t form by maintaining geographical boundaries. “We have to consider the condition in the surrounding areas of our neighbouring countries. For accurately measuring the weather and creating a forecast, we need data from India, Myanmar and the Gulf region and we also do that.”

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.