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The Philippine Atmospheric Geophysical and Astronomical Services Administration (PAGASA) is the top source of information whenever weather disturbances threaten the country.
Aside from providing various weather data such as the 24-hour public weather forecasts, weather bulletins, farm weather forecasts, and shipping forecasts, the bureau also offers live broadcast reports for different media outlets.
The busiest days at the PAGASA office is when a tropical cyclone threatens the country. Through constant monitoring, PAGASA is able to disseminate weather updates—a must in ensuring public safety.
These updates are not all real-time; some of them come in the form of weather forecasts, which predict the different aspects of the tropical cyclone—its wind speeds, gustiness, track, and location among others. Weather forecasts are important as they allow different sectors of society, such as the government, private sectors and the general public, to prepare for disaster mitigation and management.
If forecasts are all about anticipating the cyclone’s movement, how then are they made? To learn how weather experts gather and interpret information, we go behind the scenes, right at the heart of the action.

Collective effort
PAGASA

Fortunetellers use cards, crystal balls, and palm lines to predict the future. In PAGASA’s case, a scientific-based approach is needed in creating weather forecasts.

WEATHER FORECASTING

Assessment of past conditions. Because history is a great teacher, forecasters first analyze past weather conditions. To pinpoint any developments, atmospheric models, data and climatological records are compared to current weather conditions. Climatological data, which is updated every ten years, refers to the average data based on a 30-year period.

PAGASA_CADA

Assessment of the current weather situation. Before PAGASA can look into the future, forecasters have to fully understand the “initial condition,” which refers to present weather conditions.
Prediction of the atmospheric state. By assessing past and current weather conditions, forecasters can now give an approximation of future weather conditions by applying the laws of Physics and using the Numerical Weather Prediction (NWP) models, a computer program where outputs consist of different weather parameters often used as guidance in forecasting.

PAGASA_FORECASTERS

Because the projected results are numerous, brainstorming sessions take place among the typhoon forecasters, regular forecasters and senior forecaster.
For every tropical cyclone, there are two typhoon forecasters working for 13 hours (one-day shift and one-night shift). By focusing on the tropical cyclone, the forecasters are able to deliver weather bulletins and shipping warnings.
Data is carefully weighed to come up with the most accurate weather forecast.

Observation. Data from 58 synoptic stations, including the Automatic Weather Station (AWS), satellites and radars, are transmitted to the central office through SMS phone, fax, internet, radio phone and Global Telecommunication System (GTS).

Plotting and analysis of weather data and Climatological records. Gathered data are plotted into maps, using symbols and numbers for analysis. During this stage, available climatological data are compared to predict future weather scenarios.

Modeling. For a deeper analysis, data from models like the Global Spectral Model (GSM), Navy Global Environmental Model (NAVGEM), Weather and Research Forecasting (WRF) and Consortium for Small-scale Modeling (COSMO) are used to compare with all the data on hand.

COLLAGE_PLOTTING

With all the plotted and compared data on hand, brainstorming will now take place among the typhoon forecaster, regular forecasters and senior forecaster before finalizing the output.
Through the use of gathered and computed data, plus the experience of forecasters, a weather forecast that is nearly accurate is served.

Forecasts and warnings are finalized. After the final assessment of all forecasters and upon the approval of the senior forecaster, weather forecasts and weather bulletins are established. The tropical cyclone’s location, strength, velocity, and the Public Storm Warning Signals are also integrated.

TROPICAL CYCLONE WARNING

Reports are posted. Before the final weather bulletins and forecasts are made public, the regular forecasters, typhoon forecaster and senior forecaster sign the documents. This is to confirm that every piece of information written is correct and based on all available data.

If a tropical cyclone is forecast to make a landfall, PAGASA will automatically hold a press conference. This is to inform the media about the scenarios expected over the weather disturbance. Press briefing is also done every six hours with the release of the weather bulletin. This is to update the media regarding its strength, location and speed.

We may not think much of it, but forecasts are a product of meticulous processes. Weather forecasts are gems, and must not be taken lightly. With all the literal storms we’ve weathered, we, Filipinos, know all too well how disaster preparedness can spell the difference between life and death.